TEMPORAL AND SPATIAL TRENDS OF
ATMOSPHERIC TOXIC SUBSTANCES NEAR THE
GREAT LAKES: IADN RESULTS THROUGH 2003
Integrated At
Depos
Ping Sun School of Public and Environmental Affairs and Department of Chemistry,
Indiana University
Ilora Basu School of Public and Environmental Affairs and Department of Chemistry,
Indiana University
Pierrette Blanchard
Environment Canada, 4905 Dufferin Street,
Toronto, Ontario M3H 5T4, Canada
Sean M. Backus
Environment Canada, 4905 Dufferin Street,
Toronto, Ontario M3H 5T4, Canada
Kenneth A. Brice
Air Quality Research Branch, Meteorological Service of Canada,
Environment Canada
Melissa L. Hulting
Great Lakes National Program Office,
U.S. Environmental Protection Agency
Ronald A. Kites
School of Public and Environmental Affairs and Department of Chemistry,
Indiana University
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Temporal and Spatial Trends of Atmospheric Toxic Substances near the Great Lakes:
IADN Results through 2003
Published by
Environment Canada and the United States Environmental Protection Agency
ISBN: 978-0-662-45561-5
Public Works and Government Services Canada Catalogue Number: Enl64-13/2007E
US EPA Report Number: 905-R-07-001
Report available in printed form from
Air Quality Research Branch
Environment Canada
4905 Dufferin Street
Toronto ON
M3H 5T4
Canada
Great Lakes National Program Office
U.S. Environmental Protection Agency
77 West Jackson Boulevard (G17-J)
Chicago IL
60604
U.S.A.
and in electronic form at
www.msc.ec.gc.ca/IADN/
www.epa.gov/glnpo/iadn/
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Table of Contents
1.0 Introduction 1
2.0 Method 1
2.1 Substances Considered 1
2.2 Sampling Sites and Data Range 2
2.3 Trend Analysis 3
3.0 Results and Discussion 3
3.1 ZPAHs 4
3.2 Total PCBs 7
3.3 OrganochlorinePesticides 8
3.3.1a-andy-HCHs 8
3.3.2 Total Endosulfans 10
3.3.3 Total Chlordanes 13
3.3.4TotalDDTs 14
3.3.5 Hexachlorobenzene (HCB) 19
4.0 Conclusions 19
Acknowledgements 21
References 22
Appendix A. Temporal and Spatial Trend Analysis Procedure 25
Appendix B. Annual Variation of Poly cyclic Aromatic Hydrocarbon Concentrations
in Precipitation Collected near the Great Lakes 29
Appendix C. Temporal Trends of Poly chlorinated Biphenyls (PCBs) in Precipitation
and Air at Chicago 48
Appendix D. Temporal and Spatial Trends of Organochlorine Pesticides in Great
Lakes Precipitation 64
Appendix E. Trends in Polycyclic Aromatic Hydrocarbon Concentrations in the
Great Lakes Atmosphere 88
Appendix F. Atmospheric Organochlorine Pesticide Concentrations near the Great
Lakes: Temporal and Spatial Trend 120
Appendix G. Temporal and Spatial Trends of Atmospheric Poly chlorinated Biphenyl
Concentrations near the Great Lakes 154
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List of Tables
Table 1. Data availability at IADN sites for this report 2
Table BSI. Fit parameters for PAH concentrations in precipitation at Brule River 44
Table BS2. Fit parameters for PAH concentrations in precipitation at Eagle Harbor 44
Table BS3. Fit parameters for PAH concentrations in precipitation at Sleeping Bear
Dunes 45
Table BS4. Fit parameters for PAH concentrations in precipitation at Sturgeon Point.. .45
Table BS5. Fit parameters for PAH concentrations in precipitation at Chicago 46
Table BS6. Fit parameters for PAH concentrations in precipitation at Burnt Island 46
Table BS7. Fit parameters for PAH concentrations in precipitation at Point Petre 47
Table CS1. Student's t-tesi results for the comparison of PCB concentrations between
Chicago and Sleeping Bear Dunes 62
Table DSL Chemical structures and properties of OC pesticides 82
Table DS2. Fit parameters for pesticide concentrations in precipitation at Brule River...83
Table DS3. Fit parameters for pesticide concentrations in precipitation at
Eagle Harbor 83
Table DS4. Fit parameters for pesticide concentrations in precipitation at Sleeping
Bear Dunes 84
Table DS5. Fit parameters for pesticide concentrations in precipitation at Sturgeon
Point 84
Table DS6. Fit parameters for pesticide concentrations in precipitation at Chicago 85
Table DS7. Fit parameters for pesticide concentrations in precipitation at Burnt Island..85
Table DS8. Fit parameters for pesticide concentrations in precipitation at Point Petre... 86
Table DS9. Range and Annual Mean Concentration (ng/L) of Selected
Organochlorine Pesticides in Precipitation from Various Studies 87
Table El. Half-lives (in years) of PAH concentrations in the vapor and particle
phases at seven sites near the Great Lakes 100
Table ESI. Fit parameters for PAHs in vapor phase at Brule River 107
Table ES2. Fit parameters for PAHs in vapor phase at Eagle Harbor 107
Table ES3. Fit parameters for PAHs in vapor phase at Sleeping Bear Dunes 108
Table ES4. Fit parameters for PAHs in vapor phase at Sturgeon Point 108
Table ESS. Fit parameters for PAHs in vapor phase at Chicago 109
Table ES6. Fit parameters for PAHs in vapor phase at Burnt Island 109
Table ES7. Fit parameters for PAHs in vapor phase at Point Petre 110
Table ESS. Fit parameters for PAHs in particle phase at Brule River 110
Table ES9. Fit parameters for PAHs in particle phase at Eagle Harbor Ill
Table ES10. Fit parameters for PAHs in particle phase at Sleeping Bear Dunes Ill
Table ES11. Fit parameters for PAHs in particle phase at Sturgeon Point 112
Table ES12. Fit parameters for PAHs in particle phase at Chicago 112
Table ES13. Fit parameters for PAHs in particle phase at Burnt Island 113
Table ES14. Fit parameters for PAHs in particle phase at Point Petre 113
Table Fl. Half-lives (in years) of Selected OC Pesticides in the Gas and Particle
Phases at Seven IADN Sites 132
Table FS1. Method comparison between U.S. and Canadian sites 138
II
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Table FS2. Average Concentrations and Fit parameters for Pesticides in the Gas
Phase at Brule River 139
Table FS3. Average Concentrations and Fit parameters for Pesticides in the Gas
Phase at Eagle Harbor 139
Table FS4. Average Concentrations and Fit parameters for Pesticides in the Gas
Phase at Sleeping Bear Dunes 140
Table FS5. Average Concentrations and Fit parameters for Pesticides in the Gas
Phase at Sturgeon Point 140
Table FS6. Average Concentrations and Fit parameters for Pesticides in the Gas
Phase at Chicago 141
Table FS7. Average Concentrations and Fit parameters for Pesticides in the Gas
Phase at Burnt Island 141
Table FS8. Average Concentrations and Fit parameters for Pesticides in the Gas
Phase at Point Petre 142
Table FS9. Average Concentrations and Fit Parameters for Pesticides in the Particle
Phase at Brule River 142
Table FS10. Average Concentrations and Fit Parameters for Pesticides in the Particle
Phase at Eagle Harbor 143
Table FS11. Average Concentrations and Fit Parameters for Pesticides in the Particle
Phase at Sleeping Bear Dunes 143
Table FS12. Average Concentrations and Fit Parameters for Pesticides in the Particle
Phase at Sturgeon Point 144
Table FS13. Average Concentrations and Fit Parameters for Pesticides in the Particle
Phase at Chicago 144
Table FS14. Range and Mean Concentration (pg/m3) of Selected Organochlorine
Pesticides in the Gas Phase from Various Studies 145
Table Gl. Average Total PCB Concentrations, half-lives, Clausius-Clapeyron
slopes, and phase-transition energies at the seven IADN sites 165
Table GS1. Selected PCB congener concentrations, half-lives,
Clausius-Clapeyron slopes, and phase-transition energies at the seven IADN sites 170
III
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List of Figures
Figure 1. Maps of the Great Lakes indicating the seven IADN sites 2
Figure 2. Spatial and temporal trends of ZPAHs 5
Figure 3. Average ZPAH and suite PCB concentration at the seven IADN sampling
sites as a function of the population lining within a 25-km radius of the sampling site 6
Figure 4. Spatial and temporal trends of suite PCBs 9
Figure 5. Spatial and temporal trends of a-HCH 11
Figure 6. Spatial and temporal trends of y-HCH 12
Figure 7. Spatial and temporal trends of total endosulfans 15
Figure 8. Spatial and temporal trends of total chlordane 16
Figure 9. Spatial and temporal trends of total DDTs 17
Figure 10. Spatial and temporal trends of hexachlorobenzene 18
Figure Al. Example of a temporal trend analysis for vapor phase concentration 27
Figure A2. Example of a temporal trend analysis for particle phase concentration 27
Figure A3. Example of a temporal trend analysis for precipitation phase
concentrations 28
Figure B1. Phenanthrene, pyrene, retene, benzo[a]pyrene, and total PAH
concentrations in precipitation collected at seven IADN sites near the Great Lakes 41
Figure B2.Total PAH concentrations in precipitation at the seven IADN sites 42
Figure B3. Retene concentrations and the ratio between retene and total PAH
concentrations in precipitation collected at the five U. S. IADN sites 42
Figure Cl. ZPCB concentrations in precipitation and in the gas phase in Chicago and
at Sleeping Bear Dunes, Michigan 59
Figure C2. Long-term trend of ZPCB concentrations in precipitation and in the gas
phase at Chicago 60
Figure C3. PCB congener profiles measured in the gas phase at Chicago and at
Sleeping Bear Dunes, in precipitation at Chicago and at Sleeping Bear Dunes 61
Figure CS1. Temporal trends of wet deposition flux of PCBs in Chicago and
Sleeping Bear Dune 63
Figure Dl. Map of the Great Lakes indicating the sampling sites 75
Figure D2. Concentrations of a-HCH (top), P-HCH (middle), and y-HCH (bottom) in
precipitation collected from 1997 to 2003 at the seven IADN sites 76
Figure D3. Concentrations of endosulfans (a- plus p-endosulfan) in precipitation at
the seven IADN sites 77
Figure D4. Organochlorine pesticide concentrations in precipitation collected at seven
IADN sites near the Great Lakes 78
Figure El. Total PAH concentrations (EPAH) in air (vapor plus particle), vapor and
particle phases at seven IADN sites sequenced by the population living within a
25 km radius of the sampling site 101
Figure E2. Average ZPAH concentration at the seven IADN sampling sites as a
function of the population living within a 25-km radius of the sampling site 102
Figure E3. Average PAH profiles for the vapor and particle phases at Chicago and at
Point Petre 103
Figure E4. Temporal trends of vapor and particle phase EPAH concentrations at
Chicago and at Sleeping Bear Dunes 104
IV
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Figure ESI. Temporal trends of vapor-phase PAH concentrations at seven
IADN sites 114
Figure ES2. Temporal trends of particle-phase PAH concentrations at seven
IADN sites 116
Figure Fl. Concentrations of y-HCH and a-endosulfan in the gas-phase and particle-
phase at the seven IADN sites 133
Figure F2. Concentrations of a-HCH, P-HCH, and y-HCH in the gas-phase at the
five U.S. IADN sites 134
Figure F3. Concentrations of chlordanes (sum of a-, p-chlordane, and fram'-nonachlor)
and endosulfans (a- plus p-endosulfan) in the gas-phase at the seven IADN sites 135
Figure FS1. Temporal trends of gas-phase OC pesticide concentrations at seven
IADN sites 147
Figure FS2. Temporal trends of particle-phase OC pesticide concentrations at five
U.S. IADN sites 151
Figure Gl. Map of the Great Lakes indicating the six regionally representative
IADN sampling sites 166
Figure G2. Long-term trend of temperature corrected total PCB partial pressures
in the gas phase at the six regionally representative IADN sites 167
Figure G3. Correlation between average total PCB concentration and the local
population within a 25 km radius of the sampling site 168
Figure GS1. Long-term trends of PCB congener partial pressures in the gas phase
at seven IADN sites 172
V
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TEMPORAL AND SPATIAL TRENDS OF ATMOSPHERIC
TOXIC SUBSTANCES NEAR THE GREAT LAKES:
IADN RESULTS THROUGH 2003
1. Introduction
The Integrated Atmospheric Deposition Network (IADN) was established in 1990 to
monitor the persistent organic pollutants in air and precipitation in the Great Lakes region
(Hoff et al., 1996; Buehler and Kites, 2002). The objectives of this network are to acquire
quality-assured air and precipitation concentration measurements; determine atmospheric
loadings and trends of toxic organic chemicals to the Great Lakes; and determine the
sources of continuing input of toxic chemicals.
By maintaining a master station on each of the five Great Lakes and several satellite
stations near the Great Lakes, IADN is able to monitor regionally-representative
concentrations of toxic substances in gas, particle, and precipitation samples. Biennial
loading estimates have been produced for data from 1992 through 2000 to determine the
atmospheric deposition of toxic substances to the Great Lakes (Hoff et al., 1996;
Galarneau et al., 2000; Buehler, et al., 2002; Blanchard, et al., 2004). Technical
summaries, produced prior to past peer-reviews of the network, have presented temporal
and spatial trends of selected chemicals (U.S. EPA and Environmental Canada, 1997 and
2002). For the first time, this report presents comprehensive long-term temporal and
spatial trends of atmospheric toxic substances collected in the Great Lakes basin. This
report covers data from the early 1990s through 2003.
2. Method
2.1. Substances Considered
A subset of the substances measured at the IADN sites were used for temporal and spatial
trend analysis. These substances include individual polycyclic aromatic hydrocarbons
(PAHs): fluorene, phenanthrene, anthracene, fluoranthene, pyrene, retene,
benz[a]anthracene, triphenylene and chrysene (not resolved chromatographically,
counted as one compound), benzo[&]fluoranthene, benzo[&]fluoranthene, benzo[e]pyrene,
benzo[a]pyrene, indeno[7,2,3-cJ]pyrene, benzo[g/z/]perylene, dibenz[a,/z]anthracene, and
coronene as well as the total of sixteen of these PAHs expressed as ZPAH; a sum of 56
polychlorinated biphenyl (PCB) congeners and coeluting congener groups expressed as
"total PCB"; and the organochlorine pesticides aldrin, a-chlordane, y-chlordane, p,p'-
DDT, p,p'-DDD, p,p'-DDE, o,//-DDT, dieldrin, a-endosulfan, p-endosulfan, endrin,
heptachlor epoxide, hexachlorobenzene (HCB), a-, p-and y-hexachlorocyclohexane
(HCH), methoxychlor, and trans-nonachlor. The detailed temporal and spatial trends of
these substances can be found in the Appendix B to G. In this report, the temporal and
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spatial trends of ZPAH, total PCB, and severl organochlrine pesticides including a-, y-
HCH, total endosulfans, total chlordanes, total DDTs, and HCB are presented.
2.2. Sampling Sites and Data Availability
As shown in Figure 1, data considered in this report were obtained at the five IADN
master stations (Eagle Harbor, near Lake Superior; Sleeping Bear Dunes, near Lake
Michigan; Burnt Island, near Lake Huron; Sturgeon Point, near Lake Erie; and Point
Petre, near Lake Ontario) and two satellite stations (Brule River, near Lake Superior; and
Chicago, near Lake Michigan). The IADN website (www.msc.ec.gc.ca/iadn) provides
detailed information on these sites.
Figure 1. Map of the Great Lakes indicating the seven Atmospheric Integrated
Deposition Network (IADN) sampling sites.
The air samples have been collected for both vapor and particle phases. Measurements of
organic toxic substances in the vapor phase started at different time at these sites as
shown in Table 1. Because measurements of vapor phase PAHs at Burnt Island and Point
Petre were stopped in 1992 and resumed in 1997, only vapor phase data from January
1997 onward are reported for PAHs at these two sites.
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Table 1. Data availability at seven IADN sites for this report.
IADN site
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Chicago
Burnt Island
Point Petre
Vapor phase
Jan. 1996— Aug.2002
Nov. 1990— Dec.2003
Jan. 1992— Dec.2003
Dec.2001— Dec.2003
Jan. 1996— Dec.2003
Jan. 1997— Dec.2003
Jan. 1997— Dec.2003
Particle phase Precipitation
Oct. 1996— Dec. 2003 Mar. 1997— Dec. 2003
For the particle-phase samples, data from October 1996 to December 2003 were used
because U.S. particle phase samples collected before October 1996 were combined
monthly. No data are available for organochlorine pesticide concentrations in the particle
phase at the two Canadian sites. As for PCBs, the preliminary results from 1993 to 1995
showed that, although higher molecular weight PCB congeners tended to partition onto
the particle phase, the total PCB concentrations in the particle phase were about 5-10% of
the total PCBs in atmosphere; therefore measurements of particle-bound PCB
concentrations were stopped in 1997. Thus, no trend analysis was conducted for PCB
concentrations in particle phase.
Precipitation samples have been collected at several sites (e.g. Eagle Harbor, Sturgeon
Point) since 1991. However, the analytical method changed (Carlson et al., 2004) in
March of 1997 for the U.S. sites. To ensure data consistency, only data from March 1997
to December 2003 are used to conduct the temporal trend analysis for precipitation
samples at all seven IADN sites.
2.3. Trend Analysis
For vapor phase concentrations, a temporal trend analysis procedure adopted by Cortes et
al. (1998) was used. Details are provided in Appendix A but will be summarized briefly
here. The vapor phase concentrations of the organic substances (in pg/m3) were first
converted to partial pressures using the ideal gas law. These partial pressures were then
adjusted to a reference temperature (15°C). This procedure effectively "temperature-
corrects" the data so that temporal trends can be detected. The pressures are regressed
with time to ultimately determine the rate of increase or decrease of the air
concentrations. When the rate is statistically significant, they are converted to half-lives
(t\n, in years) which indicate the time when concentrations in the air will have dropped by
half. For concentrations in particle and precipitation, another procedure was used
(Carlson and Kites, 2005), whereby the concentrations are used directly to determine the
temporal trends.
3. Results and Discussion
The spatial and temporal trends of ZPAHs, total PCB, and organochlorine pesticides are
explained in detail in the papers listed in Appendix B to G. In the summary here, for
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selected chemicals, six-panel figures were produced where the top three box plots show
the spatial difference of the pollutant concentration in the vapor (in yellow), particle (in
gray), and precipitation phases (in blue) among seven IADN sites (see Figure 2 as
example). The boxes represent the 25th to 75th percentiles, the black lines in the boxes are
the medians and the red lines are the means. The two vertical lines outside each box
extend to the outliers representing the 10th and 90th percentiles; and outliers are shown as
the 5th and 95th percentiles. The small letter "a, b, c, d, e, f' on the top of each box
indicates the spatial trends of concentration. The site marked with "a" has the lowest
average concentration and increases with 'b", "c", "d" and so on. The sites with the same
letter have statistically the same concentrations on average. Half-lives, representing the
period of time necessary for the atmosperhic concentration to decrease by half, are
plotted in the bottom left panel. The maximum to minimum concentration ratio which
provides an indication of the seasonal variation is plotted in the bottom middle panel
while the dates at which concentrations peaked are plotted in the bottom right panel. The
horizontal lines in the bottom three figures represent the average (e.g. average half-life,
average ratio of maximum to minimum concentration, and the average date with
maximum concentration). The bar color codes are the same as in the top three panels.
3.1. ZPAHs
PAHs are a class of organic compounds that have attracted environmental and health
concerns. They are ubiquitous, persisting in the environment for months to years (Beak,
et al., 1991). Many PAHs are carcinogenic and/or mutagenic (Denissenko, et al., 1996).
PAHs can be formed from both natural and anthropogenic sources. Natural sources
include combustion in nature such as volcanic eruptions and forest and prairie fires
(Ebert, 1988). Major anthropogenic sources include incomplete combustion of fossil
fuels and other organic matter, oil refining, and many other industrial activities (Junk and
Ford, 1980).
Spatial and temporal trends of EPAHs are shown in Figure 2. The highest PAH
concentrations in the vapor, particle, and precipitation phases were all observed in
Chicago followed by the semi-urban site at Sturgeon Point. In the vapor phase, the
spatial trend of PAH concentrations is: Burnt Island < Eagle Harbor ~ Brule River ~
Point Petre < Sleeping Bear Dunes < Sturgeon Point « Chicago. In the particle phase,
the spatial trend of PAH concentrations is: Eagle Harbor < Burnt Island ~ Brule River ~
Sleeping Bear Dunes < Point Petre
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Total PAHs
Vapor-phase cone, (ng/m )
103
102 -
101 -
10° -
io-1
b b c
a • •
Half-lives (years)
Particle-phase cone, (ng/m ) Precip. cone. (ng/L)
102
10° -
ID
-2
Max to min ratios
10 -
8 -
6 -
4 -
2 -
n .
I
I
I
I
JT
1
I
103 -
102 -
10°
Jan
Nov-
Sep-
Jul-
May-
Mar-
Jan
Maximum dates
Figure 2. Spatial and temporal trends of ZPAHs. Yellow bars are the vapor phase, gray bars are the particle phase, and blue bars are
the precipitation phase. "a,b,c,d,e" in the box plots means the increasing trends of concentrations with "a" has the lowest
concentration. BI: Burnt Island; EH: Eagle Harbor; BR: Brule River; PP: Point Petre; SBD: Sleeping Bear Dunes; SP: Sturgeon Point:
Chi: Chicago.
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PAHs in and around Chicago are vehicle emissions, coal and natural gas combustion, and coke
production (Simcik et al., 1999). The second highest PAH concentrations we observed were at
Sturgeon Point, which is located 25 km south of the city of Buffalo, NY, and about 110,000
people live within a 25-km radius of this sampling site. At the other five sites, the lower
atmospheric PAH concentrations likely represent a background level in the Great Lakes basin.
105
00
E
104-
O
8 103
o
102-
PAHs,r2 =0.91
\
PCBs,r2=0.!
1Q6
Local population within 25-km radius
107
Figure 3. Average ZPAH and total PCB concentration at seven IADN sampling sites as a
function of the population living within a 25-km radius of the sampling site. The error bars are
standard errors. See Figure 2 for the description of the site abbreviation.
Long-term decreasing trends of ZPAH concentrations were observed at Chicago in all three
phases (Figure 2, bottom left panel). The half-lives were about 9 years in both vapor and particle
phases, about 3 years in the precipitation phase. At the other IADN sites, vapor phase ZPAH
concentrations showed significant, but slower long-term decreasing trends (>15 years). Particle-
phase ZPAH concentrations also declined slowly at the sites that were impacted by nearby cities
e.g. Sturgeon Point (near Buffalo) and Point Petre (near Toronto). Much of the decline of ZPAH
concentrations in Chicago could be the result of a commitment to cleaner air, including improved
petroleum fuels, automobile engines, and industrial pollution control technology. Regulations on
coke ovens in steel mills in the area (as well as steel facility shutdowns), mobile source diesel
regulations, and efforts to retrofit and replace bus fleets in the region could all have contributed
to decreasing PAH concentrations at this site. For example, the Clean Cities Program has
promoted the use of alternative fuels and alternative fuel vehicles to reduce air pollution from
motor vehicles since 1998. The diesel retrofit portion of the program involves installing devices
that lower emissions by over 90% on Chicago's bus fleet. These efforts on improving air quality
in Chicago may explain the continuous decrease of ZPAH concentrations in vapor, particle, and
precipitation phases.
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Seasonal variations of ZPAH concentrations were observed in the particle and precipitation
phases (Figure 2, bottom middle panel). The ratios between the highest concentrations in the
winter and the lowest concentrations in the summer are usually about 5, indicating the ZPAH
concentrations in the winter were much higher than those in the summer. There are many
reasons that may lead to increased particle and precipitation phase PAH concentrations in the
winter; these include lower atmospheric mixing heights (Bidleman et al., 1986), decreased
photolytic reactions in the atmosphere (Baek et al., 1991), and more emissions from domestic
space heating. This seasonal trend of ZPAH concentrations was further proved by the calculated
date when the concentration peaked, which is around the end of January for both particle and
precipitation samples at the IADN sites.
3.2. Total PCBs
PCBs are mixtures of up to 209 individual chlorinated compounds (known as congeners), which
have been used as coolants and lubricants in transformers, capacitors, and other electrical
equipment due to their good stablility. PCBs have been banned in the late seventies in the U.S.
because of their bio-accumlation and harmful health effects (U.S. EPA, 2006). In this report,
total PCB represents a suite of 56 PCB congeners monitored by IADN. Each congener
contributes more than 1% to the total PCB mass for at least one site monitored by IADN. The
lexicologically important congeners (PCB 77, 105, 108, 126, 128, 138, 156, 169, and 170) are
also included. The detailed list of congeners is available in the supporting information of
Appendix G.
Total PCB concentrations in the vapor phase samples collected at six regionally representative
IADN sites (e.g. average concentration of 60-230 pg/m3) near the Great Lakes were much lower
compared to Chicago (e.g. average 1300 pg/m3) as shown in Figure 4. The spatial difference of
total PCB concentration among these sites showed the industrial and urban influence on PCB
concentrations at Chicago and Sturgeon Point similarly to that observed for PAHs (see Figure 3).
For the total PCB concentrations in precipitation phase, our results showed that the total PCB
levels in precipitation at the remote sites in U.S. are close to the field blank levels. Therefore, we
only focused on total PCB concentrations in Chicago and used Sleeping Bear Dunes as a
background site. Much higher total PCB concentrations in the vapor phase and precipitation (7.1
±0.9 ng/L) at Chicago compared to Sleeping Bear Dunes (1.1 ±0.1 ng/L) re-iterates the fact that
Chicago is a source of PCB to the atmosphere.
The long-term temporal trends of selected PCB congeners at these IADN sites are given in
Appendix G. As for the long-term temporal trends of total PCB, Brule River had a negative half-
life indicating an increase as a function of time. Given that the data for the Brule River site
covered only 6 years, we do not consider these trends reliable. For all remaining IADN sites, the
overall slower decline or no significant trend of total PCB concentrations near Lakes Superior
and Huron may be due to the colder water temperatures and larger volumes of these lakes. For
total PCBs at Sturgeon Point near Lake Erie, half-life was on the order of-20 years. This slower
rate of decrease for PCB concentrations in recent years at Sturgeon Point may indicate that
atmospheric PCB concentrations are now approaching a steady state in Lake Erie after a more
rapid decline from 1975 to 1995 (Buehler et al., 2004). On the other hand, the relatively faster
decline of gas-phase PCB concentrations around Lakes Michigan and Ontario (half-lives of 7
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years) may be due to effective reduction efforts, aimed at eliminating PCB point sources that
have occurred in the areas surrounding these two lakes. In precipitation, a long-term decreasing
trend of PCB concentrations was observed at Chicago with a half-life of 6.8 ± 3.1 years, which
agrees with the half-life in the vapor phase (8.0 ± 1.1 years), suggesting that regulatory efforts
are working in this city
In the precipitation regression (Appendix A, Equation 4), the terms bi, £3, and b$ were not
significant (p > 0.05) for total PCB concentration, indicating the seasonal effects were not
statistically significant. Therefore, the ratio between maximum and minimum concentration of
PCB in precipitation and the date at which the concentration peaked were not available.
3.3. Organochlorine Pesticides
Temporal and spatial trends of selected organochlorine pesticides including a-, and y-
hexachlorocyclohexane (HCH), total endosulfan (sum of a-endosulfan and p-endosulfan), total
chlordane (sum of a-chlordane, y-chlordane, and £ram--nonachlor), total DDT (sum ofp,p '-DDT,
/\p'-DDD, and p,p'-DDE), and hexachlorobenzene (HCB) are presented here. The detailed
information on the other organochlorine pesticides is in Appendices D and F.
3.3. la-, and y-HCH
Technical HCH contains 60-70% of a-HCH, 2-12% of P-HCH, and 10-15% of y-HCH (Iwata, et
al., 1993). The technical HCH mixture was banned in North America in 1970s and replaced by
purified y-HCH (lindane). For the study period, y-HCH was still a current-use pesticide with
continuous input. For a-HCH, its source is mainly from the previously usage of technical HCH.
a-HCH is more volatile than y-HCH, and slower to react with atmospheric hydroxyl radicals
(Willett et al., 1998); therefore, a-HCH is more readily transported through the atmosphere and
will tend to have a relatively uniform global atmospheric concentration. As shown in Figure 5,
a-HCH concentrations were slightly higher at Eagle Harbor (average 100 ± 5.3 pg/m3) compared
to the other sites. The concentrations were similar (average 82 ± 1.8 pg/m3) at Sleeping Bear
Dunes and Sturgeon Point. Chicago and Brule River showed similar but lower a-HCH
concentrations (average 54 ± 2.2 pg/m3). It has been established that a loss of a-HCH of the
order of 10-20% results from the method of collection at the Canadian sites. Taking this into
account, a-HCH concentrations are still generally smaller at Point Petre and Burnt Island relative
to the other sites. In precipitation, a-HCH concentrations were about the same at all sites except
for Eagle Harbor, which had slightly higher concentrations.
For the current-use pesticide y-HCH, Chicago, Sleeping Bear Dunes and Sturgeon Point had
similar vapor-phase concentrations (Figure 6), but these were significantly higher than y-HCH
vapor-phase concentrations at Brule River, Eagle Harbor, Point Petre and Burnt Island. The y-
HCH concentrations in precipitation at the two Canadian sites (Burnt Island and Point Petre)
were similar and significantly higher than the other five U.S. sites, which were all about the
same. The technical HCH mixture was banned in North America in 1970s and replaced by
purified y-HCH (lindane). Although the National Center for Food and Agricultural Pesticides
showed that the U.S. usage of lindane for all crops during the period of 1992 and 1997
-------
Total PCBs
Vapor-phase cone, (pg/m )
104
103 -
102 -
a a a
a • •
Half-lives (years)
40
30 -
20 -
10 -
0
-10 -
irra
Particle-phase cone, (pg/m3) Precip. cone. (ng/L)
102
not measured
10° -
io-1
high blanks
Max to min ratios
Maximum dates
no seasonality
no seasonality
Figure 4. Spatial and temporal trends of total PCBs. The color code and site abbreviation are same as in Figure 2.
-------
in the Great Lakes area was limited, the Canadian lindane usage inventories showed that
-410 t of lindane had been applied during the period 1970 to 2000 in the provinces of
Quebec and Ontario close to Lakes Ontario and Huron (Li et al., 2004).
Although y-HCH was still in-use in Canada until 2004 and in the U.S. through the present
time, long-term decreasing trends were observed in both the gas and particle phases at all
seven IADN sites except for the particle phase at Brule River (Figure 6). Our results
showed that y-HCH had a half-life of 5 to 10 years around the Great Lakes, which were
longer compared to a 4-year half-life for a-HCH in all phases at most IADN sites. The
slower decline of y-HCH measured by IADN in the Great Lakes region is likely due to
the continuing usage of lindane in the U.S. and Canada.
Most of the a-HCH concentrations did not have a significant seasonal trend except in the
precipitation at Sleeping Bear Dunes and Point Petre. At these two sites, the maximum
concentrations of a-HCH in precipitation occurred in winter time, in January at Sleeping
Bear Dunes and late December at Point Petre. In contrast, the concentrations of y-HCH
in the particle and precipitation phases showed significant seasonal trends. The ratio
between the highest and the lowest y-HCH ranged between about 2-9, indicating that the
seasonal variations can be substantial. Interestingly, the concentrations peaked in the
summer for y- HCH, which agrees well with their maximum agricultural usage.
It has been suggested that competing processes could explain the winter concentration
peak for the banned pesticides such as a-HCH in precipitation (Carlson et al., 2004).
These pesticides enter the atmosphere due to re-volatilization from lake and terrestrial
surfaces, and these sources tend to maximize during the warmer summer months
(Buehler et al., 2001). However, the concentrations of these pesticides in the atmospheric
particle phase tend to increase during the winter due to enhanced partitioning to the
particles. In addition, snow is a better scavenger for both particle-associated and vapor-
phase pesticides than rain (Franz and Eisenreich, 1998). The lower intensity of sunlight
in the winter lowers the atmospheric OH radical concentration, which in turn increases
the atmospheric lifetime of the pesticides, favoring their accumulation in the winter-time
air and precipitation. All these mechanisms could contribute to higher winter
concentrations in precipitation for a-HCH.
3.3.2 Total Endosulfans
Endosulfan is used to control insects on food and non-food crops and also as a wood
preservative. Endosulfan is a current-use pesticide. For example, endosulfan is widely
used in Michigan and New York State (Hafner and Kites, 2003) and in Ontario (Harris, et
al., 2002), particularly in the southern and western portions of the province.
The endosulfan concentrations (shown as the sum of a- and y-endosulfan) in vapor phase
showed a clear increasing trend from the west to east (Figure 7), except for the remote
site of Burnt Island. At each site, the average concentration was affected by high
concentration outliers that usually occurred in the summer and were likely due to the
10
-------
a-HCH (tech. HCH)
Vapor-phase cone, (pg/m ) Particle-phase cone, (pg/m ) Precip cone. (pg/L)
103 T —i 101 T—a . ^ a—i 104
102 -
10°
bb °c.
a a JL •
Half-lives (years)
\J
4 -
3 -
2 -
1 -
n .
?
T
j
.
i
10° -
10'1 -
10-2
Max to min ratios
103 -
102 -
a a a a a a b
~ * t • 1
Maximum dates
3.0 -
2.5 -
2.0 -
1.5 -
1.0 -
0.5 -
n n .
-------
y-HCH (lindane)
Vapor-phase cone, (pg/m ) Particle-phase cone, (pg/m3) Precip. cone. (pg/L)
103 T 1 101 T 1 104
102 -
10°
c c
Half-lives (years)
10° -
10-2
a a a
Max to min ratios
u -
8 -
6 -
4 -
2 -
n
I
I
I
1
I
1
4
I
103 -
102 -
b b • I •
Maximum dates
-------
current agricultural use of endosulfan. Higher endosulfan concentrations were observed at Point
Petre, Sturgeon Point, and Sleeping Bear in vapor, particle, and precipitation phases, which could
be explained by its heavy usage in the surrounding areas (Hoh and Kites, 2004). For example,
endosulfan is widely used in Michigan and New York State (Hafner and Kites, 2003) and in
Ontario (Harris, et al., 2001), particularly in the southern and western portions of the province.
Total endosulfan concentrations showed no long-term decreasing trends in the vapor phase at
Eagle Harbor, Sleeping Bear Dunes, or Sturgeon Point (Figure 7). However, total endosulfan
concentrations in the particle phase declined at all five U.S. sites. In the precipitation phase, total
endosulfan concentrations only decreased at Point Petre, while at the other six sites, these
concentrations did not change from 1997 to 2003. The National Center for Food and Agriculture
Policy provides an endosulfan usage database for the period 1992-97 in the U.S. Although
endosulfan usage in Michigan significantly decreased from 29 tons to 19 tons between 1992 and
1997, increasing usage was also observed in the surrounding states, including New York,
Indiana, Kentucky, and Minnesota. Because of the lack of updated usage data, correlation
between the decreasing particle-bound endosulfan concentrations and its usage pattern is
difficult.
Similar to y-HCH, total endosulfan concentrations also showed a strong seasonal variation in
precipitation. The ratio between the highest and the lowest total endosulfan concentration ranged
between about 2-10. In particular, this ratio is as high as 10 at Point Petre, suggesting a heavy
usage in the surrounding area. At all sites, the total endosulfan concentrations peaked in early
July in precipitation, a time which corresponds well with its maximum agricultural usage.
3.3.3 Total Chlordanes
Technical chlordane was introduced in 1947 to control termite and phased out in the United
States and Canada in 1988 and 1990, respectively. Technical chlordane was a mixture
containing y-chlordane (13%), a-chlordane (11%), trans-nonachlor (5%), and more than 140
other compounds with six to nine chlorine atoms (Dearth and Kites, 1991). Here total chlordane
is presented as the sum of a-, y-chlordane, and /ram--nonachlor concentrations.
As shown in Figure 8, the spatial trend of the total chlordane gas-phase concentrations is: Brule
River^ Eagle Harbor ~ Burnt Island < Point Petre < Sleeping Bear Dunes < Sturgeon Point <
Chicago. Precipitation concentrations of total chlordane were also the highest in Chicago
followed by Sturgeon Point and Sleeping Bear Dunes. Brule River, Eagle Harbor, Burnt Island,
and Point Petre had similar but lower total chlordane concentrations. Chlordane's most common
use in the U.S. was for termite control near homes, suggesting that urban areas could be emission
sources (Harner et al., 2004). It has been suggested that volatilization of old chlordane residues
from soil in the southern United States was the predominant source of chlordane to the Great
Lakes (Hafner and Kites, 2003). Thus, both historical local applications used to control termites
and the influence of long-range transport from areas of historical high chlordane use could
contribute to the relatively high chlordane concentrations at Chicago. Long-range transport of
chlordane would impact all of the sites, not just Chicago. The relative difference between
Chicago and the other sites is likely due to historical local use in Chicago.
13
-------
Total chlordane concentrations in the gas phase declined at all seven IADN sites (Figure 8,
bottom left panel). Overall, chlordane concentrations in the gas phase had half-lives around 8
years at most sites except Brule River. The decline of total chlordane in the particle and
precipitation phases was not as notable compared to the vapor phase. The particle-phase
chlordane only decreased in Eagle Harbor, Sturgeon Point, and Chicago, two of these three sites
(e.g. Eagle Harbor and Sturgeon Point) had a half-life longer than 10 years. A faster decline of
total chlordane concentration in precipitation was observed at Sturgeon Point and Chicago, while
no temporal trends were observed at the other five sites for total chlordane concentrations in
precipitation.
Strong seasonal concentration variations were observed for total chlordane at most IADN sites in
both particle and precipitation phases. The ratio between the highest and the lowest total
chlordane concentrations ranged between 2 to 9. As a banned pesticide, the concentrations of
total chlordane in the particle and precipitation phases usually peaked in late January, which is
similar as a-HCH but different from y-HCH and total endosulfan, both current-use pesticides
during the data period.
3.3.4 Total DDTs
Technical DDT is consisted of/^'-DDT (65-80%), o,//-DDT (15-21 %),#// -ODD (<4%), and
small amounts of other compounds. p,p'-DDT can dehydrochlorinate in the environment to form
p,p -DDE (Ranson, et al., 2000). Although technical DDT was deregistered in the U.S. in 1972
and in Canada in 1973, it was used extensively in urban aerial sprays to control mosquitoes and
other insects in the 1940s and 1950s. Due to its high persistence, these residuals may still act as
a source of DDTs to the atmosphere. IADN measures the gas phase concentrations of several
DDT-related compounds, including p,p -DDT, p,p '-ODD, p,p -DDE, o,//-DDT, and o,p'-DDD in
gas phase, but in the particle phase, p,p'-DDE and o,p'-DDT are not measured. Here, the total
DDT is reported as the sum ofp,p -DDT, /\p '-DDE, andp,p -ODD.
The highest concentrations of total DDT were also observed in Chicago in all three phases
suggesting urban sources (Figure 9). Total DDT concentrations in the vapor phase showed
decreasing trends at most sites with half-lives ranging from 5 to 15 years except at Brule River.
No long-term trends were observed for total DDT in the particle phase except in Chicago. In the
precipitation phase, decline of total DDT was only shown at Chicago and Burnt Island.
Seasonal concentration variations of total DDT were observed at most IADN sites in both
particle and precipitation phases. The ratio between the highest and the lowest total DDT
concentrations ranged between 1.5 and 4.5. The concentrations of total DDT in the particle
phases usually peaked in late January, which is similar to other banned organochlorine pesticides
(discussed above).
14
-------
Total endosulfans
Vapor-phase cone, (pg/m3) Particle-phase cone, (pg/m3)
Precip. cone. (pg/L)
103
102 ]
101
10° -
io
-2
• *
Half-lives (years)
102
10° -
io-1
b b £
a a • - *
Max to min ratios
\£. -
10 -
8 -
6 -
4 -
2 -
n
J 1
r
M
in
|
iTT
,Vin
II
I
104 -
103-
102 -
Maximum dates
Udi i
Nov
Sep-
Jul-
May-
Mar-
.lan.
X
L
u
F
t
Figure 7. Spatial and temporal trends of total endosulfans (sum of a- and y-endosulfan). The color code and site abbreviation are same
as in Figure 2.
-------
Total chlordanes
Vapor-phase cone, (pg/m ) Particle-phase cone, (pg/m3) Precip. cone. (pg/L)
103
102 -I
10° -
aa >f
Half-lives (years)
25
20 -
15 -
10 -
5 -
0
102
10°
10-1
5 a b
cf
Max to min ratios
1^ -
10 -
8 -
6 -
4 -
2 -
n -
i
I
J
b
\
I
I
j
T T
l
I
I
T In
ll II
104
103 -
102 -
10°
a a
Maximum dates
Jan
Nov-
Sep
Jul
May-
Mar
Jan
TnTrt
Figure 8. Spatial and temporal trends of total chlordane (sum of a- and y-chlordane, and frnrm'-nonachlor). The color code and site
abbreviation are same as in Figure 2.
-------
Total DDTs
Vapor-phase cone, (pg/m ) Particle-phase cone, (pg/m3) Precip. cone. (pg/L)
103 -i 1 102 -i —i 104
102 -
10° -
cc.d
• • i
a a
Half-lives (years)
*L\J ~
20 -
15 -
10 -
5 -
n -
li
L
I
.
1
i
10° -
10-'1 -
io-2
.b a b S
Max to min ratios
u -
5 -
4 -
3 -
2 -
1 -
n .
i
r
1
i
I
[
103 -
IO2 -
10°
• J_ •
Maximum dates
Jan
Nov-
Sep-
Jul-
May-
Mar-
^
$$&$&#&
Figure 9. Spatial and temporal trends of total DDT (sum ofp,p'-DDT,p,p'-DDE andp,p'-DDD). The color code and site abbreviation
are same as in Figure 2.
-------
Hexachlorobenzene
oo
Vapor-phase cone, (pg/m ) Particle-phase cone, (pg/m3) Precip. cone. (pg/L)
103
102 -
b b c c
a a
Half-lives (years)
\J\J -
40 -
30 -
20 -
10 -
0 -
-10 -
.90 .
T .
n
i
JL
y
not measured
Max to min ratios
/
6 -
5 -
4 -
•
2 -
1 -
n
I
[
I 1 T I
'
L
103
102 -
10°
• a
a a
• a a
Maximum dates
Jan
Nov-
Sep-
Jul:
May-
Mar-
Jan
Figure 10. Spatial and temporal trends of hexachlorobenzene. The color code and site abbreviation are same as in Figure 2.
-------
3.3.5 Hexachlorobenzene (HCB)
HCB has been used for protecting the seeds of onions and sorghum, wheat, and other
grains against fungus until 1965. It was also used to make fireworks, ammunition, and
synthetic rubber. HCB is a by-product in the production of making other chemicals, in
the waste streams of chloralkali and wood-preserving plants, and when burning municipal
waste.
Relatively high concentrations of HCB were observed in the vapor phase at Chicago
(Figure 10). There is evidence of significant loss of vapour phase HCB during summer
sample collection at the Canadian sites (Fowlie, 2002), hence the smaller concentrations
seen in Figure 10. In precipitation, higher HCB concentrations were observed at the two
Canadian sites, perhaps because HCB was used as an anti-fungal seed dressing for
several crops in Canada until 1972, while it has been banned in the U.S. since 1965. In
addition, the re-volatilization of HCB from Lake Ontario may also contribute to its higher
level at Point Petre (Buehler, et al., 1998).
Vapor phase HCB concentrations showed decreasing trends at all these seven IADN
sites, much longer half-lives (around 30 years) were observed at the two Canadian sites
compared to the five U.S. sites (around 10 years) perhaps driven by wintertime
concentrations which are not affected by sample loss. Interestingly, a significant
increasing trend of HCB was observed at Brule River, which could be attributed to the
short monitoring period at this site. The monitoring at Brule River started in January
1996 and ended in August 2002, which is about half of the sampling length at Eagle
Harbor (e.g. from January 1992 to present). It is possible that the observed increasing
trend of HCB concentrations at Brule River is just a short-term aberration.
The average ratio between the highest and the lowest HCB concentrations in precipitation
was around 3 at seven IADN sites. The HCB concentration in the precipitation phase
peaked around early February, which again is similar to other banned organochlorine
pesticides.
4. Conclusions
Overall, the Chicago site has the highest concentrations of ZPAHs, total PCBs, and most
organochlorine pesticides, suggesting a strong urban atmospheric source of these
persistent organic pollutants. This urban effect could also be observed at Sturgeon Point,
a semi-urban site close to Lake Erie. The concentrations of ZPAHs, total PCBs, and
organochlorine pesticides at the other five IADN sites usually represent atmospheric
background levels of these pollutants in the Great Lakes basin.
Fast decreasing trends of ZPAH concentrations were observed at Chicago. The half-lives
were about 9 years in both the vapor and particle phases, about 3 years in the
precipitation phase. At other sites, vapor phase ZPAH concentrations showed significant,
but slower long-term decreasing trends (>15 years). The decline of ZPAH concentrations
19
-------
in Chicago could be the result of a basinwide commitment to cleaner air, including
improved petroleum fuels, automobile engines, and industrial pollution control
technology.
Significant long-term decreases of total PCB concentrations in the vapor phase, with the
half-life of 7-14 years, were observed at Chicago, Sleeping Bear Dunes, Sturgeon Point,
and Point Petre, suggesting reduction efforts are working in the surrounding areas. A
much slower decline of vapor-phase PCB concentrations at Eagle Harbor (half-life of 18
years) and Burnt Island (half-life of 27 years) potentially due to the remoteness of the
sites. In precipitation, a long-term decreasing trend of PCB concentrations was observed
at Chicago with a half-life of 7 years, which agrees with the half-life of 8 years in the
vapor phase.
Declines of organochlorine pesticide concentrations were observed at most IADN sites.
For example, our results showed that y-HCH had a half-life of 5-10 years around the
Great Lakes, which is longer than a 4-year half-life for a-HCH at most IADN sites. The
slower decline of y-HCH measured by IADN in the Great Lakes region is likely due to
the continuing usage of lindane during the study period. Since Canada withdrew
agricultural uses of y-HCH in January 2005 and the U.S. recently agreed to do likewise,
future data should reveal whether levels of y-HCH start to decline more quickly as a
result. Another example is the total chlordane concentrations in the gas phase, which had
half-lives around 8 years at most sites except Brule River.
Seasonal variations were observed for ZPAH concentration and organochlorine pesticide
concentrations in the particle and precipitation phases. Generally ZPAH concentration
showed higher concentrations in the winter time and lower concentration in the summer.
The ratios between the highest concentration and the lowest concentration are usually
larger than 2 indicating seasonal variations are substantial. The ZPAH concentrations in
the particle phase and precipitation usually peaked in late January, which could be due to
commercial and home heating. Among all the organochlorine pesticides measured by
IADN, two different seasonal trends could be observed. In the first, the concentrations
peaked in the summer for pesticides that were in-use during our sampling period such as
y-HCH and endosulfan. In the second, the concentrations peaked in the winter for
banned pesticides including a-HCH, chlordane, DDT, and HCB. Unlike PAHs and
organochlorine pesticides, the PCBs in the precipitation phase did not show significant
seasonal variations, apart from seasonality due to changes in temperature.
With more than a decade of data, IADN has successfully determined the atmospheric
temporal and spatial trends of toxic substances including PAHs, PCBs, and several
organochlorine pesticides around the Great Lakes. This report completely documented
the trends of toxic substances in the Great Lakes region. Together with previous biennial
loading reports prepared by IADN, this information will be helpful to better understand
the cycling of persistent organic pollutants in the Great Lakes environment.
20
-------
Acknowledgements
The authors would like to thank many people whose work supported the production of
the IADN trend report.
Site operators at each sampling stations
Ed Sverko and staff at the National Laboratory, Environment Canada
Frank Froude and staff at the Centre for Atmospheric Research and Experiments,
Environment Canada.
Staff at the Organic Analysis Laboratory, Environment Canada.
Karen Arnold, Jennifer Kelly, and James Bays at Indiana University
Ronald Piva at the North Central Research Stations of the USD A Forest Survey
Daniel Carlson at University of Minnesota
The U. S. Environmental Protection Agency's Great Lakes National Program Office for
funding (Grant GL995656)
21
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Appendix A. Temporal and Spatial Trend Analysis Procedure
25
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The vapor phase concentrations of the organic substances (in pg/m3) were first converted to
partial pressures (P, in atm) using the ideal gas law. These partial pressures were then adjusted
to the reference temperature of 288 K using equation 1, where AH is a characteristic phase-
transition energy of the compound (in kJ/mol), R is the gas constant, and Tis the daily average
atmospheric temperature at the sampling site (in Kelvin). This procedure effectively
"temperature-corrects" the data so that temporal trends can be detected. Concentrations of many
semivolatile organic compounds such as those measured by IADN are often higher in the
summer due to increased volatilization from soils. The value of AH was determined by a
preliminary regression of ln(P) vs. l/T, which is the Clausius-Clapeyron equation (equation 2).
An example of the correlation between In^) and l/T is given in Figure Ala. The values of
ln(P288) were then regressed vs. time (t, in Julian days relative to January 1, 1990) using equation
3 to determine the rate (a\, in days"1) of exponential increase (a\ > 0) or decrease (a\ < 0) of
these partial pressures. If this rate was statistically significant (p < 0.05), these rates were then
converted to half-lives (t\/2, in years) by dividing the values into the ln(2)/365 for each compound
at each site. Figure Alb shows an example of a decreasing trend based on the above analysis.
R
P = -—(-
(3)
In P = -—- + const (2)
R(T)
Equation 4 was used to fit the concentrations (C) in the particle phase:
InC =b
0
where t is the time in Julian Days relative to January 1 1990, bo is the intercept (unitless), b\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, #2 is the periodic amplitude (unitless), 63 is the length of the period (in days), and b4 is the
periodic offset (in days). An example of particle-phase concentration temporal trend analysis is
shown in Figure A2.
26
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-26
-28
-30
-32
3.2
OQD
3.4
3.6
1000/T
3.8
4.0
Figure Ala
oo
oo
-24
-26
-28
-30
-32
1996 1998 2000 2002 2004
Figure Alb
Figure Al. Example of a temporal trend analysis for vapor phase concentration. Figure Ala,
correlation between InP and 1/7; Figure Alb, correlation between lnP288 and time (t). Each
yellow dot is the partial pressure of a vapor phase sample; the red line indicates the linear
correlation (example is fluoranthene at Chicago, r2=0.64).
CO
E
~
10°
ci
c
o
o
CD
w
CD
.C
Q.
_0)
O
t
CO
Q_
-2
10
io-3
D OD
1996 1998
2000
2002
2004
Figure A2. Example of temporal trend analysis for particle phase concentration. Each gray dot
is the concentration in the particle phase; the red line indicates long-term significant decreasing
trend; the black curve is the fitted line of the sinusoidal model with the period length (63) set to
one year (example is chrysene at Point Petre, r2=0.40).
To establish the dates of maximum concentrations, the ratio between the highest concentration
and the lowest concentration in the particle or precipitation samples can be calculated from the
fitted b2 parameter (equation 4) by taking its anti-logarithm (e2b2, the factor of 2 in the exponent
is needed to calculate the peak-to-valley amplitude). The sine wave would have a maximum at
day 91 in a year. Therefore, the dates of the maximum of concentrations were calculated by first
27
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converting the fitted 64 values from radians to days (multiplying by 365/2ji) and then subtracting
these values from 91.
Similarly, equation (4) was also used to explain the temporal trend of the concentrations in
precipitation samples, where C is the concentration of organic compounds in precipitation phase.
Figure A3 gives an example of a temporal trend analysis in precipitation. Obviously, the fitting
parameters will be different for the particle and precipitation phases.
105
O)
Q.
"T104
o
c
o
CO
.C
Q.
9-102
o
o>
1998
2000
2002 2004
Figure A3. Example of a temporal trend analysis for precipitation phase concentration. Each
blue dot is the concentration in precipitation samples, the red line indicates the long-term
significant decreasing trend; the black curve is the fitted line of the sinusoidal model with the
period length (63) set to one year (example is p-endosulfan at Point Petre r2=0.52).
A one-way analysis of variance (ANOVA) was conducted to compare the average concentrations
of each organic compound in each phase among the seven sites to explore spatial trend. A
significance level of 0.05 was chosen for all the ANOVA analysis.
28
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Appendix B. Annual Variation of Polycyclic Aromatic Hydrocarbon
Concentrations in Precipitation Collected near the Great Lakes
Published in Environmental Science & Technology, 2006, 40, 696-701.
29
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Annual Variation of Polycyclic Aromatic Hydrocarbon Concentrations
in Precipitation Collected near the Great Lakes
Ping Sun,1 Sean Backus,2 Pierrette Blanchard,2 and Ronald A Kites*1
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 USA
and
Environment Canada
4905 Dufferin Street
Toronto, ON M3H 5T4 Canada
* Corresponding Author Email: hitesr@indiana.edu
Brief
At seven sites around the Great Lakes, concentrations of polycyclic aromatic
hydrocarbons in precipitation from 1997 to 2003 were analyzed for temporal and spatial trends.
Abstract
Polycyclic aromatic hydrocarbon (PAH) concentrations were measured in precipitation
samples collected from 1997 to 2003 at seven sites near the Great Lakes as a part of the
Integrated Atmospheric Deposition Network (IADN). The 28-day integrated concentrations of
most PAHs showed significant seasonal trends with higher concentrations in the winter and
lower concentrations in the summer. Long-term decreasing trends were observed for all PAHs
measured in precipitation at Chicago. At the sites on Lakes Superior, Michigan, and Erie, most
PAHs did not show significant long-term trends. At the two Canadian sites on Lakes Huron and
Ontario, lower molecular weight PAHs (e.g. fluorene to pyrene) showed long-term decreasing
trends; however, no long-term trends were observed for higher molecular weight PAHs at these
sites. Interestingly, retene, a marker for wood burning, showed increasing trends at the sites on
Lakes Superior and Michigan. For all the other PAHs, precipitation collected at Chicago had by
far the highest PAH concentrations followed by the site on Lake Erie. Generally, the Lake
Superior sites had the lowest PAH concentrations. However, retene concentrations in
precipitation collected at the Lake Superior site were higher compared to Lakes Michigan and
Erie, which indicate more residential wood burning in the far north of the Great Lakes basin.
Introduction
Established in 1990, the Integrated Atmospheric Deposition Network (IADN) is a joint
project operated by the United States and Canada. IADN operates five master sampling sites on
the shores of the five Great Lakes to study the atmospheric input of toxic organic compounds to
this important ecosystem (7). The concentrations of polychlorinated biphenyls (PCBs),
organochlorine (OC) pesticides, and polycyclic aromatic hydrocarbons (PAHs) have been
measured in the air and precipitation collected at these sites since 1990. Several previous
publications have focused on the long-term trends of PCB, pesticide and PAH concentrations in
30
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the gas phase at the IADN sites (2-5), and these results indicate that most of these concentrations
are decreasing with half-lives on the order of 3-8 years.
Analysis of the concentration trends of these pollutants in the precipitation phase
collected at the IADN sites has been more limited. Chan and co-workers studied OC pesticides
and PCBs in rain and snow collected in Ontario, Canada, and reported decreasing concentrations
of lindane and dieldrin over the period of 1986-1991 (6). Chan and co-workers also investigated
spatial and temporal trends in the concentrations of selected OC pesticides and PAHs in
precipitation collected at several Canadian sites from 1986 to 1999 (7). OC pesticide
concentrations decreased over this time period; however, there were few changes in the
concentrations of four PAHs (phenanthrene, fluoranthene, pyrene, and 2-methylnaphthalene).
Simcik and co-workers reported on the temporal trends of PCBs, PAHs, and several OC
pesticides in precipitation samples collected from the IADN sites from 1991 to 1997 (8). Their
results showed that the concentrations of many OC pesticides decreased during this sampling
period; however, there was no significant decrease in the concentrations of PAHs. The annual
variations of OC pesticide concentrations at the U.S. IADN sites collected from 1997 to 2002
were studied by Carlson and co-workers (9). In this case, the concentrations of most OC
pesticides did not decrease over time but showed clear seasonality. Higher concentrations were
observed in the late spring or early summer for current-use pesticides, a phenomenon related to
their agricultural use at this time of year. On the contrary, higher concentrations were observed
in the winter for most of the banned pesticides, which is likely the result of the increased
scavenging efficiency of snow compared to rain, and for some pesticides such as dieldrin, higher
concentrations in the particulate phase during winter (9).
PAHs, however, are byproducts of incomplete combustion and thus come from vehicle
emissions, space heating, and industrial activity (10). Some of these sources are more or less
constant throughout the year (vehicle emissions, for example), but others tend to maximize
during the winter months (space heating, for example). Therefore, the annual variations in PAH
atmospheric concentrations will likely be different from those of pesticides and PCBs.
In this paper, the temporal and spatial trends of PAH concentrations in precipitation at the
five U.S. IADN sites and at the two Canadian IADN sites will be presented. Although samples
had been collected at several sites since 1991, the analytical method changed in March of 1997
for the U.S. sites (9). To ensure data consistency, only data from March 1997 to December 2003
are presented here.
Experimental
Samples were collected at the five U.S. IADN sites (Brule River and Eagle Harbor, near
Lake Superior; Chicago and Sleeping Bear Dunes, near Lake Michigan; and Sturgeon Point, near
Lake Erie) and at two the Canadian sites (Burnt Island, near Lake Huron; and Point Petre, near
Lake Ontario). The IADN website (www.smc-msc.ec.gc.ca/iadn) and a previous publication (7)
provide detailed information on these sites.
MIC automated wet-only samplers (MIC Co., Thornhill, ON) are used to collect
precipitation samples at the five U.S. sites. Detail information on the performance of this
sampler was given by Carlson and co-workers (9). Each sampler consists a 46 x 46 cm shallow
stainless steel funnel connected to a 30 cm long by 1.5 cm i.d. glass column (ACE Glass,
Vineland, NJ) packed with XAD-2 resin. The sampler is normally covered; the start of a
precipitation event is sensed by a conductivity grid located outside the sampler, which signals the
cover to open. The grid is heated to prevent condensation, ice build-up, and prolonged sampling
-------
after the end of the precipitation event. Precipitation flows from the funnel through the XAD-2
column and into a large carboy used to measure the total precipitation volume. Since there is no
filter in the system, both particulate and dissolved phase organic compounds are collected on the
XAD column. The funnel and the interior of the sampler are kept at 15 ± 5 °C to melt snow that
falls into the sampler and to prevent the XAD resin column from freezing. Precipitation events
are integrated for 28 days regardless of the amount of precipitation occurring during that time.
This strategy results in 13 samples per year, but for simplicity, these samples are referred to as
monthly samples. In addition, gas and particle phase samples are also collected at the IADN
sites for 24 h every 12 days using modified Anderson high-volume air samplers. Detailed
information on the sampling procedures for the gas and particle phases is given by Basu and co-
workers (77).
For the U.S. sites, the wet XAD-2 cartridges were sent to Indiana University for analysis
of the pesticides, PAHs, and PCBs. The analytical procedures are described in detail elsewhere
(72, 73). Briefly, the XAD-2 resin was Soxhlet extracted for 24 h using a 1:1 (v/v) mixture of
hexane and acetone. The extract was then concentrated by rotary evaporation and fractionated
on 3.5% (w/w) water-deactivated silica gel. Hexane was first used to elute PCBs and some
pesticides. PAHs were then eluted with 1:1 hexane and dichloromethane. The extracts were
further concentrated by nitrogen blow-down to ~1 mL and spiked with Ji0-anthracene, d\i-
perylene, and du-benz[a]anthracene as internal standards.
The PAHs were quantitated on one of three instruments: a Hewlett-Packard (HP) 5890
gas chromatograph (GC) with a 5970A mass spectrometer (MSD); a HP 5890 GC with a 5895
MSD; or an Agilent 6890 GC with a 5973 MSD. In all cases, selected ion monitoring was used.
Sixteen PAHs were measured: fluorene, phenanthrene, anthracene, fluoranthene, pyrene, retene,
benz[a]anthracene, triphenylene and chrysene (not resolved chromatographically, counted as one
compound), benzo[&]fluoranthene, benzo [k] fluoranthene, benzo[e]pyrene, benzo[a]pyrene,
indeno[7,2,3-cd]pyrene, benzo[g/z/]perylene, dibenz[a,h]anthracene, and coronene. In all cases,
DB-5 columns (J & W Scientific; 30 m x 250 |j,m i.d.; film thickness, 0.25 |j,m) were used to
separate the PAHs.
The detailed sampling and analytical procedure at the two Canadian sites is given by
Chan and coworkers (7). Briefly, a 4-L amber glass bottle, pre-filled with 250 mL
dichloromethane, was used for precipitation sampling in a MIC automated wet-only sampler. In
this case, an XAD-filled column was not used. The liquid samples, consisting of the rain or
snow-melt water and the dichloromethane, were sent to the National Laboratory for
Environmental Testing (NLET) in Burlington for analysis. The samples were kept at 4 °C until
analyzed. The aqueous phase was separated from the dichloromethane using a separately funnel,
and the precipitation volume was measured. The residual aqueous sample was then extracted
twice with fresh dichloromethane. The combined extracts were then concentrated by rotary
evaporation and fractionated on 3% (w/w) water-deactivated silica gel. Hexane was first used to
elute PCBs, some pesticides, and some PAHs. The remaining pesticides and PAHs were then
eluted with 1:1 hexane and dichloromethane. The extracts were further concentrated by nitrogen
blow-down to ~1 mL. Equal amounts of the two fractions were combined and spiked with d\a-
anthracene, t/i2-perylene, and Ji2-benz[a]anthracene as internal standards.
The PAHs were quantitated on one of two instruments: a HP 5890 GC with a 5971 MSD;
or an Agilent 6890 GC with a 5973 MSD. In all cases, selected ion monitoring was used. The
same list of PAHs described above was measured with the exception of retene and coronene.
Perylene was also measured at these two sites. HP5-MS columns (Agilent; 25 m x 250 |j,m i.d.;
32
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film thickness, 0.25 |j,m) were used to separate the PAHs. In this paper, the so-called "total
PAH" concentration is the sum of the 14 PAHs measured by both laboratories. Prior to 2001,
precipitation samples at the Canadian sites were collected every 14 days; this frequency was
switched to 28 days at that time. Thus, the Canadian data before 2001 were combined into 28-
day averages to make these data consistent with the U.S. data.
Strict quality assurance procedures were followed by both laboratories to ensure high
data quality (14). Field blanks account for 10% and laboratory blanks account for 5% of the
number of collected samples. At Indiana University, PAH standards prepared in the laboratory
were spiked on XAD-2 resin as matrix spikes to monitor extraction efficiency. One matrix spike
experiment was performed with every other batch of samples (about 10-12 samples per batch).
The average matrix spike recovery rates ranged from 60-103% for 14 PAHs. Surrogate
standards (t/io-phenanthrene and t/io-pyrene) were used in each sample to monitor recovery. The
average percent recoveries for the surrogates were 83-89% (14). Surrogate spikes of 1,3-
dibromobenzene and endrin-ketone were added to determine recovery efficiencies at NLET. In
this case, the surrogate spike recoveries were 82-92% (7). Due to the very low PAH
concentrations in the field and laboratory blanks (14\ usually less than the instrumental detection
limit, the concentrations reported here have not been blank corrected. A split-sample inter-
laboratory comparison was conducted in early 2001 to evaluate the results from the two
participating laboratories (75). The results showed that there was no bias between the Indiana
University and NLET laboratories for PAHs concentrations.
Results and Discussion
Temporal trends. Our previous experience with IADN data suggested that a sinusoidal
model would provide a good fit to the log-transformed data for PAH concentrations in
precipitation (9). Therefore, the monthly concentrations (Cp) of a given PAH in precipitation
collected at a given site were fitted by the following time-dependent function:
InC =a0+a1t + a2sin — + a4 (1)
Ia3 )
where t is the time in Julian Days relative to January 1 1990, ao is the intercept (unitless), a\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, #2 is the periodic amplitude (unitless), a3 is the length of the period (in days), and a4 is the
periodic offset (in days).
Of the overall 117 datasets (16 PAH measured at five U.S. sites, 15 PAH measured at
two Canadian sites, and total PAHs at each site), 105 had significant periodicity, indicated by
both a2 and a3 being statistically significant at P < 0.05. The lack of significant periodicity of the
other 12 data sets was due to insufficient data for certain PAH (e.g. anthracene and
dibenz[a,h]anthracene) at remote sites. If a\ was significant (P < 0.05), either a decreasing (a\ <
0) or increasing (a\ > 0) trend in the PAH concentrations could be determined for this sampling
period. Because 74 of the 105 datasets had a period length (a3) of 368 ± 12 days, the period
length for all datasets was forced to be 365 days; this simplified the calculation of the date during
the year when the PAH concentrations reached their maximum.
Figure Bl shows the temporal trends of phenanthrene, pyrene, retene, benzo[a]pyrene,
and total PAH concentrations at the seven sites. For most PAHs, no significant long-term trends
were observed at the U.S. rural sites: Brule River, Eagle Harbor, and Sleeping Bear Dunes. In
contrast, all measured PAHs showed significant decreasing trends at the urban site in Chicago.
Among the individual PAHs, phenanthrene, pyrene, and benzo[a]pyrene showed the same trends
33
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as the total PAH at the U.S. sites. Retene, however, showed significantly increasing trends at
Brule River, Eagle Harbor, and Sleeping Bear Dunes, and a significant decreasing trend at
Chicago. At the two Canadian sites, Burnt Island and Point Petre, lower molecular weight PAHs
(e.g. fluorene, phenanthrene, fluoranthrene and pyrene) showed long-term decreasing trends.
However, the high molecular weight PAHs (e.g. larger than pyrene) did not show long-term
trends (see Table BS6-BS7). For the other PAH concentrations not plotted in Figure Bl, two
datasets at the U.S. sites showed statistically significant trends: fluorene increased at Brule River,
and coronene decreased at Sleeping Bear Dunes (see Tables BS1-BS5). The calculated half-lives
of PAH concentrations in precipitation at Chicago ranged from 2-5 years (see Table BS5), while
the half-lives ranged from 4-7 years at Burnt Island and Point Petre for the lower molecular
weight PAHs (see Tables BS6-BS7).
Previous work by Simcik and coworkers showed that there were no apparent long-term
trends for total PAH concentrations in precipitation at Eagle Harbor, Sleeping Bear Dunes, or
Sturgeon Point from 1991 to 1997 (8). The data reported here cover the period 1997-2003, and
no trends in the total PAH concentrations were observed over this period at these sites. Long-
term trends of PAH concentrations in precipitation at Brule River and Chicago have not been
reported before. Brule River is located on the south shore of Lake Superior, -230 km west of
Eagle Harbor. Because concentrations of almost all of the IADN analytes in the gas, particle,
and precipitation phases were similar at Eagle Harbor and Brule River (16), the Brule River site
was closed in 2002. Given the observed similarity of PAH concentrations at Brule River and
Eagle Harbor, we would expect to see a similar long-term trend in these concentrations. In fact,
we observe no change in the concentrations of any of the PAH except retene at these two sites
(see Figure Bl).
Another study on PAH concentrations in precipitation at rural sites was conducted by
Brun and coworkers, who measured the concentrations of 16 PAHs at five sites close to the Gulf
of St. Lawrence (77). Over the period 1980-2001, these authors reported an apparent long-term
decreasing trend at one of their sampling sites; in this case, the concentrations decreased with a
half-life of 4-6 years. Interestingly, long-term decreasing trends were also observed at two
Canadian IADN sites for lower molecular weight PAHs (MW < 202) with half-lives of 4-7 years
(see Figure Bl). The differences in trends observed by Brun and coworkers compared to our
study are likely due to geographical and source differences. Also, the longer database covering a
20 year period in the work by Brun and co-workers compared to our seven year period may
contribute to the differences in the long-term trend analyses.
The concentrations of all PAHs decreased significantly over the period 1997-2003 at
Chicago; see Table BS5. According to the Illinois EPA (75), air quality (e.g. ozone and
particulate matter) in Chicago has been improving ever since the passage of the 1970 Clean Air
Act. Much of the progress to date is the result of a nationwide commitment to cleaner air,
including improved petroleum fuels, automobile engines, and industrial pollution control
technology. For example, the Clean Cities Program has promoted the use of alternative fuels and
alternative fuel vehicles to reduce air pollution from motor vehicles since 1998. The diesel
retrofit portion of the program involves installing devices that lower emissions by over 90% on
Chicago's bus fleet. These efforts on improving air quality in Chicago may explain the
continuous decrease of PAH concentrations in precipitation and a faster decline (i.e. shorter half-
life) compared to the two rural sites in Canada: Burnt Island and Point Petre.
Higher PAH concentrations in precipitation during the winter have been observed by
many researchers (7, 19-21). Brun and coworkers suggested that anthropogenic activities, such
34
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as thermal power generation, home heating, and industrial activities, could explain the high PAH
concentration in the winter close to the Gulf of St. Lawrence (19}. Chan and co-workers
suggested that the increased use of wood and gas fireplaces during the colder months may lead to
higher PAH concentrations in the Canadian Great Lakes region (7). In addition, snow has been
reported to be 25-900 times better than rain at scavenging particle associated PAHs (22). This
higher scavenging efficiency may result in higher PAH concentrations in precipitation during the
winter. The lower intensity of sunlight, the consequently lower concentration of OH radicals,
and less efficient photochemical decomposition favors the accumulation of PAHs in the
atmosphere, and these factors may also contribute to the higher PAH concentrations observed in
precipitation in the winter (10).
The calculated dates on which the PAH concentrations in precipitation maximize at each
of the IADN sites are listed in the supplementary information (see Tables BS1-BS7). PAH
concentrations usually peaked in mid to late January at Eagle Harbor, Burnt Island, and Point
Petre and in early to late February at Brule River, Sleeping Bear Dunes, and Sturgeon Point. In
Chicago, the PAH concentrations usually peaked in early March, although eight of the results
were not significant at P < 0.05. The time of peak PAH concentration at the IADN sites showed
a slight north to south gradient. Presumably, this is the result of earlier seasonal use of fuel (and
hence PAH production) for domestic and industrial heating in cooler climates.
The ratio between the highest PAH concentration during winter time and the lowest
concentration during summer time can be calculated from the fitted a2 parameter by taking its
anti-logarithm (e2a2, the factor of 2 in the exponent is needed to calculate the peak-to-valley
amplitude). These values are presented in Tables aSl-AS7. These ratios range between about 3-
9, agreed well with other studies (17, 23), indicating that these seasonal variations are
substantial.
Spatial trends of PAH concentrations in precipitation. Figure B2 shows the
distribution of total PAH concentrations at the seven IADN sites. The concentration of total
PAHs was the highest at Chicago followed by Sturgeon Point. The concentrations of PAHs were
significantly higher at Sturgeon Point than at Sleeping Bear Dunes [F = 34.01, P < 0.0001, and df
= (1, 166)]. As expected, Brule River and Eagle Harbor showed statistically indistinguishable
PAH concentrations [F = 0.11, P = 0.74, and df = (1, 148)], but these concentrations were
significantly lower than the PAH concentrations measured at Sleeping Bear Dunes [F = 7.12, P
=0.001, and df = (2, 230)]. The two Canadian sites, Burnt Island and Point Petre had similar
PAH concentrations [F = 2.02, P = 0.15, and df = (1, 159)], but these concentrations were lower
than at Sturgeon Point [F = 3.95, P =0.02, and df = (2, 243)] and higher than at Sleeping Bear
Dunes [F = 6.23, P = 0.002, and df = (2, 241)]. Thus, the spatial trend of total PAH
concentration in precipitation is: Eagle Harbor ~ Brule River < Sleeping Bear Dunes < Burnt
Island ~ Point Petre < Sturgeon Point « Chicago. Each individual PAH had the same spatial
trend as the total PAHs with a few exceptions. For example, for fluorene, Eagle Harbor > Brule
River and Burnt Island ~ Point Petre ~ Sturgeon Point; for anthracene, Eagle Harbor ~ Sleeping
Bear Dunes; and for retene, Sleeping Bear Dunes ~ Sturgeon Point < Eagle Harbor ~ Brule River
< Chicago.
The average total PAH concentrations at the six rural IADN sites ranged from 26 to 90
ng/L, which are similar to PAH concentrations in precipitation collected at rural locations as
reported in other studies (17, 27). The high total PAH concentration at Chicago (a mean
concentration of 2300 ± 620 ng/L) is not surprising given that Chicago is a highly industrialized
city with approximately 8 million inhabitants.
35
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Among the individual PAHs, fluoranthene and phenanthrene are the most abundant, each
making up about 15-25% of the total PAH concentration. The other abundant PAHs include
pyrene and benzo[&]fluoranthene; these observations agree with other studies (20, 21).
Generally, the relative abundances of the individual PAH are similar at the remote sites (Brule
River, Eagle Harbor, Sleeping Bear, Burnt Island, and Point Petre) and at the more urban or
urban-influenced sites (Chicago and Sturgeon Point). These differences in the relative
abundances at the rural vs. the more urbanized sites suggest that different sources of PAHs affect
these sites. For example, the major sources of PAHs in and around Chicago are vehicle
emissions, coal and natural gas combustion, and coke production (24). The major PAH sources
at Sturgeon Point are similar to Chicago, but they are located 25 km away in the city of Buffalo,
New York (25, 26).
Temporal and spatial trends of retene concentrations in precipitation. Retene is
formed from abietic acid, which is a natural product mainly found in coniferous trees. Abietic
acid can be decarboxylated and aromatized to form retene by the combustion of coniferous wood
(27, 28) or by slower, low-temperature degradation processes (29) (see below). Franz and
Eisenreich reported retene concentrations in precipitation ranged from 1.4 to 50 ng/L in the
winter in Minnesota in 1991-1992 (22). However, temporal and spatial trends of retene
concentrations in precipitation have not been reported.
^COOH
Abietic acid Retene
In this study, retene concentrations in precipitation measured at the five U.S. sites showed
similar concentrations as reported by Franz and Eisenreich (22). In addition, these data showed
some interesting trends compared to other PAHs. As discussed previously, the concentrations of
retene increased significantly over time at Brule River, Eagle Harbor, and Sleeping Bear Dunes
(see Figure Bl), while the concentrations of most other PAH in precipitation at these sites did
not show any long-term changes. The increase in retene concentrations suggests that biomass
burning, particularly of wood from coniferous trees or synthetic logs (30), is increasing perhaps
due to an increase of residential fuel wood burning in these rural areas. At Chicago, retene's
concentration in precipitation has significantly decreased over time, suggesting that biomass
burning in this city has decreased during the last seven years. For example, Chicago's
Department of Environment has advocated against the open burning of leaves and other yard
waste and against the burning wood in fireplaces (31).
As mentioned earlier, retene showed a different spatial trend (Sleeping Bear Dunes ~
Sturgeon Point < Eagle Harbor ~ Brule River < Chicago) compared to the other PAHs detected
at the five U.S. IADN sites (see Figure B3, top). For the other PAHs, Sturgeon Point had the
second highest concentration, but interestingly, the retene concentration at Sturgeon Point is even
lower than at Eagle Harbor and Brule River. The average retene concentration at Chicago is
36
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about 5.5 times higher than that at Sturgeon Point, which is a much lower ratio compared to the
other PAHs (14-34 times).
These spatial differences in retene concentrations may be due to the different amounts of
wood burned in these areas. Based on renewable energy annual reports from the electric power
industry, more wood and wood waste are burned in Michigan, Wisconsin, and Minnesota
compared to New York and Illinois (32). Most residential wood burning occurred in lower
southern Michigan and in mid to northern Wisconsin (33, 34). Also, forest species composition
is different in different regions. More softwood grows in Michigan, Minnesota, and Wisconsin
(35). Thus, the relatively high retene concentrations at Brule River and Eagle Harbor are
reasonable. In Chicago, although wood burning is not advocated by Chicago's Department of
Environment, the large population of this region may explain the elevated retene concentration.
Retene is also emitted from municipal waste incinerators (36), and this may contribute to
retene's high concentration in Chicago. In addition, high concentrations of dehydroabietic acid
(the partially aromatized product of abietic acid) and abietic acid itself have been found in tire
debris (37) and in varnishes used for finishing wood in homes and furniture (35), which suggests
that tire burning and incineration of building wastes may be other retene sources in Chicago.
The fraction of the retene concentration compared to the total PAH concentration at the
five U.S. sites is shown in Figure B3, bottom. Here, total PAH is the sum of the 16 PAHs
measured by Indiana University. A much lower proportion of retene (relative to total PAH
concentration) was observed at Chicago. Sturgeon Point had the second lowest retene
proportion, while at the other rural sites (Brule River, Sleeping Bear Dunes, and Eagle Harbor),
the retene proportion was higher. These results suggest that biomass burning is less important in
urban than in rural locations. This is consistent with a U.S. Department of Agriculture survey on
residential wood consumption in the states of Michigan and Wisconsin, which found that most of
each state's residential wood consumption took place in the more rural areas (33, 34). On
average, each rural household consumed about three times more wood than its urban counterpart.
Occasionally, very high retene concentrations were observed at all U.S. sites, and we
suspected that these high levels may have been related to forest fires. In order to address this
hypothesis, data on wildfire occurrence near the Great Lakes were obtained from the National
Interagency Fire Management Integrated Database, which covers fires in the U.S. during the
period from 1970 to the present, and from the Canadian Forest Service, which covers fires in
Canada during the period of 1959 to the present. These historical records showed that more
wildfires occurred from April to September in each year, with most fires occurring in June. This
timing does not agree with our observation that most samples with high retene concentrations
were collected in either March or November. This difference suggests that wildfires are less of a
source of retene than anthropogenic wood or waste burning in the winter.
Acknowledgments
We thank Ilora Basu and Team IADN and Ed Sverko and staff at the National Laboratory
for Environmental Testing, Environment Canada for data acquisition; the U. S. Environmental
Protection Agency's Great Lakes National Program Office for funding (Grant GL995656,
Melissa Hulting, project monitor); Ronald Piva at the North Central Research Stations of the
USDA Forest Survey for information on softwood consumption; and Daniel Carlson for
suggestions and discussions on the analysis of these data.
37
-------
Supporting Information Available
The supporting Information contains seven tables of values derived from modeled
parameters for PAHs at seven IADN sites. This material is available free of charge via the
Internet at http://pubs.acs.org.
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39
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of fine organic aerosol. 3. Road dust, tire debris, and organometallic brake lining dust:
roads as sources and sinks. Environ. Sci. Technol. 1993, 27, 1892-1904.
38 Osete-Cortina, L.; Dom'enech-Carb', M. T. Analytical characterization of diterpenoid resins
present in pictorial varnishes using pyrolysis-gas chromatography-mass spectrometry with
on line trimethylsilylation. J. Chromatog. A 2005, 1065, 265-278.
40
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104
103
102
10'
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Figure Bl. Phenanthrene, pyrene, retene, benzo[a]pyrene, and total PAH concentrations in precipitation collected at seven IADN
sites near the Great Lakes. The black curve is the fitting line of the sinusoidal model with the period length (a3) set to one year. The
red lines indicate long-term significant decreasing or increasing trends. Detailed information on fitting parameters is in supporting
information.
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Figure H2. Total PAH concentrations in precipitation at the seven IADN sites. The horizontal
->th
lines represent the 10 , 50 , and 90 percentiles; the dotted red line is the mean; the boxes
-th
represent the 25 to 75 percentiles; and outliers are shown individually.
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Figure B3. Retene concentrations (top set of boxes) and the ratio between retene and total PAH
concentrations (bottom set of boxes) in precipitation collected at the five U.S. IADN sites. Note
the logarithmic scales. The horizontal lines represent the 10th, 50th, and 90th percentiles; the
boxes represent the 25th to 75th percentiles; and outliers are shown as the 5th and 95th percentiles.
42
-------
Supporting Information for:
Annual Variations of PAH Concentrations in Precipitation
Collected Near the Great Lakes
Ping Sun, Sean Backus, Pierrette Blanchard, and Ronald A Kites
This supporting Information contains seven tables of values derived from modeled parameters
for PAHs at seven IADN sites. ZPAH is the sum of 14 PAHs measured by both Indiana
University and National Laboratory for Environmental Testing (NLET) in Burlington. These
PAH are fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene,
triphenylene + chrysene (count as one compound), benzo[&]fluoranthrene,
benzo[£]fluoranthrene, benzo[e]-pyrene, benzo[a]pyrene, indeno[l,2,3-cJ]pyrene,
benzo[g/7/']perylene, and dibenz[a,/z]-anthracene.
The following equation was used to fit the data:
InC = a0 +a,t + a2 sin -- ha4
where t is the time in Julian Days relative to January 1 1990, a0 is the intercept (unitless), a\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, a2 is the periodic amplitude (unitless), a3 is the length of the period (in days), and a4 is the
periodic offset (in days).
Because 74 of the 105 datasets had a period length (#3) of 368 ±12 days, the period length for all
105 of these datasets was forced to be one year, which simplified the calculation of the date
during the year when the PAH concentrations reached their maximum.
The tables show results of the fit to this sinusoidal model with a?, of 365 days. The results are
listed as mean ± standard error. Normal font numbers are significant for 0.01 < P < 0.05; italic
font numbers are significant for 0.001 < P < 0.01, bold font numbers are significant at level of P
< 0.001. "NS" means "not significant at P > 0.05. A negative half-life is actually a doubling
time.
43
-------
Table BS1. Fit parameters for PAH concentrations in precipitation at Brule River
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
chrysene
B enzo [b ] fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno[l,2,3-
cJjpyrene
Benzo[g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Half-life (years),
(In2)/365*a!
-6.3 ±2.1*
NS
Limited data
NS
NS
-5.1 ±2.4*
NS
NS
NS
NS
NS
NS
NS
NS
Limited data
NS
NS
Peak-to-valley
ratio, e a2
3.1 ± 1.2
2.8 ± 1.2
5.8 ± 1.3
5.6 ± 1.3
3.0±1.4
NS
7.7 ± 1.3
9.3 ± 1.3
4.8 ± 1.4
6.5 ± 1.3
7.0 ± 1.4
7.4 ± 1.3
6.7 ± 1.3
8.0 ± 1.4
5.3 ± 1.2
Maximum date
(± days)
Feb 11 ± 10
Feb 14 ± 12
Feb 13 ± 7
Feb 8 ± 9
Jan 21 ± 15
NS
Feb 7 ± 6
Feb 7 ± 6
Feb 3 ± 10
Feb 7 ± 7
Feb 7 ± 8
Feb 5 ± 7
Feb 6 ± 7
Jan 31 ± 8
Feb 8 ± 7
No. of
detects
63
64
23
64
59
63
46
64
63
40
58
50
57
58
10
35
64
Average
cone.
(ng/L)
1.0±0.1
5.7 ±0.5
0.3 ±0.1
5. 3 ±0.9
3. 3 ±0.5
2.0 ±0.3
0.9 ±0.2
2.3 ±0.3
3.3 ±0.6
1.2 ±0.1
1.6 ±0.2
1.7 ±0.4
2.3 ±0.5
1.9 ±0.3
0.3 ±0.1
1.2 ±0.2
29 ±4.3
r2
0.37
0.29
0.51
0.42
0.21
NS
0.58
0.60
0.40
0.50
0.48
0.52
0.52
0.53
0.39
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
Table BS2. Fit parameters for PAH concentrations in precipitation at Eagle Harbor
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
chrysene
B enzo [b ] fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -c
-------
Table BS3. Fit parameters for PAH concentrations in precipitation at Sleeping Bear Dunes
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
chrysene
Benzo[6]fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno[l,2,3-
cJjpyrene
Benzo[g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Half-life (years),
(In2)/365*a!
NS
NS
NS
NS
NS
-9.5 ±4.7*
NS
NS
NS
NS
NS
NS
NS
NS
Limited data
8.2 ± 2.8
NS
Peak-to-valley
ratio, e a2
3.4 ± 1.2
4.9 ± 1.3
4.6 ± 1.5
5.6 ± 1.2
5.3 ± 1.2
3.9 ± 1.2
4.9 ± 1.2
4.0 ± 1.2
6.0 ± 1.2
4.5 ± 1.2
4.9 ± 1.2
4.4 ± 1.2
5.1 ± 1.2
4.7 ±1.1
5.2 ± 1.2
5.3 ± 1.2
Maximum
date
(± days)
Febll±8
Feb 17 ± 8
Feb 3 ± 7
Feb 20 ± 7
Feb 11 ±6
Feb 1 ± 7
Feb 5 ± 6
Feb 5 ± 5
Feb 5 ± 5
Feb 6 ± 7
Feb 5 ± 5
Feb 4 ± 6
Feb 1 ± 5
Jan 31 ± 5
Jan 30 ± 6
Feb 5 ± 5
No. of
detects
80
82
45
83
81
82
76
83
83
73
80
80
80
81
29
65
83
Average
cone. (ng/L)
1.3 ±0.1
6.3 ±0.6
0.3 ±0.0
8.1 ±0.7
4.6 ±0.4
1.3 ±0.1
1.6 ±0.1
3.5 ±0.3
5.3 ±0.5
1.9 ±0.2
2.5 ±0.2
2.3 ±0.2
3.6 ±0.3
3.0 ±0.2
0.5 ±0.1
1.5±0.1
43 ±3.5
r2
0.39
0.38
0.52
0.46
0.55
0.46
0.59
0.64
0.68
0.53
0.58
0.54
0.61
0.62
0.64
0.64
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
Table BS4. Fit parameters for PAH concentrations in precipitation at Sturgeon Point
PAHs
Half-life
(years)
(In2)/365*a!
Peak-to-
valley ratio,
Maximum date
(± days)
No. of
detects
Average Cone. r2
(ng/L)
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
chrysene
B enzo [b ] fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -cc/jpyrene
Benzo[g/z/]perylene
Dibenz [a, h] anthracene
Coronene
EPAH
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
2.6 ± 1.1
3.6 ± 1.2
4.3 ± 1.3
4.0 ± 1.2
4.0 ± 1.2
3.2 ± 1.2
4.0 ± 1.2
4.0 ± 1.2
3.6 ± 1.2
3.2 ± 1.2
3.6 ± 1.2
3.3 ± 1.2
3.2 ± 1.2
3.5 ± 1.2
2.4 ± 1.2
3.8 ± 1.2
3.5 ± 1.2
Feb 18 ± 7
Feb 20 ± 7
Feb 10 ± 7
Feb 12 ± 7
Feb 13 ± 8
Feb 1 ± 9
Feb 16 ± 7
Feb 6 ± 8
Feb 11 ±8
Feb 14 ± 8
Feb 13 ± 7
Feb 14 ± 8
Feb 8 ± 10
Feb 8 ± 8
Feb 24 ±11
Jan 31 ± 7
Feb 10 ± 8
85
85
73
85
85
83
81
85
85
82
84
84
84
83
65
81
85
2.3 ±1.4
13 ±1.0
0.7 ±0.1
19 ±1.5
9.4 ±0.8
1.3±0.1
3.4 ±0.3
6.8 ±0.6
10 ±0.9
3. 5 ±0.3
4.5 ±0.3
4.6 ±0.4
6.7 ±0.6
5. 3 ±0.4
l.OiO.l
2.0 ±0.2
90 ±6.9
0.43
0.45
0.47
0.45
0.39
0.34
0.47
0.43
0.36
0.37
0.41
0.35
0.30
0.40
0.27
0.46
0.40
45
-------
Table BS5. Fit parameters for PAH concentrations in precipitation s at Chicago
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
chrysene
Benzo[6]fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -c
-------
Table BS7. Fit parameters for PAH concentrations in precipitation at Point Petre
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Chrysene
Benzo[6]fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -«/]pyrene
Benzo[g/z/]perylene
Dibenz [a, h] anthracene
Perylene
Coronene
EPAH
Half-life
(years),
(In2)/365*a!
6.3 ±2.1
4.7 '±1.1
Limited data
6.3 ± 1.7
4.7 ± 1.0
Not available
NS
NS
NS
NS
NS
NS
NS
NS
Limited data
Limited data
Not available
NS
Peak-to-
valley ratio,
62a2
4.0 ± 1.2
4.6 ± 1.2
5.5 ± 1.2
4.6 ± 1.2
4.0 ± 1.4
4.2 ± 1.4
7.2 ± 1.3
9.0 ± 1.3
4.6 ± 1.4
4.5 ± 1.4
4.7 ±1.3
4.3 ± 1.3
6.2 ± 1.2
Maximum
date (± days)
Jan 23 ± 8
Jan 23 ± 7
Jan 23 ± 6
Jan 13 ± 7
Jan 11 ± 12
Jan 18 ± 12
Jan 10 ± 7
Jan 13 ± 7
Jan 18 ± 11
Jan 12 ±11
Jan 24 ± 8
Jan 26 ± 9
Jan 22 ± 6
No. of
detects
72
81
18
80
81
38
38
55
54
37
59
69
61
24
17
81
Average cone.
(ng/L)
2.3 ±0.3
17 ±2.3
1.9 ±0.8
18 ±2.2
10 ±1.2
2.2 ±0.3
7.5 ±1.0
10 ±1.5
5.9 ±0.8
4.9 ±0.6
3.1 ±0.3
4.6 ±0.4
4.4 ±0.4
0.6 ±0.1
0.6 ±0.1
76 ±8.0
r2
0.43
0.49
0.60
0.55
0.42
0.38
0.52
0.56
0.46
0.28
0.41
0.36
0.55
47
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Appendix C. Temporal Trends of Polychlorinated Biphenyls (PCBs) in
Precipitation and Air at Chicago
Published in Environmental Science & Technology, 2006, 40, 1178-1183.
48
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Temporal Trends of Polychlorinated Biphenyls (PCBs) in
Precipitation and Air at Chicago
Ping Sun, Ilora Basu, and Ronald A Kites*
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 USA
* Corresponding Author Email: hitesr@indiana.edu
Brief
Concentrations of PCBs in precipitation and air in Chicago declined from 1997 to 2003
with half-lives of about 7 years.
Abstract
Polychlorinated biphenyl (PCBs) concentrations in precipitation (1997 to 2003) and in
the atmospheric gas phase (1996 to 2003) collected in Chicago are reported. These data were
obtained as part of the Integrated Atmospheric Deposition Network (IADN). For comparison,
PCB concentrations at a remote site, Sleeping Bear Dunes on the northeastern shore of Lake
Michigan, are also reported. Much higher PCB concentrations in both precipitation (7.1 ± 0.9
ng/L) and the gas phase (1.4 ±0.1 ng/m3) at Chicago compared to Sleeping Bear Dunes (1.1 ±
0.1 ng/L and 0.1 ± 0.08 ng/m3, respectively) indicate that Chicago is a source of PCBs to the
Great Lakes. A long-term decreasing trend of PCB concentrations in precipitation was observed
at Chicago with a half-life of 6.8 ± 3.1 years. The corresponding half-life for PCB
concentrations in the gas phase was 7.7 ±1.1 years. The significant long-term decrease of PCB
concentrations in precipitation and the gas phase in Chicago suggests that regulatory efforts are
working, at least in this city.
Introduction
Production and sales of polychlorinated biphenyls (PCBs) were banned in the United
States in 1976. However, PCBs are still being emitted into the atmosphere through primary (e.g.
vaporization from products containing PCBs) or open burning of products containing PCBs or
secondary (e.g. water-air exchange) processes (7). In addition, PCBs are transported from
sources to background areas through advective and deposition processes (2-4).
The Integrated Atmospheric Deposition Network (IADN) was established in 1990 to
monitor PCBs (and many other contaminants) in the air and precipitation around the Great Lakes
(5). IADN has published several studies on PCBs in air (6-9) and precipitation (10,11) at remote
sites near the lakes; these include Eagle Harbor, near Lake Superior; Sleeping Bear Dunes, near
Lake Michigan; Sturgeon Point, near Lake Erie; and Point Petre, near Lake Ontario. In these
studies, long-term decreasing concentrations of PCBs have been observed in both air and
precipitation. For example, Buehler and co-workers reported that atmospheric PCB
concentrations decreased with a half-life of 10 years at Sleeping Bear Dunes and 6 years at Eagle
Harbor. These conclusions were based on IADN data up to the year 2000 and supplemental
historical data going back to 1977 (7). Simcik and co-workers reported on temporal trends of
PCBs in precipitation samples collected from the IADN sites during the period 1991 to 1997
49
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(77). Their results showed that these PCB concentrations decreased during this time period at
Sleeping Bear Dunes and at Point Petre with half-lives of 7 and 4 years, respectively. However,
no significant decreases in the precipitation PCB concentrations were observed in samples
collected near Lakes Superior or Erie. In general, these reported declines of PCBs in air and
precipitation agreed well with the data reported for aquatic biota (72,73).
Previous studies have shown that industrial or urban centers are PCB sources (14,15).
For example, high concentrations of PCBs in air and precipitation in Chicago have been reported
previously (16-18). Most of these measurements were on a short term basis (16,17) or over a
single year (19,20). Detailed temporal trends of PCB concentrations in Chicago, particularly in
precipitation, have not yet been reported. In this paper, we report on the temporal trends of PCB
concentrations in precipitation collected in Chicago over the period 1997 to 2003 and in air
collected in Chicago over the period 1996 to 2003. For comparison, PCB concentrations at
Sleeping Bear Dunes, a remote site located approximately 400 km north-northeast of Chicago are
also reported.
Experimental
Sampling methodology. Samples in Chicago were collected at the Illinois Institute of
Technology, approximately 1.6 km from the shore of Lake Michigan. The sampling site is
located on the roof of the Environmental Engineering Building, which is a four-story building
built in 1948. Samples at Sleeping Bear Dunes were collected at the Sleeping Bear Dunes
National Lakeshore approximately 1.5 km from the shore of Lake Michigan. This is a
background site located near the northeastern shore of the lake. The IADN website
(www.msc.ec.gc.ca/iadn/) provides detailed information on these two sites.
MIC automated wet-only samplers (MIC Co., Thornhill, ON) were used to collect
precipitation samples. The detailed sampling procedure has been reported before by Carlson and
co-workers (27). Briefly, each sampler consists a 46 x 46 cm shallow stainless steel funnel
connected to a 30 cm long by 1.5 cm i.d. glass column (ACE Glass, Vineland, NJ) packed with
XAD-2 resin. The sampler is normally covered; the start of a precipitation event is sensed by a
conductivity grid located outside the sampler, which signals the cover to open. Precipitation
flows through the XAD-2 column, which collects both particle and dissolved organic
compounds. Precipitation samples were integrated over 28 days. The precipitation volume that
passed through the resin column was recorded to calculate the concentrations. Breakthrough of
PCBs was studied by analyzing the effluent rain water from the XAD column. No PCBs were
detected. Recovery of PCBs was studied by spiking the columns with PCB surrogate standards
before sampling. About 75% of the PCBs were recovered.
Modified Anderson Hi-Vol air samplers (General Metal Works, model GS 2310) were
used to collect air samples for a 24 hour duration at a frequency of once every 12 days. Air was
pulled into the sampler through Whatman quartz micro-fiber filters (QM-A, 20.3 x 25.4 cm) at a
flow rate of 34 m3/hr and passed through dry Amberlite XAD-2 resin (Supelco, Bellefonte, PA;
20-60 mesh, 330 m2/g surface area) in a stainless steel cartridge. Particles in the air were
retained on the quartz filters, and gas-phase components were adsorbed on the XAD resin. Our
preliminary results from 1993 to 1995 showed that although higher molecular weight PCB
congeners tended to partition onto the particle phase, the total PCB concentrations in the particle
phase were about 5-10% of the total PCBs in atmosphere. Therefore, measurements of particle-
bound PCB concentrations were stopped in 1997.
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Analytical methodology. The wet XAD-2 cartridges containing PCBs in precipitation
and the dry cartridges containing gas phase PCBs were sent to Indiana University for analysis.
The XAD-2 resin was Soxhlet extracted for 24 h using a 1:1 (v/v) mixture of hexane and
acetone. The extract was then concentrated by rotary evaporation. For the precipitation extracts,
the water layer was separated, back extracted with hexane, and added to the original extract. The
concentrated extract was then fractionated on a 3.5% (w/w) water-deactivated, silica gel column.
Hexane was used to elute the PCBs. The extracts were further concentrated by N2 blow-down to
~1 mL and spiked with PCB congeners 30 and 204 as internal standards for quantitation. The
PCBs were analyzed on a Hewlett-Packard (HP) 6890 gas chromatograph with a 63Ni electron
capture detector. A DB-5 column (J & W Scientific; 60 m x 250 |j,m i.d.; film thickness, 0.10
|j,m) was used for PCB analysis.
Quality control and quality assurance procedures were followed to ensure data accuracy.
The detailed procedures are described in the IADN Quality Assurance Program Plan and in the
IADN Quality Control Project Plan (22). Surrogate standards (PCB congeners 14, 65, and 166)
were spiked into each sample prior to extraction to monitor recovery. The average percent
recoveries for the surrogates were 83-100% for the gas phase samples and 73-87% for the
precipitation samples (23). One matrix spike experiment was performed with every 20 samples
to assure high extraction efficiency; average ZPCB recoveries for the gas phase and precipitation
samples were 85 ± 5% and 77 ± 6%, respectively. Laboratory blanks were also checked
regularly. Generally, laboratory blank values were less then 5% of actual sample values.
Precipitation field blanks were not collected at Chicago. However, the levels of PCBs in the gas
phase field blanks in Chicago were less than 5% of the levels measured in the actual samples.
Assuming 100% capture efficiency at Chicago, the field blank values in precipitation should be,
on average, less than 5% of the sample values; therefore, none of the PCB concentrations
reported here have been blank corrected.
In this paper, ZPCB represents a suite of 84 PCB congeners monitored by the IADN.
Each congener contributes more than 1% to the total PCB mass for at least one site monitored by
IADN. The lexicologically important congeners (77, 105, 108, 126, 128, 138, 156, 169, and
170) are also included. The detailed list of congeners is available in the Technical Summary of
Progress of the IADN project, 1997-2002 (24).
Data analysis. The monthly concentrations (Cp) of ZPCB in precipitation were fitted by
the following time-dependent function to study the temporal trend
InC =a0+a1t + a2sin — + a4 (1)
Ia3 )
where t is the time in Julian days relative to January 1 1990, ao is an intercept (unitless), a\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, a2 is a periodic amplitude (unitless), a3 is the length of the period (in days), and a4 is the
periodic offset (in days). If a\ was significant (p < 0.05), either a decreasing (a\ < 0) or
increasing (a\ > 0) trend in the ZPCB concentrations could be determined over this sampling
period.
Atmospheric temperature variations affect the gas phase PCB concentrations, and these
variations must be removed before a valid trend can be determined. The temperature correction
procedure was given by Cortes and co-workers in detail (25). Briefly, the gas phase
concentration of each PCB congener are first converted to a partial pressure (P) using the ideal
51
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gas law. These partial pressures are then corrected to a reference temperature of 288 K by
application of the Clausius-Clapeyron equation:
R {T
where exp is the exponential function, AH is a characteristic phase-transition energy (in kJ/mol),
R is the gas constant, and Tis the mean temperature during the 24-hour sampling period (in K).
The value of AH was determined by a linear regression of the natural logarithm of the partial
pressure (P) vs. the reciprocal of T. The natural logarithms of the corrected partial pressures at
288 K (called here P28g) of ZPCB were then regressed vs. t to determine a temporal trend, if any.
Results and Discussion
Concentrations of PCBs in precipitation and air at Chicago Concentrations of ZPCB
in precipitation and in the gas phase at Chicago are shown annually in Figure Cl as a function of
sampling year. ZPCB concentrations at Sleeping Bear Dunes measured over the same time
period are also shown in Figure Bl for comparison. Note the concentration scale is logarithmic.
The ZPCB concentrations in precipitation ranged from 1.5 to 35 ng/L at Chicago and 0.1 to 6.1
ng/L at Sleeping Bear Dunes. In the gas phase, ZPCB concentrations were from 0. 1 to 9.5 ng/m3
at Chicago and from 0.04 to 0.76 ng/m3 at Sleeping Bear Dunes. Clearly, ZPCB concentrations
in both precipitation and in the gas phase are consistently higher in Chicago than at Sleeping
Bear Dunes. Student's ?-tests were conducted to compare the ZPCB concentrations at these two
sites year by year, and the detailed statistical results are given in Table BS1. These results show
that, in each year, the ZPCB concentrations at Chicago are significantly higher than those that at
Sleeping Bear Dunes (p < 0.05). On average, precipitation concentrations are 7 times higher in
Chicago, and gas phase concentrations are 12 times higher in Chicago, compared to Sleeping
Bear Dunes.
The high concentrations of ZPCB in Chicago indicate a strong source of PCBs in this
urban area. PCBs were used heavily in urban areas from 1931 until their production and sales
were banned in the U.S. in 1976. However, the continuing use of PCBs in exempt applications
(e.g. transformers and capacitors) is still allowed. Thus, there are still many potential PCB
sources in urban areas, such as Chicago, even 30 years after domestic production ceased. Hsu
and co-workers used receptor modeling and field sampling to locate PCB sources in Chicago
(26\ and their results showed that there are potentially major PCB sources to the south and
southwest of Chicago that could contribute to PCB concentrations at the Chicago site. These
potential PCB sources include transformers, capacitors, municipal sludge drying beds, and
landfills.
Due to their volatilization and stability, PCBs emitted from source areas can be
transported to remote areas such as Sleeping Bear Dunes. The average concentration of ZPCB in
precipitation at Sleeping Bear Dunes is 1.1 ±0.1 ng/L. However, the calculated concentration
ratio between the field blanks and the precipitation samples was 0.72 ± 0.06 at this site
suggesting the concentrations reported above may not be accurate but should be considered
upper bounds. Similarly low concentrations of PCBs have been reported at other remote sites.
For example, Franz and Eisenreich sampled precipitation at three remote sites along the eastern
shore of Green Bay, Lake Michigan, from April 18, 1989 through May 15, 1990 and measured
86 PCB congeners (4). Their reported mean ZPCB concentration was 2.2 ng/L (4). In another
study, a concentration of 1.3 ng/L for precipitation phase PCBs (the sum of 53 congeners) was
52
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measured in southeastern Sweden from 1993 to 1995 (27). In New Jersey, ZPCB concentrations
at rural sites were in the range of 0.30-0.50 ng/L from 1998 to 1999 (25).
The average concentration of ZPCB in precipitation in Chicago is 7.1 ± 0.9 ng/L, which
is similar to concentrations reported for other cities. For example, Offenberg and Baker reported
ZPCB concentrations in Chicago precipitation ranging from 4.1 ng/L (on January 19, 1995) to
189 ng/L (on July 21, 1994) (16). Since these samples were event-based samples, the high
concentration on July 21, 1994 is likely an exceptional case. PCB concentrations in precipitation
have also been measured in New Jersey by the New Jersey Atmospheric Deposition Network
(NJADN) (25). The highest PCB concentrations were observed at the urban-industrial sites (13
± 2.8 ng/L and 3.9 ± 0.72 ng/L at Camden and Jersey City, NJ, respectively) from 1998 to 1999.
Thus, our results for Chicago are similar to those measured at other urban sites in North
America.
The wet deposition fluxes (ng-m~2d~1) of suite PCB at Chicago and Sleeping Bear Dunes
were calculated by multiplying the 28-day integrated concentration (ng/L) by the precipitation
volume (L) and dividing by the sampling time (28 days) and the surface area (0.212 m2) of the
collection funnel. In Chicago, the average wet deposition flux was 8.4 ng-m~2d~1, which is about
6 times higher than 1.4 ng-m~2d~1 at Sleeping Bear Dunes. These calculated values are similar to
those reported by other studies (7,25). For example, NJADN reported a wet flux of
approximately 0.8 ng-m~2d~1 at Pinelands, a background site, and 11 ng-m~2d~1 at Jersey City, an
urban site (25).
The average concentration of ZPCB in the gas phase at Sleeping Bear Dunes is 0.1 ± 0.08
ng/m3 over our study period. Similar concentrations have been reported at other remote sites.
Sampled in July 1997, an average concentration of 0.55 ng/m3 for ZPCB was observed near the
Chesapeake Bay (3). Motelay-Massei and coworkers sampled air in Egbert, a rural site located
north of Toronto from June 2000 to July 2001. Their results showed a range of 0.06 to 0.27
ng/m3 for ZPCB (sum of 13 PCB congeners) concentrations (29).
From 1996 to 2003, the concentration of ZPCB in the gas phase in Chicago ranged from
0.1 to 9.5 ng/m3 with a mean of 1.4 ± 0.1 ng/m3, which was similar to concentrations previously
reported for Chicago. For example, Pirrone and co-workers reported an average PCB
concentration of 2.1 ± 1.2 ng/m3 from July 8 to August 9, 1991 without providing information on
the congener profile (20). Tasdemir and co-workers observed an average ZPCB (sum of 50
congeners) concentration of 1.9 ± 1.7 ng/m3 from June to October, 1995 (30). Simcik et al.
reported a range of 0.27 to 14 ng/m3 for ZPCBs (sum of 87 congeners) during May and July
1994 and January 1995 (77). In addition, a range of 2.4 to 4.1 ng/m3 for annual average ZPCB
concentrations in the gas phase in Chicago from 1997 to 1999 was also reported (5).
The ZPCB gas phase concentrations at Chicago measured in this study are similar to
those observed at other urban sites including New Jersey, Milwaukee, and Baltimore. For
example, the concentration of ZPCB ranged from 0.02 to 3.4 ng/m3 in June, 1996, for samples
collected in Baltimore, MD (31). Measurements by the NJADN, gave PCB concentrations in the
gas phase at Camden and Jersey City from October 1997 to May 2001 of 3.2 and 1.3 ng/m3,
respectively (32). Most recently, Wethington and Hornbuckle demonstrated that Milwaukee, WI
was a potential source of atmospheric PCBs to Lake Michigan (33). The average ZPCB (sum of
88 congeners) gas phase concentration here was 1.9 ± 0.78 ng/m3 during June of 2001. The
range of PCB concentrations measured in Chicago falls in the range observed in these other
cities in North America.
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Temporal trends. Figure C2 shows the long-term trends of Chicago ZPCB
concentrations in both precipitation (top) and in the gas phase (bottom). The scatter of ZPCB
concentrations in the precipitation phase may indicate the effects of storm type, wind direction of
the prevailing storm track, and other complex interactions between the atmospheric gas phase
and precipitation (1,4). In the precipitation regression (see equation 1), the terms a2, a3, and a4
were not significant (p > 0.05), indicating the seasonal effects were not statistically significant.
The a\ term indicated that ZPCB concentrations significantly decreased from 1997 to 2003 with
a half-life of 6.8 ±3.1 years. In the gas phase, ZPCB concentrations also significantly decreased
from 1996 to 2003 with a half-life of 7.7 ±1.1 years. Note the half-lives in precipitation and in
the gas phase are statistically the same.
Previous studies have shown that PCBs concentrations in Chicago had been declining
faster. For example, over the period 1993-1997, gas phase PCBs concentrations declined with a
half-life of 2.7 ±1.3 years (34). Offenberg and Baker reported a 3 year half-life for PCB
concentrations in Chicago based on air samples collected from 1994-1995 (35). These reported
half-lives are somewhat faster than reported here (~7 years) for the time period from 1997 to
2003. A slower rate of decrease for PCB concentrations in recent years may indicate that
atmospheric PCB concentrations are now approaching a steady state after a rapid decline from
1970 to 1995 (7,36). This suggestion is supported by the observation that PCB concentrations in
Great Lakes lake trout declined rapidly between 1974 and 1986 but have not changed much since
then (37). On the other hand, other studies reported PCB concentration half-lives (in water and
biota) on the order of 8 ± 2 years (11,35). Buehler and co-workers reported a half-life of 8.3 ±
1.5 years for PCBs in the atmospheric gas phase at Sleeping Bear Dunes for IADN samples
collected up to 2001 (6). No newer data are available on trends of PCBs, particularly around
Chicago.
Long-term decreasing trends for PCB concentrations in precipitation have been observed
at some locations around the Great Lakes (10,11); however, this is the first time that a decreasing
trend in Chicago precipitation has been reported. Simcik and co-workers reported on the
temporal trends of ZPCB (sum of 98 congeners) in precipitation collected from the IADN sites
from 1991 to 1997. These concentrations showed significant decreases at Sleeping Bear Dunes
with a half-life of 6.9 ± 3.5 years (77). In our study, if we ignore the relatively high blank levels,
a similar decreasing trend for PCB concentrations in precipitation was also observed at this
remote site from 1997 to 2003. However, as mentioned above, the concentrations we measured
in these precipitation samples were close to those in the field blanks, and thus, a numerical trend
for ZPCB concentrations in Sleeping Bear Dunes precipitation is not reported here.
The decrease of PCB concentrations in both the gas phase and precipitation at Chicago
may be due to efforts aimed at PCB reduction in the Great Lakes area. On April 7, 1997, the
"Canada-United States Strategy for the Virtual Elimination of Persistent Toxic Substances in the
Great Lakes Basin" (the so-called Binational Toxics Strategy) was signed by the environmental
administrators of the U.S. and Canada. This strategy targets many toxic substances for virtual
elimination, including PCBs. Under this Strategy, the U.S. EPA seeks a 90% reduction of PCBs
used in electrical equipment by 2006 and assurance that all PCBs retired from use are properly
managed and disposed (38). Numerous successful reduction activities have been reported in the
2004 Great Lakes Binational Toxics Strategy Report. For example, the International Steel Group
has removed from service and destroyed PCB-containing equipment from several facilities
including ones in Burns Harbor, Indiana, which is close to Chicago. ComEd, a subsidiary of
Exelon Energy, operating in northern Illinois close to Chicago, has removed 95% of all PCB-
54
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containing capacitors at its substations (38). In Chicago, the U.S. EPA and local partners
established a PCB Clean Sweep program in 1999 to collect PCB-containing articles then in use.
This program collects a wide range of PCB-containing articles, including old light ballasts,
switches, transformers, and small capacitors, and disposes of these items properly (39). All of
these efforts may have caused the decline of PCB concentrations in the gas phase and in
precipitation that we have observed in Chicago.
Previous work has shown that there were no significant temporal trends of PCB wet
deposition fluxes at Chicago or Sleeping Bear Dunes from 1996 to 2000 (40). Currently, IADN
is working on expanding this loading analysis up to 2003. Preliminary calculations based on the
data presented here indicate that there is no temporal trend for PCB wet fluxes at either Chicago
or Sleeping Bear Dunes (see Figure BS1), but these results will be confirmed by a more
complete study that will be available soon.
Congener profile. A PCB congener profile is the concentration of each measured
congener (or chromatographically un-resolvable group of congeners) divided by the total
concentration of all PCBs in the sample. These profiles are usually expressed in percent. Figure
C3 shows the average congener profile for PCBs in the gas phase and in precipitation from
Chicago and from Sleeping Bear Dunes. The small standard errors (and other statistical tests)
suggest that none of these profiles have changed much over the years.
The PCB profiles for the gas phase in Chicago and in Sleeping Bear Dunes are virtually
identical (r2 = 0.91), suggesting that the composition of PCB congeners in the atmosphere is
uniform even though the absolute concentrations vary dramatically. On the other hand, the PCB
profiles in precipitation from Chicago and Sleeping Bear Dunes differ somewhat (r1 = 0.67),
suggesting that the composition of PCB congeners in precipitation can be quite variable. These
differences mat be due to spatial PCB concentration gradients, different heights of rain clouds, or
differences in total suspended particulate levels, all of which can alter the atmospheric
gas/particle distribution and influence the PCB congener profiles in precipitation (4,41,42).
Comparing the PCB profiles on a site specific basis, we notice that the PCB composition
in precipitation is enriched by more highly chlorinated congeners in both cases. For example,
the more highly chlorinated congeners 110, 132+153+105, and 163+138 are dominant in the
Chicago precipitation samples, while less chlorinated congeners 18, 33, and 52 are more
dominant in the Chicago gas phase samples. This indicates that, compared with less chlorinated
congeners, the more highly-chlorinated PCB congeners are more efficiently removed from the
atmosphere by wet deposition (41).
The PCB congener distributions in our study are similar to profiles observed in rain
samples collected by NJADN: Van Ry and co-workers extensively sampled gas, particle, and
precipitation samples from August 7-11, 2000 and found a dominance of heavy PCB congeners
in rain samples (25). By comparing PCB profiles in rain, particle, and gas phases, they
concluded that wet washout of particle-bound PCBs is the dominant removal mechanism (16,28).
We did not analyze for PCBs in particle-phase samples in our study; thus, the distribution of
PCB congeners in the particle phase could not be measured.
Although more highly chlorinated congeners were also present in the precipitation
samples at Sleeping Bear Dunes, their contribution to ZPCB was lower compared to that in
Chicago: The contribution of congeners heavier than penta-chlorinated PCB to ZPCB is 42 ±
5% at Sleeping Bear Dunes and 57 ± 6% at Chicago. A study by Mandalakis and Stephanou on
wet deposition of PCBs in the eastern Mediterranean showed higher contributions of lower
molecular weight congeners (e.g tri- and tetra- chlorinated congeners) to ZPCB in rain samples
55
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(7). According to Van Ry et al. (25), the relative importance of higher chlorinated PCBs in
environmental samples decreases with the increasing distance away from sources because
heavier congeners tend to be associated with particles and have correspondingly lower residence
times. This suggestion is compatible with our findings.
Acknowledgments
We thank Team IADN (including Karen Arnold and Jennifer Hamilton) for data
acquisition and the U.S. Environmental Protection Agency's Great Lakes National Program
Office for funding (Grant GL995656, Melissa Hulting, project monitor).
Supporting Information Available
The supporting Information contains a table of Student's t-tesi results from comparison of
gas and precipitation phase PCB concentrations between Chicago and Sleeping Bear Dunes, a
figure of temporal trends of wet deposition fluxes at Chicago and Sleeping Bear Dunes. These
materials are available free of charge via the Internet at http://pubs.acs.org.
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29. Motelay-Massei, A.; Harner, T.; Shoeib, M.; Diamond, M.; Stern, G.; Rosenberg, B. Use
passive air-sampler to assess urban-rural trends for persistent organic pollutants and
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polycyclic aromatic hydrocarbons. 2 Seasonal trends of PAHs, PCBs, and Organochlorine
pesticides. Environ. Sci. Technol. 2005, 39, 5763-5773.
30. Tasdemir, Y.; Vardar, N.; Odabasi, M.; Holsen, T. M. Concentrations and gas/particle
partitioning of PCBs in Chicago. Environ. Pollut. 2004, 131, 35-44.
31. Offenberg, J. H.; Baker, J. E. Influence of Baltimore's urban atmosphere on organic
contaminants over the northern Chesapeake Bay. J. Air Waste Manage. Assoc. 1999, 49,
959-965.
32. Totten, L. A.; Gigliotti, C. L.; Vanry, D. A.; Offenberg, J. H.; Nelson, E. D.; Dachs, J.;
Reinfelder, J. R.; Eisenreich, S. J. Atmospheric concentrations and deposition of
polychlorinated biphenyls to the Hudson River Estuary. Environ. Sci. Technol. 2004, 38,
2568-2573.
33. Wethington, D. M.; Hornbuckle, K. C. Milwaukee, WI, as a source of atmospheric PCBs to
Lake Michigan. Environ. Sci. Technol. 2005, 39, 57-63.
34. Simcik, M. F.; Basu, L; Sweet, C. W.; Kites, R. A. Temperature dependence and temporal
trends of polychlorinated biphenyl congeners in the Great lakes atmosphere. Environ. Sci.
Technol. 1999, 33, 1991-1995.
35. Offenberg, J. H.; Baker, J. E. PCBs and PAH in southern Lake Michigan in 1994 and 1995:
Urban atmospheric influences and long-term declines. J. Great Lakes Res. 2000, 26, 196-
208.
36. Schneider, A. R.; Stapleton, H. M.; Cornwell, J.; Baker J. E. Recent declines in PAH, PCB,
and toxaphene levels in the northern Great Lakes as determined from high resolution
sediment cores. Environ. Sci. Technol. 2001, 35, 3809-3815.
37. De Vault, D. S.; Hesselberg, R.; Rodgers, P. W.; Feist, T. J. Contaminant trends in lake
trout and walleye from the Laurentian Great Lakes. J. Great Lakes Res. 1996, 22, 881-895.
38. Great Lakes Binational Toxic Strategy 2004 Progress Report, http://www.binational.net
39. Cook County PCB and Mercury Clean Sweep Program. PCB & Mercury Fact Sheet.
http://www.erc.uic.edu/cleansweep/
40. Atmospheric Deposition of Toxic Substances to the Great Lakes: IADN Results Through
2000, www.epa.gov/glnpo/monitoring/air/iadn/iadn.html
41. Bidleman, T. F. Atmospheric processes: wet and dry deposition of organic compounds are
controlled by their vapor-particle partitioning. Environ. Sci. Technol. 1988, 22, 361-367.
42. Ligocki, M. P.; Leuenberger, C. Pankow, J. F. Trace organic compounds in rain-Ill.
Particle scavenging of neutral organic compounds. Atmos. Environ. 1985, 19, 1619-1626.
58
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Figure Cl. ZPCB concentrations in precipitation (top) and in the gas phase (bottom) in Chicago
(yellow) and at Sleeping Bear Dunes, Michigan (green). The horizontal lines represent the 10th,
50th, and 90th percentiles; the red line is the mean; the boxes represent the 25th to 75th percentiles;
and outliers are shown individually.
59
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100
1996 1998
2000
2002 2004
Figure C2. Long-term trend of ZPCB concentrations in precipitation (top) and in the gas phase
(bottom) at Chicago. Red lines indicate regressions of the data as shown. A statistically
significant long-term decrease is observed in both cases; the half-lives for PCB concentrations in
precipitation and the gas phase are 6.8 ± 3.1 and 7.7 ± 1.1 years, respectively.
60
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Supporting Information
Temporal Trends of Polychlorinated Biphenyls (PCBs) in
Precipitation and Air at Chicago
Ping Sun, Ilora Basu, and Ronald A Kites*
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 USA
* Corresponding Author Email: hitesr@indiana.edu
Table CS1. Student's t-tesi results for the comparison of PCB concentrations between Chicago
and Sleeping Bear Dunes
Year
1996
1997
1998
1999
2000
2001
2002
2003
t
4.20
7.21
6.15
6.28
9.03
6.78
6.26
6.02
Gas phase
P
0.0001
0.0001
0.0001
O.0001
O.0001
O.0001
O.0001
O.0001
df*
53
43
52
52
56
57
58
55
t
2.12
3.49
3.78
4.22
2.67
5.47
3.57
Precipitation
P
0.048
0.002
0.001
0.0006
0.01
O.0001
0.002
df
19
21
18
17
21
23
21
*df: degree of freedom
62
-------
20
15
10
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^=0.0026
% V
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%• •
•••
Sleeping Bear Dunes
r2 = 0.0034
1996 1998 2000 2002 2004
Figure CS1. Temporal trends of wet deposition flux of PCBs in Chicago and Sleeping Bear
Dune (bottom).
63
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Appendix D. Temporal and Spatial Trends of Organochlorine Pesticides in
Great Lakes Precipitation
Published in Environmental Science & Technology, 2006, 40, 2135-2141.
64
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Temporal and Spatial Trends of Organochlorine Pesticides in
Great Lakes Precipitation
Ping Sun,1 Sean Backus,2 Pierrette Blanchard,2 and Ronald A Kites*1
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 USA
and
Environment Canada
4905 Dufferin Street
Toronto, ON M3H 5T4 Canada
* Corresponding Author Email: hitesr@indiana.edu
Brief
Concentrations of organochlorine pesticides in Great Lakes precipitation were analyzed
for temporal and spatial trends from 1997 to 2003.
Abstract
Organochlorine pesticide concentrations in precipitation samples collected from 1997 to
2003 at seven Integrated Atmospheric Deposition Network sites around the Great Lakes are
reported. The 28-day volume weighted mean concentrations of several pesticides, including y-
hexachlorocyclohexane (HCH), endosulfan, hexachlorobenzene, chlordane, and DDE, showed
significant seasonal trends. For current-use pesticides (endosulfan and y-HCH), their
concentrations peaked in late spring to summer just after their agricultural application. For the
banned pesticides, higher concentrations were observed in the winter due to their enhanced
partitioning to particles and scavenging by snow. Long-term decreasing trends were observed
for several pesticides such as y-HCH and DDE. On the other hand, P-HCH showed significant
increasing concentrations as a function of time at Brule River, Eagle Harbor, and Sleeping Bear
Dunes. Generally, Chicago had the highest concentrations for chlordanes, dieldrin, and DDT,
indicating that urban areas could be a source for these compounds to precipitation. For y-HCH
and endosulfans, Point Petre had the highest concentrations due to the application of these
pesticides in the surrounding areas.
Introduction
Founded in 1990, the objectives of the Integrated Atmospheric Deposition Network
(IADN) were to measure the concentrations of persistent organic pollutants, including
polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides, and polycyclic aromatic
hydrocarbons (PAHs) in air and precipitation around the Great Lakes. One special focus of
IADN has been the OC pesticides, many of which were banned in the 1970s in North America
due to their toxicity, environmental persistence, and tendency of bioaccumulate. More than 20
years after their phase-out, these compounds are still present in the environment (1,2).
65
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Long-term monitoring of OC pesticide concentrations has shown decreasing trends in
Great Lakes air (3,4), biota (5,6), water, and sediment (7). Precipitation (both as rain and snow)
is an important pathway for the transport and deposition of OC pesticides. However, long-term
measurements of OC pesticides in precipitation are limited. One study conducted by Chan and
co-workers reported decreasing trends of OC pesticide concentrations in rain and snow collected
in southern Ontario, Canada, over the period of 1986-1991 (8). The concentrations of several
OC pesticides, such as the hexachlorocyclohexanes (HCHs) at some Canadian Great Lakes sites
(e.g. Burlington and Point Petre), decreased over the time period 1986 to 1999 based on another
study by Chan and co-workers (9). Simcik and co-workers reported on the temporal trends of
several organochlorine pesticides (including the HCHs, dieldrin, chlordane, and DDTs) in
precipitation samples collected at three U.S. and two Canadian IADN sites from 1991 to 1997
(JO). Their results showed that the concentrations of many pesticides decreased during this
sampling period, which agreed with the results of Chan and coworkers. Most recently, Carlson
and co-workers reported the annual variations of OC pesticide concentrations in precipitation
collected from 1997 to 2002 at five U.S. IADN sites (77). In this case, the concentrations of
most pesticides did not decrease over time but showed clear seasonality: Higher concentrations
were observed in the summer for current-use pesticides, and higher concentrations were
observed in the winter for most of the banned pesticides.
In this paper, the temporal and spatial trends of OC pesticide concentrations in
precipitation at seven IADN sites (five American and two Canadian), covering the Great Lakes
basin, from 1997 to 2003 will be presented to provide information on the long-term transport and
fate of OC pesticides. This is the fist time that the concentration trends of these organochlorine
pesticides in precipitation have been compared between U.S. and Canadian sites.
Experimental
Precipitation samples were collected at the five U.S. IADN sites (Brule River and Eagle
Harbor, near Lake Superior; Chicago and Sleeping Bear Dunes, near Lake Michigan; and
Sturgeon Point, near Lake Erie) and at two Canadian sites (Burnt Island, near Lake Huron and
Point Petre, near Lake Ontario). The sampling site locations are shown in Figure Dl. The IADN
website (www.smc-msc.ec.gc.ca/iadn) provides detailed information on these sites.
At the five U.S. sites, MIC automated wet-only samplers (MIC Co., Thornhill, ON) were
used to collected precipitation samples. The detailed sampling procedure can be found in
Carlson and co-workers (77). Briefly, a XAD-2 resin column is used to collect both particle and
dissolved organic compounds from precipitation during a given 28-day period. Because all of
the precipitation during this time passes through the XAD-2 column, the concentrations
measured in this study can be considered to be volume weighted mean (VWM) concentrations,
minimizing the bias of high concentrations observed from storm and other events during the 28-
day sampling period. Therefore, the concentrations reported in this paper are monthly VWM
concentrations unless stated otherwise, although the sampling period is a little shorter than one
month.
After sampling, the wet XAD-2 cartridges were returned to Indiana University for the
analysis of the pesticides. The XAD-2 resin was Soxhlet extracted for 24 h using a 1:1 (v/v)
mixture of hexane and acetone. The extract was then concentrated by rotary evaporation and
fractionated on 3.5% (w/w) water-deactivated silica gel. Hexane was first used to elute PCBs,
HCB, p,p'-DDE, and o,p'-DDT. The other pesticides were then eluted with 1:1 hexane in
dichloromethane. The extracts were further concentrated by nitrogen blowdown to ~1 mL and
66
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spiked with PCB-155 as the internal standard. The OC pesticides were analyzed on a Hewlett-
Packard 5890 gas chromatograph with a 63Ni electron capture detector. A DB-5 column (J & W
Scientific; 60 m x 250 |j,m i.d.; film thickness, 0.10 |j,m) was used.
The detailed sampling and analysis procedure at the two Canadian sites were given by
Chan and co-workers (5). A 4-L amber glass bottle was pre-filled with 250 mL dichloromethane
for precipitation sampling in a MIC automated wet-only sampler. Liquid samples were returned
to the National Laboratory for Environmental Testing (NLET) in Burlington, Ontario for
analysis. The samples were kept at 4 °C until analyzed. The aqueous phase was separated from
the dichloromethane solvent in a separatory funnel, and the precipitation volume was measured.
The aqueous phase was then extracted twice with fresh dichloromethane. The combined extracts
were concentrated by rotary evaporation to 3.0 mL, and the solvent was exchanged to isooctane.
The extract was then fractionated on 3.5% (w/w) water-deactivated silica gel. Hexane was first
used to elute PCBs, HCB, />,//-DDE, and o,//-DDT. The other pesticides were then eluted with
1:1 hexane in dichloromethane. The extracts were concentrated by nitrogen blowdown to 1.0
mL. The two fractions were analyzed for pesticides by dual-capillary gas chromatography with
electron capture detection on an Agilent 6890 gas chromatograph. A HP-5 MS (30 m x 250 |j,m
i.d.; film thickness, 0.25 |j,m) column was used as the primary column, and detections were
verified on a HP1-MS (30 m x 250 |j,m i.d.; film thickness, 0.25 |j,m) column.
Quality control and assurance procedures were followed by both laboratories to ensure
data quality. Selected XAD columns were spiked with dibutylchlorendate prior to sampling to
measure the stability of OC pesticides during the 28-day sampling period. The average recovery
was -87%. Assuming a 5% loss of these compounds during extraction and sample preparation,
the loss of OC pesticides during the sampling procedure was less than 10%. At Indiana
University, laboratory mixed pesticide standards were used for matrix spikes. One matrix spike
experiment was performed per two batches of samples to assure extraction efficiency. Surrogate
standards of dibutylchlorendate and 5-HCH were used in each sample to monitor recovery. The
average percent recoveries for the surrogates were 67-117% (72). Surrogate spikes of 1,3-
dibromobenzene and endrin-ketone were added to determine recovery efficiencies at NLET. The
surrogate spike recoveries varied between 82% and 92% (9). Field and laboratory blanks were
also collected regularly. Generally, laboratory blank values were less then 5% of the actual
sample values, while field blank values were on average less than 10% of the sample values;
therefore, the pesticide concentrations reported here have not been blank corrected. In early
2001, a split-sample interlaboratory comparison was conducted to evaluate possible systematic
biases between the participating laboratories (13). No biases were found.
Eighteen pesticides were measured by both Indiana University and NLET. These
pesticides are aldrin, a-chlordane, y-chlordane, />,//-DDT, p,p'-DDD, p,p'-DDE, o,//-DDT,
dieldrin, a-endosulfan, p-endosulfan, endrin, heptachlor epoxide, HCB, a-HCH, P-HCH, y-HCH,
methoxychlor, and /ram--nonachlor. The structures and major properties (including octanol-
water partition coefficients, vapor pressures, and Henry's law constants) of these pesticides are
given in Table DS1 of the Supporting Information.
Results and Discussion
The average concentrations of the OC pesticides in precipitation measured by IADN from
1997 to 2003 are listed in Tables DS2-DS8 of the Supporting Information. The comparison of
selected OC pesticide concentrations between IADN and other studies over the same time period
is given in Table DS9. Overall, pesticide concentrations measured by IADN are within the same
67
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range as those monitored by the New Jersey Atmospheric Deposition Network (NJADN) {14).
For example, the concentrations of/>,//-DDT at Jersey City, NJ were 0.18 to 0.55 ng/L, which
falls in the range of the concentrations measured at Chicago (0.007-18 ng/L). Chlordanes also
showed similar concentrations between the rural sites at Pineland, NJ and at Sleeping Bear
Dunes, MI.
Generally, HCH concentrations were higher in Europe than in the U.S. and Canada,
which may be due to heavier applications of technical HCH and y-HCH in Europe (75). One
study in Brazil showed higher endosulfan concentrations in rainwater compared to IADN, but
this result could be attributed to the heavy use of endosulfan on cotton fields near the collection
site (16). Pesticides measured in precipitation at Senga Bay, Africa, showed lower
concentrations compared to IADN, NJADN, and France, indicating less pesticide usage in this
economically developing region (77).
Spatial trends. The spatially resolved concentrations of the three major technical HCH
isomers for 1997 to 2003 are shown in Figure D2. A one-way analysis of variance was
conducted to compare the average concentrations among these sites. a-HCH concentrations
were about the same at all sites [F = 1.60, P = 0.16 and df = (5, 355), except for Eagle Harbor,
which had slightly higher concentrations [F = 3.51, P = 0.002 and df = (6, 410)]. P-HCH
concentrations were highest in Chicago, followed by similar concentrations at Sleeping Bear
Dunes, Sturgeon Point, Burnt Island, and Point Petre [F = 1.0, P = 0.39 and df = (3, 159)]. Brule
River and Eagle Harbor had the lowest P-HCH concentrations [F = 0.14, P = 0.71 and df = (1,
80)]. Concentrations of y-HCH at Burnt Island and Point Petre were similar [F = 0.04, P = 0.84
and df = (1, 156)] and significantly higher than at Brule River, Eagle Harbor, Chicago, Sleeping
Bear Dunes, and Sturgeon Point, which were all about the same [F = 3.91, P = 0.002 and df = (5,
413)].
The uniformity of a-HCH concentrations in precipitation agrees well with other spatial
studies of this compound (9,18-20). Due to its higher volatility (21) and its slower atmospheric
reaction rate with hydroxyl radicals (22), relative to P-HCH and y-HCH, a-HCH is easily
transported into the atmosphere and has a relatively uniform atmospheric concentration on a
global scale. Unlike a-HCH, P-HCH mostly stays near its source due to its relatively low
volatility and high stability (23). Therefore, the relatively high concentration of P-HCH in
Chicago suggests heavier past usage of technical HCH, which contains 60-70% of a-HCH, 2-
12% of P-HCH, and 10-15% of y-HCH (24), around this urban area before its phase-out in the
1970s.
The relatively high concentrations of y-HCH at the two Canadian sites (Burnt Island and
Point Petre) is not surprising. The technical HCH mixture was banned in North America in
1970s and replaced by purified y-HCH (lindane). Li and co-workers modeled Canadian lindane
usage inventories with high spatial resolution (25). Their results showed that -410 t of lindane
had been applied during the period 1970 to 2000 in the provinces of Quebec and Ontario close to
Lakes Ontario and Huron. In the U.S., lindane was mainly used on fruits and vegetables and as a
seed treatment for grains, legumes, and oilseed crops (75). However, the National Center for
Food and Agricultural Pesticides showed that the U.S. usage of lindane for all crops during the
period of 1992 and 1997 in the Great Lakes area was limited.
The average ratio between a-HCH and y-HCH in precipitation ranged from 0.7 to 0.9 at
the two Canadian sites and at the Chicago site. Given that a-HCH was the major component in
technical HCH, the relatively high concentration of y-HCH may be due to the replacement of
technical HCH with lindane or to the higher water solubility of y-HCH compared to a-HCH (26),
68
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which would cause y-HCH to preferentially partition into precipitation. At the other four U.S.
rural sites, this ratio is between 1.4 and 2.4, indicating an aged HCH source.
The concentrations of endosulfan (a- plus p-endosulfan) showed a clear increasing trend
from the west to east (see Figure D3). Higher concentrations were observed at Point Petre, Burnt
Island, and Sturgeon Point. These higher levels could be explained by the agricultural
application of endosulfan in this area. For example, endosulfan is widely used in Michigan and
New York State (27) and in Ontario (28), particularly in the southern and western portions of the
province.
Precipitation concentrations of chlordane (expressed as the sum of a- and y-chlordane
and trans-nonachlof) were the highest in Chicago followed by Sturgeon Point and Sleeping Bear
Dunes. Brule River, Eagle Harbor, Burnt Island, and Point Petre had similar but lower chlordane
concentrations [F = 1.44, P = 0.23 and df = (3, 277)]. Technical chlordane was introduced in
1947 and phased out in the United Sates in 1988. Before then, chlordane was used
in approximately 20 million U.S. structures, usually as a termiticide, and it has been detected in
the home environment as long as 35 years after its agricultural application (29,30). Although
most abundant in the south and southeastern United States, subterranean termites are found in
every state except Alaska, with moderate to heavy structural infestations in Chicago. Hafner and
Kites suggested that the volatilization from soil in the southern United States was the
predominant source of chlordane to the Great lakes (27). Thus, the higher chlordane
concentration in Chicago is likely due to both historical local applications used to control
termites and the influence of long range transport from areas of high chlordane usage. In fact,
Harner and co-workers have suggested urban areas act as emission sources of chlordane (31).
Moreover, the chlordane concentrations in precipitation monitored by NJADN also showed that
the concentrations at urban sites were higher than at rural sites (14).
The highest precipitation concentrations of DDT (the sum of p,p'-DDT, p,p'-DDE and
p,p'-DDD) were also observed in Chicago, suggesting urban sources. Although technical DDT
(containing >%5%p,p -DDT) was deregistered in the U.S. in 1972 and in Canada in 1973, it was
used extensively in urban aerial sprays to control mosquitoes and other insects in the 1940s and
1950s. Due to its high persistence, these residuals may still act as a source of DDTs to the
atmosphere. One previous study showed higher DDT concentrations in window films collected
in urban areas, with a clear urban to rural trend (32). Similarly, DDT concentrations in
precipitation measured by NJADN also showed higher concentrations at the urban sites
compared to rural sites (14).
The concentrations of/\p'-DDT relative to its degradation products, p,p'-DDE and p,p'-
DDD, showed some interesting relations. On average, the concentrations werep,p -DDT >p,p'-
DDE > p,p'-DDD (see Tables CS2-CS8). The higher/>,//-DDT concentrations in precipitation
do not necessary mean that there are "fresh" DDT sources around the Great Lakes; rather, the
higher p,p '-DDT levels could be the result of the different properties of these compounds (77).
For example,/?,/''-DDE has a higher vapor pressure and a higher Henry's law constant compared
to p,p'-DDT and p,p'-DDD (Table DS1). Therefore, more p,p'-DDE tends to partition into the
gas phase. A study of pesticides in Quebec by Aulagnier and Poissant showed higher DDT
precipitation concentrations compared to DDE despite higher DDE concentrations in the air (26).
We observed the same effect at the IADN sites.
Results for the other pesticides are varied (Tables DS2-DS8). Dieldrin had the highest
concentration in precipitation collected in Chicago. HCB had higher concentrations at the two
Canadian sites, perhaps because HCB was used as an anti-fungal seed dressing for several crops
69
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in Canada until 1972, while it has been banned in the U.S. since 1965. In addition, the re-
volatilization of HCB from Lake Ontario may also contribute to its higher level at Point Petre
(33). The highest concentrations of heptachlor epoxide in precipitation were also observed in
Chicago, which may due to the application of this pesticide for termite control.
Temporal trends. The monthly VWM concentrations (Cp) of a given pesticide in
precipitation collected at a given site were fitted by the following time-dependent function:
InC =a0 +ajt + a2 sin — + a4 (1)
where t is the time in Julian days relative to January 1 1990, ao is an intercept (unitless), a\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, #2 is a periodic amplitude (unitless), a3 is the length of the period (in days), and a4 is the
periodic offset (in days). Although samples have been collected from several sites since 1991,
the analytical method changed in March of 1997 for the U.S. sites (77); thus, only data from
March 1997 to December 2003 have been used for trend analysis.
Seventy-six datasets among the total of 126 datasets (18 pesticides x 7 IADN sites) had
significant periodicity as indicating by both ^2 and a? being statistically significant at P < 0.05.
Since 52 of those 76 datasets had a period length (#3) of 366 ± 10 days, the period length for all
76 datasets with significant periodicity was forced to be one year; this simplified the calculation
of the date during the year when the pesticide concentrations reached their maximum.
Among the 126 datasets, 36 of them showed significant long-term decreasing trends and
six of them showed significant increasing trends (Figure D4). In particular, the concentrations of
y-HCH showed decreasing trends at five of the seven sites (the exceptions were Sleeping Bear
Dunes and Sturgeon Point). />,//-DDD concentrations decreased at Chicago, Sleeping Bear
Dunes, Sturgeon Point, Burnt Island, and Point Petre. p,p'-DDE is the only pesticide decreasing
at all seven IADN sites. a-Endosulfan concentrations only decreased at Point Petre, while at the
other six sites, these concentrations did not change from 1997 to 2003. Interestingly, significant
increasing trends were also observed for several pesticides. For example, P-HCH concentrations
in precipitation significantly increased at Brule River, Eagle Harbor, and Sleeping Bear Dunes;
p-endosulfan increased at Sturgeon Point; and trans-nonachlor increased at the two Canadian
sites, Burnt Island and Point Petre.
Long-term decreasing trends of organochlorine pesticides in precipitation have been
observed by other researchers (9,10,34). Simcik and co-workers reported on the temporal trends
of several pesticides (e.g. y-HCH, HCB, dieldrin, and y-chlordane) in precipitation samples
collected from the IADN sites from 1991 to 1997, with the half-lives ranging between 1 to 5
years (70). Comparing our results with those of Simcik and co-workers shows that most of the
pesticides they reported stopped decreasing during the time period from 1997 to 2003. For
example, between 1991 and 1997, a-HCH decreased with a half-life of 2-4 years at Eagle
Harbor, Sleeping Bear Dunes, and Sturgeon Point; however, no decreasing trend of a-HCH was
observed in the present study from 1997 onward. Similar situations were also observed for
HCB, dieldrin, y-chlordane, and p,p'-DDT. The lack of decreasing temporal trends for these
pesticides indicates that a much slower decline (e.g. longer half-life than the sampling period in
our study) is taking place after 1997.
A significant increase in P-HCH concentrations at Brule River, Eagle Harbor, and
Sleeping Bear Dunes, Chicago, and Sturgeon Point from 1997 to 2002 has also been reported by
Carlson and co-workers (77). P-HCH has the highest physical and metabolic stability among all
70
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the isomers in technical HCH due to its relatively planar structure (21). Thus, p-HCH's
environmental concentrations decrease more slowly than those of a-HCH and y-HCH. As a
result, it would be difficult to observe a significant decreasing trend over the seven-year time
frame of this study for a pesticide with a longer atmospheric half-life. Carlson and co-workers
suggested the observed increase in the precipitation concentrations of P-HCH is a brief exception
to a general decrease that would be evident over a longer period of time (77). Indeed, by adding
2003 data into the dataset used by Carlson et al., the significant long-term increasing trends of P-
HCH at Chicago and Sturgeon Point that they observed, disappeared.
Among all the pesticides measured by IADN, two different seasonal trends could be
observed. In the first, the concentrations peaked in the summer for in-use pesticides, and in the
second, the concentrations peaked in the winter for banned pesticides. The calculated dates on
which the pesticide concentrations in precipitation maximize at each of the IADN sites are listed
in Tables DS2-DS8. Concentrations of endosulfan and y-HCH, which are still in-use, usually
peaked in June or July, a time which corresponds well with their maximum agricultural usage
(35,36). The use of all the other pesticides is restricted in the U.S., with the exception of
methoxychlor, which is still being used in agriculture and on livestock. The concentrations of
these banned pesticides usually peaked in January or February. Higher concentration of y-HCH
and endosulfan in precipitation in the late spring to summer have been observed by other
researchers (17,26,37,38). Incidentally, lindane was used mainly in central Canada on canola (3)
and in the U.S. as a seed treatment (39) during the time of our sampling, but these uses in Canada
were abandoned at the end of 2004 (40).
It has been suggested that competing processes could explain the winter concentration
peak for the banned pesticides (77). These pesticides enter the atmosphere due to re-
volatilization from lake and terrestrial surfaces, and these sources tend to maximize during the
warmer summer months (41). However, the concentrations of these pesticides in the
atmospheric particle phase tend to increase during the winter due to enhanced partitioning to the
particles. In addition, snow is a better scavenger for both particle-associated and vapor-phase
pesticides than is rain. The lower intensity of sunlight in the winter lowers the atmospheric OH
radical concentration, which in turn increases the atmospheric lifetime of the pesticides, favoring
their accumulation in the winter-time atmosphere and precipitation. All these mechanisms could
contribute to higher winter concentrations in precipitation for banned OC pesticides.
The ratio between the highest and the lowest pesticide concentration can be calculated
from the fitted 0.2 parameter by taking its anti-logarithm (e2"2, the factor of 2 in the exponent is
needed to calculate the peak-to-valley amplitude). These values are presented in Tables S2-S8.
These ratios range between about 2-9, indicating that the seasonal variations can be substantial.
Acknowledgments
We thank Ilora Basu and Team IADN at Indiana University and Ed Sverko and the staff
at the National Laboratory for Environmental Testing, Environment Canada for data acquisition;
the U. S. Environmental Protection Agency's Great Lakes National Program Office for funding
(Grant GL995656, Melissa Hulting, project monitor); and Bruce Harrison and Mary Lou Archer
for managing the field collection at the Canadian sites.
Supporting Information
One table showing chemical structures and major properties of the OC pesticides discussed in
this paper, seven tables showing values derived from modeled parameters for OC pesticides at
71
-------
seven IADN sites, and one table showing the comparison between our data and other previous
studies. These material are available free of charge via the Internet at http://pubs.acs.org.
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74
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Sleeping
Bear Dunes
Figure Dl. Map of the Great Lakes indicating the sampling sites at Brule River and Eagle
Harbor, near Lake Superior; Chicago and Sleeping Bear Dunes, near Lake Michigan; Sturgeon
Point, near Lake Erie; Burnt Island, near Lake Huron; and Point Petre, near Lake Ontario.
Chicago is an urban site, Sturgeon Point is semi-urban site and the other sites are remote sites.
75
-------
O)
Q.
104
103
102
-101
104
o
o10s
O
102
Z101
a-HCH
P-HCH
Figure D2. Concentrations of a-HCH (top), P-HCH (middle), and y-HCH (bottom) in
precipitation collected from 1997 to 2003 at the seven IADN sites. The boxes represent the 25th
to 75th percentiles, the black lines in the boxes are the medians and the red lines are the means.
The two vertical lines outside each box exteni
percentiles; and outliers are shown individually.
The two vertical lines outside each box extend to the outliers representing the 10l and 90l
76
-------
105
O)
Q_
O
c
o
O
103
~ 102
o
i, i
iiAii
^oX ^
^X
Figure D3. Concentrations of endosulfans (a- plus p-endosulfan) in precipitation at the seven
IADN sites. See Figure D2 for the description of the box-plots.
77
-------
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o>
Q.
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a
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103
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oi 102
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1 1 1 1
••
1 1 1
••** *
H
jifefti&lft^siftfi^
^^^^^ ^^^^^ ^^^^^ ^^^^^ ^^^^^^ i
^>w\^
Figure D4. Organochlorine pesticide concentrations in precipitation collected at seven IADN sites near the Great Lakes. The black
curve is the fitting line of the sinusoidal model with the period length (#3) set to one year. The red lines indicate long-term significant
decreasing or increasing trends. Detailed information on the fitting parameters is in the Supporting Information.
-------
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Figure D4 (continued).
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Figure D4 (continued).
-------
Supporting Information for:
Temporal and Spatial Trends of Organochlorine Pesticides in
Great Lakes Precipitation
Ping Sun,1 Sean Backus,2 Pierrette Blanchard,2 and Ronald A Kites*1
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 USA
and
Environment Canada
4905 Dufferin Street
Toronto, ON M3H 5T4 Canada
* Corresponding Author Email: hitesr@indiana.edu
This Supporting Information contains nine tables. Table DS1 shows the chemical structure and
properties of the organochlorine pesticides discussed in this paper. Tables DS2-DS8 show the
values derived from modeled parameters for pesticides at seven IADN sites. Table DS9 is a
comparison between the results in this study with previous studies conducted by other
researchers.
The following equation was used to fit the data:
lnC=a0+ajt + a2 sin -- ha4
where t is the time in Julian days relative to January 1 1990, ao is an intercept (unitless), a\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, a2 is a periodic amplitude (unitless), a3 is the length of the period (in days), and a4 is the
periodic offset (in days).
Among 126 data sets, 76 datasets showed significant periodicity as indicating by both a^ and a?
being statistically significant at P < 0.05, and 52 of the 76 data sets had a period length (a3) of
366 ± 10 days. Thus, the period length for all 76 datasets with significant periodicity was forced
to be one year, which simplified the calculation of the date during the year when the
concentrations reached their maximum.
The tables show results of the fit to this sinusoidal model. The results are listed as mean ±
standard error. Normal font numbers are significant for 0.01 < P < 0.05; italic font numbers are
significant for 0.001 < P < 0.01, bold font numbers are significant at P < 0.001. "NS" means "not
significant" at P > 0.05. A negative half-life is actually a doubling time.
81
-------
Table DS1. Chemical structures and properties of OC pesticides1
OC pesticide Structure MW
a-HCH . !' x 290.83
P-HCH ' - 290.83
y-HCH i f 290.83
i "'*"
a-Endosulfan ' , 406.93
1
P-Endosulfan 406.93
a-Chlordane - T^, 409.76
r Y,,
y-Chlordane . • , 409.76
Hexachlorobenzene 284.78
p, p'-DDT _J~\_ij^ 354.49
p,p'-DDD f-\ ; /—\ 320.05
: w ;, \J r
p, p'-DDE f\ f^ 318.03
o, p'-DDT — i — i 354.49
Heptachlor epoxide 389.40
\
Aldrin ll'^ 364.91
' Cl
dieldrin ~i '?, 380.91
Cl
Endrin ? 380.90
Methoxychlor ' 345.65
•" CH.O •. r (JCll,
Vapor pressure Henry's Law log K,,w
(mm Hg) constant (atm-
m3/mol, at 25°C)
4.5 x !0-5at25°C 1 x 10'5
3.6 x 10"7at20°C 7.44 x 10'7
4.2 x 10-5at20°C 1.40 x 10'5
1 x 1Q-5 at 25°C 1 x lO'5
lx!0-5at25°C 1.91 x 10'5
2.2 x 10'5 at 20°C 1.91 x 10'5
2.9 x 10-5at20°C 8.31 x 10'5
1.09 x 10"5at20°C 5.8 x lO'4
1.6 x 10-7at20°C 8.3 x 1Q-6
1.35 x !0-6at25°C 4.0 x 10'6
6.0 x 10'6 at 25°C 2.1 x 10'5
1.1 x 10-7at20°C 5.9 xlO'7
2.6 x 10'6 at 20°C 3.2 x 10'5
7.5 x !0-5at20°C 4.9 x 10'5
3.1 x 10"6at20°C 5.2 x 10'5
2.0 x lO'7 at 20°C 4.0 x lO'7
1.4 x 10"6at25°C 1.6 x 10'5
(estimate) (estimate)
3.8
3.78
3.72
3.83
3.52
6.0
6.0
5.73
6.91
6.02
6.51
6.79
5.40
6.50
6.2
5.6
4.68-
5.08
Data is obtained from Agency for Toxic Substances and Disease Registry, www.atsdr.cdc.gov/toxprofiles/
82
-------
Table DS2. Fit parameters for pesticide concentrations in precipitation at Brule River
Pesticides
a-HCH
P-HCH
y-HCH
a-Endosulfan
(3-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p '-DDT
p,p '-ODD
p,p '-DDE
o,p '-DDT
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Half-life (years),
(In2)/365*a!
NS
-2.8 ±1.2*
3.2 ±1.6
NS
2.7 ± 1.2
NS
NS
NS
NS
-6.3 ±2.1*
NS
NS
4.7 ±2.4
Limited data
NS
Not available
1.1 ±0.4
NS
Peak-to-valley
ratio, e BI
NS
3.8 ± 1.3
6.5 ± 1.3
2.1 ±1.2
3.8 ± 1.3
5.1 ± 1.4
3.9 ± 1.3
NS
2.4 ± 1.2
4.8 ± 1.4
4.9 ±1.8
NS
4.1 ± 1.3
NS
2.3 ± 1.2
NS
NS
Maximum date
(± days)
NS
Feb 8 ± 12
Jun 24 ± 9
Jun 24 ± 16
Jul 13 ± 12
Jan 21 ± 15
Feb 10 ±13
NS
NS
Feb 3 ±10
NS
NS
NS
NS
NS
NS
NS
No. of
detects
39
34
39
39
39
63
56
49
65
65
50
22
61
13
50
24
24
* A negative half -life indicates that the concentrations are increasing and the listed value is the
Average
cone. (pg/L)
710 ±60
170 ± 24
860 ± 150
380 ±31
450 ± 53
180 ±41
33 ±5.5
16 ±2.2
270 ± 20
21 ±1.9
77 ±21
20 ± 4.6
36 ±5.7
12 ±3.7
82 ± 7.0
180 ± 45
150 ±35
doubling time.
r2
NS
0.50
0.56
0.28
0.47
0.31
0.31
NS
0.30
0.30
0.15
NS
0.52
NS
0.35
0.49
NS
Table DS3. Fit parameters for pesticide concentrations in precipitation at Eagle Harbor
Pesticides
a-HCH
P-HCH
y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
o,//-DDT
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Half-life (years),
(In2)/365*a!
NS
-3.2 ±1.0*
3.8 ±1.5
NS
4.7 ±2.4
NS
NS
NS
NS
NS
NS
NS
4.7 ±1.2
NS
NS
Limited data
NS
Limited data
Peak-to-valley
ratio, e a2
NS
2.8 ± 1.2
5.2 ± 1.3
1.5 ±1.2
5.1 ± 1.3
8.3 ± 1.3
3.3 ± 1.3
2.2 ±1.3
2.6 ± 1.2
2.9 ± 1.2
5.1 ± 1.4
NS
3.3 ± 1.2
NS
1.8 ±1.2
NS
5.2 ± 1.5
NS
Maximum date
(± days)
NS
Feb 8 ± 8
Jun 24 ± 8
Jun 14 ± 25
Jun 12 ± 8
Feb 14 ± 9
Feb 4 ± 11
Feb 1±16
Jan 24 ±7
Feb 12 ± 8
NS
NS
NS
NS
Feb 13 ±17
NS
Jan 16 ± 12
NS
No. of
detects
56
64
56
56
54
74
64
53
83
82
69
19
78
24
67
6
43
24
Average
cone. (pg/L)
890 ± 84
160 ± 14
810 ±130
400 ± 27
370 ± 40
110 ±14
22 ±2.3
12 ±1.2
250 ± 19
21 ±1.5
49 ±7.4
36 ±12
27 ±3.6
16 ±5.9
78 ±4.8
3. 5 ±2.8
200 ± 37
75 ±11
r
NS
0.54
0.54
0.10
0.52
0.52
0.30
0.20
0.32
0.41
0.25
NS
0.38
NS
0.14
NS
0.33
NS
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
83
-------
Table DS4. Fit parameters for pesticide concentrations in precipitation at Sleeping Bear Dunes
Pesticides
a-HCH
P-HCH
y-HCH
a-Endosulfan
(3-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
p,p'-DDE
o,//-DDT
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Half-life (years),
(In2)/365*a!
NS
-2.8 ±1.0*
NS
NS
NS
NS
NS
NS
9.5 ±4.7
NS
NS
3.8 ±1.5
4.7 ±1.2
NS
NS
Limited Data
2.8 ±1.4
NS
Peak-to-valley
ratio, e BI
1.8 ±1.2
3.0±1.4
4.4 ± .3
2.5 ± .2
5.4 ± .3
5.4 ± .3
2.7 ± .2
3.7 ± .2
2.7 ± .1
2.6 ± .1
NS
7.3± 1.5
2.8 ± .2
3.8 ± .3
2.4 ± .1
2.9 ±1.5
NS
Maximum date No. of
(± days) detects
Feb 4 ± 22
NS
Jun 9 ± 11
Jun 30 ± 14
Jul 18 ± 9
Jan 23 ± 8
Feb 28 ±9
Feb 22 ± 9
Mar 14 ± 8
Feb 25 ± 7
NS
Mar 1 ± 12
NS
NS
NS
Feb 3 ±20
NS
54
51
56
56
55
81
73
78
85
84
77
41
83
35
45
5
48
41
* A negative half-life indicates that the concentrations are increasing and the listed value is the
Table DS5. Fit parameters for pesticide
Pesticides
a-HCH
P-HCH
Y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
dieldrin
Hexachlorobenzene
p,p '-DDT
p,p '-ODD
p,p '-DDE
o,p '-DDT
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Half-life (years),
(In2)/365*a!
NS
NS
NS
NS
-3.8 ±1.5*
NS
NS
NS
NS
NS
NS
4.7 ±2.4
6.3 ±2.1
NS
NS
Limited Data
NS
2.2 ±0.7
concentrations
Peak-to-valley
ratio, e BI
NS
NS
3.7 ± 1.3
4.5 ± 1.2
6.6 ± 1.3
3.0±1.4
2.2 ± 1.2
NS
1.8±1.2
2.3 ± 1.2
NS
3.5 ±1.4
2.0±1.2
NS
1.7 ±1.2
NS
NS
in precipitation
Average
cone. (pg/L)
670 ± 60
270 ± 27
720 ±110
590 ± 64
600 ± 70
250 ±31
26 ±1.8
22 ± 2.0
420 ± 24
18 ±1.0
79 ±6.9
24 ± 4.2
42 ± 8.4
13 ±1.8
32 ±3.3
2.7 ±1.2
160 ± 34
250 ± 50
doubling time.
r2
0.13
0.29
0.39
0.27
0.49
0.39
0.37
0.36
0.46
0.46
NS
0.46
0.40
0.42
0.33
NS
0.39
NS
at Sturgeon Point
Maximum date No. of
(± days) detects
NS
NS
Jun 19 ± 13
Jul 24 ± 7
Aug 4 ± 9
Jan 14 ± 15
NS
NS
NS
Mar 7 ±11
NS
Feb 5 ±15
May 3 ± 18
NS
NS
NS
NS
58
44
60
59
60
68
79
84
87
87
85
61
86
48
62
7
47
52
* A negative half-life indicates that the concentrations are increasing and the listed value is the
Average
cone. (pg/L)
580 ± 62
380 ±38
690 ± 96
710 ±62
960 ±110
540 ± 62
34 ±2.5
24 ±1.8
310 ±17
19 ±1.2
130 ±13
31 ±4.0
67 ±9.1
29 ±4.9
77 ±4.5
1.4 ±0.4
180 ± 24
370 ± 66
doubling time.
r2
NS
NS
0.28
0.56
0.46
0.20
0.19
0.16
0.17
0.25
NS
0.23
0.19
NS
0.33
NS
NS
0.17
84
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Table DS6. Fit parameters for pesticide concentrations in precipitation at Chicago
Pesticides
a-HCH
P-HCH
y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
p,p'-DDE
o,//-DDT
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Half-life (years),
(In2)/365*a!
NS
NS
6.3 ±4.2
NS
NS
NS
NS
NS
NS
6.3 ±2.1
NS
2.1 ± 0.2
3.8 ±1.5
NS
NS
NS
NS
NS
Peak-to-valley
7a
ratio, e 2
NS
NS
4.1 ± 1.4
3.0±1.3
2.3 ±1.4
NS
2.7 ±1.3
2.9 ±1.3
2.6 ±1.3
2.8 ±1.3
3.2 ±1.4
3.0±1.3
4.3 ± 1.4
NS
3.0 ± 1.3
NS
NS
NS
Maximum date
(± days)
NS
NS
Jun 1 ± 13
Jul 7 ± 14
Jul 17 ±19
NS
NS
NS
NS
NS
NS
NS
May 3 ± 18
NS
NS
NS
NS
NS
No. of
detects
50
34
50
50
47
36
69
67
69
67
68
64
67
44
58
29
34
52
Average
cone. (pg/L)
470 ± 48
650 ± 82
1100 ±270
700 ± 82
680 ± 94
1100 ±230
150 ±17
100 ± 12
1400 ± 180
32 ±3.9
570 ± 93
110 ±17
210 ±37
130 ±24
290 ± 33
16 ±5.8
180 ±25
370 ± 56
r2
NS
NS
0.37
0.26
0.21
NS
0.23
0.22
0.24
0.25
0.21
0.52
0.34
NS
0.29
NS
NS
NS
Table DS7. Fit parameters for pesticide concentrations in precipitation at Brunt Island
Pesticides
a-HCH
P-HCH
y-HCH
a-Endosulfan
P-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-WT
p,p'-VVE
o,;/-DDT
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Half-life (years),
(In2)/365*a!
3.2 ± 0.5
NS
2.9 ± 0.5
NS
NS
3.2 ±1.6
NS
-1.6 ± 0.3*
NS
2.9 ±0.8
2.0 ±0.8
0.9 ± 0.1
2.6 ± 0.6
1.5 ±0.4
NS
Limited Data
NS
2.0 ±0.7
Peak-to-valley
ratio, e a2
NS
NS
4.0 ± 1.2
2.9 ± 1.2
6.4 ± 1.3
NS
NS
4.2 ±1.6
NS
3.5 ±1.4
4.8 ±2.0
NS
2.8 ±1.4
NS
NS
NS
5.5 ±1.8
Maximum date
(± days)
NS
NS
Apr 28 ±11
Jul 3 ± 12
Jul 10 ± 8
NS
NS
Feb 5 ±16
NS
Feb 15 ± 14
NS
NS
Feb 8 ±17
NS
NS
NS
Jun 8 ± 23
No. of
detects
58
32
80
80
80
68
47
51
80
59
32
32
71
38
65
3
18
42
Average
cone. (pg/L)
660 ± 56
340 ± 76
1400 ± 220
600 ± 93
760 ± 85
540 ± 62
86 ±19
110 ±42
300 ± 26
82 ±16
92 ±21
29 ±6.9
130 ±36
100 ± 27
100 ±11
470 ± 230
230 ±88
280 ± 80
r
0.38
NS
0.50
0.26
0.36
0.20
NS
0.39
NS
0.34
0.31
0.62
0.32
0.33
NS
NS
NS
0.33
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
85
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Table DS8. Fit parameters for pesticide concentrations in precipitation at Point Petre
Pesticides
a-HCH
P-HCH
y-HCH
a-Endosulfan
(3-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
P.//-DDT
p,p'-DDD
p,p'-DDE
o,//-DDT
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Half-life (years),
(In2)/365*a!
2.2 ± 0.3
NS
2.5 ± 0.3
5.3 ±2.0
5.8 ±2.6
NS
NS
-1.6 ± 0.3*
7.3 ±2.8
NS
3.2 ±1.0
1.5 ± 0.3
6.3 ±2.1
2.7 ±0.8
NS
Limited Data
1.8 ±0.7
3.8 ±2.3
Peak-to-valley
ratio, e a2
1.7 ± 1.2
NS
2.9 ± 1.2
6.4 ± 1.3
14 ± 1.4
NS
NS
NS
2.0 ±1.2
2.4 ±1.3
NS
NS
NS
2.6 ± 1.5
NS
NS
3.6 ±1.7
Maximum date
(± days)
Dec 3 ± 26
NS
NS
Jun 17 ± 8
Jun 17 ± 7
NS
NS
NS
Feb 1 ± 18
Jan 29 ±17
NS
NS
NS
NS
NS
NS
Jun 20 ± 22
No. of
detects
81
36
79
80
80
46
36
29
77
65
59
45
77
42
52
o
J
20
46
* A negative half-life indicates that the concentrations are increasing and the listed value is the
Average cone.
(pg/L)
630 ± 68
390 ± 88
1400 ± 170
600 ± 93
760 ± 85
50 ±13
110 ±58
110 ±42
300 ±35
55 ±9.3
200 ± 40
57 ±14
180 ± 23
71 ±14
78 ±7.4
470 ± 230
180 ± 52
420 ± 92
doubling time.
r2
0.48
NS
0.58
0.44
0.52
NS
NS
0.39
0.19
0.34
0.12
0.30
0.16
0.38
NS
NS
0.25
0.33
86
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Table DS9. Range and Annual Mean Concentration (ng/L) of Selected Organochlorine
Pesticides in Precipitation from Various Studies
Pesticide
a-HCH
P-HCH
y-HCH
a-Endosulfan
(3-Endosulfan
SChlordane
p,p'-DDT
p,p'-DDE
Sample
Location
Gdansk region, Poland
Paris, France
Chicago, U.S.
Quessant, France
Senga Bay, South Africa
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Senga Bay, South Africa
Chicago, U.S.
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Paris, France
Chicago, U.S.
Quessant, France
Senga Bay, South Africa
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Cuiaba, Brazil
Jersey City. U.S.
Chicago, U.S.
Pineland, U.S.
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Cuiaba, Brazil
Jersey City. U.S.
Chicago, U.S.
Pineland, U.S.
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Jersey City. U.S.
Chicago, U.S.
Pineland, U.S.
Senga Bay, South Africa
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Jersey City. U.S.
Gdansk region, N. Poland
Chicago, U.S.
Senga Bay, South Africa
Pineland, U.S.
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Senga Bay, South Africa
Chicago, U.S.
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Site
type
Urban1
urban
urban
rural
rural
rural
rural
rural
urban
rural
rural
urban
urban
rural
rural
rural
rural
urban
urban
urban
rural
rural
rural
urban
urban
urban
rural
rural
rural
urban
urban
rural
rural
rural
rural
urban
urban
urban
rural
rural
rural
rural
rural
urban
rural
rural
Sample time
1998-2000
Oct. 99-Oct. 00
Jun 99-Dec 03
Oct. 99-Oct. 00
Feb 97-May 98
Jun 99-Dec 03
Mar 97-Dec 03
Feb 97-May 98
Jun 99-Dec 03
Jun 99-Dec 03
Mar 97-Dec 03
Oct. 99-Oct. 00
Jun 99-Dec 03
Oct. 99-Oct. 00
Feb 97-May 98
Jun 99-Dec 03
Mar 97-Dec 03
Nov. 99- Mar 00
JanOO-MayOl
Jun 99-Dec 03
JanOO-MayOl
Jun 99-Dec 03
Mar 97-Dec 03
Nov. 99-Mar 00
JanOO-MayOl
Jun 99-Dec 03
JanOO-MayOl
Jun 99-Dec 03
Mar 97-Dec 03
JanOO-MayOl
Mar 97-Dec 03
JanOO-MayOl
Feb 97-May 98
Mar 97-Dec 03
Mar 97-Dec 03
JanOO-MayOl
98-00
Mar 97-Dec 03
Feb 97-May 98
JanOO-MayOl
Mar 97-Dec 03
Mar 97-Dec 03
Feb 97-May 98
Mar 97-Dec 03
Mar 97-Dec 03
Mar 97-Dec 03
Cone.
Range
1-12
0.6-7.4
0.066-1.6
0.3-0.9
0.06-0.3
0.2-2.4
0.04-2.5
0.06
0.018-1.8
0.013-0.93
0.009-1.5
5.2-28.6
0.031-13.6
0.5-2.6
0.04-0.5
0.072-4.1
0.074-33.7
4-14
0.025-0.067
0.038-3.0
0.071-0.24
0.037-3.3
0.020-7.0
8-57
0.16-0.42
0.10-3.4
0.20-0.36
0.050-2.6
0.006-4.9
0.13-0.14
0.057-41.3
0.058-0.074
0.23
0.004-1.7
0.002-4.6
0.18-0.55
1-10
0.007-18.1
0.35
0.039-0.077
0.004-1.0
0.002-4.6
O.03
0.011-3.5
0.0089-0.59
0.002-1.7
Mean
Cone.
2.8
0.47
0.48
0.13
0.67
0.66
0.024
0.64
0.27
0.34
15.9
1.1
1.7
0.15
0.72
1.84
9
0.046
0.70
0.15
0.58
0.60
20
0.29
0.68
0.28
0.60
0.76
0.18
1.8
0.066
0.029
0.026
0.22
0.37
0.96
0.075
0.058
0.09
0.30
0.014
0.30
0.044
0.13
Ref.
(42)
(37)
this study
(37)
(17)
this study
this study
(17)
this study
this study
this study
(37)
this study
(37)
(17)
this study
this study
(16)
(14)
this study
(14)
this study
this study
(16)
(14)
this study
(14)
this study
this study
(14)
this study
(14)
(17)
this study
this study
(14)
(37)
this study
(17)
(14)
this study
this study
(17)
this study
this study
this study
:.As defined by the census bureau in 1990, "urban" comprises all territory, population, and housing units in
urbanized areas and in places of 2,500 or more persons outside urbanized areas. Territory, population, and housing
units not classified as urban constitute "rural."
87
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Appendix E. Trends in Polycyclic Aromatic Hydrocarbon Concentrations
in the Great Lakes Atmosphere
Published in Environmental Science & Technology, 2006, 40, 6221-6227.
88
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Trends in Polycyclic Aromatic Hydrocarbon Concentrations
in the Great Lakes Atmosphere
Ping Sun,1 Pierrette Blanchard,2 Kenneth A. Brice2 and Ronald A. Kites*1
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 U.S.A.
and
Environment Canada
4905 Dufferin Street
Toronto, ON M3H 5T4 Canada
* Corresponding Author Email: hitesr@indiana.edu
Brief
Polycyclic aromatic hydrocarbons in the Great Lakes atmosphere are still an
urban problem but a decline in their concentrations was observed with a decade of
monitoring.
Abstract
Atmospheric polycyclic aromatic hydrocarbon (PAHs) concentrations were
measured in both the vapor and particle phases at seven sites near the Great Lakes as a
part of the Integrated Atmospheric Deposition Network. Lower molecular weight PAHs,
including fluorene, phenanthrene, fluoranthrene, and pyrene, were dominant in the vapor
phase, and higher molecular weight PAHs, including chrysene, benzo[a]pyrene, and
coronene, were dominant in the particle phase. The highest PAH concentrations in both
the vapor and particle phases were observed in Chicago followed by the semi-urban site
at Sturgeon Point, NY. The spatial difference of PAH concentrations can be explained by
the local population density. Long-term decreasing trends of most PAH concentrations
were observed in both the vapor and particle phases at Chicago, with half-lives ranging
from 3-10 years in the vapor phase and 5-15 years in the particle phase. At Eagle Harbor,
Sleeping Bear Dunes, and Sturgeon Point, total PAH concentrations in the vapor phase
showed significant, but slow, long-term decreasing trends. At the Sturgeon Point site,
which was impacted by a nearby city, particle-phase PAH concentrations also declined.
However, most particle-phase PAH concentrations did not show significant long-term
decreasing trends at the remote sites. Seasonal trends were also observed for particle
phase PAH concentrations, which were higher in the winter and lower in the summer.
Introduction
Atmospheric polycyclic aromatic hydrocarbons (PAH) concentrations have been
measured by many researchers worldwide. Most of these studies were short-term
measurements covering time periods ranging from a few months to a few years (1,2).
Long-term measurements of PAH concentrations to determine temporal trends are still
89
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limited (3,4). The Integrated Atmospheric Deposition Network (IADN) was begun in
1990 to measure PAHs and other persistent organic pollutant concentrations in air and
precipitation around the Great Lakes (5). Previous IADN studies based on samples
collected up to 1997 showed decreasing PAH concentrations in both the vapor and
particle phases at several remote sites (5,6,7). Recently, we reported on the temporal
trends of PAH concentrations from 1997 to 2003 in precipitation at the same sites
discussed in this paper (8). However, long-term decreasing trends for PAH
concentrations in precipitation were observed only at the urban site in Chicago (with half-
lives of 2-5 years); there were few other significant temporal trends for PAH
concentrations in precipitation at the remote IADN sites. Therefore, it was interesting to
determine if PAH concentrations in the vapor and particle phases behave similarly to
those in precipitation, or if these concentrations show long-term temporal trends that are
different from the previously published results.
In this paper, the PAH concentrations in both the vapor and particle phases for
samples collected up to December 2003 at seven IADN sites are reported. This paper not
only extends the work of Cortes et al. (6) with an additional 6 years of data (1998-2003),
but covers both U.S. and Canadian sites. In particular, we focused on the spatial and
temporal trends of PAH concentrations to determine if they are responding to recent
improvements in pollution control technology and to other pollution reduction efforts.
Experimental
Sampling and analytical methodology. Vapor and particle phase samples were
collected at five U.S. IADN sites (Brule River and Eagle Harbor, near Lake Superior;
Chicago and Sleeping Bear Dunes, near Lake Michigan; and Sturgeon Point, near Lake
Erie) and at two Canadian sites (Burnt Island, near Lake Huron; and Point Petre, near
Lake Ontario). The detailed site information is given at the IADN website
(www.msc.ec.gc.ca/iadn).
Sampling procedures at the U.S. sites are described in detail by Basu and Lee (9).
Briefly, 24-hour air samples were collected by modified Anderson high-volume air
samplers (General Metal Works, model GS 2310) every 12 days. Particles were retained
on quartz fiber filters (Whatman QM-A), and the vapor-phase organic compounds were
retained on 40 g of XAD-2 resin (20-60 mesh). Prior to May 4, 1992, polyurethane foam
(PUF) was used to collect vapor-phase samples. Temperature and other meteorological
data were also recorded at each site concurrently with the sampling events.
After sampling, the XAD-2 sorbent and quartz fiber filters were Soxhlet extracted
separately for 24 h using a 1:1 (v/v) mixture of hexane and acetone, concentrated by
rotary evaporation and fractionated on 3.5% (w/w) water-deactivated silica gel. Hexane
was first used to elute some pesticides. PAHs were then eluted with 1:1 hexane and
dichloromethane. The extracts were further concentrated by N2 blowdown to ~1 mL and
spiked with dio-anthracene, 6?i2-perylene, and du-benz[a]anthracene as internal standards.
All PAHs were analyzed using gas chromatographic mass spectrometry with selected ion
monitoring on DB-5 columns (J & W Scientific; 30 m x 250 |j,m i.d.; film thickness, 0.25
Urn).
At the two Canadian sites, General Metal Works PS-1 high-volume samplers were
used to collect air samples. The sampling head held a 10.2 cm diameter glass fiber filter
(GFF, Gelman A/E Microfiber) for particle collection followed by a 7.5 cm high x 6.2 cm
90
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diameter PUF plug (Levitt Safety) for vapor phase absorption. Sampling events occurred
every 6 days through April 1994 and every 12 days since then. The PUF was Soxhlet
extracted with hexane for 24 h. The extract was dried using anhydrous granular Na2SC>4
(12-60 mesh), filtered through a small bed of anhydrous Na2SC>4 supported by a
Whatman glass fiber filter, and concentrated to 0.5 mL in isooctane. The volume was
adjusted to 2 mL of isooctane and split into two equal portions. One portion was
cleaned-up with a silica cartridge before analysis.
Prior to early 1999, the GFFs containing the particle phase PAHs were extracted
with dichloromethane for 24 hr. After that time, an accelerated solvent extractor was
used to extract the GFFs with a 30 mL of a 7:3 (v/v) mixture of hexane and acetone. Full
details of the optimized extraction procedure were given by Alexandrou et al. (10). The
PAHs were quantitated with a FTP 1090 high performance liquid chromatograph (HPLC)
with a 1046A programmable fluorescence detector using a 150 mm x 4.6 mm Vydac
202TP5415 Ci8 reverse phase column.
Sixteen PAHs were measured by both the U.S. and Canadian laboratories:
fluorene, phenanthrene, anthracene, fluoranthene, pyrene, retene, benz[a]anthracene,
triphenylene and chrysene (not resolved chromatographically at Indiana University and
counted as one compound for both U.S. and Canadian sites), benzo[6]fluoranthene,
benzo [k] fluoranthene, benzo[e]pyrene, benzo[a]pyrene, indeno[7,2,.3-cd]pyrene,
benzo[g/z/]perylene, dibenz[a,/z]-anthracene, and coronene. Measurements of PAHs in
the vapor phase started at Eagle Harbor in November 1990, at Sturgeon Point in
December 1991, at Sleeping Bear Dunes in January 1992, at Brule River and Chicago in
January 1996. Although some vapor phase PAH measurements were available in the
early 1990s at Point Petre and Burnt Island, the measurement of PAHs were stopped in
1992 and resumed in 1997. Therefore, only vapor phase data from January 1997 onward
are reported at these two Canadian sites. For the particle-phase samples, data for all
seven IADN sites from October 1996 to December 2003 were used because U.S. particle
phase samples collected before October 1996 had been composited by month.
Strict quality assurance procedures were followed by both laboratories to ensure
high data quality (10,11). Generally, field blanks account for at least 10% and laboratory
blanks for at least 5% of the number of collected samples for both laboratories. The
reported concentrations were not blank-corrected due to the low PAH concentrations in
the blanks. At Indiana University, one matrix spike experiment was performed with
every 20-24 samples. Surrogate standards (t/io-phenanthrene and t/io-pyrene) were also
used in each sample to monitor recovery; the average percent recoveries were 83-89%
(11,12). At Environment Canada, the extraction efficiencies, measured by matrix
spike experiments, exceed 80% for the GFF and 70% for the PUF samples.
A split-sample, inter-laboratory comparison study was conducted in early 2001 to
ensure data comparability (12). The results showed there was no bias in the PAH
concentrations in the vapor and particle phase samples between the laboratories, except
that unexpectedly high benzo[e]pyrene concentrations were reported in the vapor phase at
Burnt Island and Point Petre. Therefore, in this paper, the total PAH (ZPAH)
concentration is the sum of the concentrations of the sixteen PAHs measured by both
laboratories, except that benzo[e]pyrene was not included in the vapor phase
concentrations at the two Canadian sites. Due to its small contribution to total vapor
91
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phase PAH concentrations (usually less than 2%), omitting benzo[e]pyrene will not affect
the spatial trend analysis of EPAH.
Trend analysis. In brief, the vapor-phase concentrations (in ng/m3) of PAHs
were first converted to partial pressures (P, in atm) using the ideal gas law. These partial
pressures were then adjusted to a reference temperature of 288 K using equation 1 to
remove the temperature effect on PAH gas-phase concentrations (6)
D I O O O "T* \
i\ \Zoo 1 j
where AH is a characteristic phase-transition energy of the compound (in kJ/mol), R is
the gas constant, and Tis the daily average atmospheric temperature at the sampling site
(in Kelvin).In equation 1, the value of AH was determined by a preliminary regression of
In^) vs. 1/r. The values of In^ss) were then regressed vs. time (t, in Julian days
relative to January 1, 1990) to determine the rate of exponential decrease or increase of
these partial pressures. If these rate constants were statistically significant, they were
then converted to half-lives (^1/2) by dividing the rates into ln(2) for each compound at
each site. In this case, negative half-lives indicate that the concentrations were increasing
over time.
The particle-phase PAH concentrations (C) were fitted by the following time-
dependent function to study their temporal trends (5)
In C = a0 + a^t + a2 sin h a4
1*3
(2)
where a0 is the intercept (unitless), a\ is a first-order rate constant (in days l) describing
the rate of exponential decrease or increase over time, 0.2 is the periodic amplitude
(unitless), a3 is the length of the period (in days), and a4 is the periodic offset (in days). If
a\ values were significant (p < 0.05), either a decreasing (ai < 0) or increasing (a\ > 0)
trend in the PAH particle-phase concentrations could be determined for this sampling
period, and these values were converted to half-lives by dividing the rate constants into
ln(2) for each compound at each site. The anti-logarithm of 2a2 is the peak to valley
amplitude of the seasonal variation, and a4 indicates the time of the maximum
concentration.
Results and Discussion
PAH concentrations and spatial trends Concentration ranges of ZPAH in the
vapor and particle phases at the seven IADN sites are shown in Figure El, sequenced by
human population within a 25-km radius of the sampling site. The overall mean ZPAH
concentration in Chicago was 70 ± 5.2 ng/m3 and 12 ± 0.7 ng/m3 in the vapor and particle
phases, respectively. These values are >10 times higher than those measured at the six
other IADN sites. Sturgeon Point has the second highest ZPAH concentration in both the
vapor and particle phases with means of 6.3 ± 0.2 ng/m3 and 1.1 ± 0.1 ng/m3,
respectively.
Student's Mests (a = 0.05) were conducted to compare the PAH concentrations in
the vapor and particle phases at the other sites. Overall, for the ZPAH concentrations in
air (vapor plus particle phase), the spatial trend is: Burnt Island < Eagle Harbor < Brule
92
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River ~ Sleeping Bear Dunes ~ Point Petre < Sturgeon Point « Chicago (Figure El,
top). However, the spatial trends of the PAH concentrations in the vapor and particle
phases were different from the above trend. In the vapor phase, the spatial trend of PAH
concentrations is: Burnt Island < Eagle Harbor ~ Brule River ~ Point Petre < Sleeping
Bear Dunes < Sturgeon Point« Chicago. Brule River and Eagle Harbor, both near Lake
Superior, had vapor phase PAH concentrations similar to those at Point Petre near Lake
Ontario. Because atmospheric temperature will affect the vapor-phase PAH
concentrations, especially for the low molecular weight PAHs, this effect was reduced by
adjusting each concentration at each site to a reference temperature of 288 K using
equation 1. These temperature-corrected, average vapor phase ZPAH concentrations are
given in Tables ES1-ES7. Using the corrected values, Sleeping Bear Dunes showed
ZPAH vapor-phase concentrations similar to those at Eagle Harbor, Brule River, and
Point Petre. In the particle phase, the spatial trend of ZPAH concentrations is: Eagle
Harbor < Burnt Island ~ Brule River ~ Sleeping Bear Dunes < Point Petre
-------
those reported by Pirrone et al. (75) and Simcik et al. (19) but lower than those reported
by Vardar et al. However, acenaphthene (approximately 80 ng/m3) was included in the
reported total vapor-phase PAH concentration by Vardar et al., and this compound was
not measured in IADN samples. Therefore, the PAH concentrations reported by IADN
agreed well with these previously reported data.
The second highest PAH concentrations we observed were at Sturgeon Point,
which is located 25 km south of the city of Buffalo, NY, and about 110,000 people live
within a 25-km radius of this sampling site. Due to the lower population, atmospheric
PAH concentrations were lower at Sturgeon Point compared to Chicago (Figure E2). At
the other five sites, the generally low atmospheric PAH concentrations may represent a
background level in the Great Lakes basin of about 1.4 ng/m3. The most remote site,
Burnt Island, has by far the lowest population density (500 people within a 25-km radius)
and by far the lowest ZPAH concentration (0.6 ng/m3). PAH sources to these remote
regions include small cities such as Duluth, MN (5) and ship traffic along the St.
Lawrence River and through the Great Lakes (27).
The atmospheric PAH concentrations at these sites are also comparable to data
reported by previous studies. At rural sites in New Jersey, such as Delaware Bay,
Alloway Creek, and the Pinelands measured by NJADN, the atmospheric PAH
concentrations from October 1997 to May 2001 were similar to the concentrations
reported here (4). A recent paper by Mandalakis et al. reported atmospheric EPAH
concentrations ranging from 0.6 to 10 ng/m3 at three European background sites (22).
The average atmospheric EPAH concentration measured at Finokalia, Crete, a coastal site
in the eastern Mediterranean Sea, was 19 ng/m3 during 2000-2001 (23), which is
comparable to the concentration at Sturgeon Point.
Several previous studies on the effects of wind and air trajectory directions on
atmospheric concentrations of persistent organic pollutants were conducted to help locate
the sources of these compounds (19,24). The results showed that PAHs have an urban
source at Chicago - not surprisingly. At Sleeping Bear Dunes, air from the south was
suggested to be the major source of PAHs. At Sturgeon Point, Cortes et al. investigated
the hourly local wind directions and found that PAH concentrations were a factor of 3-5
times higher when the wind was coming to the sampling site from 30° to 89° (6); Buffalo,
NY is located within this angle. At Brule River and Eagle Harbor, air trajectories
originating from the southwest could transport PAHs to these two sites (24).
PAH Profiles. The concentration of each measured PAH was divided by the total
concentration of the 16 PAHs in that sample to obtain a PAH profile in either the vapor
or particle phase at a given site. These profiles are usually expressed in percent, and each
profile consists of 16 percentages (one for each compound). The profiles for a given
phase at a given site were then averaged, and standard errors were calculated. As
examples, the profiles for the vapor phase in Chicago and at Point Petre are shown in
Figure E3, top, and those for the particle phase at these two sites are shown in Figure E3,
bottom. The agreement of these profiles with one another was measured by Pearson's
correlation coefficients (r2), which for 14 degrees of freedom has a critical value of 0.247
(a = 0.05). These correlations were calculated for the 21 possible pairs of data in either
the vapor or particle phases.
In general, the correlation coefficients for the vapor phase PAH profiles, taken
pair-wise, were high (0.81 < r2 < 0.99), which indicated a high similarity of PAH sources
94
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at all seven sites. Similarly, the correlation coefficients for the particle phase profiles,
2
taken pair-wise, were also high (0.66 < r < 0.97), except between Point Petre and
2
Chicago, where r = 0.40 (see Figure D3, bottom). In this case, high relative amounts of
phenanthrene, fluoranthene, and pyrene were observed in the particle phase at Chicago
compared to Point Petre. The higher contributions of these three compounds in Chicago
may indicate a coal combustion source (25). In both the vapor and particle phases, retene
(RET) is relatively high at Point Petre as compared to Chicago; see Figure 3. Retene is
usually considered a marker for wood burning, particularly of wood from coniferous trees
(26). Our results suggest that wood burning may be more important at the rural site at
Point Petre vs. the urban site at Chicago.
By comparing the average PAH profiles in the vapor phase vs. that in the particle
phase (Figure E3 top vs. bottom), it is clear that the vapor phase is dominated by the
lighter, more volatile compounds, such as phenanthrene, and that the particle phase is
dominated by the heavier, less volatile compounds, such as the benzopyrenes. The PAH
profiles in the vapor and particle phases in our study are similar to those observed in air
samples collected by NJADN and by other studies (¥,7(5,79,27). This distribution is
primarily the result of vapor-particle partitioning driven by the individual compounds'
vapor pressures (25). In addition, higher molecular weight PAHs are largely formed with
soot particles (29); thus, the partitioning of PAHs between the vapor and particle phases
is also dependent on the aerosol type (30).
Temporal trends. Figure E4 shows the long-term trends of ZPAH
concentrations in the vapor and particle phases at Chicago (top) and at Sleeping Bear
Dunes (bottom). The detailed temporal trends of the other PAHs at the seven IADN sites
are given in the Supporting Information (Figures ESI and ES2). Concentrations of
ZPAH in both the vapor and particle phases showed significant decreases at Chicago.
However, at Sleeping Bear Dunes, the particle-phase ZPAH concentrations did not
change over time while the vapor-phase ZPAH concentrations showed a significant but
slow decline. The calculated half-lives of PAHs in both the vapor and particle phases at
the seven sites are given in Table El. The half-life of ZPAH in Chicago was 8.7 ±2.1
years in the vapor phase and 8.9 ± 2.6 years in the particle phase. At two sites, Sturgeon
Point and Point Petre, the EPAH concentrations showed faster declines in the particle
phase (ti/2 ~ 6 years) compared to the rate of decline in the vapor phase. At the rural sites
Eagle Harbor, Sleeping Bear Dunes, and Burnt Island, the ZPAH concentrations either
showed very slow declines (e.g. half-lives >15 years) or no significant temporal trends.
This is the first time that a long-term decreasing trend of PAH concentrations in
Chicago's atmosphere has been reported. Demashki et al. showed atmospheric PAH
concentrations have decreased appreciably between 1992 and 1997 at an urban site in
Birmingham, U.K. (37), and they suggested that this decrease could have been due to
legislation that required mandatory catalytic converters on new vehicles in 1993.
Schauer et al. compared particle phase PAH concentrations observed in Munich,
Germany from 2001 to 2002 with historical data from 1980 to 1993 and reported
decreasing PAH concentrations over time (32). Our observed decline of PAH
concentrations in air agreed well with the decline of PAH concentrations in precipitation
at Chicago (5). These declines are likely due to a commitment to cleaner air, including
improved petroleum fuels, automobile engines, and industrial pollution control
technology, as discussed in detail in our previous work (5).
95
-------
Decreasing trends of vapor-phase PAH concentrations at Eagle Harbor, Sleeping
Bear Dune, and Sturgeon Point (with half-lives of 2-9 years) had been reported by Cortes
et al. based on samples collected from 1991 to 1997 (6). We note that these earlier
reported vapor-phase half-lives are significantly faster than those reported in this study
(average half-lives longer than 16 years). A slower rate of decline of PAHs in the
atmosphere in recent years is reasonable if atmospheric PAH concentrations are
approaching a non-zero steady state (33). In this study, the observed decline of particle
phase PAH concentrations at Sturgeon Point is also different from that observed by
Cortes et al. (6), who reported that, at Sturgeon Point from 1991 to 1997, most PAHs in
the particle phase did not show significant temporal trends. Our results, however, suggest
that most PAH concentrations in the particle phase significantly decreased from 1996 to
2003 at this site (see Table El). Because decreasing PAH concentrations in the particle
phase were also observed at Point Petre and Brule River and because these sites are likely
impacted by nearby cities, it is possible that efforts to reduce pollution in these cities have
led to decreased PAH concentrations in the particle phase at these locations. Indeed, the
Toxic Release Inventory of PAHs showed decreasing emissions around the U.S. Great
Lakes from 1987 to 2003, particularly near Lakes Superior and Michigan (34).
The half-lives of each PAH in the vapor and particle phases at the 7 IADN sites
are listed in Table El. Retene, a marker for biomass burning (26), showed a slower rate
of decline at the more rural sites compared to Chicago, perhaps indicating that biomass
burning continues to be popular at the rural sites, while it is being eliminated in Chicago
(8). Because the other PAHs have multiple sources, it is not possible to interpret their
half-lives. In fact, some PAHs showed statistically increasing trends (e.g., benzopyrenes
in the particle phase at Sleeping Bear Dunes and fluoranthene in the vapor phase at Point
Petre and at Burnt Island). Generally, these increasing trends are slow, with doubling
times of >10 years. It is not yet clear if these trends are real, and if so, what they mean.
Significant seasonal trends in particle phase PAH concentrations were also
observed with higher concentrations in the winter (Figure E4, Figures ESI and ES2).
The ratios between the highest concentrations in the winter and the lowest concentration
in the summer are given as the peak-to-valley ratio in Tables ESS to ES14. These values
are usually larger than 2 indicating the PAH concentrations in the winter were more than
twice as high as those in the summer. There are many reasons that may lead to increased
particle phase PAH concentrations in the winter; these include lower atmospheric mixing
heights (35), decreased photolytic reactions in the atmosphere (36), and more emissions
from space heating. This same effect was observed for PAH concentrations in the
precipitation phase (8).
Acknowledgments
We thank Ilora Basu, Nick Alexandrou, and Team IADN for chemical
measurements; Environment Canada's Meteorological Services for some data
acquisition; Environment Canada and the U.S. Environmental Protection Agency's Great
Lakes National Program Office for funding (Grant GL995656, Melissa Hulting, project
monitor).
96
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Table El. Half-lives (in years) of PAH concentrations in the vapor and particle phases at seven sites near the Great Lakes1.
o
o
Fluo2
Phen
Anth
Flan
Pym
Ret
Bra] A
JJL"J-* *-
Chiy
B[b]F
B[k]F
B[e]P
B[a]P
I123P
BgP
DaA
Cor
ZPAHs3
Brule
Vapor
7.0 ±2.0
NS
NS
NS
NS
7.1 ±3.1
NS
NS
-3.2 ±1.0
LD
LD
LD
LD
LD
LD
LD
NS
River
Particle
NS
6.3 ±2.1
LD
4.4 ±1.1
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
4.0 ±1.0
Eagle
Vapor
NS
9.4 ±2.5
17 ±7.8
16 ±4.7
7.7 ± 1.3
10 ±3.1
LD
6.3 ± 0.9
LD
LD
LD
LD
LD
LD
LD
LD
19 ± 5.5
Harbor
Particle
NS
NS
LD
12 ±4. 8
NS
NS
NS
11±4.5
NS
NS
NS
NS
NS
NS
LD
NS
6.8 ±1.9
Chicago
Vapor
9.4 ±2.5
8.8 ±2.2
6.2 ± 1.5
10 ±2.6
6.7 ±1.2
2.6 ± 0.2
3.7 ± 0.6
3.9 ± 0.5
6.3 ±2.0
NS
NS
NS
NS
NS
NS
NS
8.7 ±2.1
Particle
5.6 ±1.1
9.5 ±4.8
5.5 ± 1.2
9.8 ±3.1
8.3 ±2.5
7.9 ±2.7
6.8 ±1.8
7.4 ± 1.8
14 ±5. 9
8.1 ±2.2
15 ±7.0
9.6 ±3. 9
NS
10 ±3.5
8.8 ±2.8
7.0 ±1.6
8.9 ±2.6
Sleeping Bear
Vapor
17 ±5.0
13 ±2.9
NS
16±5.3
8.7 ±1.6
12 ±4.0
LD
6.2 ± 1.0
LD
LD
LD
LD
LD
LD
LD
LD
15 ±4.3
Particle
NS
NS
NS
NS
NS
NS
NS
NS
NS
-9. 5 ±4.8
-11 ±5.4
-11±5.6
NS
NS
LD
NS
NS
Sturgeon Point
Vapor
21 ± 6.3
12 ±2.1
NS
15 ±3.7
7.8 ± 1.2
NS
12±5^
7.2 ±1.1
NS
NS
NS
NS
LD
LD
LD
LD
15 ±3.3
Particle
5.2 ± 0.8
4.8 ± 1.2
7.9 ±2.6
4.7 ± 0.7
4.5 ± 0.7
NS
50±09
4.5 ± 0.7
8.1 ±2.4
6.6 ±1.5
9. 1 ±2.9
4.8 ± 1.2
8.6 ±2.7
8.4 ±2.4
NS
9.2 ±2.8
5.6±1.1
Burnt Island Point Petre
Vapor Particle Vapor Particle
NS 1.9 ±0.3 -12 ±4.0 2. 2 ±0.3
NS 9.4 ±2.8 NS 7.0 ±1.5
4.2 ±0.6 5.2 ±1.1 6.1 ±1.6 5.3 ±1.0
-11±5.1 7.4±1.9 -19±11 5.1±0.9
9.2 ±2.4 7.9 ±2.2 NS 6.5 ±1.6
NS 6.0 ±1.4 8.3 ±3.6 5.5 ±1.9
25±10 50±09 42±12 57±11
6.2 ±2.4 8.8 ±2.7 NS 5.9 ±1.4
LD 8.7 ±2.6 2.1 ±0.5 5.8 ±1.3
LD 8.4 ±2.4 2.1 ±0.5 7.1 ±1.8
N/A 5.0 ±0.9 N/A 5.6 ±1.2
LD 11 ±4.5 LD 11 ±4.1
LD 6.6 ±1.4 LD 6.2 ±1.4
LD 7.9 ±2.1 LD 6.5 ±1.4
LD 7.3 ±2.1 LD 6.6 ±1.6
N/A LD N/A LD
NS NS NS 6.7 ±1.6
The results are listed as mean ± standard error. Normal font numbers are significant for 0.01 0.05. "LD" means "Limited data" and no regression analysis was conducted. "N/A"
means "no data are available". A negative half-life is actually a doubling time.
Fluo: fluorene; Phen: phenanthrene; Anth: anthracene; Flan: fluoranthene; Pyrn: pyrene; Ret: retene; B[a]A: benz[a]anthracene; Chry: triphenylene and chrysene; B[b]F:
benzo[6]fluoranthene; B[k]F: benzo[&]fluoranthene; B[e]P: benzo[e]pyrene; B[a]P: benzo[a]pyrene; I123P: indeno[7,2,3-ct/|pyrene; BgP: benzo[g/z/]perylene; DaA:
dibenz[a,/z]anthracene; Cor: coronene.
EPAH is the total concentration of the 16 compounds listed here in note 2.
-------
103
102
10°
_ 103
O
E
o> 102
o
< 10°
Q_
[XI
102
10°
ID
'2
Vapor + Particle
Vapor Phase
Particle Phase
Figure El. Total PAH concentrations in air (vapor plus particle) (top), vapor (middle) and
particle (bottom) phases at seven IADN sites sequenced by the population living within a 25-km
,th
radius of the sampling site (75). The horizontal lines represent the 10 ,50 , and 90 percentiles;
th
-th
the red lines are the means; the boxes represent the 25 to 75 percentiles; and outliers are
shown as the 5th and 95th percentiles.
101
-------
102
^)
d
o
o
X
£ 10° -I
10
-1
= 0.91
Chicago1
Brule River
Eagle Harbor
V / \Sleeping Bear
Sturgeon Pt.
Pt. Petre
Burnt Isl.
102 103 104 105 106 107
population
Figure E2. Average ZPAH concentration at the seven IADN sampling sites as a function of the
population living within a 25-km radius of the sampling site. The error bars are standard errors.
102
-------
60
o
§40
Chicago
Point Petre
Vapor Phase
1^=0.81
JU-r
•F-F-
Particle Phase
r^O.40
Figure E3. Average PAH profiles for the vapor (top) and particle (bottom) phases at Chicago
and at Point Petre. The error bars represents one standard error. The compound abbreviations
are given in Table Dl.
103
-------
D)
1996 1998 2000 2002
2004
-26
<§ -28
CM
Q_
- -30
10
0.1
0.01
Vapor
^^k ,
*»rc« <**•
.*••*•
• ••
1996 1998 2000 2002
2004
Figure E4. Temporal trends of vapor and particle phase EPAH concentrations at Chicago (top)
and at Sleeping Bear Dunes (bottom). Only data from 1996 through 2003 are shown for the
vapor phase at Sleeping Bear Dunes. The completed data set is shown in Figure DSL The black
curves are the fitting lines of the sinusoidal model (equation 2) with the period length (a3) set to
one year; the red lines indicate long-term, significant decreasing trends.
104
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Supporting Information for:
Trends in Polycyclic Aromatic Hydrocarbons Concentrations
in the Great Lakes Atmosphere
P. Sun, P. Blanchard, K. A. Brice, and R. A. Kites
This Supporting Information contains 14 tables of values derived from modeled parameters for
PAH concentrations in the vapor and particle phases at seven IADN sites; and two figures
showing temporal trends of PAH concentrations in the vapor and particle phases. Plots for PAH
larger than benzo[&]fluoranthrene in the vapor phase are not shown because of the very limited
data. ZPAH is the sum of the 16 PAHs measured by both Indiana University and Environment
Canada. These PAH are fluorene, phenanthrene, anthracene, fluoranthene, pyrene, retene,
benz[a]anthracene, triphenylene plus chrysene (which are not resolvable by gas chromatography
at Indiana University and thus count as one compound), benzo[6]fluoranthrene,
benzo[&]fluoranthrene, benzo[e]pyrene, benzo[a]pyrene, indeno[l,2,3-cd]pyrene, benzo[g/z/]-
perylene, and dibenz[a,/7]anthracene, and coronene.
The vapor phase PAH concentrations (in pg/m3) were first converted to partial pressures (P, in
atm) using the ideal gas law. These partial pressures were then adjusted to the reference
temperature of 288 K using equation 1, where AH is a characteristic phase-transition energy of
the compound (in kJ/mol), R is the gas constant, and T is the daily average atmospheric
temperature at the sampling site (in Kelvin). The value of AH was determined by a preliminary
regression of ln(P) vs. l/r(see equation 2). The values of In^ss) were then regressed vs. time
(t, in Julian days relative to January 1, 1990) using equation 3 to determine the rate (b\, in days"1)
of exponential increase (b\ > 0) or decrease (b\ < 0) of these partial pressures. If this rate was
statistically significant (p < 0.05), these rates were then converted to half-lives (t\n, in years) by
dividing the values into the ln(2)/365 for each compound at each site.
0)
R ^288 Tj
lnP = — + const (2)
R [_Tj
Tables ESI to ES7 show the values of AH and the calculated half-lives from the b\ values in
equation 3. The results are listed as mean ± standard error. Normal font numbers are significant
for 0.01 0.05. "LD" means "limited
data", and no regression was calculated. "N/A" means "not available". A negative half-life is
actually a doubling time.
105
-------
Equation 4 was used to fit the PAH concentrations (C) in the particle phase:
InC =a0 + a1t + a2sin -- ha4 (4)
where t is the time in Julian Days relative to January 1 1990, ao is the intercept (unitless), a\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, a2 is the periodic amplitude (unitless), a3 is the length of the period (in days), and a4 is the
periodic offset (in days).
The ratio between the highest PAH concentration during winter time and the lowest
concentration during summer time can be calculated from the fitted a2 parameter by taking its
anti -logarithm (e2"2, the factor of 2 in the exponent is needed to calculate the peak-to-valley
amplitude). The sine wave would have a maximum at day 91 in a year. Therefore, the dates of
the maximum of PAH concentrations were calculated by first converting the fitted ^values from
radians to days (multiplying by 365/2-n) and then subtracting these values from 91.
Tables ESS to ES14 show results of the fit using equation 4 with a3 set to 365 days. The results
are listed as mean ± standard error. Normal font numbers are significant for 0.01 > 0.05. A negative half-life is actually a doubling time.
Figure ESI shows the temporal trends of vapor phase total PAH concentrations at the seven
IADN sites. The concentrations were converted to P288 by equation (1). The values of In^ss)
were then plotted vs. time based on equation (3). The red lines indicate long-term significant
decreasing or increasing trends.
Figure ES2 shows the temporal trends of particle phase total PAH concentrations at the seven
IADN sites. The black curves are the fitting lines using the sinusoidal model with the period
length (a3) set to one year (equation 4); the red lines indicate long-term significant decreasing
trends (a\ < 0).
106
-------
Table ESI. Fit parameters for PAHs in vapor phase at Brule River
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
Benz[a]anthracene
Triphenylene +
Chrysene
Benzo [AJfluoranthrene
Benzo [&]fluoranthrene
Benzo [ejpyrene
Benzo [a]pyrene
Indeno[l,2,3-cJ|pyrene
Benzo [g/z/']perylene
Dibenz [a, /zjanthracene
Coronene
EPAH
Temperature-corrected
EPAH cone. (288 K)
Average cone.
(pg/m3)
560 ± 30
610 ±40
32 ±8.7
95 ± 6.2
37 ±2.5
34 ±8.7
5.5 ±1.0
8.0 ±0.8
13 ± 1.7
6.2 ±0.9
7.8 ±1.0
7.8 ±1.3
8.6 ±1.4
7.9 ±1.2
4.1 ±0.8
6.3 ±0.8
1340 ±75
1480 ± 83
Half-life
(years)
7.0 ±2.0
NS
NS
NS
NS
7.1 ±3.1
NS
NS
-3.2 ±1.0*
LD
LD
LD
LD
LD
LD
LD
NS
AH
(kJ/mol)
NS
NS
20 ±6.7
8.2 ±3. 5
17 ± 3.6
21 ±4.7
15 ±6.6
NS
NS
LD
LD
LD
LD
LD
LD
LD
NS
No. of
detects
188
188
74
188
172
147
47
107
48
22
26
20
21
21
9
10
188
r2
0.06
NS
0.12
0.03
0.12
0.16
0.11
NS
0.19
N/A
N/A
N/A
N/A
N/A
N/A
N/A
NS
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
Table ES2. Fit parameters for PAHs in vapor phase at Eagle Harbor
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
Benz[a]anthracene
Triphenylene +
Chrysene
Benzo [AJfluoranthrene
Benzo [&]fluoranthrene
Benzo [e]pyrene
Benzo [a]pyrene
Indeno [ 1 ,2,3 -cc/|pyrene
Benzo [g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Temperature-corrected
EPAH cone. (288 K)
Average cone.
(pg/m3)
390 ±18
600 ± 50
44 ±14
100 ± 5.7
60 ±5.3
48 ±6.5
15 ±6.8
15 ±5.2
14 ±3. 8
11 ±2.2
10 ±2.5
18 ±3.4
10 ±3.0
12 ±2.7
4.7 ±3.2
2.4 ±0.8
1210 ±80
1740 ± 140
Half-life
(years)
NS
9.4 ± 2.5
17 ±7.8
16 ±4.7
7.7 ± 1.3
10±3.1
LD
6.3 ± 0.9
LD
LD
LD
LD
LD
LD
LD
LD
19 ±5.5
AH
(kJ/mol)
17 ± 2.5
33 ± 2.5
42 ± 5.5
29 ± 2.8
17 ± 3.6
32 ± 5.4
LD
12 ±4.0
LD
LD
LD
LD
LD
LD
LD
LD
27 ± 2.5
No. of
detects
367
368
168
366
325
230
62
188
43
22
17
20
9
16
4
o
J
368
r2
0.12
0.34
0.27
0.24
0.12
0.16
N/A
0.02
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
0.25
107
-------
Table ESS. Fit parameters for PAHs in vapor phase at Sleeping Bear Dunes
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
Chrysene
Benzo [AJfluoranthrene
Benzo [&]fluoranthrene
Benzo [ejpyrene
Benzo [a]pyrene
Indeno[ 1 ,2,3 -c
-------
Table ESS. Fit parameters for PAHs in vapor phase at Chicago
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
Chrysene
Benzo[6]fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -cc/|pyrene
Benzo[g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Temperature-corrected
EPAH cone. (288 K)
Average cone.
(pg/m3)
16000 ± 930
39000 ± 3800
1500 ± 92
9500 ± 600
3900 ± 220
250 ±18
76 ± 7.0
200 ± 14
120 ±11
51 ±5.5
50 ±4.4
54 ±7.0
58 ±6.5
48 ±4.9
16 ±2.1
23 ± 2.4
70000 ± 5200
73400 ±3 100
Half-life
(years)
9.4 ±2.5
8.8 ±2.2
6.2 ± 1.5
10 ±2.6
6.7 ± 1.2
2.6 ± 0.2
3.7 ± 0.6
3.9 ± 0.5
6.3 ±2.0
NS
NS
NS
NS
NS
NS
NS
8.7 ±2.1
AH
(kJ/mol)
40 ± 3.0
40 ± 3.1
32 ± 4.3
45 ± 2.6
32 ± 2.9
45 ± 3.2
12 ± 4.9
46 ± 3.4
NS
NS
NS
NS
NS
NS
NS
NS
40 ± 2.9
No. of
detects
218
218
209
218
218
204
168
217
168
132
141
122
114
116
58
61
218
r2
0.47
0.45
0.27
0.60
0.43
0.66
0.20
0.54
0.06
NS
NS
NS
NS
NS
NS
NS
0.50
Table ES6. Fit parameters for PAHs in vapor phase at Burnt Island
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
Benz[a]anthracene
Triphenylene +
Chrysene
Benzo [AJfluoranthrene
Benzo [&]fluoranthrene
Benzo [ejpyrene
Benzo [a]pyrene
Indeno[l,2,3-cJ|pyrene
Benzo [g/z/']perylene
Dibenz [a, /zjanthracene
Coronene
EPAH
Temperature-corrected
EPAH cone. (288 K)
Average cone.
(pg/m3)
180 ±9.6
230 ±8.9
3.5 ±0.3
78 ±13
31 ±1.6
67 ±7.1
3.8 ±1.6
22 ±1.6
4.9 ±1.3
1.9 ±0.5
N/A
1.7 ±0.7
15.3
10 ±1.8
3.3 ±0.5
N/A
590 ± 27
560 ± 26
Half-life
(years)
NS
NS
4.2 ± 0.6
-11±5.1*
9.2 ±2.4
NS
2.5 ±1.0
6.2 ±2.4
LD
LD
N/A
LD
LD
LD
LD
N/A
NS
AH
(kJ/mol)
15 ± 2.4
NS
NS
NS
15 ± 2.5
23 ±6.1
NS
18 ±4.8
LD
LD
N/A
LD
LD
LD
LD
N/A
NS
No. of
detects
200
201
198
199
200
113
54
145
15
11
N/A
3
1
35
33
N/A
201
r2
0.18
NS
0.20
0.03
0.21
0.13
0.13
0.14
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
NS
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
109
-------
Table ES7. Fit parameters for PAHs in vapor phase at Point Petre
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
Chrysene
B enzo [b ] fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -cc/|pyrene
Benzo[g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Temperature-corrected
EPAH cone. (288 K)
Average cone.
(pg/m3)
350 ±17
520 ± 22
7.6 ±0.8
190 ± 16
74 ±5.0
97 ± 9.0
4.8 ±0.8
50 ± 8.0
14 ±4.5
3.1±0.8
N/A
13 ±9.6
11±3.8
14 ±2.4
4.9 ±0.9
N/A
1300 ±55
1200 ± 45
Half-life
(years)
-12 ±4.0*
NS
6.1 ±1.6
-19±11*
NS
8.3 ±3.6
4.2 ±1.2
NS
2.1 ±0.5
2.1 ± 0.5
N/A
LD
LD
LD
LD
N/A
NS
AH
(kJ/mol)
24 ± 2.7
NS
13 ±4.2
NS
NS
13 ±5.4
NS
21 ± 6.5
NS
NS
N/A
LD
LD
LD
LD
N/A
11 ±3.1
No. of
detects
207
208
203
207
208
149
98
173
48
48
N/A
10
2
30
29
N/A
208
r2
0.31
NS
0.12
0.06
NS
0.07
0.12
0.05
0.24
0.33
N/A
N/A
N/A
N/A
N/A
N/A
0.06
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
Table ESS. Fit parameters for PAHs in particle phase at Brule River
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
Chrysene
Benzo[6]fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -«/]pyrene
Benzo[g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Average
cone, (pg/m3)
10 ±2.0
45 ±5. 8
7.4 ±1.8
58 ±7.5
43 ±5.0
25 ±3.1
14 ±1.6
37 ±4.0
57 ±6.2
23 ±2.1
26 ±2.3
21 ±2.0
37 ±3.9
27 ±2.4
6.4 ±0.7
18 ±1.8
370 ±39
Half-life
(years)
NS
6.3 ±2.1
LD
4.4±1.1
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
LD
NS
4.0 ±1.0
Peak-to-
valley
ratio
3.0 ± 1.2
5.1 ± 1.2
10.4 ± 1.2
9.6 ± 1.2
2.4 ±1.2
8.1 ± 1.2
11.3 ±1.2
7.8 ± 1.2
4.6 ± 1.3
4.7 ± 1.2
4.3 ± 1.3
4.4 ± 1.2
4.1 ± 1.2
4.1 ± 1.3
9.2 ± 1.2
Maximum
date
(± days)
Feb 3 ± 11
Jan 25 ± 5
Jan 26 ± 5
Jan 24 ± 5
Jan 6 ± 13
Jan 17± 6
Jan 18 ± 5
Jan 21 ± 5
Jan 14 ± 8
Jan 28 ± 7
Jan 28 ± 8
Jan 24 ± 8
Jan 27 ± 7
Jan 26 ± 7
Jan 20 ± 5
No. of
detects
98
163
36
166
132
160
117
152
147
107
116
104
125
126
38
87
167
r2
0.22
0.42
N/A
0.52
0.50
0.14
0.45
0.49
0.39
0.26
0.32
0.27
0.27
0.29
N/A
0.29
0.46
110
-------
Table ES9. Fit parameters for PAHs in particle phase at Eagle Harbor
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
Benz[a]anthracene
Triphenylene +
Chrysene
Benzo [AJfluoranthrene
Benzo [&]fluoranthrene
Benzo [ejpyrene
Benzo [a]pyrene
Indeno [1,2,3 -cd\py rene
Benzo [g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Average cone.
(pg/m3)
3.6 ±0.7
17 ±1.0
4.2 ± 1.1
5.1 ±0.5
23 ±1.4
8.4 ± 1.0
6.6 ±0.6
15 ±0.9
27 ±1.6
12 ±1.2
13 ±0.7
10 ±0.7
18 ±1.0
14 ±0.8
4.0 ±0.8
12 ±1.0
150 ±9.4
Half-life
(years)
NS
NS
LD
11.9±4.8
NS
NS
NS
11.3 ±4.5
NS
NS
NS
NS
NS
NS
LD
NS
6.8 ±1.9
Peak-to-
valley
ratio
1.9 ± .1
2.8 ± .1
5.6 ± .2
3.0 ± .2
2.5 ± .2
NS
3.1 ± 1.2
1.9 ± 1.1
NS
NS
NS
NS
NS
NS
3.3 ± 1.2
Maximum
date
(± days)
Feb3±ll
Feb 15 ± 6
Feb 4 ± 6
Feb 7 ± 7
Dec 31 ± 12
NS
Jan 26 ± 7
Jan 16 ± 13
NS
NS
NS
NS
NS
NS
Jan 30± 8
No. of
detects
85
210
22
82
215
151
111
197
179
108
145
104
152
149
27
88
215
r2
0.20
0.32
N/A
0.24
0.13
0.13
NS
0.25
0.10
NS
NS
NS
NS
NS
N/A
NS
0.23
Table ES10. Fit parameters for PAHs in particle phase at Sleeping Bear Dunes
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
Benz[a]anthracene
Triphenylene +
Chrysene
Benzo [AJfluoranthrene
Benzo [&]fluoranthrene
Benzo [e]pyrene
Benzo [a]py rene
Indeno [ 1 ,2,3 -cc/|pyrene
Benzo [g/z/']perylene
Dibenz [a, h] anthracene
Coronene
EPAH
Average cone.
(pg/m3)
4.4 ±0.3
32 ±2.3
3.5 ±0.3
53 ±4.5
37±3.1
7.2 ±0.5
13 ± 1.4
29 ±2.5
50 ±4.0
19 ±1.6
24 ±1.8
20 ±1.8
33 ±2.8
26 ± 2.0
7.4 ±0.8
17 ±1.3
320 ± 26
Half-life
(years)
NS
NS
NS
NS
NS
NS
NS
NS
NS
-9.5 ±4.8*
-11.4 ±5.4*
-11.0 ±5.6*
NS
NS
LD
NS
NS
Peak-to-
valley
ratio
2.1 ± 1.2
3.6 ± 1.1
NS
4.2 ± 1.2
3.4 ± 1.2
2.3 ± 1.2
2.8 ± 1.2
4.7 ±1.2
4.2 ± 1.2
1.6 ±1.2
2.6 ± 1.2
1.8±1.2
2.9 ± 1.2
2.6 ± 1.2
2.1 ± 1.2
5.0 ± 1.2
Maximum
date
(± days)
Feb 1 ± 12
Feb 16 ± 6
NS
Feb 13 ± 7
Feb 17 ± 9
Jan 29 ± 10
Feb 2 ± 11
Feb 7 ± 7
Feb 5 ± 7
Jan 23 ± 21
Feb 9 ± 10
Feb 10 ±18
Feb 5 ± 9
Feb 5 ± 10
Jan 16 ± 12
Feb 7 ± 7
No. of
detects
120
208
61
213
186
147
147
200
204
150
167
152
185
185
44
128
214
r2
0.16
0.30
NS
0.25
0.19
0.15
0.16
0.27
0.26
0.08
0.16
0.08
0.18
0.16
N/A
0.14
0.26
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
Ill
-------
Table ES11. Fit parameters for PAHs in particle phase at Sturgeon Point
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
Chrysene
Benzo[6]fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -c
-------
Table ES13. Fit parameters for PAHs in particle phase at Burnt Island
PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Retene
B enz [a] anthracene
Triphenylene +
Chrysene
Benzo[6]fluoranthrene
Benzo[&]fluoranthrene
Benzo[e]pyrene
Benzo[a]pyrene
Indeno [ 1,2,3 -c
-------
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-26
-28
-30
-32
-34
-26
-28
-30
-32
-34
-28
-30
-32
-34
-36
-38
-28
-30
-32
-34
-36
-28
-30
-32
-34
-36
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Figure ESI. Temporal trends of vapor-phase PAH concentrations at seven IADN sites. The red lines indicate long-term significant
decreasing or increasing trends. Detailed information on the fitted parameters is in Tables DS1 to DS7.
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Figure ESI (continued). Temporal trends of vapor-phase PAH concentrations at seven IADN sites.
-------
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o
c
o
o
o$e
103
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o
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104
103
102
10
104
103
102
10
103
10
103
102
10
1
:<• .
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. *<»>.
_| 0 I
Figure ES2. Temporal trends of particle-phase PAH concentrations at seven IADN sites. The black curve is the fitted line using the
sinusoidal model with a period length (a3) set to one year. The red lines indicate long-term significant decreasing or increasing trends.
Detailed information on the fitted parameters is in Tables DS8 to DS14.
-------
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2
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c
o
c
o
o
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o
N
103
102
10
104
103
102
10
104
103
102
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104
102
10
104
103
10
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iff
* t
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Figure ES2 (continued). Temporal trends of particle-phase PAH concentrations at seven IADN sites.
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Appendix F. Atmospheric Organochlorine Pesticide Concentrations
near the Great Lakes: Temporal and Spatial Trends
Published in Environmental Science & Technology, 2006, 40, 6587-6593.
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Atmospheric Organochlorine Pesticide Concentrations
near the Great Lakes: Temporal and Spatial Trends
Ping Sun,1 Pierrette Blanchard,2 Kenneth, Brice2, and Ronald A Kites*1
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 USA
and
Environment Canada
4905 Dufferin Street
Toronto, ON M3H 5T4 Canada
* Corresponding Author Email: hitesr@indiana.edu
Brief
Concentrations of most OC pesticides are decreasing with half-lives of 5-10 years based
on data acquired by the Integrated Atmospheric Deposition Network during the period -1990
through 2003.
Abstract
As a part of the Integrated Atmospheric Deposition Network, atmospheric organochlorine
pesticide concentrations were measured in both the gas and particle phases at seven sites near the
Great Lakes. Much higher organochlorine pesticide concentrations were found in the gas phase
compared to that in the particle phase. Long-term decreasing trends were observed for most
pesticides in both phases. Two different seasonal trends were observed in the particle phase: (a)
In-use pesticides, such as endosulfan, showed higher concentrations in the summer, a time
corresponding to their agriculture use. (b) Restricted organochlorine pesticides, such as lindane,
showed higher particle-phase concentrations in the winter, presumably due to their enhanced
partitioning from the gas phase to particles. Generally, Chicago had the highest concentrations of
chlordanes, dieldrin, and ZDDT, suggesting that urban areas could be sources of these
compounds to atmosphere. Point Petre had the highest concentrations of endosulfan, likely due
to its agricultural application in Southern Ontario.
Introduction
Organochlorine (OC) pesticides were widely used in North America before the 1970s,
and some of these compounds are still present in the environment 20-30 years after their use was
restricted. Several studies have shown that OC pesticides are re-volatilized from agricultural
soils in the southern United States, Mexico, and the Canadian prairies and atmospherically
transported to the Great Lakes (1,2). To study this transport, the Integrated Atmospheric
Deposition Network (IADN) was founded in 1990. The network monitors OC pesticides in air,
atmospheric particles, and precipitation around the Great Lakes, and IADN scientists have
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published several studies on OC pesticides in air, reporting on their concentrations (3,4), their
spatial variations (5), and their sources (6).
Only a few studies have examined long-term temporal trends of OC pesticides in air.
Hung et al. reported a long-term decline of atmospheric OC pesticide concentrations from 1993
to 1997 in the Canadian Arctic (7). Cortes et al. (S), reported decreasing concentrations, with
half-lives of <10 years for most gas-phase OC pesticides at five remote sites around the Great
Lakes covering the period from November, 1990 to January, 1996. In this paper, we continue
the work of Cortes et al. (5) by adding eight years of gas-phase results (from January 1996 to
December 2003). The gas-phase OC pesticide concentrations at two additional sites (Brule
River, near Lake Superior, and Chicago, near Lake Michigan) and particle-phase OC pesticide
concentrations at five United States sites were also added. Using this extended database, the
temporal and spatial trends of OC pesticide atmospheric concentrations around the Great Lakes
have been investigated.
Experimental
Sampling and Analytical Methodology. The OC pesticides measured by IADN are
aldrin, a- and y-chlordane, p,p'- and o,p '-DDT, p,p'- and o,p '-DDD,/\p'-DDE, dieldrin, a- and P-
endosulfan, endrin, heptachlor epoxide, hexachlorobenzene, a-, P-, and y-hexachlorocyclohexane
(HCH), methoxychlor, and fr'am'-nonachlor.
Seven IADN sampling sites were chosen in this study, and a map of these locations is
given elsewhere (9). Chicago is the only site located in an urban area, while Sturgeon Point is a
semi-urban site located about 25 km south of Buffalo, NY. The other five sites (Eagle Harbor
and Brule River, near Lake Superior; Sleeping Bear Dunes, near Lake Michigan; Burnt Island,
near Lake Huron; and Point Petre, near Lake Ontario) are located in unpopulated areas near the
Great Lakes. Detailed site information can be found at the IADN website
(www.msc.ec.gc.ca/iadn).
Measurements of OC pesticides in the gas phase started at Eagle Harbor, MI in
November 1990, at Sleeping Bear Dunes, MI and Sturgeon Point, NY in December 1991, at
Point Petre, ONT in January 1992, at Burnt Island, ONT in January 1993, and at Brule River, WI
and Chicago, IL in January 1996. The particle phase samples at the two Canadian sites (Burnt
Island and Point Petre) are not discussed in this paper due to the limited data available. At the
five U.S. sites, particle-phase data reported here started in October 1996 because prior to that
time, two or three particle-phase samples had been combined into monthly samples. In all cases,
the database ends with samples collected through December 2003 except at Brule River, which
was closed in August 2002.
The methodologies employed for collection and analysis of samples up to January 1996
have been previously summarized in detail by Cortes et al. (5) and so will not be repeated here.
There have been minimal modifications to these methodologies since January 1996 for samples
collected up to December 2003 at all sites considered here. The detailed comparison of sampling
and analytical procedures between the U.S. and Canadian sites is listed in Table FS1 of the
Supporting Information.
Quality control and assurance procedures were followed to ensure data quality (10,11).
For the OC pesticides that are the focus of this paper, the results of the QA activities have
confirmed that the data from the U.S. and Canadian sites can be regarded, with a few possible
exceptions (e.g. the HCHs), as generally equivalent so that spatial differences in ambient
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concentrations can be considered to be real and not caused by artifacts or biases arising from
differences in the sampling or analytical methodologies. The Canadian sampling method used
one PUF plug to sample the gas phase. To evaluate the potential for breakthrough, two such
PUF plugs were placed in series for several experiments during the summer of 2003. The results
indicated breakthrough of the HCHs of the order of 10-20% (77). The Canadian HCH
concentrations were not corrected in this paper, but the spatial distributions of HCHs are only
discussed for the five U.S. sites.
Temporal Trend Analysis. A temporal trend analysis procedure adopted by Cortes et
al. (5) will be used here. Briefly, the gas-phase pesticide concentrations are first converted to
partial pressures (P) using the ideal gas law. The atmospheric temperature effect on the pesticide
concentration was then corrected by adjusting the partial pressures to a reference temperature of
288 K. This corrected partial pressure, P288, was calculated from
288 yj OQQ T
xv y ^oo 1 J
where P is the partial pressure converted from concentration (in atm), A// is a characteristic
phase-transition energy of the compound (in kJ/mol), T is the average temperature at the
sampling site during the day the sample was collected (in K), and R is the gas constant. The
coefficient, AH/R, was determined by a preliminary regression of ln(P) vs. l/T. These
temperature- corrected partial pressures were then regressed vs. sampling date in Julian days
relative to January 1, 1990 (t) to find a first-order rate constant («i in days"1) for the rate of
decrease (or increase) of the atmospheric concentrations:
ln(JD288) = a0-a/ (2)
The particle-phase concentrations (Cp~) of the pesticides at the five U.S. sites were fitted
by the following time-dependent function to study their temporal trends (9)
InC =b0+b,t + b2sin — + bj (3)
Ib3 J
where b2 is the periodic amplitude (unitless), bj, is the length of the period (in days), and b4 is the
periodic offset (in days). If b\ was significant (p < 0.05), either a decreasing (b\ < 0) or
increasing (b\ > 0) trend in the pesticide concentrations could be determined for this sampling
period.
Results and Discussion
The average concentrations of the OC pesticides in the gas and particle phases as
measured by IADN are listed in Table FS2-FS13 of the Supporting Information. Generally,
pesticide concentrations in the particle phase are much lower (usually less than 10%) than those
in the gas phase. For example, the average y-HCH concentration in the particle phase at Chicago
was 0.96 ± 0.07 pg/m3, which is about 3% of this compound's concentration in the gas phase (35
± 2.5 pg/m3), and the total a- and y-chlordane concentrations in the particle phase were less than
-10% of those in the gas phase. Similar results have been reported by the New Jersey
Atmospheric Deposition Network (NJADN) (72). The preferred partitioning of OC pesticides
toward the gas phase is consistent with what would be expected from their relatively high vapor
pressures.
Comparisons of selected OC pesticide concentrations in the gas phase with measurements
made by IADN and by other studies over the same time period are given in Table FS14. In
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general, the IADN results are similar to other gas-phase OC pesticide concentrations reported for
North America. The average concentration of gas-phase a- and y-HCH at Jersey City, NJ were
23 and 22 pg/m3, respectively, which are lower than those measured by IADN at Chicago (52 ±
2.5 pg/m3 and 35 ± 2.5 pg/m3 for a- and y-HCH). The gas phase concentrations of a- and y-
chlordane were similar at Jersey City and at Chicago, while these concentrations were higher at
Pineland, NJ, a rural site compared to Sleeping Bear Dunes, MI, a background site. One study
showed higher chlordane concentrations at Rohwer, Arkansas compared to IADN, but this result
could be attributed to the historically heavy use of chlordane near that Arkansas collection site
(13).
Shen et al. measured a-endosulfan, /\p'-DDT, and p,p'-DDE at two IADN sites, Point
Petre and Burnt Island, from May 2000 to May 2001 using passive samplers (14). A comparison
of the concentrations of these three pesticides at Burnt Island (Table FS14) suggests that the
results matched well between these two studies. Other studies reported selected OC pesticide
concentrations in the gas phase in Birmingham, U.K.; Seoul, Korea; and Senga Bay, South
Africa (15,16,17). Generally, the y-HCH concentrations were higher in the U.K. than in North
America, presumably due to heavier applications of purified y-HCH (lindane) in Europe (18).
The a-HCH concentrations were an order of magnitude higher in Seoul, Korea compared to
Chicago and Jersey City, suggesting that technical HCH was more widely or more recently used
in Korea than in North America. Pesticides measured at Senga Bay, South Africa showed lower
atmospheric concentrations compared to the U.S. and the U.K., indicating less pesticide usage in
this economically developing region (77).
Temporal trends. Most of the OC pesticide concentrations showed significant decreases
over time either in the vapor or particle phase. The calculated half-lives of these OC pesticides
in the gas and particle phases are listed in Table Fl. Although different half-lives between the
gas and particle phase were observed for some OC pesticides, most of the half-lives ranged from
4 to 9 years. For example, similar half-lives were observed in both the vapor and particle phases
for y-HCH (lindane) at Chicago and at Sturgeon Point and for dieldrin at all five U.S. sites.
Figure El shows the temporal trends of y-HCH and a-endosulfan in the vapor and particle
phases, respectively while the long-term trends of the restricted OC pesticides are shown in
Figures FS1 and FS2. Significant increasing trends were observed for some restricted pesticides.
For example, in the gas phase, the o,p -DDT concentration increased at Sleeping Bear Dunes and
Sturgeon Point, and endrin increased at Chicago. However, for these cases, only data from 1999
to 2003 were available.
Although y-HCH was still in-use in Canada until 2003, long-term decreasing trends were
observed in both the gas and particle phases at all the sites except for the particle phase for at
Brule River (Figure Fl). Technical HCH contained 60-70% a-HCH, 2-12% P-HCH, 10-15% y-
HCH, and 3-28% other minor isomers and had been widely used in North America until it was
phased out in the 1970s and replaced by lindane, which is the purified y isomer (19). Long-term
decreasing trends of atmospheric HCH concentrations have been observed by other researchers
(7,8,20). Garmouma and Poissant reported a longer half-life of atmospheric a-HCH (>10 years)
compared to y-HCH (~5 years) in Quebec, Canada (21). Hung et al. observed a slow decrease of
a-HCH concentrations (average half-life of 17 years) in Arctic air based on data collected from
1993 to 1997. After adding two more years-worth of data, Hung et al. estimated that the half-life
a-HCH concentrations in Arctic air had significantly decreased to 9 years (7). However, the
half-life of y-HCH did not change using the extended the data set. Although we observed similar
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half-lives for HCHs, our results showed that y-HCH had a longer half-life (5 to 10 years)
compared to a 4-year half-life for a-HCH at most IADN sites (Table Fl). The only exception
was at Sleeping Bear Dunes, where these two pesticides showed similar half-lives of ~4 years.
Similar results were reported by Buhler et al. for Eagle Harbor and Sturgeon Point based on
IADN samples collected from 1990 to 2001 (4). The slower decline of y-HCH measured by
IADN in the Great Lakes region is likely due to the continuing usage of lindane in Canada. In
fact, -8660 t of lindane have been applied during the same period in the Canadian prairies, and
there is evidence that atmospheric transport of this pesticide to the Great Lakes region was
occurring (22).
Unlike a- and y-HCH, P-HCH concentrations did not show significant trends at most sites
(Figure FS1). This difference may be the result of the various properties of the HCH isomers.
Compared to a- and y-HCH, P-HCH has the highest physical and metabolic stability because of
its relatively planar structure (23). As a result, P-HCH's environmental concentrations seem to
decrease more slowly than those of a- and y-HCH. Thus, it is possible that we will need samples
over a longer time period before we are able to observe a decreasing trend of P-HCH
concentrations at these sites.
a-Endosulfan, a current-use pesticide, showed no long-term decreasing trends in the
vapor phase at Eagle Harbor, Sleeping Bear Dunes, or Sturgeon Point (Figure Fl). However, a-
endosulfan's concentrations in the particle phase declined at all five U.S. sites. The National
Center for Food and Agriculture Policy provides an endosulfan usage database for the period
1992-97 (24). Although endosulfan usage in Michigan significantly decreased from 29 tons to
19 tons between 1992 and 1997, increasing usage was also observed in the surrounding states,
including New York, Indiana, Kentucky, and Minnesota. Because of the lack of updated usage
data, we are reluctant to correlate the decreasing a-endosulfan concentrations in the particle
phase with its usage pattern.
Chlordane concentrations in the gas phase declined at all seven sites (Figure FS1).
Overall, a-chlordane concentrations in the gas phase had half-lives greater than 10 years and
slightly less than 10 years in the particle phase (Table Fl). Gas phase y-chlordane concentrations
decreased with half-lives of ~7 years at most sites except Burnt Island, trans-nonachlor
concentrations showed similar decreasing trends as a-chlordane with half-lives of -10 years.
Technical chlordane was a mixture containing y-chlordane (13%), a-chlordane (11%), trans-
nonachlor (5%), and more than 140 other compounds with six to nine chlorine atoms (25). Of
these components, y-chlordane is generally regarded as the most susceptible to degradation by
microorganisms in soil (26,27). This observation generally agreed with our results, which
showed a faster rate of decline of y-chlordane compared to a-chlordane and trans-nonachlor.
The half-lives of chlordane in this study were slightly longer than in other studies. For example,
Bidleman et al. observed a decline of a- and y-chlordane and trans-nonachlor concentrations in
Arctic air with half-lives ranging from 4.9 to 9.7 years over the time period 1984 to 1998 (25).
Hung et al. reported the half-lives of 6.1, 5.5, and 6.2 years for a-, y-chlordane and trans-
nonachlor, respectively, at Alert, Canada from 1993 to 1999 (7). A previous publication by
IADN also reported shorter half-lives for chlordane concentrations at Sleeping Bear Dunes,
Sturgeon Point, and Point Petre based on samples collected from 1990 to 1996 (8). Technical
chlordane was introduced in 1947 and phased out in the United Sates in 1988, thus, the faster
decline reported previously could have been a response to its restriction. The slower decline rate
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of chlordane that we now observe may be a result of these concentrations approaching a steady
state in recent years (29).
Technical DDT consisted ofp,p'-DDT (65-80%), 0.//-DDT (15-21 %), p,p'-ODD (<4%)
and small amounts of other compounds. p,p'-DDT can dehydrochlorinate in the environment to
form p,p'-DDE (30). IADN measures the gas phase concentrations of several DDT-related
compounds, including p,p'-DDT, p,p'-DDD, p,p'-DDE, 0.//-DDT, and o,/»'-DDD in the gas
phase, but in the particle phase, p,p'-DDE and 0.//-DDT are not measured. As shown in Figures
ESI and ES2, no long-term trends were observed for DDT-related compounds in the particle
phase with two exceptions: p,p'-DDD concentrations decreased at Chicago, and o,p'-DDD
concentrations decreased at Sleeping Bear Dunes. In the gas phase, p,p'-DDT, P,p'-DDD, p,p'-
DDE, and o,p'-DDD concentrations showed decreasing trends at most sites, although shorter
datasets resulted in a significant increasing trend of o,/?'-DDT concentrations at Sleeping Bear
Dunes and Sturgeon Point. Hung et al. also found an increasing trend for o,/?'-DDT at Alert,
Canada from 1993 to 1997 (20). Given that DDT was banned in 1970s in the North America, no
newly manufactured or applied DDT is now entering the North American environment; thus, the
cause of these increasing trends is not clear.
In general, most of the OC pesticide half-lives listed in Table Fl are longer than those
reported by Cortes and co-workers (8). For example, a-chlordane has a half-life of 10 ±1.3 years
at Sturgeon Point compared to a previously reported 4.1 ±1.4 years. At Sleeping Bear Dunes, the
half-life ofp,p -DDT increased from 2.3 ± 0.6 years to 11 ±3.1 years. With the additional eight
years of data, the longer half-lives of OC pesticides that we now observe suggest that these
concentrations are now approaching a steady state. In addition, with a longer sampling period,
the calculated half-lives in our study showed lower relative standard errors compared to the
previously reported results (8).
We also compared the decline of OC pesticide concentrations in the vapor and particle
phase with those measured in different environmental compartments including precipitation, lake
surface water, and biota in the Great Lakes (9,31,32,33). Some similarities were observed for
selected pesticides. For example, y-HCH had a half-life of 4 to 6 years in precipitation at Eagle
Harbor and Chicago (9), which is similar to those in the vapor and particle phases. Trends of
chlorinated organic contaminants in rainbow smelt from Lake Huron, Michigan, and Superior
from 1983 to 1999 have recently been reported (31). The half-lives of chlordane (7-11 years)
and p,p -DDE (7-9 years) in biota in these three lakes agree with the half-lives measured in our
study. We note that, although the reported half-lives for OC pesticides in different compartments
had a wide range (e.g. 2 to 35 years in lake trout, 33), most of them are around 6 to 10 years,
similar to the values we measured in the atmosphere. These similarities suggested that those
pesticides are at a long-term equilibrium among these environmental compartments (34).
Two different seasonal trends were observed for OC pesticide concentrations measured
by IADN in the particle phase: First, the concentrations peak in the summer for current in-use
pesticides, such as endosulfan, a time which corresponds well to their agricultural use (4,35).
For example, the highest p-endosulfan concentration was -30 times higher than the lowest
concentration (Table FS8-FS12) at Sleeping Bear Dunes, indicating substantial seasonal
variations. Second, the concentrations peak in the winter (in January or February) for restricted
pesticides, such as chlordane. These restricted pesticides enter the atmosphere from re-
volatilization from lake and terrestrial surfaces (33), and their concentrations in the atmospheric
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particle phase tend to increase during the winter due to enhanced partitioning from the gas phase
to the particle phase.
Spatial Trends. The spatially resolved concentrations of the three major technical HCH
isomers in the gas phase are summarized in Figure F2. Among these five U.S. sites, the a-HCH
concentrations were slightly higher (average 100 ± 5.3 pg/m3) at Eagle Harbor [F = 24.9, p <
0.001]. These concentrations were similar (average 82 ± 1.8 pg/m3) at Sleeping Bear Dunes and
Sturgeon Point [F = 2.56, p = 0.06]. Chicago and Brule River showed similar but lower a-HCH
concentrations (average 54 ± 2.2 pg/m3 [F= 1.54, p= 0.21]. P-HCH concentrations were highest
in Chicago, followed by Sturgeon Point and Sleeping Bear Dunes. Similar and the lower P-HCH
concentrations were observed at Brule River and Eagle Harbor. [F = 2.39, p = 0.07]. Chicago,
Sleeping Bear Dunes, and Sturgeon Point had similar y-HCH concentrations [F = 1.0, p = 0.39],
but these were significantly higher than y-HCH gas-phase concentrations at Brule River and
Eagle Harbor [F= 12,/?< 0.001].
The different spatial trends of the three HCH isomers could be related to their different
physical and chemical properties. a-HCH is more volatile than P-HCH and y-HCH, and a-HCH
is slower to react with hydroxyl radicals (23). Therefore, a-HCH is more readily transported
through the atmosphere, and it tends to have a relatively uniform global atmospheric
concentration. The higher P-HCH concentrations at Chicago and Sturgeon Point suggests past
use of technical HCH in urban areas (36).
Since a- and y-HCH have different vapor pressures, we corrected the atmospheric
temperature effect on their concentrations (see eq 1) and calculated the corrected ratio between
a- and y-HCH at 288 K in the gas phase. This ratio was around 5 at Brule River and Eagle
harbor, the two sites closest to Lake Superior; around 4 at Sturgeon Point and Point Petre; and
around 2 at Chicago and Burnt Island. A slightly higher value of 7 was calculated at Sleeping
Bear Dunes. In the technical HCH mixture, the ratio between a- and y-HCH is expected to be
between 4 and 7 (19). The lower values at Burnt Island, Point Petre, and Sturgeon Point could
be due to the relatively high concentrations of y-HCH recently used in Canada. The low ratio of
2 at Chicago may indicate historically heavy use of y-HCH at that location. At Brule River,
Eagle Harbor and Sleeping Bear Dunes, this ratio is similar to that of technical HCH, perhaps
indicating past use of technical HCH in the northern Great Lakes region.
As shown in Figure F3, the spatial trend of the gas-phase concentrations of chlordanes
(presented as the sum of a- and y-chlordane and trans-nonachlor concentrations) is: Chicago>
Sturgeon Point > Sleeping Bear Dunes > Point Petre > Brule River- Eagle Harbor ~ Burnt
Island. Chlordane's most common use in the U.S. was for termite control near homes,
suggesting that urban areas could be emission sources (37,35). Indeed, NJADN also reported
higher gas-phase chlordane concentrations at urban as compared to rural sites (12). Although
most abundant in the south and southeastern United States, subterranean termites are found in
every state except Alaska, with moderate to heavy structural infestations in Chicago. It has been
suggested that volatilization of chlordane from soil in the southern United States was the
predominant source of chlordane to the Great lakes (6). Thus, both historical local applications
used to control termites and the influence of long-range transport from areas of high chlordane
use could contribute to the relatively high chlordane concentrations at Chicago.
In the technical product, the ratio between y- to a-chlordane is 1.2. Considering the
slightly higher volatility of y-chlordane, this ratio is expected to be 1.4 at 20 °C in the atmosphere
(14). Since y-chlordane is more susceptible to degradation by microorganisms in soil (26), a
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ratio of <1.4 indicates a weathered chlordane source. In this study, the ratio of y- to a-chlordane
concentrations in the gas phase was similar at all the seven sites, ranging from 0.88 to 0.95. In
the particle phase at the five U.S. sites, the ratio was also similar but lower, at around 0.7, which
could be due to the lower vapor pressure of a-chlordane, leading to more sorption of a-chlordane
on atmospheric particles. The relatively low ratios we observed in air collected near the Great
Lakes suggests that the chlordane is from historically usage - as opposed to the technical
product.
The endosulfan concentrations (shown as the sum of a- and y-endosulfan) showed a clear
increasing trend from the west to east (Figure F3, bottom), except for the remote site at Burnt
Island. At each site, the average concentration was affected by high concentration outliers that
usually occurred in the summer and were likely due to the current agricultural use of endosulfan.
Higher endosulfan concentrations were observed at Point Petre, Sturgeon Point and Sleeping
Bear Dunes, which could be explained by its heavily use in the surrounding areas (13). For
example, endosulfan is still widely used in Michigan and New York states and in the southern
and western portions of Ontario, Canada (6, 39).
The highest concentrations of DDT (presented as the sum of /?,//-DDT, p,p'-DDE and
p,p'-DDD) were also observed in Chicago. Similarly, DDT concentrations in air measured by
NJADN also showed higher concentrations in urban areas compared to rural areas (12). Among
the DDT isomers measured by IADN, the gas-phase concentrations of p,p'-DDE were the
highest, which is not surprising given its relatively high vapor pressure among the DDT-related
compounds. Similarly, a study of pesticides showed higher DDE concentrations in the air in
Quebec (40), and Shen et al. reported higher/>,//-DDE concentration in air samples collected in
North America (14).
Although the spatial distributions of the other pesticides in the gas and particle phases
varied (Tables FS2-FS13), most restricted pesticides had higher concentration in Chicago's
atmosphere. For example, dieldrin concentrations were an order of magnitude higher in Chicago
than at the other sites. Hexachlorobenzene and heptachlor epoxide also had relatively high
concentrations at Chicago. This re-iterates the importance of urban areas as sources of
atmospheric contaminants, including restricted pesticides, to the Great Lakes.
Acknowledgments
We thank Ilora Basu and Team IADN at Indiana University and staff at the Organic
analysis Laboratory of Environment Canada for data acquisition; the U. S. Environmental
Protection Agency's Great Lakes National Program Office for funding (Grant GL995656,
Melissa Hulting, project monitor); and Frank Froude and his staff for sample collection at the
Canadian sites.
Supporting Information
Tables of sampling and analytical method comparisons between U.S. and Canadian sites
(Table FS1), average organochlorine (OC) pesticide concentrations and values derived from
modeled parameters for pesticide concentrations in the vapor and particle phases at seven IADN
sites (Tables FS2-FS13), and comparisons between the results in this study and previous studies
conducted by other researchers (Table FS14) and figures of temporal trends of OC pesticide
concentrations in the vapor and particle phases (Figures FS1 and FS2). This material is available
free of charge via the Internet at http://pubs.acs.org.
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131
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Table Fl. Half-lives (in years) of Selected OC Pesticides in the Gas and Particle Phases at Seven IADN Sites1.
to
Brule River
Gas
a-HCH2 3.1
±0.3
P-HCH NS
y-HCH 10
±4.5
a-Endo 7.6
±3.1
p-Endo 5.2
±2.4
a-chlor 8.8
±2.5
y-chlor NS
/-nona NS
dieldrin 9.6
±4.7
HCB 9.5
±2.8
DDT NS
ODD NS
DDE 7.9
±2.5
HPED NS
Part.
1.6
± 0.5
2.1
±0.9
NS
5.2
±1.5
4.6
±1.6
10
±5.1
7.3
±2.2
NS
9.5
±4.7
N/A
NS
NS
N/A
-4.8
± 1.9
Eagle
Gas
4.2
±0.1
4.5
±1.8
5.9
±0.4
NS
5.8
±1.9
13
±2.6
6.5
±0.9
13
±2.9
4.9
±0.5
18
±2.7
16
±5.8
14
±5.2
6.0
±0.5
-2.5
±0.4
Harbor
Part.
1.9
±0.4
4.9
±2.3
3.5
±0.5
5.4
±1.0
5.9
±2.5
6.6
±1.5
8.4
±2.6
NS
3.9
±0.5
N/A
NS
LD
N/A
NS
Gas
4.1
±0.4
NS
5.6
±0.9
8.4
Chicago
Part.
NS
NS
5.1
±1.0
8.1
Sleeping Bear
Gas
4.0
±0.2
NS
4.2
±0.3
NS
±2.7 ±2.3
3.2
±0.7
11
±2.7
6.7
±1.2
13
±4.5
6.1
±1.2
8.3
±0.9
14
±6.1
5.8
±2.1
6.3
±0.8
7.7
±3.3
8.0
±3.8
4.7
±1.1
11
±3.0
NS
6.2
±1.2
N/A
NS
3.8
±0.8
N/A
NS
5.2
±1.5
11
±1.7
6.1
±0.8
12
±2.7
5.3
±0.7
12
±1.0
11
±3.1
9.2
±2.7
5.9
±0.5
7.3
±2.7
Part.
1.7
±0.3
1.5
±0.6
3.1
±0.5
3.4
±0.5
3.0
±0.5
9.2
±3.2
7.0
±1.6
7.7
±2.4
4.3
±0.7
N/A
NS
NS
N/A
6.3
±1.9
Sturgeon PL
Gas
3.8
±0.2
2.7
±1.1
5.0
±0.4
NS
5.7
±1.3
10
±1.3
7.4
±0.8
9.6
±1.4
5.7
±0.6
15
±1.4
9.1
±1.8
5.0
±0.8
7.0
±0.6
7.6
±3.8
Part.
2.3
±0.7
LD
4.1
±0.9
7.7
±2.2
7.1
±2.3
7.7
±2.7
8.5
±2.4
NS
4.0
±0.5
N/A
NS
NS
N/A
NS
Burnt Island
Gas
4.0
±0.1
NS
7.7
±0.8
19
±6.9
9.7
±2.6
11
±1.8
11
±1.9
7.7
±1.0
8.9
±1.4
32
±7.2
5.2
±0.6
5.1
±0.6
6.5
±0.7
6.8
±1.6
Part.
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Point Petre
Gas Part.
4.1 N/A
±0.1
-14 N/A
±5.0
7.8 N/A
±0.7
8.2 N/A
±1.4
4.1 N/A
±0.4
9.3 N/A
±1.0
8.6 N/A
±1.0
7.0 N/A
±0.6
8.1 N/A
±0.9
30 N/A
±5.6
5.4 N/A
±0.5
6.0 N/A
±0.6
6.3 N/A
±0.5
5.8 N/A
±0.7
The results are listed as mean ± standard error. Normal font numbers are significant for 0.01<0.05; italic font numbers are significant for
0.001 0.05. "LD" means "Limited data"
and no regression analysis was conducted. "N/A" means "no data is available". A negative half-life is actually a doubling time.
a-Endo: a-endosulfan; P-Endo: |3-Endosulfan; a-chlor: a-chlordane; y-chlor: y-chlordane; t-nona: fra«s-nonachlor; DDT:/>,/>'-DDT; DDD: p,p'-
DDD; DDE: p,p'-DDE, HPED: heptachlor epoxide.
-------
O
-38
in
1 «E 10
u i
m
••»«
. t
t m f • .
rCuvii • :..
N/A
N/A
°^\<^^^^
Figure Fl. Concentrations of y-HCH and a-endosulfan in the gas-phase (upper) and particle-phase (lower) at the seven IADN sites. The
red lines indicate long-term significant decreasing trends; the blue curve is the fitting line of the sinusoidal model with the period length
(63) set to one year.
-------
CO
g
+-i
OJ
0)
o
c
o
o
CO
OJ
CO
OJ
O)
IU
A f\ey
1CK
•in2
IU
1 0^
10°
ins
IU
102
101
mo
a-HCH
• i •
" 6 h
I
j_
T • T
p-HCH
T
-T- -T- i
ATI
.
4r ±
y-HCH
' t T i
ii-
— _L
_ i
T T
i i i
_j_ i
i i
i i
_,_
T
J.
1 •
i i
i j_
_L ,
Figure F2. Concentrations of a-HCH (top), P-HCH (middle), and y-HCH (bottom) in the gas-
phase at the five U.S. IADN sites. The boxes represent the 25th to 75th percentiles, the black
lines in the boxes are the medians and the red lines are the means. The two vertical lines outside
each box extend to the outliers representing the 10th and 90th percentiles; and outliers are shown
-th
th .
at 5m and 95m percentile.
134
-------
c
CD
8
CD
CO
CD
CO
CO
o
103
102
10°
102
10°
Chlordanes
Endosulfans
Figure F3. Concentrations of chlordanes (sum of a-, p-chlordane, and /ram'-nonachlor, top) and
endosulfans (a- plus p-endosulfan, bottom) in the gas-phase at the seven IADN sites. See Figure
F2 for the description of the box-plots.
135
-------
Supporting Information for:
Atmospheric Organochlorine Pesticide Concentrations
near the Great Lakes: Temporal and Spatial Trends
Ping Sun,1 Pierrette Blanchard,2 Kenneth, Brice2, and Ronald A Kites*1
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana, 47405 USA
and
Environment Canada
4905 Dufferin Street
Toronto, ON M3H 5T4 Canada
* Corresponding Author Email: hitesr@indiana.edu
This Supporting Information contains 14 tables and 2 figures. Table FS1 is the sampling and
analytical method comparison between U.S. and Canadian sites. Table FS2 to FS13 show the
average organochlorine (OC) pesticide concentrations and values derived from modeled
parameters for pesticide concentrations in the vapor and particle phases at seven IADN sites.
Table FS14 is a comparison between the results in this study and previous studies conducted by
other researchers. Figures FS1 and FS2 show temporal trends of OC pesticide concentrations in
the vapor and particle phases. Eighteen pesticides were measured. These pesticides are aldrin,
a-chlordane, y-chlordane, p,p'-DDT., p,p'-DDD., p,p'-DDE, 0.//-DDT, dieldrin, a-endosulfan, P-
endosulfan, endrin, heptachlor epoxide, HCB, a-HCH, P-HCH, y-HCH, methoxychlor, and
trans -nonachlor.
The vapor phase pesticide concentrations (in pg/m3) were first converted to partial pressures (P,
in atm) using the ideal gas law. These partial pressures were then adjusted to the reference
temperature of 288 K using equation 1, where AH is a characteristic phase-transition energy of
the compound (in kJ/mol), R is the gas constant, and T is the daily average atmospheric
temperature at the sampling site (in Kelvin). The value of A// was determined by a preliminary
regression of In^) vs. l/T, which is the Clausius-Clapeyron equation (see equation 2). The
values of In^gg) were then regressed vs. time (^, in Julian days relative to January 1, 1990)
using equation 3 to determine the rate (a\, in days"1) of exponential increase (a\ > 0) or decrease
(a\ < 0) of these partial pressures. If this rate was statistically significant (p < 0.05), these rates
were then converted to half-lives (t\/2, in years) by dividing the values into the ln(2)/365 for each
compound at each site.
— - (1)
R 288 T ^ }
136
-------
\nP = \ — \ +const (2)
R (T)
Tables FS1 to FS7 show the values of AH and the calculated half-lives from the a\ values in
equation 3. The results are listed as mean ± standard error. Normal font numbers are significant
for 0.01 0.05. "LD" means "limited
data", and no regression was calculated. "N/A" means "not available". A negative half-life is
actually a doubling time.
Equation 4 was used to fit the pesticide concentrations (C) in the particle phase:
InC = b0+blt + b2sm\^- + bA (4)
where t is the time in Julian Days relative to January 1 1990, bo is the intercept (unitless), b\ is a
first-order rate constant (in days"1) describing the rate of exponential decrease or increase over
time, #2 is the periodic amplitude (unitless), 63 is the length of the period (in days), and b4 is the
periodic offset (in days).
To establish the dates of maximum pesticides concentrations, the ratio between the highest
pesticide concentration and the lowest concentration can be calculated from the fitted b2
parameter (equation 4) by taking its anti-logarithm (e2b2, the factor of 2 in the exponent is
needed to calculate the peak-to-valley amplitude). The sine wave would have a maximum at day
91 in a year. Therefore, the dates of the maximum of pesticide concentrations were calculated by
first converting the fitted b$ values from radians to days (multiplying by 365/27i) and then
subtracting these values from 91.
Tables FS8 to FS12 show results of the fit using equation 4 with £3 set to 365 days. The results
are listed as mean ± standard error. Normal font numbers are significant for 0.01 0.05. A negative half-life is a doubling time.
Figure FS1 shows the temporal trends of vapor phase OC pesticide concentrations at the seven
IADN sites. The concentrations were converted to P^ by equation (1). The values of In^gg)
were then plotted vs. time based on equation (3). The red lines indicate long-term significant
decreasing or increasing trends.
Figure FS2 shows the temporal trends of particle phase OC pesticide concentrations at the five
IADN sites. The black curves are the fitting lines using the sinusoidal model with the period
length (£3) set to one year (equation 4); the red lines indicate long-term significant decreasing
trends (b\ < 0) or increasing trends (b\ > 0).
137
-------
The complete monitoring results (e.g. concentrations of pesticides, PCBs, and PAHs) can be
downloaded from the IADN website: www.msc.ec.gc.ca/iadn. In addition, the meteorological
data such as temperature can also be found at this website.
Table FS1. Method comparison between U.S. and Canadian sites
U.S. SITES
CANADIAN SITES
Sampling time/frequency
Sampler Type
Typical Air Volume
Sampler Media
Sample Extraction
Cleanup/Fractionation
Instrumental Measurement
Instrument Calibration
24 hours /every 12 days
General Metal Works GS310
816m3
QFF + XAD-2
XAD-2 Soxhlet (24 hours) with 1:1
hexane: acetone
OFF same as for XAD-2
Silica gel (3.5% w/w water-deactivated)
column chromatography:
Fraction 1: hexane elution of HCB, p,p'-
DDE, o,p'-DDT;
Fraction 2: 50% hexane / 50%
dichloromethane elution of other target OC
pesticides.
GC-ECD (HP5890): heated splitless/split
injector, 60-m DB-5 capillary column
Internal standardization
24 hours /every 12 days
General Metal Works PS-1
350m3
OFF + PUF
PUF Soxhlet (24 hours) w. hexane
OFF not analyzed routinely for OC
pesticides
Florisil (~3% water-deactivated)
column chromatography:
Fraction 1: hexane elution of PCBs,
HCB, heptachlor, aldrin, p,p'-DDE,
o,p'-DDT, t-nonachlor (partial), p,p'-
DDT (partial);
Fraction 2: 15% DCM / 85% hexane
elution of HCHs, o,p'-DDD, p,p'-
DDD, chlordanes, t-nonachlor
(partial), p,p'-DDT (partial) +
coplanar PCBs;
Fraction 3: DCM elution of polar OC
pesticides (dieldrin, endosulfans,
methoxychlor, endrin, heptachlor
epoxide).
GC-ECD (HP5890 Series II): dual
heated splitless/split injectors, dual
capillary columns (60-m DB-5 and
30-mDB-17)
External standardization
138
-------
Table FS2. Average Concentrations and Fit parameters for Pesticides in the Gas Phase at Brule
River
OC Pesticide
a-HCH
P-HCH
y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
p,p'-DDE
o,//-DDT
o,//-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
57 ±3. 3
1.7±0.19
16 ±1.8
23 ±3. 8
2.1 ±0.4
3.2±0.18
2.4 ±0.17
2.0 ±0.15
8.0 ±0.81
66 ±1.4
1.6±0.18
1.4±0.13
1.2 ±0.10
0.53 ±0.09
3.7 ±0.58
5.4 ±0.53
0.17 ±0.02
3.4 ±0.30
1.6 ±0.41
Half-life (years),
(In2)/365a
3.1 ±0.3
NS
10 ±4.5
7.6 ±3.1
5.2 ±2.4
8.8 ±2.5
NS
NS
9.6 ±4.7
9.5 ±2.8
NS
NS
7.9 ±2.5
NS
LD
NS
NS
LD
LD
AH
30 ± 2.0
16 ±6.8
54 ± 3.7
80 ± 4.4
36 ± 6.7
33 ± 2.6
27 ±4.1
40 ± 3.1
73 ± 4.0
11 ± 2.4
25 ±6.2
NS
53 ± 3.3
71 ± 7.8
LD
66 ± 4.0
NS
LD
LD
No. of
detects
191
66
182
177
113
182
171
180
174
190
135
117
180
51
71
118
51
66
20
r2
0.64
0.09
0.56
0.64
0.22
0.50
0.22
0.48
0.67
0.14
0.11
N/A
0.59
0.64
N/A
0.71
N/A
N/A
N/A
Table FS3. Average Concentrations and Fit Parameters for Pesticides in the Gas Phase at Eagle
Harbor
OC Pesticide
a-HCH
P-HCH
y-HCH
a-Endosulfan
P-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-WT
p,p'-VVE
o,p'-DDT
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(Pg/m3)
100 ±5.3
1.9 ±0.21
20 ±1.4
27 ±3.6
2.2 ±0.32
3.3±0.16
2.9 ±0.24
2.5 ±0.15
10 ±0.78
68 ±1.4
2.7 ±0.20
1.2 ±0.09
1.9±0.12
0.47 ±0.05
2.4 ±0.30
5.5 ±0.46
0.07 ±0.01
3.0 ±0.33
0.94 ±0.21
Half-life (years),
(In2)/365a
4.2 ± 0.1
4.5 ±1.8
5.9 ± 0.4
NS
5.8 ±1.9
13 ± 2.6
6.5 ± 0.9
13 ± 2.9
4.9 ± 0.5
18 ± 2.7
16±5.8
14 ±5.2
6.0 ± 0.5
NS
1.8 ± 0.3
7.7 ±3.3
2.4 ± 0.3
NS
LD
AH
26 ± 1.4
24 ± 4.7
48 ± 2.1
100 ± 4.5
61 ± 6.6
40 ± 2.1
42 ± 3.3
52 ± 2.6
84 ± 3.5
10 ± 1.4
41 ± 3.9
9.7 ±4.6
49 ± 2.4
54 ± 4.8
12 ±4.6
70 ± 4.4
13 ±3.7
NS
LD
No. of
detects
363
107
362
250
153
309
301
301
341
357
280
217
353
81
99
165
68
112
26
r
0.75
0.24
0.66
0.67
0.38
0.55
0.41
0.58
0.66
0.2
0.31
0.06
0.60
0.62
0.29
0.64
0.50
N/A
N/A
139
-------
Table FS4. Average Concentrations and Fit Parameters for Pesticides in the Gas Phase at
Sleeping Bear Dunes
OC Pesticide
a-HCH
P-HCH
y-HCH
a-Endosulfan
(3-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
p,p'-DDE
o,//-DDT
o,//-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
78 ± 4.0
3.5 ±0.40
47 ± 8.2
86 ±14
8.9 ±1.3
6.5 ±0.37
6.1 ±0.39
5.3 ±0.36
24 ±2.1
74 ±1.6
4.9 ±0.45
1.8 ±0.17
8.1 ±0.51
1.2 ±0.13
2.6 ±0.21
9.8 ±1.0
0.08 ±0.01
3.6 ±0.32
2.1 ±0.41
Half-life (years),
(In2)/365a
4.0 ± 0.2
NS
4.2 ± 0.3
NS
5.2 ±1.5
11 ±1.7
6.1 ± 0.8
12 ± 2.7
5.3 ± 0.7
12 ± 1.0
11 ±3.1
9.2 ±2.7
5.9 ± 0.5
-6.3 ±2.1*
3.3 ± 0.7
7. 3 ±2.7
3.7 ±1.0
NS
LD
AH
22 ± 1.8
32 ± 6.3
61 ± 2.8
130 ± 5.0
92 ± 6.8
48 ± 2.3
53 ± 3.4
64 ± 2.7
92 ± 3.8
13 ± 1.2
60 ± 4.0
18 ±5.0
72 ± 2.3
73 ± 4.5
NS
75 ± 3.8
25 ± 4.6
NS
LD
No. of
detects
341
103
336
223
193
323
312
322
336
339
295
231
339
113
111
167
78
96
34
r2
0.65
0.20
0.65
0.74
0.50
0.60
0.49
0.64
0.65
0.42
0.45
0.10
0.76
0.71
0.17
0.71
0.32
N/A
N/A
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
Table FS5. Average Concentrations and Fit Parameters for Pesticides in the Gas Phase at
Sturgeon Point
OC Pesticide
a-HCH
P-HCH
Y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DD1
p,p'-DDD
p,p'-DDE
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
84 ± 4.2
8.5 ±1.3
31 ±2.2
9.5 ± 1.0
11 ±0.56
10 ±0.51
7.7 ±0.42
26 ±1.9
77 ±1.5
9.0 ±0.61
3. 5 ±0.36
17 ±0.92
2.1 ±0.20
5.4 ±0.61
7.9 ±0.65
0.14 ±0.03
4.6 ±0.33
1.7 ±0.21
*A negative half-life indicates that the concentrations
Half-life (years),
(In2)/365a
3.8 ± 0.2
2.7 ±1.1
5.0 ± 0.4
NS
5.7 ± 1.3
10 ± 1.3
7.4 ± 0.8
9.6 ± 1.4
5.7 ± 0.6
15 ± 1.4
9.1 ± 1.8
5.0 ± 0.8
7.0 ± 0.6
-3.0 ± 0.8*
3.3 ± 0.9
7.6 ±3.8
LD
NS
LD
are increasing and
AH
27 ± 1.8
26 ±8.8
56 ± 2.5
130 ± 4.3
86 ± 5.4
57 ±1.8
57 ± 2.5
67 ± 2.3
85 ± 3.2
16 ± 1.0
68 ± 3.5
NS
76 ± 2.0
71 ± 5.3
12 ±5.2
58 ±4.1
LD
NS
LD
the listed value is
No. of
detects
354
81
348
272
213
331
323
331
340
349
336
259
353
110
87
115
48
96
72
r2
0.67
0.20
0.65
0.76
0.55
0.76
0.65
0.73
0.69
0.52
0.54
0.13
0.81
0.64
0.18
0.65
N/A
N/A
N/A
the doubling time.
140
-------
Table FS6. Average Concentrations and Fit Parameters for Pesticides in the Gas Phase at
Chicago
OC Pesticide
a-HCH
P-HCH
Y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
Traws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDE
o,;/-DDT
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
52 ±2.9
12 ±1.2
35 ±2.5
72 ±9.2
6.0 ±0.75
39 ±2.8
46 ±3.8
23 ±1.6
110 ± 11
90 ±3.0
23 ±1.9
4.2 ±0.46
29 ±1.9
7.2 ±0.63
8.8 ±1.4
28 ±2.8
16 ±2.2
9.4 ±1.2
4.0 ±0.76
*A negative half-life indicates that the concentrations
Half-life (years),
(In2)/365a
4.1 ± 0.4
NS
5.6 ± 0.9
8.4 ±2.7
3.2 ± 0.7
11 ±2.7
6.7 ± 1.2
13 ±4.5
6.1 ± 1.2
8.3 ± 0.9
14 ±6.1
5.8 ±2.1
6.3 ± 0.8
NS
LD
7.7 ±3.3
NS
-2. 4 ±0.9*
LD
are increasing and
AH
21 ± 2.5
28 ± 6.5
32 ± 3.2
88 ± 4.1
48 ± 7.3
59 ± 2.4
55 ± 2.8
62 ± 2.8
68 ± 3.5
20 ± 1.3
66 ± 3.3
NS
60 ± 2.1
60 ± 3.6
LD
70 ± 4.4
34 ±9.1
18 ± 6.2
LD
the listed value is
No. of
detects
215
87
210
211
143
215
215
215
215
216
211
144
216
132
23
163
135
90
76
r2
0.46
0.18
0.41
0.69
0.34
0.74
0.66
0.71
0.65
0.60
0.66
0.05
0.80
0.68
N/A
0.63
0.11
0.15
N/A
the doubling time.
Table FS7. Average Concentrations and Fit Parameters for Pesticides in the Gas Phase at Burnt
Island
OC Pesticide
a-HCH
P-HCH
Y-HCH
a-Endosulfan
P-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
p,p'-DDE
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
26 ±0.9
0.65 ±0.12
9.2 ±0.6
21 ±2.8
2.6 ±0.41
2.4 ±0.14
1.9 ±0.12
2.4 ±0.15
9.2 ±0.59
29 ±0.52
0.68 ±0.04
0.17 ±0.01
2.2±0.11
0.98 ±0.06
0.31 ±0.03
1.7 ±0.13
0.91 ±0.06
0.78 ±0.07
3.0 ±0.79
Half-life (years),
(In2)/365a
4.0 ± 0.1
NS
7.7 ± 0.8
19 ±6.9
9.7 ±2.6
16 ± 3.4
11 ±1.9
7.7 ± 1.0
8.9 ± 1.4
32 ± 7.2
5.2 ± 0.6
5.1 ± 0.6
6.5 ± 0.7
7.6 ± 1.4
8.8 ± 2.1
6.8 ± 1.6
11 ±5.2
5.7 ± 1.0
LD
AH
22 ± 0.87
55 ±22
39 ± 1.6
60 ± 2.4
75 ± 3.6
51 ± 1.8
46 ± 2.1
53 ± 2.2
61 ± 2.4
NS
42 ± 2.7
27 ± 3.0
38 ± 2.1
40 ± 3.0
32 ± 3.3
29 ± 4.5
40 ± 3.9
38 ± 3.8
LD
No. of
detects
286
166
315
312
276
313
313
314
309
316
300
200
313
298
178
239
189
195
63
r
0.86
0.08
0.68
0.67
0.63
0.73
0.61
0.67
0.69
0.20
0.51
0.42
0.57
0.41
0.37
0.21
0.39
0.42
N/A
141
-------
Table FS8. Average Concentrations and Fit Parameters for Pesticides in the Gas Phase at Point
Petre
OC Pesticide
a-HCH
P-HCH
Y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDE
o,;/-DDT
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
28 ±0.9
0.54 ±0.02
12 ±0.7
110 ±22
24 ±4.3
3. 9 ±0.20
3.6 ±0.18
4.0 ±0.21
13 ±0.86
32 ±0.63
2.8 ±0.19
0.43 ± 0.02
11 ±0.69
2.9 ±0.18
0.76 ±0.05
2.9 ±0.13
0.97 ±0.06
1.3±0.12
3.4 ±0.78
Half-life (years),
(In2)/365a
4.1 ± 0.1
NS
7.8 ± 0.7
8.2 ± 1.4
4.1 ±0.4
9.3 ± 1.0
8.6 ± 1.0
7.0 ± 0.6
8.1 ± 0.9
30 ± 5.6
5.4 ± 0.5
6.0 ± 0.6
6.3 ± 0.5
19 ±4.7
4.5 ± 0.3
5.8 ± 0.7
NS
4.0 ± 0.3
NS
AH
21 ±1.1
20 ± 3.4
47 ±2.1
100 ± 3.6
140 ± 4.3
60 ± 2.0
52 ± 2.4
61 ± 2.3
72 ± 2.5
NS
25 ± 6.2
0.3 ±0.01
53 ± 3.3
NS
46 ± 3.2
28 ± 3.7
24 ± 5.0
41 ± 4.0
NS
No. of
detects
388
213
388
385
347
388
384
387
382
387
385
290
386
383
250
339
191
256
112
r2
0.82
0.15
0.60
0.69
0.76
0.72
0.58
0.24
0.70
0.46
0.66
0.52
0.72
0.34
0.55
0.27
0.14
0.44
N/A
Table FS9. Average Concentrations and Fit Parameters for Pesticides in the Particle Phase at
Brule River
OC Pesticide
a-HCH
P-HCH
Y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
p,p'-DDE
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
1.6 ±0.38
1.2 ±0.23
0.47 ±0.05
3.6 ±0.24
1.1±0.19
0.61 ±0.05
0.36 ±0.03
0.27 ± 0.02
2.2 ±0.16
N/A
0.95 ±0.18
0.57 ±0.06
N/A
1.6 ±0.24
0.90 ±0.10
N/A
0.30 ±0.04
0.87 ±0.21
Half-life
(years),
(In2)/365b!
1.6 ±0.5
2.1 ±0.9
NS
5.2 ±1.5
4.6±1.6
10±5.1
7.3 ±2.2
NS
9.5 ±4.7
N/A
NS
NS
N/A
NS
-4.8 ± 1.9*
N/A
LD
LD
Peak-to-
valley ratio,
62b2
NS
NS
NS
2.4 ± .2
7.5 ± .3
2.3 ± .2
2.4 ± .2
2.9 ± .2
2.0 ± .2
N/A
NS
4.6 ± 1.3
N/A
NS
2.0 ± 1.2
N/A
N/A
N/A
Maximum date
( ± days)
NS
NS
NS
Aug 4 ±12
Sep 19 ± 43
Jan 19 ± 11
NS
Jan 10 ± 12
Mar 1 ± 15
N/A
NS
Aug 31 ± 56
N/A
NS
Mar 1 ± 15
N/A
N/A
N/A
No. of
detects
55
44
118
171
120
163
153
135
171
N/A
50
106
N/A
61
110
N/A
43
9
r2
N/A
0.10
NS
0.18
0.33
0.17
0.27
0.14
0.12
N/A
NS
0.23
N/A
N/A
0.36
N/A
N/A
N/A
*A negative half-life indicates that the concentrations are increasing and the listed value is the doubling time.
142
-------
Table FS10. Average Concentrations and Fit Parameters for Pesticides in the Particle Phase at
Eagle Harbor
OC Pesticide
a-HCH
P-HCH
y-HCH
a-Endosulfan
(3-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-VW
p,p'-DDE
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
0.93 ±0.14
0.53 ±0.06
0.49 ±0.04
4.2 ±0.22
1.1±0.16
0.4 ±0.03
0.28 ±0.02
0.23 ±0.01
2.7 ±0.19
N/A
0.41 ±0.04
0.43 ±0.09
N/A
0.76 ±0.12
0.84 ±0.07
N/A
0.26 ± 0.02
1.1 ±0.21
Half-life
(years),
(In2)/365b!
1.9 ± 0.4
NS
3.5 ± 0.5
5.4 ± 1.0
5.9 ±2.5
6.6 ± 1.5
8.4 ±2.6
NS
3.9 ± 0.5
N/A
NS
LD
N/A
NS
NS
N/A
LD
LD
Peak-to-
valley ratio,
62b2
NS
4.0 ± .2
4.0 ± .2
2.4 ± .1
18 ± 1.3
2.2 ± .1
2.4 ± .2
2.9 ± .2
2.8 ± .1
N/A
1.8 ± 1.2
N/A
N/A
3.8±1.5
2.5 ± 1.2
N/A
N/A
N/A
Maximum date
( ± days)
NS
Feb 8 ± 8
March 12 ± 7
Aug 16 ± 8
Sep 13 ± 26
Jan 26 ± 10
Feb 7 ± 9
Feb 3 ± 9
Feb 18 ± 7
N/A
Jan 28 ± 22
N/A
N/A
Jan 22 ± 16
Feb 11 ± 10
N/A
N/A
N/A
No. of
detects
79
86
176
201
134
172
175
141
200
N/A
90
27
N/A
59
137
N/A
48
10
r2
0.26
0.37
0.40
0.29
0.46
0.25
0.23
0.24
0.37
N/A
0.19
N/A
N/A
0.18
0.28
N/A
N/A
N/A
Table FS11. Average Concentrations and Fit Parameters for Pesticides in the Particle Phase at
Sleeping Bear Dunes
OC Pesticide
a-HCH
P-HCH
Y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
p,p'-DDE
o,;/-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
0.91 ±0.25
0.92 ±0.25
0.42 ± 0.04
11±3.6
4.0 ±1.0
0.61 ±0.06
0.42 ± 0.02
0.30 ±0.02
4.1 ±0.28
N/A
0.69 ±0.11
0.40 ±0.03
N/A
0.55±0.11
0.86 ±0.05
N/A
0.46 ± 0.04
1.0 ±0.16
Half-life (years),
(In2)/365b!
1.7 ± 0.32
1.5 ± 0.57
3.1 ±0.51
3.4 ± 0.49
3.0 ± 0.50
9.2 ± 3.2
7.0 ± 1.6
7.3 ±2.4
4.3 ± 0.67
N/A
NS
NS
N/A
2.6 ± 0.95
6.3 ±1.9
N/A
NS
LD
Peak-to-valley
ratio, e 2
NS
NS
2.8 ± 1.2
3.0 ± 1.2
29 ± 1.2
2.9 ± 1.2
3.0 ± 1.1
3.1 ± 1.2
4.3 ± 1.1
N/A
NS
4.1 ± 1.2
N/A
NS
4.0 ± 1.2
N/A
NS
LD
Maximum
date
( ± days)
NS
NS
NS
NS
Jun 26 ±
19
Jan 25 ± 8
Feb 14 ± 7
Feb 3 ± 7
Feb 17 ± 5
N/A
NS
Sep 3 ± 49
N/A
NS
Feb 14 ± 6
N/A
NS
LD
No. of
detects
77
34
171
201
169
187
183
158
201
N/A
101
107
N/A
55
144
N/A
63
35
r2
0.28
0.13
0.26
0.31
0.61
0.26
0.34
0.31
0.44
N/A
N/A
0.28
N/A
0.28
0.50
N/A
N/A
N/A
143
-------
Table FS12. Average Concentrations and Fit Parameters for Pesticides in the Particle Phase at
Sturgeon Point
OC Pesticide
a-HCH
P-HCH
y-HCH
a-Endosulfan
(3-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-VVV
p,p'-DDE
o,//-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
0.77 ±0.23
0.79 ±0.14
0.46 ± 0.04
7.8 ±0.83
3.7 ±0.47
1.5±0.11
0.60 ±0.03
0.36 ±0.03
4.1 ±0.24
N/A
1.0 ±0.09
0.60 ±0.05
N/A
0.99 ±0.11
0.94 ±0.07
N/A
0.69 ±0.08
1.2 ±0.13
Half-life (years),
(In2)/365b!
2.3 ±0.57
LD
4.1 ± 0.86
7.8 ±2.1
7.0 ±2.3
7.7 ±2.7
8.5 ± 2.4
NS
4.0 ± 0.53
N/A
NS
NS
N/A
NS
NS
N/A
NS
NS
Peak-to-valley
ratio, e 2
NS
NS
2.0 ± 1.2
2.6 ± 1.1
19 ± 1.2
1.8±1.2
3.3 ± 1.1
2.6 ± 1.2
3.2 ± 1.1
N/A
4.9 ±1.8
4.4 ± 1.8
N/A
NS
1.8 ± 1.2
N/A
NS
NS
Maximum date
( ± days)
NS
NS
NS
Jun 24 ± 16
Jul 18 ± 18
Jan 15 ± 17
Feb 15 ± 6
Jan 19 ± 12
Feb 9 ± 6
N/A
NS
Sep 14 ± 41
N/A
91
Mar 13 ± 5
N/A
NS
NS
No. of
detects
60
26
160
209
195
203
201
174
210
N/A
130
128
N/A
91
133
N/A
53
53
r2
0.31
N/A
0.16
0.24
0.59
0.10
0.33
0.14
0.43
N/A
0.06
0.26
N/A
0.21
0.09
N/A
NS
NS
Table FS13. Average Concentrations and Fit Parameters for Pesticides in the Particle Phase at
Chicago
OC Pesticide
a-HCH
P-HCH
Y-HCH
a-Endosulfan
p-Endosulfan
a-Chlordane
y-Chlordane
/raws-Nonachlor
Dieldrin
Hexachlorobenzene
p,p'-DDT
p,p'-DDD
o,p'-DDD
Heptachlor epoxide
Aldrin
Endrin
Methoxychlor
Average cone.
(pg/m3)
0.56 ±0.11
1.3 ±0.09
0.96 ±0.07
5.6 ±0.31
3.3 ±0.40
9.3 ±0.9
3.4 ±0.17
1.4 ±0.08
22 ±1.3
N/A
7.6 ±0.44
1.4±0.13
N/A
3.1 ±0.20
2.3 ±0.14
N/A
1.0 ±0.10
3.6 ±0.3
Half-life (years),
(In2)/365b!
NS
NS
5.1 ± 1.0
8.1 ±2.3
8.0 ±3.8
4.7 ±1.1
11 ±3.0
NS
6.2 ± 1.2
N/A
NS
3.8 ± 0.8
N/A
NS
NS
N/A
NS
NS
Peak-to-
valley ratio,
NS
3.6 ± 1.2
3.2 ± 1.2
1.5 ± 1.1
18 ± 1.3
2.0 ±1.2
3.4 ± 1.1
4.0 ± 1.2
3.6 ± 1.1
N/A
1.8±1.2
2.1 ±1.2
N/A
2.0 ±1.2
2.8 ± 1.2
N/A
NS
NS
Maximum
date
( ± days)
NS
Jan 20 ± 9
Feb 7 ± 8
Sep 9 ± 18
Jul 16 ± 25
Dec 14 ± 17
Jan 28 ± 5
Jan 9 ± 6
Feb 8 ± 6
N/A
Jan 25 ± 15
NS
N/A
NS
Feb 1 ± 9
N/A
NS
NS
No. of
detects
62
123
158
199
161
158
201
196
201
N/A
188
158
N/A
121
163
N/A
86
113
r2
NS
NS
0.35
0.11
0.46
0.16
0.46
0.32
0.37
N/A
0.09
0.18
N/A
0.09
0.24
N/A
NS
NS
144
-------
Table FS14. Range and Mean Concentration (pg/m3) of Selected Organochlorine Pesticides in the Gas Phase from Various Studies
Pesticide
a-HCH
P-HCH
y-HCH
a-Endosulfan
p-Endosulfan
Sample
location
Birmingham, UK*
Seoul, Korea*
Chicago, U.S.
Jersey City. U.S.
Pinelands, NJ
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Senga Bay, South Africa
Senga Bay, South Africa
Chicago, U.S.
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Birmingham, UK*
Seoul, Korea*
Chicago, U.S.
Jersey City. U.S.
Pinelands, NJ
Senga Bay, South Africa
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Seoul, Korea*
Camden, NJ, U.S.
Chicago, U.S.
Pineland, U.S.
Sleeping Bear Dunes, U.S.
Burnt Island, Canada
Burnt Island, Canada*
Senga Bay, South Africa
Seoul, Korea*
Camden, NJ, U.S.
Chicago, IL, U.S.
Pineland, NJ, U.S.
Sleeping Bear Dunes, NI, U.S.
Burnt Island, Canada
Site
^JlPJ^.
urban
urban
urban
urban
rural
rural
rural
rural
rural
urban
rural
rural
urban
urban
urban
urban
rural
rural
rural
rural
urban
urban
urban
rural
rural
rural
rural
rural
urban
urban
urban
rural
rural
rural
Sample time
April 1999-July 2000
July 1999-May 2000
Jan 1996-Dec 2003
Jan 2000-May 2001
Jan 2000-May 2001
Jan 1992-Dec 2003
Jan 1993 -Dec 2003
Feb 1997-May 1998
Feb 1997-May 1998
Jan 1999-Dec 2003
Jan 2000-Dec 2003
Jan 1993 -Dec 2003
April 1999-July 2000
July 1999-May 2000
Jan 1996-Dec 2003
Jan 2000-May 2001
Jan 2000-May 2001
Feb 1997-May 1998
Jan 1992-Dec 2003
Jan 1993 -Dec 2003
July 1999-May 2000
Jan 2000-Jan 2001
Jan 1996-Dec 2003
Jan 2000-May 2001
Jun 1995-Dec 2003
Jan 1993-Dec 2003
May 2000-May 2001
Feb 1997-May 1998
July 1999-May 2000
Jan 2000-May 2001
Jan 1996-Dec 2003
Jan 2000-May 2001
Jan 1995-Dec 2003
Jan 1993-Dec 2003
Concentration
__Range
34-2000
3.6-290
8.2-700
8.7-250
1.8-10
0-34
1.0-73
0.27-23
0.06-26
5.1-310
1.4-300
0-176
0.30-1900
2.5-260
34-2000
0.20-1200
0.12-1600
0.50-580
0-61
8.9-1100
0.048-65
0.013-120
0.018-77
Mean
Con. ± Std Err
30
230 ± 22
52 ±2.9
23
55
78 ±4.0
74 ± 2.7
9.4 ±0.57
5.3 ±0.72
12 ±1.2
3.5 ±0.4
1.9 ±0.4
453
39 ±22
35 ±2.5
22
48
25 ±3.1
47 ± 8.2
26 ±1.7
230 ± 22
102
72 ± 9.2
59
84 ± 4.2
21 ±2.8
18
24 ± 1.2
330 ±22
1.8
6.0 ±0.75
10
8.9 ±1.3
2.6 ±0.41
Ref.
(15)
(16)
this study
(12)
(12)
this study
this study
(17)
(17)
this study
this study
this study
(15)
(16)
this study
(12)
(12)
(17)
this study
this study
(16)
(12)
this study
(12)
this study
this study
(14)
(17)
(16)
(12)
this study
(12)
this study
__l!!ilSi3^___
-------
Table FS14 (continued). Range and Mean Concentration (pg/m3) of Selected Organochlorine Pesticides in the Gas Phase from
Various Studies
Pesticide
EChlordane
p,p '-DDT
p,p '-DDE
Sample
location
Jersey City. NJ, U.S.
Chicago, IL, U.S.
Rohwer, AR, U.S
Pineland,NJ,U.S.
Senga Bay, South Africa
Sleeping Bear Dunes, MI, U.S.
Burnt Island, Canada
Birmingham, UK*
Seoul, Korea*
Chicago, IL, U.S.
Senga Bay, South Africa
Sleeping Bear Dunes, MI, U.S.
Burnt Island, Canada
Burnt Island, Canada*
Seoul, Korea*
Birmingham, UK*
Chicago, IL, U.S.
Bloomington, IN, U.S.
Sleeping Bear Dunes, MI, U.S.
Burnt Island, Canada
Burnt Island, Canada*
Site
™J&E£_.
urban
urban
rural
rural
rural
rural
rural
urban
urban
urban
rural
rural
rural
rural
urban
urban
urban
urban
rural
rural
rural
Sample time
Jan 2000-May 2001
Jan 1996-Dec 2003
Feb 2002-Sep 2003
Jan 2000- Jan 2001
Feb 1997-May 1998
Jul 1992-Dec 2003
Mar 1997-Dec 2003
April 1999-July 2000
July 1999-May 2000
Jan 1996-Dec 2003
Feb 1997-May 1998
Jan 1992-Dec 2003
Jan 1993 -Dec 2003
May 2000-May 2001
July 1999-May 2000
April 1999-July 2000
Jan 1996-Dec 2003
Feb 2002-Sep 2003
Jan 1992-Dec 2003
Jan 1993 -Dec 2003
May2000-May2001
Concentration
Range
2.4-860
15-600
ND-298
0.36-130
0.21-48
34-2000
0.34-160
ND-140
0.0049-74
0.0014-4.9
ND-29
0.58-160
0.66-35
0.12-74
0.054-16
Mean
Con. ± Std Err
114
110±8.1
200 ± 20
127
51 ±4.4
18 ±1.0
6.6 ±0.38
3.1
25 ± 8.4
23 ±1.9
12 ±3.4
4.9 ±0.45
0.68 ±0.04
0.59
8.6 ±3.6
8.4
29 ±1.9
6.4 ±0.9
8.1 ±0.51
2.2±0.11
2.7
Ret
(12)
this study
(13)
(12)
(17)
this study
this study
(15)
(16)
this study
(17)
this study
this study
(14)
(16)
(15)
this study
(13)
this study
this study
(14)
*gas + particle phase
-------
00
00
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o
n:
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n:
o
n:
tn
o
£1
LU
ns -:
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73
iS
ai
30
31
32
-33
-34
-35
-36
-34
-36
-38
-40
-31
-32
-33
-34
-35
-36
32
34
36
38
34
36
38
40
42
rfS®
*v
• »v
*
*••*
III
Figure FS1. Temporal trends of gas-phase OC pesticide concentrations at seven IADN sites. The red lines indicate long-term
significant decreasing or increasing trends. Detailed information ion the fitted parameters is in Tables FS1 to FS7.
-------
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Figure FS1. (Continued)
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10
1
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0.1
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1
0.1
0.01
• t .
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. • ? •..?*
I I I L
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Figure FS2. Temporal trends of particle-phase OC pesticide concentrations at five U.S. IADN sites. The black curve is the fitted line
using the sinusoidal model with a period length (£3) set to one year. The red lines indicate long-term significant decreasing or
increasing trends. Detailed information on the fitted parameters is in Tables ESS to ES12.
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Figure FS2 (Continued).
-------
Appendix G. Temporal and Spatial Trends of Atmospheric Poly chlorinated
Biphenyl Concentrations near the Great Lakes
Environmental Science & Technology, 2007, 41, 1131-1136.
154
-------
Temporal and Spatial Trends of Atmospheric Polychlorinated Biphenyl
Concentrations near the Great Lakes
Ping Sun,1 Ilora, Basu1, Pierrette Blanchard,2 Kenneth A. Brice2 and Ronald A. Kites*1
School of Public and Environmental Affairs
Indiana University
Bloomington, Indiana 47405
U.S.A.
and
Environment Canada
4905 Dufferin Street
Toronto ON M3H 5T4
Canada
* Corresponding Author Email: hitesr@indiana.edu
Brief
Atmospheric PCB concentrations are decreasing relatively rapidly near Lakes Michigan
and Ontario and correlate with local population, observations which indicate controllable, urban,
PCB sources.
Abstract
Polychlorinated biphenyl (PCB) concentrations were measured in the atmosphere at six
regionally representative sites near the five Great Lakes from 1990 to 2003 as part of the
Integrated Atmospheric Deposition Network (IADN). Concentration data for several individual
PCB congeners and for total PCBs were analyzed for temporal and spatial trends after correcting
for the temperature dependency of the partial pressures. Atmospheric PCB concentrations are
decreasing relatively slowly for tetra- and pentachlorinated congeners, an observation that is in
agreement with primary emissions modeling. Relatively rapid decreases in PCB concentrations
at the sites near Lakes Michigan and Ontario may reflect successful reduction efforts in Chicago
and Toronto, respectively. Atmospheric PCB concentrations near Lakes Superior and Huron are
now so low that the air and water concentrations may be close to equilibrium. Atmospheric PCB
concentrations at sites near Lakes Michigan, Erie, and Ontario are relatively higher than those
measured at sites near Lakes Superior and Huron. The highest PCB level was observed at the site
near Lake Erie, most likely due to nearby urban activity. However, this relatively higher
concentration is still 6-10 times lower than that previously reported at the Chicago site. A
correlation between average gas-phase PCB concentrations with local population indicates a
155
-------
strong urban source of PCBs. The temperature dependence of gas-phase PCB concentrations is
similar at most sites except at Burnt Island on Lake Huron, where very low concentrations,
approaching virtual elimination, prevent reliable temperature correlation calculations.
Introduction
The use and sale of polychlorinated biphenyls (PCBs) have been banned in industrialized
countries since the 1970s; for example, PCBs have not been sold in the United States since 1976
(7). Nevertheless, even after 30 years, PCBs are still being detected in various environmental
compartments such as air, water, sediment, and biota (2-4), and PCBs are still being emitted into
the atmosphere through primary sources (e.g. vaporization from products containing PCBs) or
through secondary sources (e.g., vaporization from the Great Lakes). Once in the atmosphere,
PCBs are transported from sources to remote areas of the globe through advective and
depositonal processes (5,6).
The Integrated Atmospheric Deposition Network (IADN) is a long-term monitoring
program that has measured the atmospheric concentrations of PCBs and many other
contaminants in air near the Great Lakes since 1990 (7). Several previously published studies by
IADN have shown long-term decreasing concentrations of PCBs in air at regionally
representative sites near the Great Lakes, such as Eagle Harbor, Sleeping Bear Dunes, Sturgeon
Point, and Point Petre (8,9). Half-lives of 10 years at Sleeping Bear Dunes and 6 years at Eagle
Harbor for gas-phase PCB concentrations were reported based on IADN data up to the year 2000
and supplemental historical data going back to 1977 (5). More recently, we reported on the
temporal trends of PCB concentrations in precipitation (from 1997 to 2003) and in air (from
1996 to 2003) at Chicago. A decline of PCB concentrations in both phases with half-lives of ~7
years was reported, suggesting that reduction efforts are working at this location (JO). In
general, these reported rates of decline for PCB concentrations in air and precipitation agreed
well with trend data previously reported for aquatic biota (11,12).
In this paper, we have extended the previous IADN trend study (13) on gas-phase PCB
concentrations with an additional three year's of data (up to 2003) at the U.S. IADN sites. For
the first time, congener-specific PCB concentrations measured at all IADN sites (including the
Canadian sites near Lakes Ontario and Huron from 1990 to 2003) have been used to determine
temporal trends. The PCB concentrations measured at all regionally representative sites were
compared to those previously reported for Chicago to study the spatial distribution of PCBs at
these sites.
Experimental
Sampling and Analytical Methodology. The locations of the six regionally
representative IADN sites (and Chicago) are shown in Figure Gl. Detailed information about
these sites is given at the IADN website (www.msc.ec.gc.ca/iadn). Collection and measurement
of gas phase samples started at Eagle Harbor (near Lake Superior) in November 1990, at
Sturgeon Point (near Lake Erie) in December 1991, at Sleeping Bear Dunes (near Lake
Michigan) and Point Petre (near Lake Ontario) in January 1992, at Burnt Island (near Lake
Huron) in January 1993, and at Brule River (near Lake Superior) in January 1996.
Measurements stopped at Brule River in August, 2002 because most pollutant concentrations
measured there were similar to those measured at Eagle Harbor. Data through December 2003
156
-------
are presented in this study for the other five sites. In addition, PCB data from January 1996 to
December 2003 measured at the urban site in Chicago are presented in this paper for comparison.
Indiana University is responsible for collecting and measuring samples at the U.S. sites:
Brule River, Eagle Harbor, Sleeping Bear Dunes, Sturgeon Point, and Chicago, while the
Meteorological Service at Environmental Canada handles samples collected at the two Canadian
sites: Burnt Island and Point Petre. For both the U.S. and Canadian operations, it is significant
that there have been minimal fundamental modifications to the sampling and analytical
methodologies since the inception of IADN. Such adherence to established procedures over such
an extended time period has been a deliberate decision taken in the quest for measurement
consistency and continuity, which are crucial and which allow us to interpret long-term trends in
the data.
The detailed sampling and analytical procedures have been described elsewhere (14-17).
The sampling and analytical methodologies for the U.S. and Canadian sites differ in some
significant aspects. Sun et al. have summarized these differences with specific regard to
atmospheric organochlorine pesticides, but the comparison is also applicable to PCBs (18). In
summary, both research groups used hi-volume air samplers; however, at the U.S. sites, gas-
phase PCBs were retained on 40 g of XAD-2 resin (Sigma, Amberlite, 20-60 mesh) with a total
air sample volume of approximately 820 m3. After fractionation, PCBs were analyzed using a
DB-5 column (J & W Scientific; 60 m x 250 |j,m i.d.; film thickness, 0.10 |j,m) on a Hewlett-
Packard (HP) 6890 gas chromatograph with a 63Ni electron capture detector. At the Canadian
sites, vapor-phase PCBs were retained on a polyurethane foam plug, 7.5 cm high x 6.2 cm
diameter (PUF, Levitt Safety) with a total air sample volume of approximately 350 m3. After
fractionation, PCBs were analyzed using a DB-5 (60 m x 250 |j,m i.d.; film thickness, 0.25 |j,m)
and a DB-17 column (30 m x 250 |j,m i.d.; film thickness, 0.25 |j,m) on a Hewlett-Packard 5890
gas chromatograph with dual 63Ni electron capture detectors.
These differences in sampling and analytical procedures required comprehensive quality
control (QC) and quality assurance (QA) procedures, which are documented in detail in the
IADN Quality Assurance Program Plan and in the IADN Quality Control Project Plan (19).
Surrogate standards (e.g. PCB congeners 14, 65, and 166 for the U.S. samples and PCB 30 and
204 for the Canadian samples) were spiked into the samples prior to extraction to monitor PCB
recovery. The average percent recoveries for these surrogates were 83-100%. While laboratory
blanks for PCBs were generally satisfactory (19), field blanks have proved to be of concern,
particularly as ambient PCB levels have decreased. At the U.S. sites, the field blank levels were
usually less then 10% of actual sample values. At the Canadian sites, field blanks were about
40% of the average PCB concentrations at Burnt Island and 12-15% at Point Petre. This resulted
in PCB concentrations at or near the method detection limit (defined as the average blank value
plus 3 times the standard deviation of this average) for the Burnt Island site. None of the
concentrations reported here have been blank corrected.
Considerable QA effort has been expanded over the years to ensure data compatibility
between the U.S. and Canadian laboratories. A common reference standard was distributed in
2001 to determine the level of analytical agreement between the two laboratories. For the PCB
congeners chosen for this study, the agreement was between 65 and 140% of the standard value,
which was considered acceptable. In early 2001, a split-sample inter-laboratory comparison was
conducted to evaluate possible systematic biases between the participating laboratories from the
extraction, fractionation, and analytical procedures (20). U.S. laboratory values were 20-60%
157
-------
higher than Canadian laboratory values for PCB congeners 18, 37+42, 45, 49, 52, 95, 101,
132+105+153, 123+149, and 180, congeners selected to represent tri- to heptachlorinated
homologues. (The notation "xxx + yyy" is used to indicate chromatographically unresolvable
congeners that are quantitated together.)
In 1998, a co-located sampler study was initiated at the Point Petre site to determine if
and how sampling practices contributed to potential biases between the two research
laboratories. This co-location experiment gave PCB concentrations that sometimes differed by
up to a factor of 2.5 between the two laboratories during the summertime. In order to quantify
the sources of these differences, an intensive inter-laboratory study was conducted in 2003, in
which 8 samples were collected under winter and summer conditions. For these samples, four
co-located samplers were used, and media (PUF and XAD) were exchanged between the two
laboratories to investigate variables such as analytical methodology, sampling media, and
sampler. A separate breakthrough study was also conducted in the summer of 2004 using two
PUF plugs in series; this latter special study revealed appreciable breakthrough of some of the
mono- and dichlorinated PCB congeners but showed that for tri chlorinated congeners (e.g. PCB
18) the potential errors resulting from the use of a single PUF plug were acceptable. For
congeners with four or more chlorines, breakthrough on PUF was found to be essentially
insignificant. The 2003 study suggested that PCB 18 in the U.S. data may have been over-
reported by a factor of 2.2; the source of this discrepancy has not yet been determined.
Temporal Trend Analysis. Atmospheric temperature variations affect the gas phase
PCB concentrations, and these variations must be removed before a temporal trend can be
determined. The temperature correction procedure was given by Cortes et al. in detail (77).
Briefly, the gas phase concentrations of each PCB congener were first converted to a partial
pressure (P) using the ideal gas law. These partial pressures were then corrected to a reference
temperature of 288 K by application of the Clausius-Clapeyron equation:
AHfl 1
P7S8 = P exp
Zoo 1
(1)
R ^T 288x
where exp is the exponential function, A// is a characteristic phase-transition energy (in kJ/mol),
R is the gas constant, and T is the mean atmospheric temperature during the 24-hour sampling
period (in K). The value of AH was determined by a linear regression of the natural logarithm of
the partial pressure (P) versus the reciprocal of T.
lnP = _ _ _ + const (2)
The natural logarithms of the corrected partial pressures at 288 K (called here /^ss) of individual
PCB congeners and total PCBs (see the Supporting Information for the list of congeners included
in this total) were then regressed against time (in Julian days relative to January 1, 1990) to
determine if a temporal trend was present.
Results and Discussion
Temporal trends. The calculated half-lives of several PCB congeners are listed in Table
GS1 of the Supporting Information, and the half-lives of total PCB are listed in Table Gl.
Figure G2 shows the significant long-term trend of total PCB concentrations in the gas phase at
the six regionally representative IADN sites. Brule River individual PCB congener half-lives
were generally not statistically significant or negative, indicating an increase as a function of
158
-------
time. The total PCB concentrations at Brule River also showed a significant increasing trend
over time. Given that the data for the Brule River site covered only 6 years, we do not consider
these trends reliable; thus, PCB trends at this site will not be discussed further. For all remaining
IADN sites, average PCB half-lives were 7-8 years for the trichlorinated congeners (PCB 18 and
37), 8-13 years for the tetra- and pentachlorinated congeners (PCB 45, 49, 52, 95, and 101), 7-8
years for the hexachlorinated congeners (PCB 132, 149, and 153), and 4-6 years for the
heptachlorinated congener (PCB 180). Similar trend behavior, as a function of PCB
chlorination, has been observed by Hung et al. (27), who suggested that the decline of
atmospheric PCB concentrations during the 1990s was mostly driven by declines in primary
emissions. Indeed, the half-lives of primary emissions mirrored the half-lives obtained for the
Great Lakes region.
For many congeners (e.g. PCB 45, 52, 95, and 101) and total PCBs, half-lives at Sturgeon
Point were on the order of -20 years. This slower rate of decrease for PCB concentrations in
recent years at Sturgeon Point may indicate that atmospheric PCB concentrations are now
approaching a steady state in Lake Erie after a more rapid decline from 1975 to 1995 (13). This
suggestion agrees with the study by Hickey et al., who suggested that PCB concentrations in
Great Lakes' lake trout have declined rapidly with relatively short half-lives of 5-10 years after
PCBs were banned, but these concentrations have not changed much since 1990 (22). Congeners
representing tri- and tetrachlorinated PCBs had faster rates of decline at Sleeping Bear Dunes
and Point Petre, while much slower rates of decrease were observed at Eagle Harbor and Burnt
Island. For PCB 52, there is no statistically significant decline over the sampling period at these
two sites. The overall slower decline of PCB concentrations near Lakes Superior and Huron may
be due to the colder water temperatures and larger volumes of these lakes. On the other hand,
the relatively faster decline of gas-phase PCB concentrations around Lakes Michigan and
Ontario may be due to effective reduction efforts, aimed at eliminating PCB point sources that
have occurred in the areas surrounding these two lakes.
PCBs are among the pollutants that were targeted for reduction in the "Canada-United
States Strategy for the Virtual Elimination of Persistent Toxic Substances in the Great Lakes
Basin" (the so-called Binational Toxics Strategy). Based on the 2004 Great Lakes Binational
toxics strategy report, approximately 88% of Ontario's high-level PCB-containing wastes had
been destroyed (23). In addition, many successful PCB reduction efforts have been reported.
For example, Canada's Niagara Power, located in Fort Erie, ON, had removed all their PCB-
containing transformers and capacitors by 2003. These efforts may have led to a faster rate of
decline of PCB concentrations around Lakes Erie and Ontario.
In general, the decreasing trends of gas-phase PCB concentrations found in this study
agree with the declining PCB concentrations in other environmental compartments near the
Great Lakes. A study on PCB concentrations in Lake Michigan water showed a decline from
1980 to 1991 with a half-life of 9 ± 2 years (24), which is statistically the same as those
measured in the gas phase at Sleeping Bear Dunes and Chicago, the two sites located near Lake
Michigan (see Table Gl). Marvin et al. studied the temporal trends of PCB concentrations in
Lake Erie sediments and reported a -70% decline of PCB concentrations from 1971 to 1997,
which gives a half-life of 15 years (25). At our Lake Erie site, Sturgeon Point, the gas-phase
total PCB half-life was 20 ± 4 years, which agrees with that observed in sediments. Another
study conducted by Marvin et al. showed that surficial sediment PCB concentrations declined by
about six-fold in Lake Ontario from 1981 to 1998, giving a half-life of -7 years (26). Our
159
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measured decreasing trend of gas phase PCB concentrations at our Lake Ontario site, Point Petre,
showed a half-life of 7 ± 0.4 years.
Correlation of gas-phase total PCB concentrations with local population. The
average concentrations of selected PCB congeners in the gas phase at each IADN site are listed
in Table GS1, and the total PCB concentrations are shown in Table Gl. Among the six
regionally representative sites, the highest concentrations of PCB congeners and total PCB are
usually observed at Sturgeon Point, and the other five sites have concentrations similar to one
another. However, the relatively higher PCB concentrations at Sturgeon Point are still
approximately 6-10 times lower than PCB's gas-phase concentrations at Chicago (JO).
A strong positive correlation between the average total PCB concentration and the human
population within a 25 km radius of each sampling site was observed; see Figure G3. Clearly,
higher total PCB concentrations are associated with larger populations. The watersheds of Lake
Michigan, Erie, and Ontario are more populated compared to the watersheds of Lakes Superior
and Huron, and this larger population could provide more PCB sources, resulting in higher PCB
concentrations (27). Previous studies have shown that industrial or urban centers are PCB
sources (27,25). One example is the higher concentrations of PCBs in air and precipitation in
Chicago (25,29), indicating a strong source of PCBs in this urban area (JO). Similarly, the
relatively higher PCB concentrations observed at Sturgeon Point compared to other regionally
representative sites could be attributed to an urban effect of Buffalo, New York, which is located
approximately 25 km northeast of the Sturgeon Point sampling site.
Interestingly, Hafner and Kites (30) studied the potential sources of PCBs to the
atmosphere at Sturgeon Point, Sleeping Bear Dunes, and Eagle Harbor. Based on their analyses,
the sources of PCBs at Sturgeon Point were predominantly the east coast of the United States.
The historically heavy-usage of PCBs in the Boston-Washington area and substantial PCB
discharge into the local waterways (including the Hudson River) could have contributed to the
higher atmospheric PCB concentrations measured at Sturgeon Point (31). A recent study on the
wind and air trajectory directions predicted that the PCB source direction is nearly 120° south of
Buffalo (32). Thus, it is still not clear whether Buffalo is the source of PCBs or whether there
are additional sources at Sturgeon Point.
The other five IADN sites (i.e. Brule River, Eagle Harbor, Sleeping Bear Dunes, Burnt
Island, and Point Petre) are all located more than 40 km from areas of more than 10,000
inhabitants, heavy industry, or other major sources of air pollutants. The lower PCB
concentrations at Eagle Harbor, Brule River and Burnt Island indicate that there are few nearby
PCB sources. Indeed, Hafner and Kites suggested the source of PCBs around Eagle Harbor
could be long-range atmospheric transport from the greater Chicago area (30). The slightly
higher PCB concentrations at Sleeping Bear Dunes and Point Petre may be due to their relative
proximity to PCB sources (e.g. Chicago and Toronto) as compared to Eagle Harbor and Burnt
Island.
We expected lower PCB concentrations at the Canadian sites not only because less
population at these sites but also became the historical consumption of PCB was much less in
Canada than in the U.S. According to Breivik et al., nearly 46% of the global production and
consumption of PCBs occurred in the U.S., but only 3% occurred in Canada from 1930 to 1993
(27). Our results, however, demonstrated that the average gas-phase PCB concentrations for
several congeners at Point Petre were similar to those at Sleeping Bear Dunes. Point Petre is
located about 160 km east of Toronto and approximately 85 km north of Rochester, NY. These
160
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urban areas could be sources of gas phase PCBs at Point Petre. In addition, Lake Ontario itself
could be a source of PCBs to Point Petre. Lake Ontario consistently has large PCB volatilization
fluxes, and volatilization of all PCB congeners were observed from this Lake (33). The primary
sources of PCBs into Lake Ontario were the Niagara River and the Niagara River watershed in
western New York (34,35).
The gas phase concentrations of PCB measured at these IADN sites are comparable with
other studies. For example, in this study, average concentrations of PCB congeners 18, 52, and
101 are 31 ± 1.6, 19 ± 0.9, and 12 ± 0.6 pg/m3, respectively, at the Sturgeon Point site. Similar
average gas-phase concentrations for PCB congeners 18, 52, and 101 of 34, 31, and 14 pg/m3
were observed at Sandy Hook, New Jersey, near the Atlantic Ocean from February 1998 to 1999
(36). Manodori et al. reported PCB concentrations at two sites in the Venice Lagoon not directly
influenced by urban/industrialized influences (37). Their concentrations for selected PCB
congeners were 6-25 pg/m3 for PCB 18, 4-6 pg/m3 for PCB 49, 7-12 pg/m3 for PCB 52, 5-7
pg/m3 for PCB 95, 6-9 pg/m3 for PCB 105+132+153, and 3-5 pg/m3 for PCB 149. These
reported values are similar to those measured at the five remote IADN sites (see Table GS1),
especially for the lighter congeners. Similarly, gas-phase PCB concentrations for congener 18
(3.1 pg/m3), 49 (1.1 pg/m3), 52 (7.7 pg/m3), 95 (4.1 pg/m3), and 101 (4.4 pg/m3) were reported
for the islands of the Chagos Archipelago, which is near Jakarta, Indonesia, and Singapore (38),
and these values are also similar to those measured at the five remote IADN sites.
Temperature effects on PCB concentrations. The regression slopes and the calculated
phase transition energy AH values of several PCB congeners are reported in Table GS1, and this
information for total PCBs is given in Table Gl. The slopes for the trichlorinated PCBs (PCB 18
and 37) are shallower at the Canadian sites than at the U.S. sites. This may be the result of
sampling artifacts rather than different processes influencing the PCB behavior of the lighter
congeners. For example, breakthrough of PCB 18 from PUF at the Canadian sites and over-
reporting of PCB 18 at US sites (as mentioned in the experimental section) may lead to some of
the discrepancy observed. Both these sampling artifacts occur in the summer and thus would
bias the temperature dependency of lighter PCBs. For all other congeners, the slopes observed
between all IADN sites are similar, except at Burnt Island where slopes are somewhat shallower.
Several studies have discussed the effect of temperature on the atmospheric
concentrations of semi-volatile organic pollutants. Wania et al. (39) and Hoff et al. (40)
suggested that long-distance transport of organic pollutants could lead to shallower regression
slopes between ln(P) and l/T, while a local source could result in steeper slopes. Burnt Island is
a very remote site with only -500 people living within a 25-km radius of the sampling site, and
there are no nearby PCB sources. Therefore, the shallower slope at Burnt Island could be due to
the long-range transport of PCBs according to Wania et al. (39) and Hoff et al. (40). However,
Carlson and Kites studied the temperature dependence of atmospheric PCB concentrations, and
they argued that the magnitude of the slope was not due to local vs. long-range PCB sources, but
it was due to other factors including the size of the data set, the temperature range, low measured
concentrations, and the PCB congener profiles (41). The slope tends to be shallower as more
low temperature data are included in the data set and when PCB concentrations are just above
field blank levels. Winter temperatures at Burnt Island were 7 to 10 °C lower than at Eagle
Harbor during the sampling period and ambient PCB levels, having dropped considerably over
the last 10 years, are now at or near the method detection limit. These two factors likely
contributed to the shallower slopes at Burnt Island. Thus, it seems that at the remote Canadian
161
-------
site of Burnt Island, PCB concentrations are now approaching "virtual elimination" from the
atmosphere.
Acknowledgments
We thank Team IADN (including Karen Arnold and Jennifer Kelley) and Environment
Canada's Organic Analysis Laboratory for chemical measurements; Environment Canada's
Science and Technology Branch for data acquisition: IADN QA officer, Rosa Wu; and
Environment Canada and the U.S. Environmental Protection Agency's Great Lakes National
Program Office for funding (Grant GL995656, Melissa Hulting, project monitor).
Supporting Information
This Supporting Information contains one table of average concentrations of PCB
congener 18, 37, 45, 49, 52, 95, 101, 105+132+153, 123+149, and 180, and the values derived
from modeled parameters at the seven IADN sites and one figure for temporal trends of the
temperature corrected PCB congener partial pressures in the gas phase at the seven sites. This
material is available free of charge via the Internet at http://pubs.acs.org
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164
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Table Gl. Average Total PCBa Concentrations, Half-lives, Clausius-Clapeyron Slopes, and
Phase-transition Energies at the Seven IADN Sites.
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago (ref 10)
Ci
3.VS ~~^
std err
(ps/m3)
86 ±6.9
86 ±5.4
110±6.5
230 ± 11
60 ±2.1
80 ±2.6
1300 ±74
a. For the complete list of the
Information.
b. The results of half-life, slope
t b
tl/2
(year)
-10 ±2.8
26 ±9.5
7.7 ± 0.8
20 ± 4.3
NS
7.1 ± 0.4
8.0 ±1.1
Slope c
-5300 ± 280
-5200 ± 270
-5600 ± 270
-6200 ± 220
-1500 ± 220
-4100 ± 190
-5400 ± 230
PCB congeners that make up
:, and phase-transition energies
AHd
(kJ/mol)
43 ± 2.3
42 ± 2.2
46 ± 2.2
51 ± 1.7
12 ±1.8
34 ± 1.5
44 ± 1.9
Ne
187
361
332
355
345
392
219
this total, see the
are listed as
mean
ft
0.67
0.51
0.60
0.70
0.12
0.64
0.74
Supportir
± standa
error. Normal font numbers are significant for 0.01 < p < 0.05; italic font numbers are
significant for 0.001
-------
"' 230
460 690
920
• Kilometers
Figure Gl. Map of the Great Lakes indicating the six regionally representative
Integrated Atmospheric Deposition Network (IADN) sampling sites. The location of the
urban site in Chicago is also given.
166
-------
00
03
Figure G2. Long-term trend of temperature corrected total PCB partial pressures in the
gas phase at the six regionally representative IADN sites. Red lines indicate statistically
significant (p < 0.05) regressions of the data. A significant long-term increasing trend is
observed at Brule River. Significant decreasing trends are observed at Eagle Harbor,
Sleeping Bear Dunes, Sturgeon Point, and Point Petre.
167
-------
CO
E
^3)
g
"OB
-i—•
§
CD
O
Q_
104
103 -
102 -
r2=0.88
CH
EH BR
102
107
Local population within 25-km radius
Figure G3. Correlation between average total PCB concentration and the local
population within a 25 km radius of the sampling site. The error bars are standard errors.
BI, Burnt Island; EH, Eagle Harbor; BR, Brule River; PP, Point Petre; SB, Sleeping Bear
Dunes; SP, Sturgeon Point; and CH, Chicago.
168
-------
Supporting Information
Temporal and Spatial Trends of Atmospheric Polychlorinated Biphenyl
Concentrations near the Great Lakes
Ping Sun, Ilora, Basu, Pierrette Blanchard, Kenneth A. Brice and Ronald A. Kites*
Congeners included in the total PCB summation are: 15+17, 16+32, 18,19, 22, 26, 28, 31,
33+53, 37+42, 41+64+71, 45, 47+48, 49, 52, 56+60+84+92, 70+76, 74, 77+110, 83, 85,
87+81,89, 91, 95+66, 97, 99,100, 101, 105+132+153, 114+131, 118, 119, 123+149, 126,
128+167,135+144,138+163, 156+171+202, 169, 170+190, 172, 174, 180, 194+205, 199,
201, 206, and 207. (The notation "xxx + yyy" is used to indicate chromatographically
unresolvable congeners that are quantitated together.) Each congener in this list either
contributes more than 1% to the total PCB mass for at least one site within the network or
is regarded to be lexicologically important (PCB 77, 105, 126, 128, 138, 156, 169 and
170). All results reported here are for PCBs in the vapor-phase, which is operationally-
defined by the sampling procedures employed.
This supporting Information contains one table of average concentrations of PCB
congener 18, 37, 45, 49, 52, 95, 101, 105+132+153, 123+149, and 180, and the values
derived from modeled parameters at seven IADN sites; and one figure for temporal
trends of these PCB congeners in gas phase.
The vapor-phase concentrations (in pg/m3) of PCB congeners were first converted to
partial pressure (P, in atm) using the ideal gas law. These partial pressures were then
adjusted to the reference temperature of 288 K using equation 1, where AH is a
characteristic phase-transition energy of the compound (in kJ/mol), R is the gas constant,
and Tis the daily average atmospheric temperature at the sampling site (in Kelvin). The
value of A// was determined by a preliminary regression of ln(P) vs. l/T, which is the
Clausius-Clapeyron equation (equation 2). The values of \n(P2ss) were then regressed vs.
time (^, in Julian days relative to January 1, 1990) using equation 3 to determine the rate
of exponential increase (a > 0) or decrease (a < 0) of these partial pressures. If this rate
was statistically significant (p < 0.05), these rates were then converted to half-lives (ti/2, in
years) by dividing the values of a into the ln(2)/365 for each compound at each site.
R 88 T
In P = -- — + constant (2)
R T
(3)
169
-------
Table GS1 lists all the values of AH and the calculated half-life times from the a values in
equation 3. The results are listed as mean ± standard error. Normal font numbers are
significant for 0.01 0.05. A negative half-life is actually a doubling time.
Table GS1. Selected PCB congener concentrations, half-lives, Clausius-Clapeyron
slopes, and phase-transition energies at the six regionally representative IADN sites.
Data at the Chicago site are also presented for comparison.
PCB 18
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 37
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 45
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 49
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 52
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Cavg ± std err
(pg/m3)
8.3 ±0.7
8.1 ±0.4
12 ±0.7
31 ±1.6
6.6 ±0.2
9.6 ±0.3
97 ±5.7
5.7 ±0.7
3.1 ±0.3
3.2 ±0.2
4.9 ±0.3
1.0 ±0.1
2.1 ±0.1
20 ±1.2
0.5 ±0.
0.7 ±0.
0.8 ±0.
1.8 ±0.
1.3 ±0.
1.8 ±0.
10 ±0.6
1.9 ±0.2
2.3 ±0.2
2.7 ±0.2
5.9 ±0.3
1.6 ±0.1
2.9 ±0.1
30 ±1.6
7.1 ±0.6
5.8 ±0.4
6.9 ±0.3
19 ±0.9
2.3 ±0.1
5.6 ±0.2
tl/23
(year)
-12 ± 4.4
NS
8.8 ± 1.1
13 ± 1.8
8.8 ± 0.8
7.9 ± 0.6
7.8 ± 1.5
NS
11 ±2.7
5.2 ± 0.5
8.7 ±1.1
NS
8.2 ± 0.3
5.3 ± 0.6
-7.1 ±2.1
17 ±5.2
8.8 ± 1.3
32 ±14
18 ± 4.5
10 ±1.1
6.6 ± 0.9
-6.2 ± 1.2
11 ±1.7
7.0 ± 0.7
11 ± 1.4
NS
16 ± 2.3
7.2 ± 0.9
-7 ± 1.4
NS
11 ± 1.4
22 ± 5.6
NS
9.0 ± 0.7
Slope b
-4400 ± 290
-4500 ± 240
-5100 ± 270
-5200 ± 220
-2100 ± 150
-2900 ± 190
-4300 ± 320
-8100 ± 490
-6100 ± 400
-6100 ± 340
-6100 ± 300
-3300 ± 250
-4800 ± 240
-5500 ± 270
-4100 ± 410
-4900 ± 350
-5200 ± 310
-5300 ± 270
-4000 ± 210
-3800 ± 240
-5200 ± 270
-5100 ± 300
-5400 ± 280
-5600 ± 270
-6100 ± 230
-3400 ± 170
-4600 ± 200
-5500 ± 230
-5400 ± 270
-5100 ± 260
-5200 ± 230
-6500 ± 220
-3300 ± 160
-4700 ± 190
AHC
(kJ/mol)
36 ± 2.4
37 ± 2.0
42 ± 2.2
43 ± 1.8
17 ±1.2
23 ± 1.5
35 ± 2.0
67 ± 4.0
50 ± 3.3
50 ± 2.8
50 ± 2.4
27 ± 2.0
39 ± 2.0
45 ± 2.2
34 ± 3.3
40 ± 2.8
42 ± 2.6
44 ± 2.2
33 ± 1.7
31 ± 2.0
42 ± 2.2
42 ± 2.4
44 ± 2.3
46 ± 2.2
50 ± 1.9
28 ± 1.4
38 ± 1.6
45 ± 1.9
44 ± 2.2
42 ± 2.1
43 ± 1.9
53 ± 1.8
27 ± 1.3
38 ± 1.5
Nd
187
361
310
353
321
390
218
170
345
320
345
319
388
218
168
334
322
349
279
375
219
187
350
330
353
319
390
218
187
361
332
355
317
384
r2e
0.57
0.51
0.56
0.63
0.49
0.51
0.51
0.62
0.50
0.57
0.58
0.37
0.56
0.71
0.43
0.38
0.49
0.52
0.58
0.47
0.67
0.65
0.53
0.62
0.68
0.56
0.59
0.75
0.71
0.52
0.63
0.71
0.57
0.67
170
-------
Chicago
PCB95
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 101
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 105+132+153
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 123+149
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
PCB 180
Brule River
Eagle Harbor
Sleeping Bear
Sturgeon Point
Burnt Island
Point Petre
Chicago
90 ±4.6
3.0 ±0.2
3.2 ±0.3
3.3 ±0.2
10 ±0.5
2.0 ±0.1
4.6 ±0.2
52 ±2.9
3.4 ±0.2
4.0 ±0.3
4.4 ±0.2
12 ±0.6
1.0 ±0.1
2.8 ±0.1
68 ±3.6
1.3±0.1
2.5 ±0.2
2.6 ±0.2
5.7 ±0.3
0.7 ±0.1
2.0 ±0.1
41 ±3.0
1.0 ±0.
1.3 ±0.
1.6 ±0.
3.7 ±0.2
0.5 ±0.
1.2 ±0.
24 ±1.5
0.2 ±0.1
0.3 ±0.1
0.3 ±0.1
0.7 ±0.2
0.1 ±0.0
0.3 ±0.1
3.6 ±0.3
11 ±2.0
-6.3 ± 1.1
21 ±5.7
10 ± 1.3
20 ± 4.8
7.4 ± 0.8
6.8 ± 0.5
14 ± 3.4
-11 ±3. 3
20 ±6.0
10 ± 1.4
17 ± 3.2
8 ±0.7
5.9 ± 0.4
11 ±2.1
NS
4.7 ± 0.3
4.9 ± 0.4
7.5 ± 0.7
6.3 ± 0.7
5.1 ±0.3
7.4 ± 1.0
NS
7.1 ±0.9
6.7 ± 0.6
10 ±1.1
9.2 ± 1.5
7.1 ±0.6
8.4 ± 1.2
NS
4.4 ± 0.3
5.1 ±0.5
5.6 ± 0.5
4.3 ± 0.4
4.9 ± 0.4
6.1 ±0.8
-5500 ± 210
-5000 ± 260
-5300 ± 270
-5400 ± 240
-6800 ± 230
-4400 ± 220
-5100 ± 240
-5800 ± 210
-5200 ± 250
-5500 ± 280
-5600 ± 250
-7000 ± 230
-4400 ± 180
-5900 ± 230
-6000 ± 210
-5200 ± 290
-5200 ± 290
-5500 ± 280
-7100 ± 250
-4300 ± 270
-5600 ± 280
-7400 ± 250
-5200 ± 270
-5500 ± 270
-5700 ± 260
-6500 ± 210
-4600 ± 270
-5400 ± 260
-6700 ± 220
-4900 ± 560
-4000 ± 320
-5400 ± 360
-6400 ± 320
-3000 ± 310
-4300 ± 330
-9300 ± 280
44 ± 1.7
41 ±2.1
44 ± 2.2
44 ± 2.0
56 ± 1.9
36 ± 1.8
42 ± 2.0
47 ± 1.8
42 ± 2.1
45 ± 2.3
45 ± 2.1
57 ± 1.9
36 ± 1.5
46 ± 1.9
49 ± 1.8
43 ± 2.3
43 ± 2.4
45 ± 2.3
58 ± 2.1
35 ± 2.2
46 ± 2.3
61 ± 2.0
43 ± 2.2
45 ± 2.2
46 ± 2.2
54 ± 1.7
38 ± 2.2
44 ± 2.1
55 ± 1.8
40 ± 4.6
32 ± 2.6
45 ± 3.0
53 ± 2.6
24 ± 2.5
36 ± 2.7
76 ± 2.3
219
187
358
330
353
321
390
219
187
361
332
355
319
388
219
187
347
327
349
320
389
219
187
276
327
352
303
386
219
138
300
271
337
280
374
215
0.76
0.69
0.53
0.63
0.71
0.58
0.60
0.78
0.71
0.51
0.62
0.73
0.67
0.67
0.80
0.65
0.57
0.63
0.71
0.50
0.61
0.82
0.68
0.63
0.63
0.74
0.52
0.58
0.82
0.38
0.52
0.55
0.61
0.42
0.46
0.84
Notes for Table GS1
a. The results of half-life, slope, and phase-transition energies are listed as mean ± standard error.
Normal font numbers are significant for 0.01 < p < 0.05; italic font numbers are significant for
0.001
-------
-30
-32
2 -34
CD
O Tfi
0_ SW
-38
-32
£-34
g-36
°- -38
-34
g-36
-38
-40
-32
fN
-34
-38
^
^"WWi'^IHP
-30
s -32
g -34
-36
-38
5 -32
m -34
" -36
-38
S -40
+
3 -34
8 -36
8 -38
"• -40
1-34
a -se
O
o- -40
Figure GS1. Long-term trends of PCB congener partial pressures in the gas phase at
seven IADN sites. Each dot is a measured partial pressure that has been adjusted to a
standard temperature of 288 K. Red lines indicate statistically significant decreasing or
increasing long-term trends where/? < 0.05.
172
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PUF Breakthrough Study, 2004
This sampling study was conducted in July and August 2004, using a glass fiber filter
followed by two 7.5 cm diameter x 7.5 cm long PUF filters in series installed in a
Meteorological Services of Canada PS-1 Hi-Vol air sampler at Point Petre. Samples of
approximately 350 m3 were taken over 24 hours. A blank and a co-located sample from
another sampler were also collected using a single 7.5 x 7.5 cm PUF filter. The MSC
Organic Analysis Laboratory carried out analysis of these PUF samples for PCB
congeners and pesticides. Sampling dates and atmospheric temperatures were:
Date Temperature (°C)
26-Jul-04 21.2
07-Aug-04 17.7
19-Aug-04 18.3
31-Aug-04 20.9
A breakthrough statistic (BT%) showing the percent analyte retained on the downstream or back PUF plug
(B) after passing through the upstream or front PUF plug (F) was calculated as:
(F + B)
Average BT% values determined were:
Congener BT%
PCB 18 11%
PCB 37+42 1.5%
PCB 45 2.5%
PCB 49 2.5%
PCB 52 2.5%
For further details see: Fowlie, P. (2005). "Integrated Atmospheric Deposition Network
(IADN). Air Sampling Breakthrough Test for PCB Congeners and Pesticides from
Polyurethane Foam (PUF)". Cornerstone Scientific, May 19, 2005.
173
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