CBP/TRS 104/94
March 1994
903R94032
Chesapeake Bay Atmospheric
Deposition Study Phase I:
July 1990-June 1991
U.S,
TD
225
.C5A
A24
Chesapeake Bay Program
> Printed on recycled paper
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Chesapeake Bay Atmospheric
Deposition Study Phase I:
July 1990-June 1991
March 1994
Printed by the U.S. Environmental Protection Agency for the Chesapeake Bay Program
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Chesapeake Bay Atmospheric Deposition
Study
Phase I: July 1990 - June 1991
Principal Investigators:
Joel E. Baker1, Thomas M. Church2, John M. Ondov3, Joseph R. Scudlark2
Co-Investigators:
Kathryn M. Conko2, Dianne L. Leister1, Zhong Y. Wu3
Technical Assistants:
Cheryl Clark1, Judy Leonard2, Zhi Lin3, Sheila Moore2, Mike Newell4
Chesapeake Biological Laboratory Department of Chemistry and Biochemistry
Center for Environmental and Esruarine University of Maryland
Studies College Park, MD 20742
The University of Maryland System
Solomons, MD 20688
2College of Marine Studies
University of Delaware
Lewes, DE 19958
4Wye Research and Education Center
University of Maryland
P.O. Box 169
Queenstown, MD 21658
Prepared for:
IJ,§, Envtomwerbl Protection
rmatiefl Resource
State of Maryland ^f^il
Department of Natural Resources f-^^rk^t, PA 19107 '
Tidewater Administration
Chesapeake Bay Research and Monitoring Division
Annapolis, MD 21401
December 1992
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FOREWORD
The report was prepared for Dr. Paul E. Miller of the
Chesapeake Bay Research and Monitoring Division,
Tidewater Administration Maryland Department of
Natural Resources by Dr. Thomas M. Church under
Contract CB90-002-004. Contributing investigators
and authors were supported under Contract PR90-003-
004. This project was co-funded by the Maryland
Department of the Environment and managed at MDE
by Dr. Robert Summers.
The purpose of the study was to determine atmospheric
loadings of selected trace elements and organic com-
pounds directly into the Chesapeake Bay. This work
represents the first year of the Chesapeake Bay Atmo-
spheric Deposition Study.
Constructive criticism was provided by four anony-
mous reviewers who are gratefully acknowledged for
their contribution.
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EXECUTIVE SUMMARY
Aone-yearstudy(6/90-7/91) was conducted to estimate
the deposition of atmospheric contaminants to the
Maryland portion of the Chesapeake Bay. The studied
contaminants included the trace elements (Aluminum,
Arsenic, Cadmium, Chromium, Copper, Iron,
Manganese, Nickel, Lead, Selenium, and. Zinc),
polychlorinated biphenyl (PCBs) congeners, and
polycyclic aromatic hydrocarbons (PAHs). Weekly
integrated samples of aerosol and precipitation were
collected for elemental constituents at two sites, one on
thenortheastern (Wye) and one on the mid-bay western
(Elms) Maryland shore. Organic contaminants in
precipitation samples were collected bi-weekly at the
Elms site only. Major elements in wet deposition, as
related to acid rain monitoring, are being measured at
these sites by other groups.
Dry aerosol deposition fluxes were estimated from the
measured aerosol concentrations for crustal and
noncrustal modes and literature-derived deposition
velocities. As described in Section IV, these contain
considerable uncertainties. Wet deposition was
calculated directly from contaminant concentrations in
precipitation and the measured precipitation volume.
The total atmospheric flux was calculated as the sum of
dry and wet depositional fluxes. The atmospheric
loading to the Maryland portion of the Bay is calculated
as the total site-averaged atmospheric flux times the
combined surface area of the mainstem Bay, north of the
Maryland-Virginia state line, including the tidal
tributaries below the fall line (5.3 x 109 m2).
Organic Contaminants
Individual PAH concentrations in the atmosphere
ranged from 0.05 to 2.1 ng» nr3 and the volume-weighted
mean concentrations in rain ranged from 1.4 to 21.9 ng /
L. Temporal bi-weekly variability ranged from 60% to
as high as 120% for the PAH concentrations in air.
Phenanthrene concentrations in air were less variable
than most of the higher molecular weight compounds,
such as benzo[ghi]perylene. Compounds like
benzo[ghi]perylene, due to their low vapor pressures,
sorb readily to atmospheric particles. Total aerosol
concentrations fluctuate over short time scales due to
the variability in air mass type and source. The temporal
bi-weekly variability for individual PAHs in rainfall
was observed to be as large as 1 order of magnitude. The
mean PCB air concentration was 0.33 ng»nv3, with a
relative standard deviation of about 66%. The volume-
weighted mean concentration of total PCB in
precipitation was 2 ng/L with variations as large as 1
order of magnitude.
Compounds with similar physical properties were
observed to follow the same atmospheric signal. For
example, phenanthrene and total PCBs followed similar
seasonal variations in both air and precipitation.
Phenanthrene was observed to increase slightly in the
winter time, presumably due to increased combustion
emissions. Total PCBs also followed a similar trend,
although these compounds do not have the same source.
Due to similarities in physical properties, it is not
uncommon for the compounds to have a common
atmospheric pattern.
Combined wet and dry atmospheric loadings for
individual PAH compounds to the Maryland portion of
the Bay ranged from 15 to about 200 kg/year. These
were calculated using the assumed dry deposition
velocity of 0.49 cm/sec.
Aerosol Trace Elements
More than 180 samples were analyzed for > 30 elements,
including Al, As, Cr, Fe, Mn, S, Se, and Zn by instrumental
neutron activation analysis (INAA); Pb, Ni, and Cu by
inductively coupled plasma-atomic emission
spectrometry; and Cd and Ni' by Zeeman/graphite
furnace-atomic absorption spectrometry.
Concentrations of anthropogenic elements such as Cr,
Se, V, and Zn exhibit similar seasonal trends, generally
peaking in late summer and winter months. Presumably,
that trend reflects elevated emissions during peak air
conditioning and heating, and periods of low
precipitation scavenging. Concentrations of elements
associated with crustal material (e.g., Al, Fe, and Mn)
ill
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tendedto be elevated in the spring and summer months,
probably reflecting increased agricultural and
construction activities. Concentrations of S are
characteristically elevated during the summer months
when more photochemical oxidants are available for
the conversion of SO2 to participate forms as measured
in this study. Overall, average concentrations
determined for the Wye and Elms sites differed by <
15% for As, Br, Cd, Cr, Cu, Mn, Ni, Pb, S, Se, and Zn; <
23% for Fe, and V; and < 35% for Al.
Preliminary estimates of annual deposition fluxes to
Bay waters were calculated for each element as the
product of the annual average airborne concentration
and a deposition velocity (Vd) for each element taken
from the literature as described in the text. Lower limits
of V. were taken to be 0.26 em's"1 for noncrustal
d
components and 1.4 em's'1 for crustal components.
Upper limits of Vd are taken to be 0.72 em's'1 for
noncrustal components and 4 em's"1 for crustal
components. The average of the high- and low-flux
estimates for the Wye and Elms sites are as follows: Al,
120,000 (57,000); As, 100 (50); Br, 490 (230); Cd, 21 (10);
Cr, 200 (96); Cu, 400 (190); Fe, 65,000 (31,000); Mn, 1,300
(640); Ni, 540 (250); Pb, 690 (320); S, 440,000 (210,000); Se,
240 (110); V, 680 (320); and Zn, 2,000 (960) ng-m^yr1,
where values in parentheses are the difference between
the average and low flux estimates. These dry deposition
estimates, however, are highly uncertain as they are
based on limited experimental data that may not be
appropriate for the Chesapeake Bay; that may not
adequately account for differences in concentrations
between air over land and water, contributions of large
particles, and extremes in turbulence and stability
regimes that may occur over the Chesapeake Bay; and
that might significantly influence the estimates.
Nevertheless, deposition velocities used here are
comparable to those used by Gatz (1975) for Southern
Lake Michigan.
Precipitation Trace Elements
Eleven trace elements in precipitation were successfully
collected and accurately analyzed in more than 100
weekly precipitation samples at the Wye and Elms sites.
The averaged annual wet flux (jig'nr^yr'1) averaged
for the two sites were: Al (13,600), As (49), Cd (48), Cr
(88), Cu (260), Fe (10,400), Mn (1,190), Ni (257), Pb (556), '
Se (214), and Zn (1,335).
Most of the examined elements appear to have a
dominant anthropogenic source. With the exception of
Fe and Al (and to a lesser'extent Cr and Mn), crustal
sources do not provide an important source of wet-
deposited trace elements. For the studied elements, the
annual wet deposition at the Wye site was consistently
higher than at the Elms site, with the Wye/Elms
deposition ratio for the elements studied ranging from
1.0 to 2.6. Presumably, this difference reflects the
increased scavenging of upwind westerly emissions at
the eastern shore site. Temporally, the average monthly
flux of an element at a given site varied by as much as
a factor of 50 during this phase of the CBADS project.
On a decreasing time scale (e.g., weekly), this variability
was even greater. Around Chesapeake Bay, the
atmospheric wet deposition of trace metals thus appears
to be a very heterogeneous process with respect to space
and time.
The proportion of dry deposition for crustal elements
appears greater than for wet deposition (e.g., Al, Fe),
while for noncrustal elements (e.g., Pb, Se, Cd) the
relative contribution of wet deposition appears to be
comparable. However, the inherent uncertainty in the
dry deposition estimates, particularly for the noncrustal
elements, currently prevents a more accurate
quantitative apportionment of wet versus dry
atmospheric deposition.
Overall
The temporal variation in the concentrations and
depositional fluxes of trace elements in precipitation
and organic contaminants was large around Chesapeake
Bay. Concentrations of organic contaminants and crustal
trace elements in precipitation were more variable than
those of noncrustal trace elements in aerosols. Seasonal
spikes are observed in contaminant concentrations
precipitation but not in aerosol records. This may
indicate that long-range transport by overlying air
masses and variable conditions of scavenging dominates
below- cloud scavenging. Temporal variations in
contaminant concentrations in both the air and in
precipitation reflect changes in source strengths, local
IV
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meteorology, and scavenging processes. For example,
greater concentrations of trace elements were observed
in precipitation at the Wye site than at the Elms site but
not in aerosol particles. Thus, local variation in
meteorology that may control local deposition appears
critical in driving atmospheric deposition to this estuary.
Generally, dry deposition fluxes of both organic and
trace element contaminants are similar in magnitude to
wet deposition fluxes, but the uncertainty is considerable
in dry deposition. Dry depositional fluxes of gaseous
organic contaminants to the water surface are not
considered here but may be important. As contaminant
deposition appears to be a very heterogenous process
with respect to space and time, future studies will
require continued deployment of multiple sites
(including some over the water) over a longer time
period to obtain a more accurate assessment of
atmospheric deposition of contaminants to the
Chesapeake Bay.
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TABLE OF CONTENTS
FOREWORD ii
EXECUTIVE SUMMARY iii
SECTION I - INTRODUCTION 1-1
Background 1-1
Statement of the Problem 1-2
Study Objectives 1-3
Study Limitations 1-3
SECTION II - THE STUDY 2-1
Design 2-1
Sampling Site Locations and Descriptions 2-1
SECTION III - METHODS 3-1
Organic Compounds in Air and Precipitation 3-1
Trace Elements in Aerosol 3-13
Trace Elements in Precipitation 3-16
SECTION IV - RESULTS AND DISCUSSION 4-1
Organic Contaminants 4-1
Elemental Concentrations in Aerosol Particles 4-76
Trace Elements in Precipitation 4-86
SECTION V - CONCLUSIONS 5-1
Common Trends and Interpretations 5-1
Atmospheric Deposition to Chesapeake Maryland Waters 5-1
Future Research Initiatives 5-3
ACKNOWLEDGEMENTS
LITERATURE CITED
Vll
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LIST OF TABLES
Table DL1 Description of sensors on the organic precipitator collector. 3-3
Table TTT.? Organic compounds analyzed in Chesapeake Bay airshed. 3-5
Table DL3 Chromatographic conditions for the analysis of polychlorinated
biphenyls via electron capture detection. 3-6
Table ffl.4 Chromatographic conditions for the analysis of polycyclic aromatic
hydrocarbons via selected ion mass spectrometry. 3-7
Table ffl.5 Select ion monitoring mode for polycyclic aromatic hydrocarbons. 3-7
Table ffl.6 Mean field measured vapor concentrations and mean analytical
detection limits for several PAHs and PCBs, Chesapeake Bay, 1990-1991. 3-9
Table ffl.7 Summary of laboratory surrogate compounds for Chesapeake Bay
atmospheric deposition sampler, Elms site, 1990-1991. 3-10
Table ffl.8 Mean mass (ng) summary of polycyclic aromatic hydrocarbons and
polychlorinated biphenyls in laboratory and field blank matrices,
Chesapeake Bay Atmospheric Deposition Project, 1990-1991. 3-11
Table DI.9 Concentrations of elements determined in MIST Standard Reference
Materials. 3-14
Table ffl.10 Comparison of laboratory and field blanks, ng/filter. 3-15
Table ffl.ll Analytical detection limits (ug/L) for determination of trace elements
in precipitation. 3-18
Table ffl.12 Results of quality control check solutions for trace element wet
deposition. 3-21
Table IV. 1 Mean total (vapor + particulate) concentrations of polycyclic aromatic
hydrocarbons and total polychlorinated biphenyls, Chesapeake Bay,
1990-1991. 4-1
Table IV.2 Several polycyclic aromatic hydrocarbon concentrations in air, ng/m3. 4-25
Table IV.3 Total polychlorinated biphenyls in air. 4-28
Table IV.4 Mean total (particulate [filter + funnel] and dissolved) rain
concentrations of polycyclic aromatic hydrocarbons and total
polychlorinated biphenyls, Chesapeake Bay, 1990-1991. 4-52
Table IV.5 Mean dry and wet fluxes of polycyclic aromatic hydrocarbons and
total polychlorinated biphenyls, Chesapeake Bay, 1990-1991. 4-53
Table IV.6 Summary of concentrations of elements determined at the Wye and
Elms sites, ng/m3. 4-81
Table IV.7 Summary of concentration ratios, Wye/Elms. 4-82
Table IV.8 Concentrations of airborne elements determined in Beltsville, MD,
College Park, MD and Lewes, DE, ng/m3. 4-83
Table IV.9 Deposition velocities determined for aerosol particles over water. 4-84
Table IV.10 Data summary and annual flux estimates for the Chesapeake Bay. 4-85
Table IV.ll Deposition velocities and annual flux estimates for the Chesapeake Bay. 4-86
Table IV. 12 Comparative precipitation concentrations (Hg/L) at five Mid-Atlantic
. sites (volume-weighted average). 4-109
Table W.13 Annual wet deposition (6/90 - 7/91) at two Maryland CBADS
sites (mg/mVyear). 4-110
Table V.I Summary of atmospheric fluxes during year 1 (7/90 - 6/91) for the
Chesapeake Bay Atmospheric Deposition Study. 5-2
Vlll
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LIST OF FIGURES
Figure HI Chesapeake Bay Atmospheric Deposition Study sites. 2-1
Figure ffl.1 Calibration curve used to set the flow rate on the high-volume
air sampler. 3-2
Figure ffl.2 In situ sampling train for precipitation collector. 3-2
Figure m.3 Flow chart of logic for precipitation sampler. 3-3
Figure ffl.4 Analytical procedure for PAH and PCB quantification. 3-5
Figure ffl.5 Comparison of PCBs in a precipitation sample to field detection limits. 3-8
Figure m.6 Comparison of a dissolved precipitation sample to its corresponding
laboratory blank. 3-12
Figure ffl.7 Monthly summary of precipitation amount (cm) and number of events
at two Maryland CBADS sites for 6/90 - 7/91. 3-17
Figure ffi.8 Comparison of absolute wet deposition field blank (n moles) at two
CBADS sites with that at the Lewes, Delaware base station. 3-19
Figure HI.9 Comparison of relative wet deposition field blank and lab blank
contributions to levels at two CBADS sites. 3-20
Figure ffl.10 Field blank contribution to precipitation samples [(n moles in average FB
+ n moles in average sample) x 100%], at two CBADS sites. 3-20
Figure IH.ll Comparison of rain gauge (inches) with collected precipitation
volume (ml) at two CBADS sites. 3-22
Figure IV. 1 Fluorene concentrations in air collected at the Elms site. 4-2
Figure FV.2 Phenanthrene concentrations in air collected at the Elms site. 4-3
Figure IV.3 Anthracene concentrations in air collected at the Elms site. 4-4
Figure IV.4 Fluoranthene concentrations in air collected at the Elms site. 4-5
Figure FV.5 Pyrene concentrations in air collected at the Elms site. 4-6
Figure IV.6 Benz[a]anthracene concentrations in air collected at the Elms site. 4-7
Figure IV.7 Chrysene concentrations in air collected at the Elms site. 4-8
Figure IV.8 Benzo[b]fluoranthene concentrations in air collected at the Elms site. 4-9
Figure IV.9 Benzo[k]fluoranthene concentrations in air collected at the Elms site. 4-10
Figure IV.10 Benzo[e]pyrene concentrations in air collected at the Elms site. 4-11
Figure IV.ll Benzo[a]pyrene concentrations in air collected at the Elms site. 4-12
Figure IV.12 Indeno[l,2,3-cd]pyrene concentrations in air collected at the Elms site. 4-13
Figure IV.13 Dibenz[a,h]anthracene concentrations in air collected at the Elms site. 4-14
Figure IV.14 Benzo[g,h,i]perylene concentrations in air collected at the Elms site. 4-15
Figure IV.15 Total PCB concentrations in air collected at the Elms site. 4-16
Figure IV.16 Total dichlorobiphenyl concentrations in air collected at the Elms site. 4-17
Figure FV.17 Total trichlorobiphenyl concentrations in air collected at the Elms site. 4-18
Figure IV.18 Total tetrachlorobiphenyl concentrations in air collected at the Elms site. 4-19
Figure IV.19 Total pentachlorobiphenyl concentrations in air collected at the Elms site. 4-20
Figure IV.20 Total hexachlorobiphenyl concentrations in air collected at the Elms site. 4-21
Figure IV.21 Total heptachlorobiphenyl concentrations in air collected at the Elms site. 4-22
Figure IV.22 Total octachlorobiphenyl concentrations in air collected at the Elms site. 4-23
Figure FV.23 Atmospheric vapor concentrations for phenanthrene and total PCBs,
Chesapeake Bay, 1990-1991. 4-24
Figure IV.24 Temporal variability in % aerosol distribution of several PAHs, Elms site. 4-26
Figure IV.25 Temporal variability in total suspended particulate matter concentrations,
Solomons, MD 4-27
Figure FV.26 Comparison of atmospheric PCB congener data from Chesapeake Bay
to that of southern Ontario (Hoff et al., 1992) 4-29
Figure IV.27 Fluorene concentrations in precipitation integrated biweekly at
the Elms site. 4-30
IX
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LIST OF FIGURES (continued)
Figure IV.28 Phenanthrene concentrations in precipitation integrated biweekly
at the Elms site. 4-31
Figure FV.29 Anthracene concentrations in precipitation integrated biweekly
at the Elms site. - 4-32
Figure IV.30 Fluoranthene concentrations in precipitation integrated biweekly
at the Elms site. 4-33
Figure IV.31 Pyrene concentrations in precipitation integrated biweekly at the
Elms site. 4.34
Figure IV.32 Benz[a]anthracene concentrations in precipitation integrated biweekly
at the Elms site. 4-35
Figure FV.33 Chrysene concentrations in precipitation integrated biweekly at the
Elms site. 4-36
Figure IV.34 Benzo[b]fluoranthene concentrations in precipitation integrated
biweekly at the Elms site. 4-37
Figure IV.35 Benzo[k]fluoranthene concentrations in precipitation integrated
biweekly at the Elms site. 4-38
Figure FV.36 Benzo[e]pyrene concentrations in precipitation integrated biweekly
at the Elms site. 4-39
Figure IV.37 Benzo[a]pyrene concentrations in precipitation integrated biweekly
at the Elms site. 4-40
Figure IV.38 Indeno[l,2,3-cd]pyrene concentrations in precipitation integrated
biweekly at the Elms site. 4-41
Figure IV.39 Dibenz[a,h]anthracene concentrations in precipitation integrated
biweekly at the Elms site. 4-42
Figure FV.40 Benzo[g,h,i]perylene concentrations in precipitation integrated biweekly
at the Elms site. 4-43
Figure FV.41 Total PCB concentrations in precipitation integrated biweekly at the
Elms site. 4-44
Figure IV.42 Total dichlorobiphenyl concentrations in precipitation integrated
biweekly at the Elms site. 4-45
Figure IV.43 Total trichlorobiphenyl concentrations in precipitation integrated
biweekly at the Elms site. 4-46
Figure FV.44 Total tetrachlorobiphenyl concentrations in precipitation integrated
biweekly at the Elms site. 4-47
Figure FV.45 Total pentachlorobiphenyl concentrations in precipitation integrated
biweekly at the Elms site. 4-48
Figure IV.46 Total hexachlorobiphenyl concentrations in precipitation integrated
biweekly at the Elms site. 4-49
Figure TV.47 Total heptachlorobiphenyl concentrations in precipitation integrated
biweekly at the Elms site. 4-50
Figure FV.48 Total octachlorobiphenyl concentrations in precipitation integrated
biweekly at the Elms site. 4-51
Figure IV.49 Fluorene wet depositional fluxes measured at the Elms site. 4-54
Figure FV.50 Phenanthrene wet depositional fluxes measured at the Elms site. 4-55
Figure IV.51 Anthracene wet depositional fluxes measured at the Elms site. 4-56
Figure IV.52 Fluoranthene wet depositional fluxes measured at the Elms site. 4-57
Figure IV.53 Pyrene wet depositional fluxes measured at the Elms site. 4-58
Figure FV.54 Benz[a]anthracene wet depositional fluxes measured at the Elms site. 4-59
Figure IV.55 Chrysene wet depositional fluxes measured at the Elms site. 4-60
Figure IV.56 Benzo[b]fluoranthene wet depositional fluxes measured at the Elms site. 4-61
Figure F/.57 Benzo[k]fluoranthene wet depositional fluxes measured at the Elms site. 4-62
Figure IV.58 Benzo[e]pyrene wet depositional fluxes measured at the Elms site. 4-63
Figure FV.59 Benzo[a]pyrene wet depositional fluxes measured at the Elms site. 4-64
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LIST OF FIGURES (continued)
Figure IV.60 Indeno[l,2,3-cd]pyrene wet depositional fluxes measured at the
Elms site. 4-65
Figure IV.61 Dibenz[a,h]anthracene wet depositional fluxes measured at the
Elms site. 4-66
Figure IV.62 Benzo[g,h,i]perylene wet depositional fluxes measured at the
Elms site. 4-67
Figure IV.63 Total PCB wet depositional fluxes measured at the Elms site. 4-68
Figure IV.64 Total dichlorobiphenyl wet depositional fluxes measured at the Elms
site. 4-69
Figure IV.65 Total trichlorobiphenyl wet depositional fluxes measured at the Elms
site. 4-70
Figure IV.66 Total tetrachlorobiphenyl wet depositional fluxes measured at the Elms
site. 4-71
Figure IV.67 Total pentachlorobiphenyl wet depositional fluxes measured at the
Elms site. 4-72
Figure IV.68 Total hexachlorobiphenyl wet depositional fluxes measured at the Elms
site. 4-73
Figure IV.69 Total heptachlorobiphenyl wet depositional fluxes measured at the
Elms site. 4-74
Figure IV.70 Total octachlorobiphenyl wet depositional fluxes measured at the Elms
site. 4-75
Figure FV.71 Concentrations of elements in aerosol particles collected at the Wye
Research and Elms Educational Institutes and Haven Beach (Al, As,
Cd, Cr). 4-77
Figure IV.72 Concentrations of elements in aerosol particles collected at the Wye
Research and Elms Educational Institutes and Haven Beach (Se, Zn,
V, Br). 4-78
Figure IV.73 Concentrations of elements in aerosol particles collected at the Wye
Research and Elms Educational Institutes and Haven Beach (Cu, Ni,
Pb, S). 4-79
Figure IV.74 Concentrations of elements in aerosol particles collected at the Wye
Research and Elms Educational Institutes and Haven Beach (Fe, Mn,
weekly rainfall). 4-80
Figure IV.75 Weekly integrated aluminum concentrations in precipitation from
the Wye CBADS site. 4-87
Figure FV.76 Weekly integrated aluminum concentrations in precipitation from
the Elms CBADS site. 4-88
Figure IV.77 Weekly integrated arsenic concentrations in precipitation from the
Wye CBADS site. 4-89
Figure FV.78 Weekly integrated arsenic concentrations in precipitation from the
Elms CBADS site. 4-90
Figure FV.79 Weekly integrated cadmium concentrations in precipitation from
the Wye CBADS site. 4-91
Figure IV.80 Weekly integrated cadmium concentrations in precipitation from
the Elms CBADS site. 4-92
Figure IV.81 Weekly integrated chromium concentrations in precipitation from
the Wye CBADS site. 4-93
Figure FV.82 Weekly integrated chromium concentrations in precipitation from
the Elms CBADS site. 4-94
Figure FV.83 Weekly integrated copper concentrations in precipitation from the
Wye CBADS site. 4-95
Figure FV.84 Weekly integrated copper concentrations in precipitation from the
Elms CBADS site. 4-96
XI
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LIST OF FIGURES (continued)
Figure IV.85 Weekly integrated iron concentrations in precipitation from the
Wye CBADS site. 4-97
Figure IV.86 Weekly integrated iron concentrations in xipitation from the
Elms CBADS site. 4-98
Figure IV.87 Weekly integrated manganese concentrations in precipitation from
the Wye CBADS site. 4-99
Figure IV.88 Weekly integrated manganese concentrations in precipitation from
the Elms CBADS site. 4-100
Figure FV.89 Weekly integrated nickel concentrations in precipitation from the
Wye CBADS site. 4-101
Figure IV.90 Weekly integrated nickel concentrations in precipitation from the
Elms CBADS site. 4-102
Figure IV.91 Weekly integrated lead concentrations in precipitation from the
Wye CBADS site. 4-103
Figure IV.92 Weekly integrated lead concentrations in precipitation from the
Elms CBADS site. 4-104
Figure IV.93 Weekly integrated selenium concentrations in precipitation from the
Wye CBADS site. 4-105
Figure TV.94 Weekly integrated selenium concentrations in precipitation from the
Elms CBADS site. 4-106
Figure IV.95 Weekly integrated zinc concentrations in precipitation from the
Wye CBADS site. 4-107
Figure IV.96 Weekly integrated zinc concentrations in precipitation from the
Elms CBADS site. 4-108
Figure IV.97 Monthly average wet deposition of aluminum at two Maryland
CBADS sites. 4-111
Figure FV.98 Monthly average wet deposition of arsenic at two Maryland CBADS
sites. 4-112
Figure IV.99 Monthly average wet deposition of cadmium at two Maryland
CBADS sites. 4-113
Figure IV.100 Monthly average wet deposition of chromium at two Maryland
CBADS sites. 4-114
Figure IV.101 Monthly average wet deposition of copper at two Maryland
CBADS sites. 4-115
Figure IV.102 Monthly average wet deposition of iron at two Maryland CBADS
sites. 4-116
Figure IV.103 Monthly average wet deposition of lead at two Maryland CBADS
sites. 4-117
Figure IV. 104 Monthly average wet deposition of manganese at two Maryland
CBADS sites. ' 4-118
Figure IV. 105 Monthly average wet deposition of nickel at two Maryland
CBADS sites. ' 4-119
Figure IV. 106 Monthly average wet deposition of selenium at two Maryland
CBADS sites. 4-120
Figure IV.107 Monthly average wet deposition of zinc at two Maryland CBADS
sites. 4-121
Figure IV. 108 Variability in the wet deposition of selected trace elements at
various sites in the Chesapeake Bay region. 4-123
XII
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SECTION I
INTRODUCTION
Background
Atmospheric transport and deposition of
anthropogenically mobilized acids, trace elements, and
organic chemicals may be a significant source of
contaminants to coastal waters, including the
Chesapeake Bay. Contaminants are released into the
atmosphere from a variety of activities, including direct
emissions from stationary sources (e.g., combustion
sources), mobile sources (e.g., motor vehicles), and
regional activities (e.g., agrichemical applications, and
soil erosion). Once in the atmosphere, contaminants
maybe chemically altered, partitioned between gaseous
and participate phases, and transported great distances.
Contaminants are removed from the atmosphere and
delivered to the Earth's surface by a variety of
mechanisms, including scavengingduringpretipitation
events (wet deposition) and by diffusive and turbulent
transport during dry periods (dry deposition).
Estimating the potential impact of atmospherically
deposited contaminants to surface waters requires not
only an accurate quantitative measurement but also a
thorough understanding of the processes that transport
and scavenge these chemicals from the atmosphere.
Evidence of Atmospheric Deposition
The atmosphere is an important environmental pathway
for the transport and deposition of contaminants to
surface water systems. Numerous trace organic
pollutants are dispersed worldwide predominantly due
to extensive atmospheric transport in vapor form. Fish
collected from Siskiwit Lake, a small lake on Lake
Superior's Isle Royale, contain residues of polycyclic
aromatic hydrocarbons (McVeety and Hites, 1988),
polychlorinated biphenyls (Swackhamer and Hites,
1988), toxaphene and other airborne contaminants
(Swain, 1978). As there are no local sources of these
contaminants on Isle Royale, aerial transport and
deposition is the source of contamination to this isolated
location. Recent evidence suggests that the Arctic food
chains have become contaminated with atmospherically-
derived organochlorine contaminants (Bidleman et al.,
1989).
Duceet al. (1992) have recently synthesized the available
data quantifying atmospheric deposition of trace
elements, nutrients, and organic contaminants to the
world's oceans. Atmosphericinputcan also be important
for small bodies of water in the vicinity of major
atmospheric sources. For example, both dry and wet
deposition were found to be important sources of lead
to the 2-ha Skinface Pond located about 5.5 km from the
coal-fired Savannah River Power Plant (Weiner, 1979).
Atmospheric deposition is also an important source of
Cu, Cr, Pb, Zn, and other metals to the Great Lakes
(Sievering et al., 1981) and other bodies of water
characterized by low watershed area-to-water surface
area ratios. Excess Cu, Pb, and Zn in surface sediments
of the Chesapeake Bay have been attributed to
atmospheric deposition (Helz et aL, 1985a; Helz et al.,
1985b).
Mechanisms of Atmospheric Deposition
Chemicals are removed from the atmosphere during
precipitation events via various wet deposition
processes. Particulate and gaseous contaminants are
scavenged by hydrometeors; in-cloud processes such
as diffusion, nucleation, coagulation, and coalescence,
or below-cloud processes such as impaction interception;
and diffusion into hydrometeors. The efficiency of
particle scavenging depends on the ambient suspended
aerosol particle concentration and size, as well as the
micrometeorology of the precipitation event. Gas phase
species may be scavenged from the atmosphere via
dissolution into rain drops. If the mass transfer of the
gas into the drop is rapid, then gas scavenging by
precipitation may be modelled as an equilibrium
distribution following Henry's Law. Because
precipitation scavenges organic particles much more
efficiently than organic gases, the gas-particle
distribution of many organic contaminants may control
the magnitude of wet depositional fluxes.
During dry periods, particle-associated chemicals are
removed from the atmosphere as particles are deposited
on water, soil, and vegetation surfaces. The magnitude
of particle transport and deposition depends in a
1-1
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complex "way upon macro- and micrometeorological
conditions, and has been modeled as a series of
resistances to transfer in the bulk atmosphere and across
the stagnant boundary layer. Combustion-derived
contaminants are generally associated with
submicrometer particles that are not efficiently dry
deposited, while many soil-derived (particles)
components are attached to large particles that deposit
rapidly. Gaseous contaminants actively exchange
between the atmosphere and water and terrestrial
surfaces at rates proportional to their instantaneous
concentration gradients. Recent evidence suggests that
the exchange of volatile organic contaminants is highly
dynamic, with volatilization during wanner months
offsetting efficient deposition during the winter season
(Baker and Eisenreich, 1990; Hoff et al., 1992).
Review of Previous Work
Atmospheric deposition may supply significant
quantities of nutrients, organic carbon, and potentially
toxic trace metals and organic chemicals to the
Chesapeake Bay. A 1988 report suggested that
atmospheric deposition of inorganic nitrogen provides
25% of the total loading of this important nutrient to the
Chesapeake Bay (Fisher et al., 1988; Fisher and
Oppenheimer, 1991). An independent evaluation
concluded that as much as 35% of the nitrogen loading
to the bay is derived from the atmosphere (Hinga et al.,
1991).
Studies sponsored by the United States Environmental
Protection Agency's Chesapeake Bay Program Office
during the early 1980s indicated that aerial loadings of
organic carbon to the southern Chesapeake Bay are of
the same order of magnitude as the estimated lower
limit of organic carbon fixation by phytoplanktpn
production (Velinsky et al., 1986). Also, these studies
determined that atmospheric deposition of
hydrocarbons to Chesapeake Bay was comparable in
magnitude to the input from wastewater treatment
plants and accidental discharges (Webber, 1983).
Anthropogenic hydrocarbons were estimated to account
for approximately 50% of the hydrocarbons aerially
deposited to the lower Chesapeake Bay (Webber, 1983).
In the early 1980s, the EPA-sponsored Chesapeake Bay
Aerial Precipitation Survey measured trace element
wet fluxes in coordinated studies in the Maryland
(Conkwrightetal.,1982)and Virginia (Wade andWong,
1982) portions of the estuary. Data from that one-year
"pilot project" are discussed in Section IV of this report.
Bulk deposition (i.e., wet'and dry combined) of
agrichemicals to the Chesapeake Bay region were
measuredby Williams (1986),Glotfeltyetal. (1990),and
Wu (1981). In these studies, open collectors were
deployed for extended periods in locations adjacent to
agricultural fields. While these studies provide some
importantfirstmeasurementsofagrichemicaldeposition
rates, the dose proximity of sampling to agrichemical
use areas likely resulted in overestimating the true,
regional deposition fluxes. Church and Scudlark (1992)
havemeasuredwetdepositionalfluxes of trace elements
atacoastalsiteadjacenttotheChesapeake Bay watershed
(Lewes, Delaware) since 1982. This record of
contaminant deposition revealed distinct seasonal and
annual trends. For example, concentrations and fluxes
of many trace elements peaked in the summer months
coincident with increased automobile and boat traffic.
Lead levels in precipitation have decreased by more
than a factor of 5 during the 10 years of sampling,
presumably reflecting the phase-out of alkylated lead in
gasoline during this period. Precipitation and aerosols
were sampled synoptically with rain events at two sites,
one near the Baltimore-Washington area (USDA
Research site, Beltsville, Maryland) and one downwind
at the mid-Atlantic coast (Lewes, Delaware). The
purpose was to examine source apportionment of trace
elements, comparing aerosol with precipitation-based
receptor models (Church, Scudlark, Ondov, and Hahn,
unpublished).
Statement of the Problem
As tighter controls are exerted on conventional point
source discharges, the relative contributions of non-
point contaminant sources are increasing. As is the case
for nutrients, the inventory of 'toxic' chemical sources
includes several important non-point sources, including
atmospheric deposition. The Chesapeake Bay Basinwide
Toxics Reduction Strategy outlined a plan to determine
both the absolute and relative contributions of a variety
of sources of contaminants to the Chesapeake Bay, and
specifically calls for quantification of atmospheric
1-2
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loadings (U.S. EPA, 1988). The 1990 Amendments to the
Clean Air Act also recognize the importance of
atmospheric deposition to coastal water quality,
requiring that the federal government establish and
maintainmonitoringnetworks around Chesapeake Bay
and other coastal waters. The problem was simply
stated: What quantity of inorganic and organic
contaminants is entering the Chesapeake Bay via
atmospheric deposition? Beginning in 1990, we initiated
a field study to answer this question. This report
describes the first phase of the study in which the fluxes
of atmospheric contaminants to the Maryland portion
of the Chesapeake Bay were estimated for 12 months
beginning in July 1990.
Study Objectives
The overall objective of the Chesapeake Bay Atmospheric
Deposition Study (CBADS) was to estimate the atmospheric
fluxes of trace elements and organic contaminants to the
surface of the Chesapeake Bay. To adequately address this
question, we also needed to quantify the spatial and
temporal variability in atmospheric concentrations.
Our primary objectives for Phase 1 of the CBADS study
were:
a) to accurately measure the concentration of selected
trace elements and organic contaminants in
precipitation and in atmospheric aerosols;
b) to determine the temporal and spatial variability in
precipitation concentrations and, where feasible,
fluxes;
c) to evaluate the relative magnitude of atmospheric
depositional processes (wet versus dry); and
d) to estimate the annual areal fluxes of the
contaminants to the Chesapeake Bay surface waters.
Study Limitations
This report covers the first phase of CBADS and does
not explicitly address several related issues currently
under investigation. Specifically, no attempt is made to
either model contaminant scavenging, to determine the
sources of the deposited contaminants, or to quantify
recycling of organic contaminants (i.e., revolatilization)
from the Chesapeake Bay. In addition, because of the
large uncertainties in estimating the transport of
chemicals through the watershed into the Chesapeake
Bay and because our sampling locations may not be
representative of the entire drainage basin, we have not
calculated the magnitude of atmospheric deposition to
the drainage basin. Finally, because highly heterogenous
conditions were anticipated, sampling within the urban
environment was consciously avoided. Therefore, the
loadings in this report are only indirectly influenced by
urban air masses and reflect conservative estimates of
bay-wide loadings. The role of urban areas in supplying
chemicals to coastal waters via the atmosphere remains
unclear.
1-3
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SECTION II
THE STUDY
Design
This field-based study was designed to estimate
atmospheric depositional loadings of trace elements
and organic contaminants to the Chesapeake Bay. As
such, this work was constrained both by the limited
understanding of depositional processes and by the
available resources. Because little a priori information
was available to anticipate the regional-scale variations
in deposition rates, we chose initially to establish two
sampling stations in the Maryland portion of Chesapeake
Bay. In a collaborative study sponsored by the U.S.
EPA, Chesapeake Bay Program Office, others initiated
operation of a third site in Matthews County, Virginia
(Dickhut et al., 1992). Due to limited resources, sampling
for organic contaminants in this study has only been
conducted at the Elms site.
To ensure that every precipitation event was collected,
we employed automated wet-only precipitation
samplers to collect integrated wet deposition samples
over weekly (trace elements) or bi-weekly (organic
contaminants) intervals. Continuous aerosol sampling
provided weekly integrated trace element
concentrations at each site, while 12- to 16-hour
integrated air samples were collected bi-weekly for
organic contaminants (gas and aerosol).
A key characteristic of this study was the co-deployment
of specialized, high-quality samplers for trace elements
and organic contaminants, with the subsequent analyses
following stringent analytical protocols. The sampling
and analytical procedures employed in this study
resulted in reproducible data, with concentrations
consistently well above our analytical detection limits
and with a minimum of contamination resulting from
sample handling.
Sampling Site Locations and Descriptions
All CBADS precipitation and aerosol sampling described
within this report was conducted at two sites in the
Maryland portion of the Chesapeake, subsequently
referred to as the Wye and Elms sites (Figll.l). Table II.l
summarizes the sampling activities at both sites.
Figure 11.1.
sites.
Chesapeake Bay Atmospheric Deposition Study
Wye Site
The northernmost site is located on the grounds of the
University of Maryland's Agriculture Experiment
Station, Wye Research and Education Center in
Queenstown, Maryland (38°53'N, 76°08'W), on the
eastern shore of the Chesapeake Bay. This site is located
< 5 km from the shoreline of the Chesapeake Bay in a
primarily rural agricultural region. Under typical
meteorological conditions, this site is downwind from
the heavily populated Washington, D.C./ Baltimore,
Maryland corridors, approximately 65 km east of
Washington, D.C., and 45 km southeast of Baltimore.
Trace elements in precipitation and aerosol particulates
were sampled at this location. The sampling equipment
was co-located at existing National Atmospheric
Deposition Program (NADP)/acid rain station in the
middle of a large, flat, open, grassy field. The nearest
buildings and roads were approximately 200 m away.
The site operator, Mr. Mike Newell, was also responsible
for the NADP site activities.
2-1
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SECTION III
METHODS
Organic Compounds in Air and Precipitation
Atmospheric organic contaminants exist as vapors that
adsorb to suspended particulate material. Because the
washout efficiencies of these two phases differ, the
partitioning behavior of the contaminants strongly
influences their overall depositional fluxes. In an effort
to assess the magnitude of these fluxes, we used samplers
that collected vapor and particulate organic
contaminants from the atmosphere and that isolated
dissolved and particulate organic contaminants from
precipitation. The sampling protocol will be discussed
in the following section, along with a detailed description
of sample extraction/fractionation methods, analyte
analysis and quality assurance efforts made.
Sampling
Air Sampling. A high-volume air sampler (General
Metals Works, Cleves, Ohio) was deployed to collect bi-
weekly ambient air samples. This sampler operationally
isolates the vapor and aerosol phases of atmospheric
contaminants by successively drawing air through a
20.3 x 25.4 cm glass fiber filter (Schleicher & Schuell #25)
to collect aerosols and a polyurethane foam plug (8.5 cm
x 10 cm) to collect vapors (Bidleman and Foreman, 1987,
and references cited within). This type of sampler has
been used extensively over the past decade for remote
atmospheric sampling of organic contaminants (Atlas
et al., 1981, Eisenreich et al., 1981, Bidleman et al, 1988,
McVeety and Hites, 1988, Baker and Eisenreich, 1990).
The glass fiber filters utilized in this study are composed
of 100% borosilicate glass fibers, arranged in layers that
entrap particles. The mean pore diameter is 2.9 (im.
Separation of aerosols from an air stream occurs through
retention by mechanical sieving and impaction,
interception and diffusion by aerosol adsorption.
Particles captured within the matrix of the fiber filter
form a filter cake upon which deposition of particles
occur. The fibrous matrix allows low air resistance,
keeping the pressure drop across the filter low (~ 5 Pa).
The filters are ~ 95% free of organic material and offer
low background levels of contaminants to samples
(Grosjean, 1983). The filtration efficiencies of several
brands of glass fiber filters have been measured to be
> 99.1% (John and Reischl, 1978).
The polyurethane foam is an efficient adsorbent of
hydrophobic organic contaminants and has been used
extensively in remote environments such as the Arctic
(Bidleman et al., 1989), the Great Lakes (Baker and
Eisenreich, 1990) the western North Atlantic Ocean,
and the Adirondack Mountains (Knap and Binkley,
1991). The foam has a density of ~ 0.022 g»cm'3 and its
open structure allows air to flow through easily,
permitting large volumes of air to be sampled readily
(Pankow, 1989).
Two potential sampling artifacts can occur with this
type of air sampling. First, the measured particulate
concentrations of hydrophobic organic contaminants
may be overestimated due to the adsorption of low
molecular weight vapor phase compounds onto the
filter surface during sample collection. Natural organic
material, such as gaseous hydrocarbons, may enhance
this artifact by "coating" the particle-loaded filter.
Hydrophobic organic contaminants (HOCs) may
partition into this coating (Gotham and Bidleman, 1992).
In an effort to assess the extent of this adsorption, a
routine backup filter was deployed with each sample
(Ligocki, 1985b). Coated organic material may desorb
from the front filter and readsorb to the backup filter,
thus acting as a "stationary phase" that would enhance
the sorption of organochlorines and other HOCs.
However, it is probable that the amount of
organochlorines found on the backup filter does not
overestimate the actual adsorption to the front filter
because one would expect at least as much organic
material to be present on the front filter. With this in
mind, routine back filter subtraction as a correction for
the adsorption artifact is partially correct (Gotham and
Bidleman, 1992;McDow and Huntzicker, 1990). In this
study, low molecular weight polycyclic aromatic
hydrocarbons (e.g., phenanthrene, fluorene) were
occasionally detected on back-up filters. In five air
samples, average phenanthrene concentrations on the
backup filter were 19% of those measured on the front
3-1
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filter. Backup filter concentrations for fluorene,
anthracene and fluoranthene were similar. Because the
backup contaminant concentrations were low relative
to the front filter concentrations for those preliminary
samples, we did not correct the remaining front filter
data for vapor adsorption.
Evaporative losses of adsorbed contaminants may lead
to an underestimation of the filter-retained material.
Evaporative losses occur due to the gas phase
concentration differential between the surface of the
filter cake and the ambient air at the sampler inlet. This
concentration gradient may result from a) changes in
vapor phase organic contaminant concentrations during
the collection period, b) the pressure drop associated
with the air flow across the filter, and c) increases in
ambient temperature. However, Zhang and McMurry
(1991) have published sampling efficiency curves for air
samplers with pressure drops equal to 10 Pa that suggest
evaporative losses due to pressure drops are < 10%. To
minimize losses resulting from temperature changes,
samples in this study were generally collected between
late afternoon and night.
0.5
Flow Rite (n
Air sampling times ranged from 12-16 hours with flow
rates between 0.5-0.8 m^mirr1. Some samples were
collected for longer periods (16-24 hours), particularly
those in the winter seasons. Flow rates were estimated
for each sample from the measured pressure drop across
the sampling train. The flow rate (mVmin) is
proportional to the square root of the pressure drop as
measured with a manometer (inches of water). The
pressure drop wasmeasured in the field at the beginning
and end of each sample period, and an average flow rate
was calculated using the calibration curve in Figure
ni.l. A flow controller installed in the sampling train
maintained a constant sampling rate independent of
the amount of aerosols collected. The door of the
sampler house was kept ajar during sampling to allow
for venting of pump exhaust, and a peaked lid above the
sampler house repelled birds and prevented
precipitation and very large (> 100 pm) particles from
entering the sampler.
Filter
XAD-2|
Resin
Optical Liquid
Level Sensors
Peristaltic
Pump
Reservoir
Figure 111.1. Calibration curve used to set the flow rate on the
high-volume air sampler.
Figure III.2. In situ sampling train for precipitation collector.
Precipitation Sampling. For the assessment of low-level
organic contaminants in precipitation, a modified, wet-
only collector was developed to a) collect large volumes
of precipitation and b) to operationally isolate the
3-2
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particulate and dissolved fractions of the contaminants
during a precipitation event. The design schematic of
the in situ filtration system is shown in Figure ffl.2. The
collection area is a 1 m2 stainless steel funnel that is kept
dosed during dry periods by a 1 m2 aluminum lid
tightly sealed over the top flange of the funnel. At the
onset of a precipitation event, a moisture sensor (Table
ELI) activates a Campbell Scientific CR-10 data module,
which in turn energizesapressurizedpneumaticsystem
to open the lid (Figure ffl.3). Collected precipitation is
channeled down the funnel, filtered through a glass
fiber filter (142mm diameter, Schleicher &Schuell #25),
and passed through a stainless steel column (2.5 on x 30
cm) that contains a slurry (250 ml, ~ 80 g dry weight) of
XAD-2macroreticular resin (Amberlite,Rohm and Haas,
Philadelphia, Pennsylvania). The XAD-2 resin (a
styrene-divinylbenzene non-polar, hydrophobic
copolymer) isolates dissolved organic contaminants
from the precipitation. Hydrophobic organic
contaminants are physically bound to the resin
principally by van der Waal's forces. Because van der
Waal's forces are relatively weak, HOCs exhibit low
chemisorption values (-35 kcal/mol), which in turn
facilitates ready desorption of the compounds from the
resin (Daignault et al., 1988). A peristaltic pump (Table
in. 1) prevents rainwater from accumulating in the funnel
and ensures a constant flow rate through the resin
column at 200ml/min. Liquid level sensors (Table D3.1)
control the pump to ensure that the filter and resin
remain wet, minimizing any sampling artifacts caused
by volatilization of contaminants from a dry filter or
drying of the resin. Contamination of the sample could
result if the resin beads cracked or split open as a result
of drying.
All systems are inactivated
LID CLOSED
Moisture begins;
precipitation sensor is weaed
dew.
light mist
Precipitation sensor
detects rain
Moisture evaporates;
preapaatron sensor dries;
M remains closed
Control valve activates
actuator ID open lid;
PrGcipitaooo enters funnel
Upper uqnd level sensor
is weaed. sends signal
u> pump; Pump ON
t
Precipitation flows through
filler and XAD-2 column;
filtrate flows to reservoir
V
Lower liqvid level sensor
dnes: Pomp OFF
CR-10 chats rain sensor.
Is it coll raining?
Yes
No
Control valve activates
actuator lo close lid
I
AD moisture is evaporated
from precipitation sensor
A
Figure 111.3. Row chart of logic for precipitation sampler.
The entire precipitation sample system is powered by
12V DC that is routinely recharged by 110V AC. A CR-
10 data logger continuously monitors all of the sensors
(Table EX1), recording data every 15 minutes during
dry periods and every 3 minutes during a precipitation
event (Appendix ALT). The moisture sensor is heated
to ensure the evaporation of early morning or evening
dew and to quickly dry the sensor after a precipitation
event. A tipping bucket gauge provides an independent
measurement of the amount of precipitation that fell
during each sampling period. The entire lower portion
Sensor
Tipping Bucket Gage (0.01" tip)
Temperature and Relative Humidity
Probe (10-96%) w/ Radiation Shield
Moisture Sensor (40 cm 2)
Micro Variable Speed Pump w/ 1 head
Liquid Level Sensors
Model No.
TE525
207
A-1
7020
11-506A
Manufacturer
Texas Electronics
Campbell Scientific
MIC Company
Mastertlex
Ayers Sales
Table 111.1. Description of sensors on the organic precipitator collector.
3-3
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of the sampler is housed by aluminum panels that are
insulated with a thin layer of fiber-glass. During winter,
a cable wanner is wrapped around the resin column to
prevent the resin from freezing.
Air Sample Collection Protocol. Ambient air samples
were collected bi-weekly, concurrently with the rain
sampling strategy. An air sample was collected on the
day the precipitation sampler was serviced (generally
every other Tuesday). Prior to sampling, the glass fiber
filters were individually wrapped in aluminum foil and
ashed at 450°C for 24 hours. The polyurethane foam
plugs were cleaned via 24-hour extractions with
petroleum ether. The extracted plugs were dried in a
vacuum desiccator to remove any remaining solvent,
wrapped in aluminum foil, and, along with the glass
fiber filters, stored in the laboratory until used. The
sampling train was loaded in the laboratory with two
glass fiber filters and one foam plug, covered with
aluminum foil, and transported to the site. After
sampling, the entire train was brought back to the
laboratory; the filters and plug were removed with
stainless steel forceps and then wrapped in foil and
stored at 4°C in the dark until analysis. Blank filters and
foam plugs were routinely placed in the field to
determine if either matrix accumulated analy tes during
the sampling period. Appendix A.1.8 lists the volume
of air collected and other field notes for each sample.
Precipitation Sample Collection Protocol. Precipitation
samples were integrated over 14 days and changed
every other Tuesday. Resin columns were packed in the
laboratory and transferred to the field capped with
stainless steel fittings. The XAD-2 resin was precleaned
in the laboratory by sequential 24-hour extractions with
solvents in the following order: methanol, acetone,
hexane, dichloromethane, hexane, acetone, and
methanol, then rinsed with deionized water and stored
in a 4 L amber glass bottle as an aqueous slurry. All
solvents were pesticide residue grade (J. T. Baker Co.).
The glass fiber filters were pre-cut and ashed at 450°C
for 4 hours before sampling and were transported to the
field wrapped in aluminum foil and sealed in a plastic
bag.
Upon arrival at the site, an immediate check was made
to ensure the sampler was functioning by wetting the
moisture sensor with tap water. A portable computer
was then connected to the CR-10 module to download
the sensOT data for the 14-day period. The resin column
and the glass fiber filter were then removed from the
sampler. The filter was removed from the filter plate
with stainless steel forceps, folded in half, and then
wrapped in clean aluminum foil and labeled. The
stainless steel funnel was then scrubbed with pre-cleaned
(solvent extraction, 24 hours, acetone:hexane, 50:50)
glass wool and deionized water to remove any adhering
particles that were not effectively washed down the
sampling train during the precipitation event Because
the funnel remains "sealed" during dry periods,
particulate matter in the funnel originated from the
atmosphere during precipitation events. The funnel
rinse, consisting of the wetted glass wool, was wrapped
in foil, labeled, put into a plastic bag, and transported to
the laboratory. The funnel rinse was analyzed as a
separated sample to measure the contribution of the
funnel-retained particles to the total measured
contaminant concentrations.
After the glass wool scrubbing, the funnel was
thoroughly rinsed with deionized water, methanol, and
dichloromethane to ensure that the funnel surface and
sampling train were clean. The lid was then closed, and
a new filter and resin column were put in place. A small
volume of deionized water was then rinsed down the
sampling train to make sure the water level was above
the liquid level sensors. The volume of precipitation
collected in the reservoir was measured, recorded, and
then discarded. The CR-10 data module was then reset,
and the system was ready for a new sampling period.
Before leaving the site, the moisture sensor was activated
again to ensure the sampler was -functioning and that
the lid was closing properly. All samples were stored in
the laboratory in the dark either in the refrigerator (resin
samples) or freezer (rain filters, air filters, and air vapor
samples) until analyzed. The resin samples were
removed from the stainless steel column and stored in
glass jars with Teflon-lined lids. All filters and foam
plugs were stored wrapped in aluminum foil.
3-4
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PAHs
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo[a]anthracene
Chrysene
Benzo[b]fluoranthene
Benzo[k]fluoranthene
Benzo[e]pyrene
Benzo[a]pyrene
lndeno[123-cd]pyrene
Dibenz[ah]anthracene
Benzo[ghi]perylene
PCBs
78 Polychlorinated
biphenyl congeners
Chlorinated Agrichemicals *
Hexachlorobenzene
cc-hexachlorocyclohexane
p-hexachlorohexane
G-hexachlorohexane
Heptachlor
Heptachlor epoxide
Aldrin
Endrin
p,p'-DDE
p.p'-DDD; p.p'-DDT
p.p'-DDT; o,p'-DDT
'future work
Table III.2.
airshed.
Organic compounds analyzed in Chesapeake Bay
Analytical Procedures
Sample Extraction. All samples were analyzed for
14polycyclic aromatic hydrocarbons (PAHs) and 78
polychlorinated biphenyls (PCBs) (Table ffl.2). Target
PAHs are listed as EPA priority pollutants. These
compounds were chosen because their molecular
weights, vapor pressures, and aqueous solubilities span
a wide range and thus are expected to demonstrate
variable atmospheric deposition patterns.
Sample extraction and analysis procedures are outlined
in Figure III.4. Resin samples were extracted for 24
hours with 1:1 acetone:hexane. Filter samples were
sequentially extracted for 24 hours in methanol followed
by dichloromethane. Vapor samples were extracted for
24 hours in petroleum ether. Resulting fractions of each
matrix extraction were combined, and the more polar
solvent was removed by liquid-liquid partitioning into
deionized water. The remaining non-polar fractions
were then dried over anhydrous Na2SO4 (J. T. Baker Co.)
and concentrated to < 10 ml in a Kudema-Danish (KD)
apparatus. The dichloromethane fractions were
exchanged for hexane during the evaporation process.
The extracts were further concentrated to ~ 4 ml under
a stream of chromatographic grade nitrogen, transferred
Add lib
surrogates
SOXHLET Extraction; 24 boon each iota*
XAP-2, FW FILTERS POP
Acetone
Haunt
Methanol
DCM
Pet. Ether
Liquid-liquid pntitiang into infer
Discard polar factions
Dry Don-polar Traction over N»2SO4
Kudenu-Dmuh solvent concentration to < 10 ml
(Switch DCM and pet edier to hexane)
Subtample 10-25*
Remaining Fraction
Add donemed internal standards;
c to 10 111 with Nj
FracuauaDon w/ 13g Ronsil
(1.25* deactivated)
Hutew/ 80 ml hexane
2ndehnio.w/l:10DEE-Hg
PAH quantification
CC/MSD
Kuderaa-Dai
< 10 ml; N2 concentration to 100 ill
Add internal standards
PCB quantification
OOECD
Figure III.4. Analytical procedure for PAH and PCB
quantification.
from the KD apparatus to weighed amber vials, and a
10-25% subsample was reserved for PAH analysis. The
remaining extract was concentrated to ~ 1 ml under
nitrogen and further purified by fractionation on a 13 g
magnesium aluminum silicate column (Florisil, 60 -100
meshj. T. Baker Co.). The Florisil, partially deactivated
with 1.25% deionized water, acts as a polar stationary
phase to remove any polar interferences present in the
extract such as lipids, phthalates, and some of the more
polar pesticides. The non-polar PCBs are eluted through
the column with 80 ml hexane. A second elution with 80
ml of a 10% (v/v) solution of diethyl ether/hexane
removes the retained polar organic compounds such as
lindane (y-hexachlorocyclohexane), o,p' and p,p'- DDT
and dieldrin. A small Na2SO4 layer was placed on the
Florisil column prior to elution to remove any traces of
water present in the extract and to prevent further
deactivation of the Florisil. All Florisil was cleaned by
extracting with a 1:1 acetone/hexane solution for 24
hours and was activated at 550°C for a minimum of 4
hours prior to use. Following the Florisil separation, the
fractions were concentrated to ~ 8 ml in a KD apparatus
and further to 1 ml under nitrogen. The concentrated
extracts were then transferred to amber autosampler
3-5
-------
vials, sealed with a Teflon-faced cap and stored at 4°C
in the dark until analysis.
Jel
Hewlett Packard 5890A GC, w/ Hewlett Packard
7673 autosampler
Columns
Stationary Phases:
Model *s:
Lengths:
Internal Diameters:
Film Thickness:
Plates:
Gas
5% crosslinked phenylmethyl silicon
(Hewlett Packard)
DB-5 (J & W Scientific)
19091B-105, 123-5062
50 m, 60 m
0.32 mm, 0.25 mm
0.25 jun
4600/meter
Carrier
Make-up:
Head Pressure:
Ultra pure hydrogen, - 1 ml/min
Ultra pure nitrogen, 49 ml/min
100kPa
Injection Port
Mode: Splitless
Temperature: 225°C
Vent Time: 0.50 min
Injection Volume: 2 ^1
Program
Initial Oven:
Ramp 1:
Ramp 2:
Final time:
100°C, 2 min
4°C/minto170°C
3°C/min to 280°C
5 min
Detector
Make: 63 Ni (13 producer)
Temperature: 280°C
Signal: -79 cycles/second
Acquisition Maxima Chromatographic Software
Table 111.3. Chromatographic conditions for the analysis of
polychlorinated biphenyls via electron capture detection.
internal standard were added to each sample prior to
injection. The use of the internal standard method
eliminates errors propagated by inconsistent sample
injections, and it is independent of the final extract
volume (Swackhamer, 1987). A single calibration
standard was used to generate response factors for each
congener relative to the internal standards. The standard
solution was a mixture of three Arodor commercial
mixtures (1232,1248, and 1262) that were obtained from
me EPA Repository for Toxic and Hazardous Materials,
Research Triangle Park, North Carolina. Following the
procedure of Mullin (1985), a 610 ng/ml PCB solution
was made in a 25:18:18 ratio for the three mixtures,
respectively. Congeners were identified based on
retention times and relative response factors and were
calculated from calibration standards as follows:
RRF = (response standard congener/response
internal standard)
x (mass internal standard/mass standard congener)
The congener masses in the samples were then calculated
as follows:
Mass = (response congener/response internal
standard)
x (mass internal standard/RRF)
The corresponding concentrations were then calculated
by dividing the mass in the sample by the sample
volume in liters for precipitation or cubic meters for air.
In instances where congeners could not be separated
completely, their combined concentrations are reported.
Total PCB concentrations were calculated as the sum of
the 78 congeners.
Quantification of Analytes. Concentrations of PCBs
were determined by capillary gas chromatography
equipped with electron capture detection using a
Hewlett-Packard 5890 GC (Table m.3). Congeners that
were not commercially produced in the Arodor mixtures
and hence are not present in the environment (2,4,6
trichloro- and 2,2',3,4,4',5,6,6' octochlorobiphenyl, Ultra
Scientific, North Kingstown, Rhode Island) were used
as internal standards to quantify the individual
congeners in each sample. Five nanograms of each
The PAH subfracrion was quantified with a Hewlett
Packard 5890A GC coupled to a 5970 mass selective
detective (Table in.4). Five perdeuterated PAH internal
standards (MSD Isotopes, Cambridge, Massachusetts;
Supelco Separation Technologies, Bellefonte,
Pennsylvania) were combined as a mixture and used to
calculate relative response factors for individual PAHs
using Equation 1. The selected ion program is listed in
Table III.5. Identification of individual PAHs was based
on appropriate retention times and was confirmed by
3-6
-------
Model
Hewlett Packard 5890A GC, w/ Hewlett Packard
7673 autosampler
Columns
Stationary Phases:
Model #:
Length:
Internal Diameter
Rim Thickness:
Plates:
Gas
Carrier:
Row rate:
Head Pressure:
Injection Port
Mode:
Temperature:
Vent Time:
Injection Volume:
Program
Initial Oven:
Ramp 1 :
Ramp 2:
Final time:
Detector
Make:
Temperature:
Source Pressure:
Acquisition:
5% crosslinked phenylmethyl silicon
(Hewlett Packard)
19091B-105
25 m
0.2mm
0.33 urn
4600/meter
Ultra pure helium
0.6 ml/min
100 kPa
Splitless
225°C
1 .6 min
2 |il
50°C, 0.5 min
5°C/min to 280°C
2°C/min to 290°C
5 min
Hewlett Packard 5970A Mass Selectiv
Detector
280°C
> 1 x E-6 ton-
Select Ion Mode; Unix based software
Window 1
Fluorene
Phenanthrene
Anthracene
d- 10 Phenanthrene*
d- 10 Anthracene
Window 2
Ruoranthene
Pyrene
Benzo[a]Anthracene
Chrysene
d-10 Ruoranthene
d-10 Pyrene
d-12 Benzo[a]Anthracene*
Window 3
Benzo[b]Fluoranthene
Benzo[k]Fluoranthene
Benzo[e]Pyrene
Benzo[a] Pyrene
d-12 BenzofbJFIuoranthene
d-12 Benzo[a]Pyrene *
Window 4
ldeno[1 ,2,3-cd]Pyrene
Dibenz[a,h]Anthracene
Benzo[ghi]Perylene
d-12 Benzo[ghi]Perylene *
'internal standard
Quantification
Ion (amu)
166
178
178
188
188
202
202
228
228
212
212
240
252
252
252
252
264
264
276
278
276
288
Confirmation
Ion (amu)
165.167
176,177
176,177
N/A
N/A
200,203
200,203
227,229
227,229
N/A
N/A
N/A
253
253
253
253
N/A
N/A
277
279
277
N/A
Table III.4. Chromatographic conditions for the analysis of
polycyclic aromatic hydrocarbons via selected ion mass
spectrometry.
Table III.5. Select ion monitoring mode for polycyclic aromatic
hydrocarbons.
the abundance of a secondary ion relative to the
molecular ion. All 14 target PAHs were
chromatographically resolved.
Detection Limits. In this study the limit of detection was
based on the signal-to-noise ratio of thebaseline adjacent
to expected analyte peaks. Individual sample analytical
detection limits were estimated by assuming a minimum
quantifiable peak area of 400 for a GC/MSD
chromatographic peak and a minimum peak area of 100
for a GC/ECD chromatographic peak. In general, for
both the GC/ECD and the GC/MSD, the peak-to-peak
noise ratio was > 2. A comparison of the mean vapor
concentrations of several PAHs and total PCBs to the
mean analytical detection limit is shown in Table IU..6.
PAHs that are generally absent from the vapor phase
approach the analytical detection limit such that the
signal-to-noise ratio is closer to 1.
Precipitation sampler detection limits were calculated
based on an annual precipitation of 75 cm (2.88 cm/14
days), resulting in an estimated 28.8 L sample collected
3-7
-------
2
30
10
• 30
2
10
30
10
73.2
Rims Precipitation Sample 8/9-8/15/90
Held detection
limit; vol « 28.8 L
Funnel
Filter
1
XAD-2 Resin
«121I174»4|44«913Si4101S08713«77 13 Ui 135107 UB1311K7187113174177XaMlfl03Dl 23 2M
IUPAC Dominant Congener #
Figure IIL5. Comparison of PCBs in a predpitation sample to field detection limits. Field detection limits assume a minimum chromatographic
peak area of 100 and an annual precipitation rate of 75 cm. Sample volume « 53.9 L
3-8
-------
during a two-week period. Dividing the analytical
detection limit by this estimated volume gives field
detection limits in ng/L. A comparison of sample field
detection limits to the measured concentrations in a
precipitation sample from early Augustin 1990 is shown
in Figure in.5 for several PCB congeners. Congeners are
plotted in order of decreasing vapor pressure. With the
exception of congener 200, all matrices are generally
well above the field detection limits. The detection limit
of congener 136 is dose to the dissolved concentration.
Congener 48 was not detected in the funnel sample.
Generally, the less volatile PCBs are not present in the
dissolved phase, and as a result the sample
concentrations are dose to the field detection limits.
Congener 180 is an exception - in all three matrices its
sample concentration is 10 times larger than the field
detection limit.
Polycyclic Mean Vapor
Aromatic Concentration
Hydrocarbon (P9*nr3)
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo[a]anthracene
Chrysene
Benzo[b]fluoranthene
Benzo[k]fluoranthene
Benzo[e]pyrene
Benzo[a]pyrene
lndeno[1 23-cd]pyrene
Dibenz[ah]anthracene
Benzo[ghi]perylene
Total polychlorinated
biphenyls
686
2011
52
337
413
9
24
10
6
7
4
2
2
2
330
Mean Analytical
Detection Limit
(pgrrr3)
0.5
0.3
0.3
0.3
0.3
0.8
1.2
1.0
0.8
1.1
1.0
2.0
2.2
1.5
1.1
Table III.6. Mean field measured vapor concentrations and
mean analytical detection limits for several PAHs and PCBs,
Chesapeake Bay, 1990-1991.
Quality Assurance
In this study, quality assurance procedures specified
the use of surrogate spikes to all matrices, laboratory
blanks, and field blanks. These procedures help ensure
that the data obtained are of acceptable quality and that
they represent the true environmental signal.
Extraction Efficiencies. In an effort to evaluate the
efficiency of the analytical procedures, recoveries of
several perdeuterated PAHs and non-cormnerdally
produced PCBs that were added to all samples as
surrogates prior to extraction were measured. Surrogate
compounds are listed in Table EU..7, along with average
recoveries for each compound in each sample matrix.
Because the same surrogates were not used in all
matrices, analyte concentrations were not corrected for
sample recoveries. Resulting recovery data for
individual samples are listed in Appendix A1.6.
In addition to analytical evaluations, we began using
field surrogates in June of 1991 to assess the efficiency of
the sampling procedures. The efficiency of the XAD-2
resin was evaluated by adding known amounts of
perdeuterated PAHs to the column prior to deployment
in the field. Average recoveries of surrogates spiked
onto two columns were d-10 anthracene - 64% and d-10
pyrene -65%. Volumes of rain for these samples ranged
from 0 (no precipitation) to 66 L. Junk et al. (1974), using
similar extraction procedures, reported an average
recovery of a wide variety of organic compounds in
water at the 10 - 100 ug/L level from XAD-2 resin of
78% ± 6%. The results indicate that the porous polymer
canbeusedwith confidence for analysis of trace organic
compounds present in natural waters. Again, because
field surrogates were not routinely used in every sample,
no attempt was made to correct existing data for field
recoveries.
The retaining ability of the polyurethane foam was
evaluated with the use of d-12 fluoranthene. Prior to
sampling, a foam plug was spiked with 371 ng of d-12
fluoranthene in hexane. The solvent was then allowed
to evaporate, and the spiked plug was placed into the
sampling train. The recovery for this compound was
55% (N = 1). The spiking strategy employed here is
analogous to using an elution chromatography system
- the sample is introduced to the polyurethane foam
"column" as a single slug that is then eluted as a band.
Assuming linear adsorption isotherms, the retention
volume for an elution experiment should be identical to
the breakthrough volume for a frontal experiment in
3-9
-------
Deuterated Polycyclic
Aromatic
Hydrocarbon
d-10 Anthracene
d-10 Anthracene
d-10 Pyrene
d-12 Fluoranthene
d-12 Benzo [b] fluoranthene
d-10 Anthracene
d-10 Pyrene
d-12 Fluoranthene
d-12 Benzo [b] fluoranthene
d-10 Anthracene
d-10 Pyrene
d-12 Fluoranthene
d-12 Benzo [b] fluoranthene
d-10 Anthracene
d-12 Fluoranthene
d-12 Benzo [b] fluoranthene
non-commercial
Polychlorinated
Biphenyl
3,5 dichlorobiphenyl
2,3,5,6 tetrachlorobiphenyl
3,5 dichlorobiphenyl
2,3,5,6 tetrachlorobiphenyl
3,5 dichlorobiphenyl
2,3,5,6 tetrachlorobiphenyl
3,5 dichlorobiphenyl
2,3,5,6 tetrachlorobiphenyl
'relative STD DEV = STD DEV *
"number of samples
*70%<%Rec<130%
Sample
Matrix
Funnel Wash
Rain Filter
Rain Dissolved
Air Filter
Air Vapor
Sample
Matrix
Rain Filter
Rain Dissolved
Air Filter
Air Vapor
100/Imean]
Mean %
Recovery
53.6
59.1
52.6
28.1
56.1
75.5
73.5
34.3
93.2
55.8
108.2
72.5
111.7
59.6
70.1
130.5
Mean %
Recovery
68.1
90.3
73.3
69.1
62.4
75.9
101.5
83.3
Relative *
STD Dev (%)
68.3
48.4
22.4
27.6
302
30.3
49.7
19.1
29.3
45.6
16.4
37.3
24.3
462
53.6
27.3
Relative*
STD Dev (%)
39.0
34.1
37.1
35.9
51.8
55.5
40.0
30.4
N**
10
19
13
8
18
24
19
5
23
9
6
16
22
14
7
10
N"
30
12
30
7
15
15
30
10
70% < x
x<130%
2
7
3
0
4
16
10
0
17
4
1
8
14
5
4
5
70%
-------
Laboratory Field
Polycyclic Mean Mean Mean Mean Mean Mean
Aromatic Resin %ReI Filler %Rel Foam %Rel Resin %Rel RKer %Rel Foam
Hydrocarbon
Fluorene
Phenanlhrene
Anthracene
Fluoranthene
Pyrene
Benzo (a) Anthracene
Chrysene
Benzo |b] Fluoranthene
Benzo [k] Fluoranthene
Benzo (ej Pyrene
Benzo [a] Pyrene
lndeno[123] Pyrene
Dibenzo [a] Anthracene
Benzo [ghi] Peryleno
Total PCBs'"
N=5)" STD* (N=6) STD (N=1) STD (N=2) STD (N=3) STD (N=2)
21.3 150
50.9 152
19.5 131
29.9 1 16
199.7 204
7.7 166
13.6 122
10.1 190
11.2 189
5.0 95
9.2 224
NO
3.4 224
12.4 167
14.9 39
0.9 134
5.4 24
0.4 245
0.7 124
0.5 159
0.5 107
0.2 137
0.1 245
0.2 155
0.2 157
0.3 159
NO
ND
0.7 245
44.3 85
ND
17.1
1.6 --
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
48.3 64
1.7 141
10.0 1
2.1 105
2.0 70
2.4 49
0.4 141
5.8 52
ND
ND
12.0 126
24.9 141
ND
2.7 141
ND
32.7 56
0.5 134
3.7 161
2.6 62
0.3 90
10.6 168
2.2 143
2.8 124
4.2 153
4.3 153
0.2 141
0.3 173
ND
0.3 173
0.3 173
0.9
48.6 126
212.6 130
12.4 129
23.0 134
8.5 123
0.8 141
0.7 141
0.9 141
0.8 141
ND
0.6 141
ND
ND
0.9 141
I 27.5 30
•relative STD DEV = STD DEV * 1 00/Imean]
"number of samples
'"86 congeners, N=5 lor lab filters, N=2 lor lab foam; N=1 for field filters; N=2 for field foam
Table 111.8. Mean mass (ng) summary of potycydic aromatic hydrocarbons and polychlorinated biphenyls in laboratory and field blank
matrices, Chesapeake Bay Atmospheric Deposition Project, 1990 -1991.
which the sample is continuously introduced to the
column and subsequently moved through the column
by air flow (Simon and Bidleman, 1979). Breakthrough
volume for a frontal experiment is taken at the point at
which one-half the concentration of the solute in the
column effluent is one-half the concentration introduced
to the column (Simon and Bidleman, 1979 and references
cited within). Breakthrough volumes for a 7.5 on
diameter x 15 cm (diametenlength = 0.5) foam plug for
several PAHs have been correlated with subcooled
liquid vapor pressures (You and Bidleman, 1984) such
that
log VB = -1.104 PL- 0.773 (3)
where VB is the breakthrough volume, (m3), and PL is the
subcooled liquid vapor pressure (torr). The maximum
temperature experienced over the sampling period of
our recovery experiment was 25°C. By calculating the
solid vapor pressure for fluoranthene at this temperature
from the relationship given in Sonnefeld and Zoller
(1983), the subcooled liquid vapor pressure can be
estimated from the equation (MacKay et al., 1982).
lnPs/PL = -6.8(Tm-T)/T
(4)
where Ps is the solid vapor pressure, PL is the subcooled
liquid vapor pressure, Tm is the absolute melting point,
and T is the absolute ambient temperature. The constant
6.8 is the ratio of the entropy of fusion to the universal
gas constant, (ASf/R = 6.8, where ASf is ~ 13.5 cal/°mole
for PAHs and PCBs). Using the subcooled liquid vapor
pressure calculated from [4] at 25°C, a breakthrough
volume for fluoranthene is estimated from [3] to be
~ 400 m3. The sample volume for the recovery
experiment was 860 m3. Hence, some breakthrough
could have contributed to the 45% loss of the d-12
3-11
-------
fluoranthene.However,ourfoamplugis slightly bigger
(diametenlength = 0.85) than the one used to generate
the breakthrough volume curves, such that the
breakthrough volumeforfluoranthene on a larger foam
plug would be closer to 700 m3. Based on the laboratory
recovery of 56% for d-12 benzo[b]fluoranthene, it seems
evident that the 45% loss of the field surrogate occurred
in the extraction and concentration steps rather than in
the field during sampling. The retention of several PCB
congeners on polyurethane foam has been investigated
by an elution chromatography system such that
recoveries of the total quantity of isomer applied to the
spike plug ranged from 76-95% (Simon and Bidleman,
1979), and similar results are reported for several
chlorinated pesticides (Turner and Glotfelty, 1977) in a
similar sampling apparatus. Thus, we are confident
that the polyurethane foam is an efficient trap for
hydrophobic organic contaminant vapors.
Procedural and Field Blanks. Accurate trace chemical
determinations require accurate knowledge of the
analyte blanks. Procedural matrix blanks were extracted
with each set of samples to characterize any laboratory
sources of contamination and to determine if the pre-
cleaned filters, resin, and PUF plugs contributed
significant interferences to the sample extracts. Listed
in Table in.8 are the mean masses of PAHs and PCBs
found in our laboratory and field matrix blanks. In
cases where a field blank was extracted with a group of
samples, the laboratory blank was not used for
quantification purposes. Instead the field blank was
used as was the case with most of the air vapor samples.
The largest laboratory and field blank analyte in the
polyurethane foam was phenanthrene, and these values
were generally only 13% of the sample analyte. All
other PAHs in the foam blanks were insignificant
compared to the samples. Total PCBs in the laboratory
foam blank were about 18% of the average vapor phase
concentration, assuming an average sample volume of
800m3.
Comparison of a dissolved precipitation sample
collected in February 1991 to its corresponding
laboratory blank is shown in Figure III.6. The average
blank value for each compound is also shown.
Benzo[k]fluoranthene was not detected in the
precipitation sample. The average blank mass for pyrene
was higher than the other PAHs by a factor of 2,
indicating that a few isolated blank resin samples were
contaminated with pyrene. In general, individual
compounds in the blank were less than 20 to 50% of the
analyte in the sample, and often were less. In instances
where the blank mass was larger then 50% of the analyte
mass in the sample, the analyte was reported as being
"non-quantifiable," or "NQ." In those cases where the
blank contribution was less then 50% of the sample
analyte, blank subtraction was inhibited because the
blank values were highly variable. As a result, the
reported data are not corrected for blanks. All matrix
FLU ANT FYR CHR B[kJP BfiJP *{ilJA. T-PCB.
THEN TLA B[.)A B[b]P B{*JP Ip2JJP
Figure 111.6. Comparison of a dissolved precipitation sample to
its corresponding laboratory blank. Average blank values for XAD-
2 are denoted by A.
laboratory and field blank data are listed in Appendices
A1.1-A1.4. Because concentrations of PCBs and lower
molecular weight PAHs (< 202 amu) on air and rain
filters were very low, the relatively low laboratory
blanks provide a substantial contribution (> 50%) to the
total analyte present. Toward the end of the one-year
sampling period, glassware and solvent blanks
approached the threshold of the matrix blanks. This
3-12
-------
indicated that most of the blank contamination was
being acquired during the extraction and concentration
procedures and that sample matrices were dean. The
blank value of PCB congeners 8/5 on the XAD-2 resin
was extremely large and precluded any dissolved phase
quantification. If congener 8/5 was included in the total
mass of dissolved sample analyte, its mass value would
be at least 50% that of the total PCB mass for that sample.
A coeluting chromatographic peak for congener 8/5
was present in most of resin samples and as a result it
could not be determined if the peak present in the
sample chromatogram was indeed congener 8/5.
Trace Elements in Aerosol
Sampling
Samples at each site were collected continuously for 168
hours at a flow rate of 10 L'nv1, on 2-um-pore, 47-mrn,
Gelman "Teflo" Filters using dichotomous samplers
each equipped with a single-stage impactor to remove
particles >10 um in diameter. Each sampler was
equipped with a "dry" gas meter with cumulative
display to determine sample volume. As shown in
Table ELI, sampling was initiated at the Wye and Elms
sites on 5 June 1990. Between 5 June 1990 and 4 June
1991,49 aerosol samples were collected at Wye and 46
were collected at Elms. Field blanks, four at each site,
were collected by installing a second loaded sampling
head beside the regular sampling head and exposing it
for the duration of the weekly sampling period.
Analyses
The 95 samples, 10 laboratory blanks, and 8 field blanks,
representing the first year of the study, were divided
into two equal parts. Half of each filter was analyzed for
more than 30 elements, including Al, As, Cr, Fe, Mn, S,
Se, and Zn, by instrumental neutron activation analysis
(INAA). Particles on the other half of the filters were
dissolved and analyzed for Cu, Ni, and Pb,
simultaneously by inductively coupled plasma-atomic
emission spectrometry (ICP-AE), and for Cd by graphite
furnace atomic absorption spectrometry with Zeeman
background correction (GFAA-Z).
To determine activities from the decay of short-lived
nuclides, each filter portion was individually heat-sealed
in precleaned polyethylene film and irradiated along
with 1-mg Ni monitors for 10 minutes at a flux of
approximately 4.5 x 1013 n • cnv2* s'1 in theNBS research
reactor located at the National Institute for Standards
and Technology (NIST) in Gaithersburg, Maryland.
Spectra of y-rays emitted by the samples were collected
after decay periods of 5 and 15 minutes with intrinsic Ge
y-ray detectors with photopeak efficiencies rangingfrom
20 to 40% at an energy of 1332 kev. At least one week
after the first irradiation, the samples were repackaged
and irradiated a second time for 4-6 hours at a flux of
approximately 1 x 10" n • cnr2* s'1, and y-ray spectra
were collected for 4 and 12 hours after respective cooling
periods of 3 days and 3-5 weeks. Analytical sensitivities
were determined by irradiating prepared elemental
standards and checked for accuracy against NIST
Standard Reference Material (SRM) 1633A (Eastern
Coal). Spectral data were reduced on a personal
computer with the Ortec Ominigam analysis package,
which corrected count rates for pulse pileup, decay
during spectral acquisition, and decay after irradiation.
Multi-element standards for INAA were prepared from
NIST-certified standard solutions, except for elements
determined from short-lived activation products.
Standards for Al, Br, Ca, Cl, In, K, Mn, Na, and V were
madefromhigh-purity laboratory reagents. Calibrations
for S and Ti were made by irradiating accurately weighed
aliquots of the these elements in their elemental forms.
Forty-four samples, 6 laboratory blanks, and 4 field
blanks were analyzed for long-lived neutron activation
products using similar procedures at the substitute
Massachusetts Institute of Technology reactor.
Prior to analyses by the atomic spectroscopy techniques,
particles adhering to the filter portions were dissolved
in ultra-high purity ("Suprapur") acids under a clean-
air fume hood located in a laboratory Class-100 dean
room. Each filter portion was placed in a 50-ml Teflon-
covered Teflon beaker and leached overnight at room
temperature in a mixture of 6 ml of concentrated nitric
and 0.1 ml 40% hydrofluoric acids. After leaching, the
Teflon covers were removed and the samples allowed
to dry on a hot plate under low heat. The residues were
then dissolved in a mixture of 4 ml concentrated HNO3
and 0.2 ml 70% HC1O4, and refluxed for 24 hours, after
which the filter is removed and rinsed with a few drops
of concentrated HNO3. The resulting clear solutions
3-13
-------
Literature
Element
Al
As
Br
Cd
Cr
Cu
Fe
Mn
Ni
Pb
S
Se
V
Zn
•MIST certified
Unit
%
H9/9
ug/g
ug/g
ng/g
us/g
%
"£/g
ng/g
ng/g
%
w/g
ng/g
ng/g
value
SRM
1632A
1632A
1632A
1648
1632A
1648
1632A
1632A
1648
1648
1632A
1632A
1632A
1632A
Method
INAA
INAA
INAA
Zeeman-AA
INAA
ICP-AE
INAA
INAA
ICP-AE
ICP-AE
INAA
INAA
INAA
INAA
Cone.
2.95
9.3
41
75
34.3
609
1.11
28
82
6550
1.55
2.6
44
28
±
±
±
±
±
±
±
±
±
±
±
±
±
±
sigma
0.1
1 *
2
7 *
1.5 *
27 *
0.02 *
2
3 *
80 *
0.1
0.7 *
3 *
2 *
Avg
2.93
7.6
' 39
73
37
586
1.16
31
88
6397
This work
±
±
±
±
±
±
±
±
±
±
sigma
1.80
0.8
4
3
2
10
0.06
7
6
65
n
7
23
23
7
23
6
23
7
6
6
ND"
2.6
43
29
±
±
±
0.5
3
6
23
7
23
"ND = not detected
Table III.9. Concentrations of elements determined in NIST Standard Reference Materials.
were allowed to dry on the hot plate at high heat and
then reconstituted with 2 drops of concentrated HNO3.
These were transferred to 15-ml polyethylene bottles,
dried with an infrared lamp, and stored in the University
of Maryland - College Park dean room. Prior to analysis,
the residues were gravimetrically reconstituted by
dissolution and dilution to a volume of 3 ml with 2%
HNO3, Dissolutions were performed in batches of 24
samples along with two aliquots of the (NIST) SRM No.
1648, "Urban Particulate Material."
The ICP-AE analyses required approximately 2.5 ml of
each of the solutions, and the remaining 0.5-ml aliquots
were used to determine Cd by GFAA-Z. For both ICP-
AE and GFAA-Z analyses, prepared standard solutions
were aspirated into the instrument (ICP-AE: Jobin-
Yvon, model JY70-Plus; AA: Perkin Elmer, model 5000)
at the beginning and end of each analysis session and at
1.5-h intervals. At least two aliquots of SRM-1648 were
analyzed during each analysis period. The ICP-AE
instrument provided for three replicate measurements
of each sample and five replicate measurements for
prepared standards and SRMs. To prevent Cd vapor
fromescapingthe graphite furnace tube during heating,
a 0.8-ul aliquot of a 0.1 ug/ul solution of PdCNO^ in 6%
citric acid was added to the graphite tube and dried at
2450°C before injecting each sample. If two replicate
determinations differed by more than 5%, a third 15-ul
aliquot of the sample was analyzed.
Quality Assurance
Analytical integrity was maintained through the use of
prepared single and multi-elemental standards for
atomic and nuclear techniques, respectively, and by
frequent analyses of NIST-certified SRMs. Sensitivities
for INAA were derived from spectra for more than 25
multi-element standards and checked by analyzing
more than 30 aliquots of SRM 1633A. As shown in Table
III.9, results of the SRM analyses are in excellent
agreement with NIST certified and published results.
Results for additional elements determined by INAA
are listed in Appendix A2.2. Overall quality of the
resultant data is evaluated from estimates of the net
uncertainty for each reported value, through
3-14
-------
comparisons with other data sets, and through the
analysis and evaluation of laboratory and field blanks.
Estimation of Uncertainties. For INAA, the uncertainty
in the measurement depends mainly on counting
statistics, imprecision in positioning the samples and
flux monitors (geometry errors), spectral background,
and the sometimes substantial concentrations of the
various elements in the blank filter substrates. The
maximum relative uncertainty associated with
geometry, 1.7%, was estimated from the coefficient of
variation of the corrected count rates of 8 Ni flux
monitors. We assume that a similar uncertainty applies
to both flux monitors and standards, so that the total
uncertainty in geometry is 1.7 • V2%. An additional
uncertainty of approximately 1.5% arises for some
elements from corrections for coincidence error, when
samples are counted very close to the detector.
Uncertainties in prepared standards and detector
intercalibrations are approximately 5%. For ICP-AE
and GFAA-Z analyses, analytical uncertainties are
derived from the deviation of replicate measurements,
uncertainties in the calibration data, and uncertainties
in the analyses of filter and reagent blanks. All of these
uncertainties are reflected in the net reported uncertainty
Evaluation of Uncertainties in Blank Corrections. The
overall quality of the resultant data may be strongly
influenced by the magnitude of corrections for filter
and, where applicable, reagent blanks. Uncertainty
arising from variations in the substrate blank
concentrations are minimized when sample-to-blank
(S:B) ratios are sufficiently large. Sample-to-blank ratios
for Al, As, Fe, Mn, S, Se, Zn, V, and Br, were quite large,
averaging 54, 660, 70, 90, 360, 180, 70, 1400, and 270,
respectively. For these elements filter blank corrections
contributed less than 10% for over 96% of the
concentration values determined (see Appendices A2.3
and A2.4). Uncertainties in the filter blank correction
(SJ often contributed significantly to S^ for Cd, Cr, Cu,
Ni, and Pb, for which the S:B ratios averaged 9,7,6,23,
and 11, for both Elms and Wye data. The effect of S:B on
the measurement uncertainty depends on the analytical
precision, Sa (derived from uncertainties in counting
statistics, geometry, and preparation of standards), and
the uncertainty in the concentration of the various
elements in the blank filters, Sb, as shown below:
neuel
(5)
where n is the S:B ratio. In this work, Sas were < 10% for
all elements except S, for which Sa was typically 10 to
20%. As shown in Table in.10, Sb was often quite large
Laboratory blanks WFB1
ave siqma n mm max mass sioma
A! 282 ± 180 10 72 598 . 445 ± 27
As 0.09 ±006 4 <001 0.09 ; 048 ± 0.04
Br 0 94 ± 1 1 4 0.16 2 73 : 0.6 ± 05
Cd 1 46 ± 1 1 7 <1.0 38 2.02 ± 0.17
Cr 10 ± 13 4 1.62 23.3 j 8.4 ± 1.8
Cu 467 ± 181 10 18.2 76.5 ,564 ± 4.0
Ft 169 ± 2 2 145 193 <40
Mn 272 ± 1.3 8 <1.2 4.4 2.3 ± 0.1
Ni 185 ± 10.1 10 6 47.2 70
Pb 434 ± 24.7 7 21 87 ' 27
S 668 ± 727 3 <320 3050 '
Se 08 ± 0.5 1 083 0.83
V 0.25 ± 0.17 4 008 1.6 : 1.55 ± 0.1
Zn 16 ± 10 4 3.1 22.9 I 28 ± 8
Dates 6/26 - 7O90
Values without uncertainties are upper limits
WFB2
mass siqma
636 ± 39
0.52 ± 0.1
1 ± 0.6
1.53 ± 0.10
5.8 ± 22
67.0 t 4.0
<40
37 ± 02
31.9 ± 12
5.54
t.79 ±013
34 ± 8
tO/9- 16/90
WFB3
mass sloma
240 ± 15
0.08 ± 0.02
22 ± 01
2.11 ± 0.23
6.9 ± 0.4
63.1 ± 2.5
114 ± 19
1 12 ± 0.06
130
131
0.93 ± 0.1
13.9 ± 2
1/t-8/91
WFB4 EFB1 EFB2 EFB3
mass siqma mass siqma mass sioma mass siqma
25.4 ± 1.8 j 470 ± 29 589 ± 36 • 342 ± 21
!
i '
086 ± 0.12 j 0.54 ± 0.06 07 ± 01 005± 46
58 ± 0.3 ' 1.56 ± 042 0.84 ± 07 1.71 ±016
I
'139 ±011 679 ±073. 0.77 ±017
1.29 ± 044 I 7.2 ± 2 I 27.8 ± 1 1
52.0 ± 4.5 j 61.6 ± \2 52.3 ± 18 : 46.8 ± 1.5
I j
; 552 ± 115
18 ' 1.58 ± 0.07 5.94 ± 0.2 3 52 ± 02
160 415 ± 71 170 150
22.0 801 ± 7.05 30.9 52.2
[
490 ± 327 ,
0.79 ± 049 !
.
NA ! 1.59 ± 0.12 1.39 ± 01 '. 10.0 ± 0.6
2.28 ± 1.15 i 120 ± 16 1140 ± 120 • 161 ± 35
45-9/91 ' 6/20- 26/90 ' 10/16-23/90 ' 1/22-29/91
EFB4
mass sioma
153 ± 10
001 ± 094
0.200 ±005
096 ± 002
2.1 ± 0.5
40 8 ± 2.0
121 ± 33
29
190
26
0 65 ± 0.07
146 ± 2
4/9- 16/91
Table 111.10. Comparison of laboratory and field blanks, ng/filter.
3-15
-------
for Cd, Cr, Cu, Ni, and Pb, and Sb contributed
significantly to S ^ which generally resulted in net
uncertainties that were substantially larger than those
obtained for the other elements. For these elements, the
percentages of values for which S^ ^ was < 20%, were
79,36,80,71, and 84%, respectively.
Evaluation of Field Blanks. Concentrations of elements
in laboratory and field blanks are compared in Table
ffl.10. Results for the four field blanks collected at Wye
fell within the range of those for laboratory blanks as
did most of the results for Elms. Exceptions were Cd in
Elms field blank #2 (EFB2), for which the measured
mass was approximately twofold larger than the
maximum laboratory blank; Zn in EFB1 and EFB2 (5-
and 50-fold larger); and V in EFB3, (6-fold larger).
Because me field blanks were exposed to the atmosphere
for the entire week, some passive aerosol collection is
likely. Therefore, elevated levels in field blanks do not
necessarily imply contamination. For V, an element for
which the sample-to-blank (S:B) ratios exceeded 260 in
every case, contamination at the level observed in EFB3
is inconsequential. The value for Zn in EFB2, however,
is equivalent to an atmospheric concentration of 16
ng»nr3 (Le., if a normal sample had been aspirated), a
value larger than the average annual concentration for
this element at either Elms or Wye. It must, therefore, be
attributed to contamination. Field blank EFB2 was run
along side sample E21, for which the Zn concentration
was 7.89 ng«m~3. The amount of Cd observed in EFB2
is equivalent to an atmospheric concentration of
0.08 ng«nr3, a value comparable to 0.13 ng»nr3, the
average Cd concentration at Elms. Despite the spector
of sporadic contamination for Cd and Zn at Elms, the
good agreement between their average concentrations
and those at Wye suggests that the Elms data set was not
widely affected.
Trace Elements in Precipitation
Sampling
Weekly integrated samples were collected every
Tuesday, coincidental with ongoing NADP (Wye) and
State of Maryland (Elms) acid rain/major ions
precipitation sampling. Trace element "clean" protocols
were followed by the on-site operators (see Appendix
A.3). At the Wye site, due to the lack of an available
clean bench, only steps 1-6 of the collection procedure
were conducted on site. The sample buckets with lids
were sealed in plastic bags and frozen in a trace metals
dedicated freezer on site pending retrieval and
processing at the University of Delaware laboratory. At
the Elms site, all sample processing was conducted at
the Chesapeake Biological Laboratory under a Class
100 dean bench. The laboratory at the University of
Delaware provided site supplies (e.g., acid-cleaned
collection buckets and bottles, ultra-high purity acid,
disposable gloves) to the site.
Precipitation was sampled using a commercially
available, automated, wet-only collector that was
specially modified for trace metals sampling (Aerochem
Metrics, Inc., Bushnell, FL 33143). Details of collection,
sample processing, and analysis can be found in
Tramontane et al. (1987) and Scudlark et al. (1992).
Briefly, this involves collection in an acid-washed clear
HOPE bucket, acidification with ultra-high purity HC1
(to 0.4% v/v), followed by partitioning after a 24-hour
desorption period into acid-washed LDPE sample
bottles. Samples were stored frozen until analysis.
Refer to Appendix A.3 for specific sample collection
protocols employed by the CBADS operators.
Sampling was initiated at the Wye site on 17 April 1990,
and at the Elms site on 5 June 1990. However, due to a
persistent sampler malfunction, for practical purposes
the data record at the Wye site did not commence until
5 July 1990. This report covers all sampling through 2
July 1991. Collected during the 13 months of sampling
at the Elms site were 44 precipitation samples, 8 field
blanks (weekly samples with no measurable
precipitation), and 4 samples not analyzed for various
reasons (3 insufficient sample volume, 1 operator error).
At the Wye site, the 12-month record yielded 44
precipitation samples, 5 field blanks, and 3 samples
with insufficient volume to analyze.
During the study period, 88 discrete precipitation events
were recorded at the Wye site (averaging 6.7 events/
month) and 108 events at the Elms site (averaging
7.7 events/month). The recorded precipitation amount
averaged 7.5 on/month at the Wye site (which equals
90 on/year) and 9.7 cm/month at the Elms site (116 cm/
3-16
-------
yr). The 12-month total precipitation at Elms was about
19% higher than the long-term annual average for this
site, while the total at Wye was about 8% below the
average of the past 7 years (M. Newell, personal
communication). The number of events and
precipitation amount at each site is summarized on a
monthly basis in Figure HI.?.
1
10-
6-
16-
10-
6-
impi
em pi
|— |
Jin
no*
•^
Jul
WO*
|—
Jul
I
tatt
•**;
Aug
Itett
A
/
AttC
ZD
KB and i
Vr
1!
6^pO
en end
Ar
^i
n
*wo
MO
Main An
muter
O
(1
et Me*
mmtoer
V
\S
n
otto*
own In
w
»f «
A
\
Beo
Elr
H«
Dee
«n
ye
•M
-
s/
Jn
ns
Milt
A
Ju
^
ft
/I
Fe*l
B
\
n
Feb
•-Nil"
V
Mv
MM
ibei
^
Apr
mi
-A
Apr
•Mai
ell
\
n
M«y
V
M«y
hMftti
n
Jun
r
Jim
r- 1
Jul
Jul
Figure 111.7. Monthly summary of precipitation amount (cm) and
number of events at two Maryland CBADS sites for 6/90 - 7/91.
Ana/yses
To remove trace element contamination introduced via
manufacture and / or prior use, all plasticware (collection
buckets and sample bottles) were rigorously cleaned.
This cleaning involved successive leaching in acids of
varying composition and strength (see Appendix A.3).
Ultra-pure ASTM Type I (18 megohm/cm) rinse water
(Millipore Milli-Q) was used for all sample processing
and cleaning (subsequently referred to as Q-H2O). The
highest grade double quartz-redistilled HC1 (Qz-HCl)
was used for sample acidification, analysis, and
processing, which included a final "polishing" leach in
the cleaning procedure. Analytical standards are
prepared gravimetrically from certified standards,
which were prepared in turn from pure metal dissolution
(SPEX Industries, Inc.). All other reagents were of at
least ACS quality. Every sample was carefully processed
under a class 100 clean bench, in a dedicated clean room.
Precipitation samples were analyzed for Al, Cd, Cu, Cr,
Fe, Mn, Ni, Pb, and Zn using a Perkin Elmer 110O-B
Atomic Absorption Spectrophotometer, equipped with
a 700 HGA graphite furnace (GFAA). This instrument
was also equipped with deuterium background
correction, and a L'vov platform is utilized to minimize
matrix (salt) suppression by delaying atomization. For
Al analysis, due to acidification with HC1, the char/ash
step is limited to 170°C to prevent volatilization of A1C1,
(b.p. 185°C). Citric acid was used as a matrix modifier
for Al and Fe to increase analytical sensitivity. The
standard analyte injection was 60 ul for all elements
except for Zn (10 ul). Multiple injections were used for
Cd, Cr, Ni and Pb, increasing the volume of analyte to
120-180 nlandthusaugmentingthesensitivity2-3 times.
GFAA calibration curves included an analytical blank
and at least three standards. The accuracy of the
calibration curve was confirmed by an EPA or NIST
reference standard (see Quality Assurance Program
discussion ). Replicate samples were run on separate
days to verify true analytical reproducibility (which
included, but was not limited to, instrument
reproducibility). Reproducibility of less than 10%
variation was deemed acceptable.
The trace elements As and Se were present in
precipitation at concentrations significantly lower than
the detection limits of commercially available hydride /
AA systems. Accurate quantification of these elements
required the application of recently developed analytical
methods (Cutter, 1986; Cutter et al., 1991). Methods for
both As and Se involved hydride generation,
preconcentration by cryogenic trapping, and selective
volatilization. Arsenic was analyzed using gas
chromatography-photoionization detection; Se analyses
utilized an air/hydrogen quartz burner and atomic
absorption detection. Larger analytical volume
requirements limited metalloid analysis to precipitation
samples greater than 400 mis (ca. 0.6 cm precipitation).
3-17
-------
Standard curves for the metalloid analyses included a
blank and at least four standards. Large-volume events
(about 30% of all analyses) were analyzed by the method
of standard additions. Samples were run at least in
triplicate, and 5-10% of the samples were replicated on
a second day to establish reproducibility. The calibration
curve was verified utilizing certified reference solutions
(see the following Quality Assurance Program section).
Employing the above methodology, we conservatively
estimate our analytical detection limits (D.L.=3X std.
deviation of analytical blank) cited in Table ITL11.
Al
As
Cd
Cr
Cu
0.12
0.007
0.006
0.10
0.12
Fe
Mn
Ni
Pb
Se
Zn
0.05
0.10
0.12
0.12
0.009
0.14
Table 111.11. Analytical detection limits (ng/L) for determination of
trace elements in precipitation.
Quality Assurance Program
Recent reviews of the historical data on the concentration
of trace elements in precipitation (Galloway et al., 1982;
Barrie et al., 1987) cast considerable doubt on the
reliability of previously reported values or the efficacy
of the collection and analysis techniques utilized. In
many of these studies, it was apparent that the authors
failed to observe proper sampling and handling
precautions, resulting in either gross contamination, or
conversely, irreversible adsorptive losses of certain
metals to container walls. Based on more than 15 years
of experience in precipitation sampling and analysis, it
was our conviction that strict adherence to a rigorous
quality assurance program was essential to establish
and maintain data accuracy.
Our QA program encompassed all components of this
study, from the initial site selection to final data
validation. Essential elements of our QA program
were:
a) conducting and evaluating operational blanks on a
regular basis,
b) use of externally certified analytical reference
solutions,
c) intra-laboratory analytical comparisons using
redundant analytical methods (GFAA and ICP-
AE),
d) inter-laboratory analytical comparisons, and
e) cross-checks on collection efficiency.
Operational Blanks. Most contamination associated
with accurately quantifying the trace elements in
precipitation was associated with field deployment and
sampling (see Figure m.9). Thus, conducting and
evaluating operational blanks on a regular basis was the
most critical component in our QA Program.
Three types of additive, diagnostic operative blanks
were routinely conducted - a field blank, laboratory
blank, and process blank. Data from these blanks were
interpreted both quantitatively, to accurately determine
the background trace element contribution from
materials and methods, and qualitatively, to identify
and remedy any source of severe contamination.
The process blank was 500 mL of Q-H2O in a sample
storage bottle, to which was been added 2.0 mL of Qz-
HC1 (i.e., 0.4% v/v, identical ratio as samples). The
process blank was a measure of the trace element
contribution from the water, acid, leaching from the
storage bottle, and analytical procedures. The laboratory
blank was 500 mL of Q-H^O poured into a clean bucket
under a dean bench, acidified, and processed as a
precipitation sample. The laboratory blank gauges
trace element input from all sources included in the
process blank, as well as metal leached from the collector
bucket or contributed from airborne dust during the
additional steps. The field blank was conducted
identically to the laboratory blank, except for use of a
bucket that was previously deployed in the collector for
a weekly interval without rain. In addition to the
sources included in the laboratory blank, the field blank
will indicate problems with site handling and with
possible contamination in the field from the input of
fugitive dust to the sample bucket during transport,
deployment, and recovery. Usually, the entire suite of
blanks were done with every field blank; however, the
laboratory blank and process blank were run at least
3-18
-------
nMoles
1003
10E
0.1 =
0.01
Al Cd Cu Fe Mn Pb Zn Cr
Ni
Elms Site (8)
Wye (14) CH Lewes (11)
Figure III.8. Comparison of absolute wet deposition field blank (n moles) at two CBADS sites with that at the Lewes, Delaware base station.
bimonthly or if there was a significant change in methods,
reagents (new batch of acid), or personnel (new or
substitute operator). Because the Wye samples were
processed at Lewes, Delaware, the Wye laboratory blank
and process blank were conducted at Lewes as well.
The field blank provided the most comprehensive
representation of actual sample collection and
processing. As an assessment of site suitability and
operator proficiency, we compared the absolute field
blank contributions at the two CBADS sites with those
measured at our Lewes, Delaware, site using identical
protocols (Figure ffi.8).
At Lewes, sampling with a more experienced operator
and with access to clean room facilities for sample
processing, the blank levels were consistently lower.
The field blank levels at the two CBADS sites were
comparable and do not indicate any severe
contamination problem. Noteworthy were the
somewhat lower blank levels of the crustal tracers Al
and Fe at the Wye site (initial concerns existed about the
potential for high soil resuspension and potential
contamination associated with fanning practices on the
grounds of the agricultural research station where the
Wye site is located). The field blank concentrations for
As and Se at both sites were consistently below our
instrumental detection limits and were not presented
graphically.
A comparison of the laboratory blanks with field blanks
at both sites (Figure ni.9) revealed that almost all of the
blank contribution was associated with field
deployment. This included the inadvertent capture of
3-19
-------
Wye Site
Elms Site
60%
Cd Cr Cu F« Un HI
Ml
Figure 111.9. Comparison of relative wet deposition field blank
and lab blank contributions to levels at two CBADS sites.
fugitive dust during bucket deployment/recovery, as
well as passive aerosol input associated with high winds
during non-precipitating periods. For the most part,
materials and reagents provided a consistently minor
contribution to the blank levels.
The most critical evaluation was the relative field blank
contribution to precipitation (Figure D110). Because the
As and Se concentrations in the field blanks were
consistently at or below analytical detection limits, their
detection limits were employed to establish an upper limit
for the field blank contribution in this figure. Generally,
the trace element blank levels did not indicate any
contamination problems associated with sampling (our
"target" level is less than 10%, which was our approximate
upper limit of analytical confidence). Although the field
blank contributions of Cd, Cu, Ni, and Zn at Wye were
marginal in this regard, we did not feel this presented a
significant concern because the absolute field blank levels
at Wye (Figure HL8) were consistent with the Elms site.
Thus,itwaspossibletoutilizetheblanks only qualitatively
for diagnostic purposes.
16% -T
Al As* Cd Cr Cu Fc Mn Ni Pb Se* Zn
Wye
Elms
Figure 111.10. Field blank contribution to precipitation samples [(n moles in average FB *• n moles in average sample) x 100%], at two CBADS
sites.
3-20
-------
SRM1643C
(Trace Elements in Water)
Certified Experimental
Al
As
Cd
Cr
Cu
Fe
Mn
Ni
Pb
Se
Zn
[Note:
Value
114.6
12.2
22.3
106.9
35.1
73.9
±STD Value
±5.1 116.0
±1.0 11.7
±2.8 22.8
±3.0 108.3
±2.2 37.3
iO.9 73.8
±STD
±3.0
±0.6
±1.1
±1.0
±1.2
40.5
Reference solutions were diluted daily
EPAWP386 EPATMA989
(Trace Metals I) (Trace Metals 0
Certified Experimental Certified Experimental
Value
500
25
100
100
100
100
100
100
100
to the
+STD
±50
±1.97
±10.20
±6.20
±8.78
±5.79
±7.89
±8.40
±7.36
Value
503.4
22.5
84.5
102.4
109.
98.0
81.8
98.2
100.9
±STD Value jSTD Value ±STD
±13.6
50.0 ±5.34 49.3 ±10.4
±1.31
±5.73
±17.2
±22.4
46.11
±13.0
j€.59
50.0 ±4.86 50.8 ±11.78
±11.13
appropriate concentrations for
precipitation analysis.]
Table 111.12. Results of quality control check solutions for trace element wet deposition.
Reference Solutions. Externally certified reference
samples were regularly included in analytical sessions
only to verify the accuracy of the calibration curve (see
Table in.12). These quality assurance samples included
NBS (NIST) SRM1643-B, Trace Elements in Water; EPA
WP386, Trace Metals I; EPA TMA989, Metals in Water:
AA method; EPA WP988, Metals in Water: ICP method.
In some instances, the reference solutions were diluted
with Q-H^O to more accurately reflect precipitation
concentrations.
Intra-Laboratory Analytical Comparisons. To verify
the accuracy of the GFAA analyses, selected samples
were analyzed by Inductively-Coupled Plasma Atomic
Emission Spectroscopy (ICP-AE) using an Instruments
SA/Jobin-Yvon-70 Plus ICP. For Al, Fe, Mn and Zn, low
instrumental detection limits coupled with
comparatively high precipitation concentrations
allowed for cross-checking analyses by both methods
without preconcentration (Jickells et al, 1992).
Inter-Laboratory Analytical Comparison. As another
independent check on the accuracy of our analyses,
selected samples from the Wye, Elms, and Haven Beach
CBADS sites were analyzed by the University of
Delaware and Old Dominion University (Dr. G. Cutter),
who is also responsible for reciprocal precipitation trace
element collection and analyses at the Haven Beach
CBADS site in Virginia. These results were sponsored
by the EPA under Year 2 of the study and will be
reported elsewhere.
Precipitation Collection Efficiency. The accuracy of the
wet deposition calculation depends equally on the
accuracy of trace element concentrations as well as the
corresponding precipitation amount. Precipitation
amount at each site was determined gravimetrically
using a Belf ort continuously recording rain gauge, with
an approximate resolution of 0.01" precipitation.
To verify the accuracy of the Belf ort precipitation gauge
and to establish the collection efficiency of the
Aerochematrics collector, the gauge reading was
compared to the precipitation volume collected. This
comparison (Figure IEI.11) revealed generally good
agreement between the predicted and actual
precipitation amount. In about 10% of the cases,
however, the precipitation gauge reading was found to
be inconsistent with the sample volume collected. In
these cases, the larger of the two values was employed
3-21
-------
WYE Site
MM
5.MO
«.OM
2.M*
MM
• 15 1 U *
G*0f« (iDClM*)
ELMS Site
7.M«
(•It)
IMt
4,«M
S.IM
I.MO
111
Gut* (Ine^M)
for deposition calculations. Overall collection efficiency
of the ACM collector was determined to be > 95% at
both sites, which included samples not analyzable due
to insufficient volume, collector malfunction, and
operator error.
Figure 111.11. Comparison of rain gauge (inches) with collected
precipitation volume (ml) at two CBADS sites.
3-22
-------
SECTION IV
RESULTS AND DISCUSSION
Organic Contaminants
Atmospheric Concentrations
Concentrations of organic contaminants measured in
the atmosphere at the Elms site were reported in Fig-
ures IV.l through IV.22. The PAHs were arranged in
order of decreasing vapor pressure and for each com-
pound the vapor/aerosol distribution is shown. As a
general observation, there was substantial temporal
variability throughout the year for all compounds. For
example, the phenanthrene concentration in week 24 of
1990 (Le., mid-June) was twice as high the following
period. Benzo[a]anthracene and chrysene were both
about 3 to 10 times higher, respectively, in week 24 than
in week 26, and indeno[123-of]pyrene decreased from
150 pg»nv3 in week 30,1990 to <3 pg«m'3 the following
period. Highly variable atmospheric concentrations
are not unexpected because the atmospheric inventory
depends upon many factors. These include emission
strengths, air mass type and source, and recent precipi-
tation events all of which change over relatively short
time spans. Mean concentrations of PAHs and total
PCBs (t-PCB = 176 congeners) in the atmosphere are
listed in Table IV.l. Compound-specific PAH concen-
trations vary from 14 to 2100 pg»nr3 over the one year
period. T-PCB concentrations range from about 0.05 to
1 ng»m'3 (Figure IV.15). Atmospheric concentrations of
t-PCB and phenanthrene co-vary closely throughout
the year (Figure IV.23). Both PCBs and phenanthrene
exist primarily in me vapor phase due to their relatively
high vapor pressures. The total atmospheric PCB con-
centrations were dominated by the more volatile di-
and trichlorobiphenyls, as shown in the congener ho-
molog plots (Figures IV.16-22). The dominant vapor
phase congeners in the dichlorobiphenyl group are the
Polycyclic
Aromatic Mean
Hydrocarbon Concentration
Ruorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo [a] anthracene
Chrysene
Benzo [b] fluoranthene
Benzo [k] fluoranthene
Benzo [e] pyrene
Benzo [a] pyrene
Indeno [123-cd] pyrene
Dibenz [ah} anthracene
Benzo [ghi] perylene
Total PCBs***
"number of samples
***76 congeners
(pg/m3)
708.0
2101.6
55.6
457.5
475.4
50.0
110.5
126.9
72.0
82.6
39.0
73.2
14.1
77.9
329.9
Range
% Paniculate
Minimum Maximum
N**
(pg/m3)
110.7
737.5
0.0
46.9
34.4
0.0
18.4
3.2
0.9
0.0
0.0
1.1
0.1
2.2
34.0
2724.5
5692.2
181.3
2274.9
1502.6
152.8
537.5
463.8
214.1
325.5
162.1
304.5
58.9
242.7
953.0
0.2
0.3
0.7
1.0
0.8
15.1
7.1
8.8
16.1
17.7
15.0
7.3
6.0
12.4
N/A
23
23
100
100
100
100
100
100
100
100
100
100
100
100
N/A
21
21
21
21
21
21
21
21
21
21
21
21
21
21
21
Table IV.L Mean total (vapor + particulate) concentrations of polycyclic aromatic hydrocarbons and total polychtorinated biphenyls,
Chesapeake Bay, 1990-1991.
4-1
-------
3000
2500
2000
- | | cerc-soi
2 1 500
o
~c
u
c
o
o
1000
500
Fluorene
Elms,199C
c
o
o
c
o
o
,,,.
JUVJU
2500
2000
1500
1000
500
-
-
-
i i i i i i i
-
-.ucrene
E'ms,i9Sl
•I v~pcr
i ce^oscl
-
-
£ —
•
I---I II. 1
15 20 25 30
Julicn Week
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = not detected on finer
* = lost vapor sample
" = lost paniculate sample
50
Figure IV. 1. Fluorene concentrations in air collected at the Elms site.
4-2
-------
6COO
5000 -
E
4000
c
.2 3000
o
c
0
0
2000
1 000
0
6000
5000 -
4000 -
.2 3000
2000 -
o
c
c
0
Pher.cr.thre'i
Elms,l9SC
•• vGDcr
j cercs
-
-
-
'
II 1 1 1 1 t 1
Elms. 1991
IHI vcpor
i i cercsoi
i
n
I
F
•
-
*
1C '5 IJ 25 30 35 ^0 *5 50
Julicr Week
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = no? detected on filter
= lost vapor sample
" = lost particulate sample
Figure IV.2. Phenanthrene concentrations in air collected at the Elms site.
4-3
-------
200
175
"V -zl
CL 125
C
.2 "'00
~D
~c 75
Q)
U
o
25
200
175
"E 15Ci
c
.2 ' oo
D
"c ~5
CD
O
O
25
A-.throcene
E:rr,s,1990
I i aerosol
- 2
_ _
-
n
r iiili ill /
i ' • ' j ....,....,-• , . . . , . . . , ' • i • | • • • ^
< i 1 1 1 1 1 t 1
Ar.i~rccer,e
Elir.s,1S9'i
•H vcpc'
; '~ "^ -
n 1
I Bn n I I n
1 ' ' 1 ' ' ' J ' ' ' 1 ' ' ' t 1 i ; |
5 10 15 20 25 30 35 40 ±5 53
Julicr. Week
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = not detected on filter
* = lost vapor sample
" = lost partculate sample
Figure IV.3. Anthracene concentrations in air collected at the Elms site.
4-4
-------
3000
^-v 250°
"E
^ 2000
CL
.0 1 500
~o
S 1000
o
c
o
° 500
3000
^ 2500
"E
x.
oi 2000
D.
.0 1500
~D
£ 1000
r*
o
° 500
Fluorcnthene
- Eims.1990
! | ceres ci
I ' i • ' i • - ' i
l i i i
-
_
-
n
S D | | I i :. |
1 ' 1 ' ( .......
5 10 i5 20
-
-
_
l.,il ,n , 1 1 1 i
i i i • i i
Fluorcnthene
Elms, 1991
[ | ceroscl
1
il.
25 30 35 40 ^5 50
Julion Week
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = not detected on filter
= lost vapor sample
" = lost paniculate sample
Figure IV.4. Fluoranthene concentrations in air collected at the Elms site.
4-5
-------
7SOO
£. *J\J\J
^ 2000
__J
cr>
c
^ 1500
c
0
"o
y
•£ 1000
QJ
O
C
o
0 500
25
^ 2000
i
X.
^^
en
c
^ 'i 500
c
o
"D
^ 1000
o
c
o
0 500
Pyrene
El rir-i ** * C C ^*'
1 1 . i 5 , • *^ —> w
[ j cercscl
- _
_
-i
n n
nO fi 1C
,,ll 1 1 1 1 1 1
' ' • ' 1 " 1 ' 1 ' ' ' 1 ' " ' 1 ' ' ' 1 ' ' ' 1 ' 1 ' ' 1 ' * ' ' '
1 J . 1 1 i . 1 i
Elms, 1991
HH vopcr
1 | cerosc'
"
- _
-
1_
11
1C 15 20 25 30
Julior. Week
1 = not quantifiable in vapor phase
2 = not quantifiable on fitter
3 = not detected in vapor phase
4 = not detected on filter
" = lost vapor sample
•• = lost particulate sample
40
Figure IV.5. Pyrene concentrations in air collected biweekly at the Elms site.
4-6
-------
250
£~* 200
E
en
-3 150
c
0
"o
_b 100
c
o
c
o
O 50
n
u
250
— 200
E
en
^3 150
c
O
D
_b 100
c
o
c
o
O 50
n
1
1 '
1
'
•
'
1
1
Benz[cjcntnrccene
Eims,199C
Hi vcpcr
-
| | cercso!
n
3
3
^
^
j
VI
0
i I
•
r
1
•
-
-
-
•
1 ' ' ' ' ' ' ' ' '
t j
i i
i
1
1
5enz[o
_
C"
L,
•1
Ims.l
^^•H
i
janthrccene
S91
HH vapor
i | aerosol
-
n -
-
i
i .
n i !
I
5 10
•j
7
p - 3
1 D M " n
15 20
•;
p
25
Julian W
m
n
30
eek
"v
5 40 45
p .
50
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = not detected on filter
• = lost vapor sample
" = lost partculate sample
Figure IV.6. Benz[a]anthracene concentrations in air collected biweekly at the Elms site.
4-7
-------
600
500 -
§? 400
•=, 300 -
8 200
c
o
o
TOO
Chrysene
Elms,1990
j | oerosol
600
500 -
400
c
:§ 300
D
i_
§ 200
c
o
o
TOO
I .I-
n
"fl n
• U ! i
Aim
Chrysene
Elms. 1991
I | aerosol
n n
ill
10
I D
1
2
3
4
25
30
45 50
Julicr. Week
not quantifiable in vapor phase
not quantifiable on filter
not detected in vapor phase
not detected on filter
lost vapor sample
lost particulate sample
Figure IV.7. Chrysene concentrations in air collected biweekly at the Elms site.
4-8
-------
-
450
t^T* 4°°
E
\ 350
"X^ ••'**' \*
C7"^
>3 300
c
.0 250
"o
i 200
c
CD
u 150
c
o
0 TOO
50
450
^T 40°
E
\ 350
en
-3 300
c
.0 250
~o
±: 200
c
o
u 1 oO
c
o
O "' 00
50
it i , l I * l ii
" Benzo[b]fluoronthene
. Elms.1S90
m vcpcr
.— —. -
\ i cercsol
-
-
-
n "
r -
1'
-1
3 •; 1
^ _
_.n I3i '\ _ m 1
, , . , , . , , . , . , . , . . , . .
Benzo[b]flucronthene
Elms.l'gSI
IHI vcpcr
| j cerosoi
rT -
3
- n
P
-
-
P
-
i i *-
i 3 n 3 4 . .
D _ i 1 n II -n 3 n n
5 10 15 20 25' 50 35 40 45 50
Julian Week
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = not detected on filter
* = lost vapor sample
" = lost paniculate sample
Figure IV.8. Benzo[b)fluoranthene concentrations in air coflected biweekly at the Elms site.
4-9
-------
250
r-i
E
^ 200
D.
.0 150
~o
0 100
c
o
0 50
x-v 25°
E
^ 200
Q.
.0 150
o
0 TOO
o
c
c
° 50
1 I ! j i i i l 1 i
Benzofkjflucrcnthene
- Elms, 1990
| | cercso r
3
\ P
i ! *
n
i
n n3
in J5, Jl' Q L .
i i i i i i • i it
Berzo[k]fluoronthene
Elrr.5,1991
3 •• vapor
| aerosol
3
_
l
i 3
- J T
' ^ n « 3 •
D I n 1 1 " H n n
5 10 15 20 25 5C 35 40 45 50
Julian Week
1 = not quantifiable in vapor phase
2 = not quantifiable on finer
3 = not detected in vapor phase
4 = not detected on filter
• = lost vapor sample
** = lost paniculate sample
Figure IV.9. Benzo[k]fluoranthene concentrations in air collected biweekly at the Elms site.
4-10
-------
A no
350
"p 300
(7>
vS 25°
.0 200
D
•£ 150
0
0
O
50
^•00
550
•o
£ 500
.
jx 250
.0 200
o
•£ 150
-------
-.en
£. ^J\J
^T 200
F
r\
v3 150
c
.2
"o
_b 100
c
Q)
O
C
o
O 50
Eenzo[o]pyrene
Elms, 1990
^^^_
^^^H vooor
I | cerosoi
~ ..
n P^
1
n
3 j
L H3 Ii 3
,....,.... i . i . . i . , .
100
•-5
E 75
O>
O.
c
•J 50
~o
"c
cu
o
0 25
o
ii i i i i
3
~
3
"i
_
J
-
3 n •
z n .-. 3 (In
1 ' 1 ...,,.,..,.... ( . , . ,
5 10 15 20 25 JO
Juiion \'\'ee*
_
_
~l
-
-
-
_ 3
n 3 3
Ml n . (1 n 2
i ...... i .... i . .
i i i i
3enzo[o]pyrene
Elms. 1991
•• vopor
! | oerosol
1 *
i ...... j . , . ( . .
55 40 45 50
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = not detected on filter
• = lost vapor sample
•* = lost paniculate sample
Figure IV.11. Benzo[a]pyrene concentrations in air collected at the Elms site.
4-12
-------
400
350
n£ 300
cr>
s3 25°
c
.2 200
o
i_
•^ 150
0
0
§ 100
O
50
lnoeno[l ,2.3— cdlpyrene
Elms.1990
Hi vopcr
I I oercsol
3 ^
_ S-?
33 If? 4
nnli! 3
400
350
s~^
"g 300
^
v3 25°
r-
.2 200
"o
•£ 150
o>
o
o
0
50
i i i i ; \
• i i
3
3
, n
4 ns h 3
• • T * • • i • — • i • • •
i i i
»
~
•
-
_
-
-
j>
r
i
i •
i
_
inc:eno[' ,2,3 — cdjpyrene -
•: Elms, 1231
3 j^ -^
• vcoor
I I ce'-osol
~
-
~
-
3
-
3
8 Ufi:-n Un
ii i i i i
5 -0 15 20 25 30
Julian Week
• ' • i • i ' • • • i • • —
35 40 45
i
50
1 = not quantifiable in vapor phase
2 = not quantifiable on finer
3 = not detected in vapor phase
4 = not detected on filter
• = lost vapor sample
" = lost partculate sample
Figure IV.12. lndeno[1,2,3-cd]pyrene concentrations in air collected at the Elms site.
4-13
-------
70
/ w
s "*• O w
"E
"o! 50
CL
C 40
O
~o
i 30
c
Q)
O
c 20
o
O
1C
70
~ 60
E
^ 50
o.
c 40
O
"o
_b 30
c
c 20
o
O
10
lit..
Dibenz[o,h]cnthrocene
Elms, 1990
|H| vapor
| | ceroso
_
s5
3
ri
n
........... i .. ...... ( ..
i i i i i
_
-
3
_ r
P
-
_
2
n
3 444^4
p 3 3 " 3 3 3
- j . . , . ( . . , . | . . | ' ' '1
5 10 15 20 25
i i i i i
_
_
3
r
*
i
r -
i! 3
3 n
n n -
44 4 4 4 4 j jj
3 3 ,,3 3 3 3 : jj
•!•••• | •••• 1 ••••,-••• I ••
1 1 1 I t
Dibenz[c,h]anthrocene
Elms, i 99 i"
HI vapor
I | aerosol
4
X
..,...,,. j , . ( . . (
30 35 40 45 50
Julian Week
1 = not quantifiable in vapor phase
2 = not quantifiable on filter
3 = not detected in vapor phase
4 = not detected on filter
= lost vapor sample
" = lost paniculate sample
Figure IV. 13. Dibenz(a,h]anthracene concentrations in air collected at the Elms site.
4-14
-------
300
250
"E
^ 200
c.
.2 150
"o
o 100
o
c
o
50
300
^ 250
"E
"oi 200
Q.
.2 1 50
D
~~ i P^
CU 1 uu
U
C
0
° 50
6enzo[g,h, ]peryiene
_ Elms, 1990
I | oerosol
iiii
3
3
3
nHlf! 3
"
3
r
i
1
3
1
_
4
K»5
3 !
-
-
m
?
i
i i i i i i i i i
i t
3
n
3
3
3
n
5 10
'
1
5
1
5
3
Ufi
20
1 t
Benzo[g,h,i]Derylene
Elms, '991 "
i cercsol • _
4
• i • • i i i '
25 30 35 40 t.
5
50
Julion \Veek
1
2
3
4
= not quantifiable in vapor phase
= not quantifiable on filer
= not detected in vapor phase
= not detected on filter
* = lost vapor sample
" = lost paniculate sample
Figure IV.14. Benzo[g,h,i]perylene concentrations in air collected at the Elms site.
4-15
-------
CD
C
c
o
0.5 -
0.6
±i 0.4
c
cu
u
c
o
0.2
Tote! PCBs
Elms,1990
| | pcrticulc:
0.5 -
0.5
c
o
D
r ° ~
5
u
c
o
O 0.2
5 10 15
Totoi PCBs
Elms, 1991
pcrticuicte
25 30
Julier. Week
lost sample
45
50
Figure IV.15. Total PCB concentrations in air collected biweekly at the Elms site.
4-16
-------
c
o
700
600
500
400
P 300
O
CJ
200
TOO
700
c
O
600 -
500
400
2 300
r;
O
O
o
200
i 00
Totol Dicnlcrotiphenyis
Elms, 1990
vcocr
ioici Dichiorobiphenyis
E!nr,s,199l
20 25 30
J'jiicn Week
= kDSt vapor sample
Figure IV.16. Total dichlorobiphenyl concentrations in air collected biweekly at the Elms site.
4-17
-------
50 -
c 60 -
o
"o
c
o
o
o
50 -
50 -
60 -
o
o
V—
c
c
o
50 -
' •
1
lotol Trichlcrczipr.c
1
1 '
'ill
ny s
_ E!ms,i99C
-
-
1
mi
_
-
-
i . • . , • • i • • • • i i • • i
i i
1
1 '
iii.
~otcl Trichlorcoipheny s
Elms, 1991
-
-
1 .
5 'i 0
•
1
5
23
25 50
vcpor
-
55 40 45 £C
lost vapor sample
Figure 1V.17. Tola) trichlorobiphenyl concentrations in air collected biweekly at the Elms site.
4-18
-------
250 -
£ 200 -
C7>
c.
o
~6
150
<- 100
o
c
o
o
50
250 -
t 200
c 150
o
c 100
o
o
<-> 50
T o ? .^( \ &* rr**r
I W h ^» I l^k-WW
Elrris,1990
•• VCCCr
U
: u
"6ifoch!crobipheny!s
'rr,s,199"
JH VCpCT
10
20
^5 50
lost vapor sample
Figure IV.18. Total tetrachlorobiphenyl concentrations in air collected biweekly at the Elms site.
4-19
-------
100
D.
c
o
0
o
c
o
o
50
Totoi Perucchicrccipher.y's
Elms,1990
•• vcocr
TOO -
CL
C
O
c
CD
O
£
O
o
50
"otcl Per.tochlorobiphenyls
~ ,-cj <; 1991
BB vcoor
50
lost vapor sample
Figure IV.19. Total pentachlorobiphenyl concentrations in air collected biweekly at the Elms site.
4-20
-------
90
60
70
60
^
CL
7
_o
~o
5 30
o
6 2C
10
90
60
^ 70
E
"^ 60
c 50
_o
o ^0
1 50
o 20
10
i otc! He
t— i * /-» /*, —
:i.irr,s, i 9So
Toici Hexcchlorobi
Ein-,s,199l
1C
20
lost vapor sample
Figure IV.20. Total hexachtorobiphenyl concentrations in air collected biweekly at the Elms site.
4-21
-------
50 [•
60 \-
C
o
'- 40
c
O
O
o 20
O
Totol h'ep:ochlcrcbiphenyis
Eirr,£,1S9j
ED t-
60 \-
C
O
- 40
C
o
c
o
o
ll
ill!
1 1 illll
11111
Tc'iCi Hep'.cchlcrobiphenyis
E!rr,s,199 !
ESI vopcr
-
20 25 50
J'jlion Week
lost vapor sample
35 40
50
Figure IV.21. Total heptachlorobiphenyl concentrations in air collected biweekly at the Elms site.
4-22
-------
15
,^~x
E
"oi 10
d
c
0
~p
~c _
0 5
o
c
o
o
j 1
i
' <
i
j
'
Totcl Octccr, lore cipnen vis
EJms,1990
H vapor
. , . . . ,
15
^^
"E
Nt
^ 10
Q.
C
O
c
QJ D
C
O
o
1
~
^
. 1 1
.1
1
5 10
i
'
1
~
\
, • • i
i
20 2
1
1
- • i
•
_
• •- - •- '
Lims
SB
1
^ **• v1
.1
i • •
1
r\ ~ - „ ,-
1991
vcpcr
•
i
1
-
-
jrobiphenyls
i
35 ^0 ^-5
• i
50
. jiiC1" /'. r^k
* = lost vapor sample
Figure IV.22. Total octachlorobiphenyl concentrations in air collected biweekly at the Elms site.
4-23
-------
10
8 -
CO
c
.g
I
o
O
CD
c
co
c
ro
c
PHEN
PCBs
1000
800
600
400
CO
"oi
o.
tn
m
O
a.
15
.o
200
2426272829303133343538404245512 5 911131517212527
Week in Sequence 1990-91
Figure IV.23. Atmospheric vapor concentrations for phenanthrene and total PCBs, Chesapeake Bay, 1990-1991.
4-24
-------
chromatographically unresolved congeners 8/5, which
can sometimes contribute up to 50% of the total PCB
concentration.
The vapor/aerosol distribution of atmospheric hydro-
phobic organic contaminants depends upon their
subcooled liquid vapor pressures, the ambient tem-
perature, mass of total suspended particulate material
(TSP), and the fraction of "non-exchangeable" bound
material present in the aerosol (Pankow and Bidleman,
1991). Polycyclic aromatic hydrocarbons with two to
four rings are mainly removed from the atmosphere via
vapor wet deposition or by partitioning across the air-
water interface. Other compounds with similar volatili-
ties include hexachlorocyclohexane isomers (HCH),
phenols, chlorobenzenes and phthalate esters (Bidleman,
1988). In this study, fluorene and phenanthrene were
predominantly in the vapor phase throughout the year
and the less volatile species, such as indeno[123-
cd]pyrene and benzo[ghi]perylene were associated with
the aerosol phase. Compounds with intermediate va-
por pressures, such as fluoranthene and chrysene,
ranged from less than 10% to greater than 90% in the
aerosol phase (Figure IV.24). The observed behavior
was consistentwith our currentunderstandingof vapor/
aerosol partitioning (Bidleman, 1988). The decrease in
aerosol contribution seen in week 28 of 1990 may have
resulted from light precipitation events prior to this
sampling date which removed a significant fraction of
the ambient atmospheric aerosols. This was reflected in
both the aerosol and precipitation data. Temporal
variability in vapor/aerosol distributions was not un-
expected, as both the ambient temperature and the
aerosol concentrations varied during the study period.
TSP measured at a station in Solomons, MD (approxi-
mately 20 km north of the Elms site) ranged from 12 to
89 Hg»nr3 and varied up to 60% about its annual mean
during the study period (MDE, 1990) (Figure IV.25).
Table IV.2 compares the atmospheric data from this
study with several other reported studies. PAH con-
centrations over Chesapeake Bay are greater than those
reported from remote Isle Royale in Lake Superior
(McVeety and Kites, 1988). Benzo[a]anthracene and
chrysene concentrations were more than twice that of
Isle Royale and those of the more volatile PAHs were
Polycyclic
Aromatic
Hydrocarbon
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo[a]anthracene
Chrysene
Benzo[b]fluoranthene
Benzo[k]fluoranthene
Benzo[e]pyrene
Benzo[a]pyrene
lndeno[123-cd]pyrene
Dibenz[ah]anthracene
Benzo[ghi]perylene
Lake Late Denver Niagara Portland Baltimore Stockholm
Superior- Superior-* Colorado** River* Oregon** Maryland** Sweden-*
0.11
0.092
0.0056
na
0.008
0.022
0.067 (a)
na
na
0.044
0.022
0.05
na
0.041
0.45
2.6
na
0.18
0.34
0.13
66 (a)
0.023
0.02
0.0063
0.005
0.018
nd
0.021
na
38
3.2
12.6
21.2
na
na
na
0.83
na
1.7
3.6
4.2
4.2
na
13.8
1
5.1
4.2
2.8 (b)
3.9 (b)
na
1.1
0.42 (b)
0.23 (b)
na
na
0.53 (b)
6.1
27 (b)
2.8 (b)
8.3
7.5
1.5
1.8
3.5
na
1.2
1.2 (b)
na
na
2(b)
na
1.8
2.9
20
27
7.6
12 (a)
10.6
10.6
5
5.8
4.6
na
8
na
2.56
0.12
1.7
1.37
0.16
0.78 (a)
na
0.48
0.42
0.16
0.41
na
0.64
Baltic Chesapeake
Sea-* Bay'
na
0.74
0.02
0.34
0.18
003
0.11 (a)
na
0.11
0.07
0.14
011
na
0.07
0.7
2.1
0.055
0457
0.475
0.05
0.115
0127
0.072
0.083
0.039
0.073
0.014
0.078
-McVeety, B.D. and Hites, R.A., 1988
~*Baker, J.E. and Bsenreich, S.J., 1990
**Foreman, W.T. and Bidleman, T.F., 1990
* Hotf, R.M. and Chan, K., 1987
"Ligocki, M.B. et al., 1985a,b
**Benner, B.A. et al., 1989
-'Broman, D. etal., 1991
"this study
(a) = chrysene and triphenytene
(b) = aerosol phase only
Table IV.2.
Several polycyclic aromatic hydrocarbon concentrations in air, ng/m3.
4-25
-------
100 -
20 -
24 26 27 28 29 30 31 33 35 38 40 42 45 51 2 5 9 11 13 15 17 21 25 27
Week in Sequence 1990-1991
Figure IV.24. Temporal variability in % aerosol distribution of several PAHs, Elms site.
4-26
-------
Average = 35 A/g/m
= 41 %)
CO
"ra
I
I
o
O
a.
P
50 -
30 -
10 -
242627282930313334353638404245512 5 91113151719212527
Week in Sequence 1990-91
Figure IV.25. Temporal variability in in total suspended participate matter concentrations, Solomons, MD, * = data not available (MDE, 1990)
4-27
-------
Location
Arctic
Siskiwit Lake
Lake Superior
Adirondacks
Bermuda
Chicago
S. Ontario
Chesapeake Bay
Total PCBs
(ng/m3)
0.017
2.7
1.2
0.95
0.6
13.4
0.2
0.33
Reference
Bidleman, T.F. etal., 1988
Swackhammer, D.L. et al., 1988
Baker, J.E. and Eisenreich, S.J., 1990
Knapp, A.H. and Binkley, K.S., 1991
Knapp, A.H. and Binkley, K.S., 1991
Holson.T.M. etal., 1991
Hoff, R.M. eta!., 1992
this study
Table IV.3.
Total polychlorinated biphenyls in air.
several times larger. The higher concentrations of PAHs
at the Elms site suggest an influence of upwind urban
emissions. With the exception of phenanthrene, the
concentrations of PAHs in the air near Chesapeake Bay
were very similar to those measured on the Baltic coast
(Broman, et al., 1991). Higher levels of PAHs detected
in urban locations, such as Chicago, Portland or
Stockholm, are likely due to the proximity of local
sources. Decomposition of PAH via photo-oxidation in
the atmosphere during transport and efficient aerosol
scavenging are suspected to drastically reduce the PAH
levels reaching non-urban areas (Korfmacher, 1981;
Webber, 1983). Total PCB concentrations in the atmo-
sphere of Chesapeake Bay were very similar to those
measured at other remote locations (Table IV.3), but
were almost four times lower then those reported for
Lake Superior (Baker and Eisenreich, 1990). Elevated
PCB inventories in the atmosphere over Lake Superior
may result from degassing of organic contaminants
during the summer months. Both the mean concentra-
tions and the congeneric distribution of PCB congeners
in the Chesapeake Bay atmosphere were remarkably
similar to those recently reported by Hoff et al. (1992) in
their study in southern Ontario (Figure FV.26). The
annual mean t-PCB concentration for these congeners
was 111 and 129 pg»nr3 for southern Ontario and
Chesapeake Bay, respectively. Congener 85 and 193
were significantly higher in Chesapeake Bay, but con-
gener 52 was higher in Southern Ontario.
Concentrations in Precipitation
Volume weighted mean (VWM) concentrations mea-
sured at the Elms site for the 16 PAHs and t-PCBs are
listed in Table rv.4, along with the
range in concentrations and percent
of each contaminant detected in the
particulate phase. Concentrations of
PAHs, t-PCBs and congener homolog
groups are plotted for each sampling
period in Figures IV.27 to 48. Pyrene
was the dominant PAH in precipita-
tion with a VWM concentration of
about 22 ng/L. Anthracene occurred
in the lowest concentration, with a
VWM concentration of about 1.4 ng/L. The VWM
concentration of t-PCBs (2 ng/L) compared well with
reported values from rural Minnesota (2.6 ng/L; Franz,
et al., 1991). Total PCB concentrations in precipitation
in Green Bay, Lake Michigan averaged 3.5 ng/L (Franz
and Eisenreich, 1991), and that collected in Madison,
Wisconsin alsoaveraged3.5ng/L (Murray and Andren,
1992).
The measured concentrations of PAHs and PCBs in
precipitation varied greatly during the study period.
Such variations may result in part from the "dilution
effect," in which most of the chemicals are scavenged
during the early phases of precipitation events, with
subsequent "clean" precipitation diluting the contami-
nant concentrations. Figures ^.27 to 48 show the
relative amounts of the dissolved, particulate and fun-
nel-retained concentrations for each sampling period.
The fraction of contaminants retained by the funnel
appeared to depend inversely upon the amount of
precipitation, presumably because the funnel is not
effectively flushed during light rainfall. In the winter
months when the average temperature ranged from 10°
to 20°C, the relative amount of PAHs associated with
particles in precipitation increased. Adsorption of HOCs
to aerosols was a strong function of vapor pressiire, and
vapor pressures for HOCs can change by more than an
order of magnitude with a 25° change in temperature.
Therefore, HOCs are more likely associated with par-
ticles in precipitation during the winter. It is interesting
to point out that even during periods of similar tem-
perature, the distribution of HOCs between the dis-
solved and particulate phase differ. For example, pyrene
was substantially in the dissolved phase during 8/28 -
9/4/90 (Week35,1990)butwasmostlyintheparticulate
4-28
-------
20
CO
£ 15
IS
o
§ 10
O
0)
Q.
tn
O
Atmospheric PCB Concentrations
i
•• Chesapeake Bay 1990-91
I I S. Ontario 1988-89
1
II
ill 1.11 li .il Illl iJ I. Jl
19 7 6 25 45 52 44 40 70 91 99 97 136 107 146 158 17S 128 177 172 193 199 189 194 206
18 27 26 22 46 4B 41 74 66 101 83 85 151 131 141 178 183 174 200 180 191 201 207 205
Figure IV.26. Comparison of atmospheric PCB congener data from Chesapeake Bay to that of southern Ontario (Hoff et al., 1992).
4-29
-------
en
c
I +0
O
Concen
C
g _._
~D
c
(J
o
Fluorene
Elms,1990
! | particulate
funnel rinse
8 -
3 3
2 8 D
-7-
I I
-
3
w
Q
-
X
3
n
3
n
I^
n
1 ......
5 10
i i.i ii
Fluorene
Elms, 1991
Hfl dissolved
I I particulate
t\\Nl funnel rinse
3
3
5 D
U
-
I"
n P
II
i • • • i • • i • ' • • i • • ' i ... i .... | .... | ...
15 20 25 30 35 ^0 45 ,50
ulian Week
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel
7 = sampler down
8 = field blank
* = lost dissolved sample
** = lost particulate sample
Figure IV.27. Fluorene concentrations in precipitation integrated biweekly at the Elms site.
4-30
-------
200
175
^
\ 150
O>
c
^— ' 125
' £~ \J
C
o
U= 100
D
L.
"c 75
(D
U
o 50
O
25
25
<->• 20
— i
C7>
c
X~"' 15
c
o
~o
1 1°
u
c
o
0 5
i i i i i i i >i
Phenanthrene n
Elms, 1990 K
Hi dissolved \
I | porticulate ^
.KNNl funnel rinse K
i i
ki
r
i ;
! 1
"I 1
S
S
_
n _ 2 _• 3 2
1 -'- l"l a = 8 n -7-
i i i i i i i ii
Frenantr.rene
E!.-ns,1991
IB dissolved
I I paniculate
kx\M fur^,e[ rinse
' '^
-
l r< 3
- n ^ P n
F; H P II 3 =
, n h ^ ! i
n 1 Illl III
1" • ' • • | ' • ' 1 . . . | . • • | • • . | • • ! . , , _ . . , . . ! , .
5 10 15 20 25 30 55 ^0 *5 50
Julion Week
1 = not quantifiable in dissolved phase 6 = not detected in funnel
2 = not quantifiable on filter 7 = sampler down
3 = not quantifiable in funnel 8 = field blank, no ppt.
4 = not detected in dissolved phase * = lost dissolved sample
5 = not detected on filter ** = lost paniculate sample
Figure IV.28. Phenanthrene concentrations in precipitation integrated biweekly at the Elms site.
4-31
-------
50
^-v 40
_i
^
^ 30
o
-4— '
D
I
•£ 20
u
c
o
0 10
0
R
A
|
c
3
c
o
"o
I
"c 2
-------
7SO
225
^ 200
^ 175
c
^ 150
1 125
o
-£ 100
^ 20
c
v~x 15
c
_0
o
•£ 10
0)
o
c
o
0 5
1 =
2 =
3 =
4 =
5 =
Fluoronthene
Elms.1990 J,
{•I dissolved ^
| j particulate £
KSNl funnel rinse ^
~* K ™"
K
s
*
— N
|
]
1
-7- 33| H ,5 el -'- "
' ' • ' 1 . . . | . ..,...,, i . i . | i ... | i . i .,. • • i ... | .... | ..
1 1 i 1 1 1 lit
Fluorcnthene
Eims.1991
12 ] particulate
|\\XJ funnel rinse
-
n
"if U!B^,.O
. | . . . . ! . , g , , . . ( . . T . ! . i . | ' • | • 'i ' |
5 10 15 20 25 30 35 40 *5 50
Julian Week
not quantifiable in dissolved phase 6 = not detected in funnel
not quantifiable on filter 7 = sampler down
not quantifiable in funnel 8 = field blank
not detected in dissolved phase ' = lost dissolved sample
not detected on filter " = lost particulate sample
-
Figure IV.30. Fiuoranthene concentrations in precipitation integrated biweekly at the Etms site.
4-33
-------
1000
cr 900
^
• —
c.
.J 800 )
~o /
^ 200
0
c.
o
° 100
i i i i i i i
Pyrene
Elms, 1990
L H dissolved £>
| J porticulote ^
-f\\N3 funnel rinse s
1 v ^ ^ s.
s \
-
-
fi-7-
' i ' ' ' 1 ' ' ' 1 ' ' l ' ' ' ' 1 ' ' ' ' 1 ' ' ' ' 1 '
30
^
10
o lb
c:
0
o
1 t 1 1 1 1
1 1 1
-
6 A
-
-
P 3
S . 8 0 -7-
...,...,,...,,
1 t i
Pyrene
Elms.1991
1
•1 dissolved
1 | porticulate
I
1
1 1
0 B2 B 1 1 : S B e c-7-. , D
• I ' ' • I • • • I • • • , I . T .,.,.• 1 | I I I ,
5 10 15 20 25 30 35
Julian Week
1 = not quantifiable in dissolved phase 6
2 = not quantifiable on filter 7
3 = not quantifiable in funnel 8
4 = not detected in dissolved phase
5 = not detected on filter
\\\l funnel rinse
'
/
40 ^5 50
= not detected in funnel
= sampler down
= field blank
= lost dissolved sample
= lost particulate sample
Figure IV.31. Pyrene concentrations in precipitation integrated biweekly at the Elms site.
4-34
-------
on
\ 15
c
1 10
o
c
o
c
o 5
O
n
4
i
Cn
c
c
o
D
1 2
o
c
o
0 1
n
1 =
2 =
3 =
4 =
5 =
II II I I I I t J
Benz[o]cnthracene
Elms.1990
HH dissolved
~[ ] porticulate
\XS3 funnel rinse h
-
-
-7- |g R R s n -7-
' ' i ' ' ' i ' • ' ' : ' * ' i ' ' ' 1 • • ' ' l ' ' ' ' i ' ' ' ' 1 ' ' ' • i • ' • i ' •
1 i t i l t iii
Benz[c]anthracene
Elms.1991
j | particulate
kN\\l funnel rinse
p
I
S
S
! D °
- - i D c
f i 5 " n n
1 1 1 1 n 1 1 1 -^ ; J.
5 10 ".5 20 25 30 35 ^0 ^5 50
Julian Week
not quantifiable in dissolved phase 6 = not detected in funnel
not quantifiable on filter 7 = sampler down
not quantifiable in funnel 8 = field blank
not detected in dissolved phase * = lost dissolved sample
not detected on filter ** = lost particulate sample
Figure IV.32. Benz[a]anthracene concentrations in precipitation integrated biweekly at the Elms site.
4-35
-------
40
35
^ 30
c£
vS 25
c
o
•J 20
o
o
c
o 10
0
5
0
10
^ 8
^
c
6
c
-i—'
o
"c 4
o
c
o
0 2
n
Chrysene
Elms.1990
1 1
- H dissolved
I | porticulate
KXXI funnel rinse
-
~
_
_
1 • • * i ' t ' ' ' '
t i
—
_
-
R
R
-
-
*
_.
. i n 6
II in
I •
1
' • • i • • i •
i i
= 1
i '
11 1-7-n n
K
n
-7- L
\t
' 1 ' ' ' • 1 '
1
1
-
_
-
—
I R s y -7-
• • • i • • • ' i • •
1 !
Chrysene
E.Tis.1991
•I
! dissolved
j | paniculate
jo\\
^ funnel rinse -
10 15 20
30
Julion Week
not quantifiable in dissolved phase
not quantifiable on filter
not quantifiable in funnel
not detected in dissolved phase
not detected on filter
6 = not detected in funnel
7 = sampler down
8 = field blank
= lost dissolved sample
*" = lost particulate sample
Figure IV.33. Chrysene concentrations in precipitation integrated biweekly at the Elms site.
4-36
-------
300
250
C?
n*j _. _,^ _.
j? 200
c.
o
•^ 150
o
c.
g 100
c.
0
o
50
0
i i i i i i i i i i
Benzo[b]fluorcnthene
_ Elms, 1990
H dissolved
| | participate
KXXl funnel rinse
-
-
—
i -7- s_
_
.
"
-
-
-
1 B 3 e 3 -•>-
i i i i i i i i i ' i
1 n
I U
_^ 8
cn
a
v~"' 6
a
o
"o
^
"c 4
(D
U
C
0
0 2
0
_
_
*
-
"'
3enzo[b]fluoranthene
Elms, 1991
HI dissolved
! | participate
NXX] funnel rinse
6
" n ^
n ' |
S 1 [ ,-7-B fi ,6
' ' ' 1 ' ' ' 1 ' ....... j ! • 1 ' 1 ' j ' ' • | ' - • 1 ' '
5 10 15 2C 25 50 35 ^0 45 50
Julion Week
1 = not quantifiable in dissolved phase 6 = not detected in funnel
2 = not quantifiable on filter 7 = sampler down
3 = not quantifiable in funnel 8 = field blank
4 = not detected in dissolved phase * = lost dissolved sample
5 = not detected on filter ** = lost partculate sample
Figure IV.34. Benz[b]fluoranthene concentrations in precipitation integrated biweekly at the Elms site.
4-37
-------
50
45
.— ^ 40
-^ 35
c
^ 30
c
o
•^ 25
D
-£ 20
(U
c 15
o
0 10
5
0
5
^
CT
c
"~" 3
c
o
"o
i
"c 2
CD
O
C
o
^ 1
0
i
1
1
1
1
i i i i i
Benzo[kjfluoranthene
Elms, 1990
Hi dissolved
| 3 particulate
KSXl funnel rinse
-
-7- |g| o
-
-
-
-
3 ^
n 8 Q -7-
i ) i i
_
-
-
1
t
4
3
2
i
5
4
1
3
*
3
L
2
- -\
T
1
i
15
-
i
i
j
i
|
1
1
i i i i i
Benzo[k]fluoranthene
Elms, 1991
|H dissolved
| | particulote
hXNl funnel rinse
4
3
11 n
-H 5 1
i •
20 25
:
|3
1 1 ' ' ' ' 1 ' ' 1 ' ' 1 ' ' ' 1 ' '
30 35 40 45 50
Julian Week
1
2
3
4
5
not quantifiable in dissolved phase
not quantifiable on filter
not quantifiable in funnel
not detected in dissolved phase
not detected on filter
6 = not detected in funnel
7 - sampler down
8 = field blank
* = lost dissolved sample
** = lost particulate sample
Figure IV.35. Benzo[k]fluoranthene concentrations in precipitation integrated biweekly at the Elms site.
4-38
-------
50
CP
c.
o
c
o
o
30
20
10
Benzo[e]pyrene
Elms,1990
I j particulate
KXX] funnel rinse
CP
c
c:
o
c
CD
O
C
o
(J
8 -
o -
-7-
-7-
Benzo[e]pyrene
Elms,1991
•• dissolved
particulate
funnel rinse
.-HD
1
2
3
4
5
I ' ' ' I 1 t
5 10 15
not quantifiable in dissolved phase
not quantifiable on filter
not quantifiable in funnel
not detected in dissolved phase
not detected on filter
i i
20 25
^0
45
50
Julian Week
not detected in funnel
sampler down
field blank
lost dissolved sample
lost particulate sample
Figure IV.36. Benzo[e]pyrene concentrations in precipitation integrated biweekly at the Elms site.
4-39
-------
200
160
x-v 160
_j
"cri 140
v~^ 120
c
o
•j= 100
o
-£ 80
c 60
o
0 40
20
n
\j
20
\ 15
cn
c
c
O
r; 10
D
~c
CD
O
C
o 5
O
n
1
> i i i i i i i i
Benzo[o]pyrene
Elms,'
990
BH dissolved
| | porticulote
KX\| funnel wash
-
'
i
_
-
_
6
i D
3 1 1
n 1 1
£
t -?-
-
_
-
_
-
-
_
-
6
- n
*- fl 83 -7-
1 i • ' • ' i ' • ' • i • • c • i • i • i • . | . . . . | , , . , | . .
i i i i i i i i i
6erizo[a]pyrene
Elms.1991
H| dissolved
[ | particulate
KNNl funnel wash
656
1 1 i 1
c 6nnnn-~-1 1 n 6
1 11 il II 1 I I I r-i«=MW
1 =
2 =
3 =
4 =
5 =
"-1 ' ' • j ...,:...,•
5 10 15
not quantifiable in dissolved phase
not quantifiable on filter
not quantifiable in funnel
not detected in dissolved phase
not detected on filter
' i 'i 'i i '
20 25 30 55
Julian Week
6 =
7 =
8 =
' 1 ' ' ' 1 ' ' '
40 45
not detected in funnel
sampler down
field blank
lost dissolved sample
lost particulate sample
• i ' ' •
50
Figure IV.37. Benzo[a]pyrene concentrations in precipitation integrated biweekly at the Elms site.
4-40
-------
30
25
i
\
c* 20
c
0
~ 15
o
c
8 10
c
o
o
5
1 1
1 1 I 1 1 1 i It
1
I
lndeno[l ,2,3 — cdjpyrene j
. Elms,1990
_
H dissolved
j | particuloie
\\\3 funnel rinse
-
' ' ' ' i ' ' ' ' i ' ' ' '
30
25
^
\
¥ 20
N~'
c
o
•J=. 15
D
C
CD , o
0 ' U
C
o
o
5
i i
-
-i-
~
16
A
6 . n
D Hi
• • • • i • • • • i • • ' •
5 1C
4 5 e 6
5 -7- |Bj t
—
-
-
3
^ 4
n s n -y-
\ ' ' ' ' i ' ' ' ' i ' ' • ' i ' ' ' • i ' • • ' i ' • ' ' i ' ' • ' i * •
i I I I > i I
lr,deno[". ,2,3-cdjpyrene
Elms, 1991
BH dissolved
I | particulate
KX\i funnel rinse
T
6 -^
4 n
I) n U-7-n [Is
i • . i i - • . i . . , | . i . . | i • • • i
15 20 25 30 35 *0 ^5 50
Julian Week
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel ;
7 = sampler down I
8 = field blank '
* = lost dissolved sample
** = lost particulate sample
Figure IV.38. lndeno[1,2,3-cd]pyrene concentrations in precipitation integrated biweekly at the Elms site.
4-41
-------
30
25 -
20
•j 15
v_
C
CD
O
C
O
o
10
c
o
-J—'
D
i_
•c 2
c
o
Dibenz[o,h]onthrocene
Elms,1990
I I porticulote
funnel rinse
6
n
6 ,
In
n
0 ->-
Dibenz[o,h]cnthracene
Elms, 1991
| porticuicte
KNXJ funnel rinse
-7-
h
i • • • • i r^ • i • ' • • ,
5 10 15 2C
' ' I ' ' 1
25 30
Julian Week
35
40
50
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel
7 = sampler down
8 = field blank
* = lost dissolved sample
** = lost paniculate sample
Figure IV.39. Dibenz[a,h]anthracene concentrations in precipitation integrated biweekly at the Elms site.
4-42
-------
20
^^
| 1 R
< ^
i i .
O"
C
c
o
•j 10
D
i_
~c
0)
0
c
o 5
O
0
20
< 15
\
Cn
C
c
o
•jr 10
0
i_
~c
CD
0
C
o 5
O
0
i i
i \ i * * > t i
Benzo[g,h,i]perylene
Elms, 1990
•H d ssolved
^^^^^H
! particulate
\\\] funnel rinse
• ' i . . i , . . ,
i i
-
^
n
_
X
5 " f
r D
6 fl 6 -
. , n
• i • i •
5 10
1 = not quantifiable in dissolved
2 = not quantifiable on filter
3 = not quantifiable in funnel
6
5 n
4 0 ':
B - y s
-
n -
4 ;
3 -
rn
IB. -7.
1 ' ' ' ! .... | .... | .... | . . . . | . , , , . .
1 1 1 1 1 1 1 1
Benzo[g,h,ijperylene
Elms, 1991
H d ssolved
! particulate
\\Xi funnel rinse
3 6
!•
«
-7-J n [I 6
1 ' 1 ' ' ' ' 1 ) ' 1 ' ' ' 1
15 20 25 30 35 40 45 50
Julian Week
Dhase 6 = not detected in funnel
7 = sampler down
8 = field blank
4 = not detected in dissolved phase " = lost dissolved sample
5 = not detected on filter
** = lost particulate sample
Figure IV.40. Benzo[g,h,i]perylene concentrations in precipitation integrated biweekly at the Elms site.
4-43
-------
en
c
o
40 -
30 -
r 20 -
o
o
c
o
O
10 -
c
CD
O
c
o
1
t
i i
1 1 1 1 1
Total PCBs
E!ms,1990
HI dissolved
I I port culote
KNSl funnel rinse
-
^
_
Pi
I
"
\
X
X
i ' • ' '
s
s
• ' • t '
i
rz
IB
n
R
1 '
i i
a
— i r~
II
~
-7- om
i
B SB -7-
1 ' ' ' 1 - .. | .... | . . . (
Total PCBs
Elms, 1991
•i dissolved
\\\
particulate
funnel rinse
—
10 15 20 25 30
Julian Week
1 = not quantifiable in resin
2 = not quantifiable on filter
7 = sampler down
8 = field blank
* = lost resin sample
** = lost particulate sample
40
Figure IV.41. Total PCB concentrations in precipitation integrated biweekly at the Elms site.
4-44
-------
1
j? 0.4
c
o
"o
~c
0) n <-)
0 U.2
c
0
o
i i i i i i i i i ,
Total Dichlorobiphenyls ^
Elms, 1990 t
H dissolved
] particulate n
KNNl funnel rinse
R
p
i ~7~ i-l
-
~
2
.2 S | -7-
1 1 1 1 1 1 1 1 . 1
Q
\
^ 0.4
c.
o
o
"c
S 0.2
c
0
o
1 1 1 1 1 1 1 1 I 1
Totcl C'chlorobipnenyls
Elms, 1991
HI dissolved
! pcrticulate
R\N funnel rinse
^
2
1
i R
2^2 n2^222 2
* 1 1 i * n • l 1 7 1 Din I
' ' ' • 1 ' ' ' 1 ' ' ' 1 ' ' ' ' 1 ' ' ' ' t ' ' • 1 ' ' 1 • ! ' ' ' i
5 10 15 20 25 30 35 ^0 ^5 DC-
Julian Week
1 = not quantifiable in resin
2 = not quantifiable on filter
7 = sampler down
8 = field blank
* = lost resin sample
** = lost paniculate sample
Figure IV.42. Total dichlorobiphenyl concentrations in precipitation integrated biweekly at the Elms site.
4-45
-------
I 3
O
0
c
O
O
Total Trichlorcbipher.yls
Elms,1990
[ i paniculate
funnel rinse
en
c
2
D
L_
C
CD
O
<§ 1
1
-7- is
8
1 -7-
Totci Trichlorobiphenyls
Elms,1991
Hi dissc.ved
j particulate
\\3 funnel rinse
IB....
-7-
5 10
23 25 30
Julian" Week
1 = not quantifiable in resin
2 = not quantifiable on filter
7 = sampler down
8 = field blank
= lost resin sample
** = lost particulate sample
40 45 50
Figure IV.43. Total trichlorobiphenyl concentrations in precipitation integrated biweekly at the Elms site.
4-46
-------
13
Tot
cl
Elms,
^j
^
c
_g
~o ^ /
-*-<
c 4
o
c 3
o
0 2
1
•
•
o
ES
L. ii *... i
/
-
-
-
r
A
*r
5 3
o~*
c
^•^
c
0 _
•J3 2
o
c
o;
o
c
0 1
o
-
-
_ x
_
ri
i
3
< '
i
Tetr
» i I i i
ccniorcbipher.yls
'
1990
dissolved "
porticuiote '
funnel rinse
•
\
v
.1
•
• , ' • • i • • i • i • i •
/
-
-
-
IB
i s| -7-
/
......... 1 ..
Tote Teiroch!crob;phenyls
Elrr.5,1991
H disslc/ed
| pcrticjlote
|\\X f u n n e
rinse
n
>
5
_
N
1 1
I!
*
-
* hri
"- 1 @ 1 1 1-7-1 i R
• • i • • ' i 'i -i 'i
i i • • • i •
0 15 20 25 30 35 40 ^5 50
Julian Week
1 = not quantifiable in resin
2 = not quantifiable on filter
7 = sampler down
8 = field blank
= lost resin sample
** = lost participate sample
Figure IV.44. Total tetrachlorobiphenyl concentrations in precipitation integrated triveekly at the Elms site.
4-47
-------
13
12
CT 11
*o?
vS 10
c
o
1 1
1
1 1
'
1 '
Total Pentachlc-cbiphe-yls
" Elms,19SO
_ H| dissolved
I particulate
-
/
'•= '/
e 2/
c
(D
O
C.
0 ,
0 '
1 ' ' , . . . . 1 . . . .
2
CT
a1!
c
c
0
•J^ 1
D
C
CD
U
C
o
o
i t
1
i 1
p
0-7-
1 ' I
j 1
-
N
R i
N 1
,.i, i
1 * •
i
-
-
/
/s
A
-
• 8 1 _7_
• I '
• • • • i ' i '
i i
Total -entacrlorobipnenyls
Elms, '991
-
_
Pi
R. Q ,
hi3 p
n 1 D r
All 1 1
p
il
•1
1
1
-1
1 1
cissolve
d
corticuiate
or 7 c, - n
^1 w jL -J ^^J
Julian V,"eek
1 = not quantifiable in resin
2 = not quantifiable on filter
7 = sampler down
8 = -eld blank
= ost resin sample
" = isst particulate sample
50
Figure IV.45. Total pentachlorobiphenyl concentrations in orecipitation integrated biweekly at the Elms site.
4-48
-------
8
7
o~> 6
c
.2 5x
Concentr
2
1j
CP
c
c
•J 1
0
c
CD
O
C
0
o
i i i i i i i i i i
Total Hexachlorobiphenyls
" Eims.1990
H dissolved P -
particulate h
/ /
>-
J -7- 9=1 5 I 1 8 1 -7-
.,....,... t .... 1 : ... t .... t .... I . . . | . . . . ! . . . 1
1 1 1 1 1 1 1 1 1 1
Total Hexachlorobiphenyls
Elms, 1991
H dissolved
I particulote
-
n I"
J , . , 1 1 1-H 1 n
5 10 i5 20 25 30 35 ^0 ^5 50
/
Julian Week
1 = not quantifiable in resin
2 = not quantifiable on filter
7 = sampler down
8 = field blank
* = lost resin sample
** = lost paniculate sample
Figure IV.46. Total hexachlorobiphenyl concentrations in precipitation integrated biweekly at the Elms site.
4-49
-------
en
c
^"" 3
c
o
~D
| '2
u
c
o
O 1
Toto! Heptcchlorcbiphenyls
Elms.1990
•H dissolved
" | participate
1.00
0.75
c
•£. 0.50
o
i_
"c
0)
u
o 0.25
n
hi
8 8 -7-
1 1, 1
Zl *
, . . . ,
5
I
i i i i i i i ii
Total Heciochlorobiphenyls
Eims,'991
I pcr-Jculate
™
mill ll
. . T , . ...... I ,: ... | ........ , • | ' ' • i ! '""
10 15 20 25 30 35 ^0 45 50
Julran Week
1 = not quantifiable in resin
2 = not quantifiable on filter
7 = sampler down
8 = field blank
* = lost resin sample
" = lost paniculate sample
Figure IV.47. Total heptachlorobiphenyl concentrations in precipitation integrated biweekly at the Elms site.
4-50
-------
c
o
c
Q)
O
C
o
o
Totcl Octochlorobiphenyls
Elrr,s,1990
HI dissolved
| | porticulate
C.5
en
C
c
•J C.4
D
i_
"c
(D
-------
Polycyclic
Aromatic
Hydrocarbon
Fluorene
Phenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo[a]anthracene
Chrysene
Benzo[b}fluoranthene
Benzo[k]fluoranthene
Benzo[e]pyrene
Benzo[e]pyrene
lndeno[1 23-ccQpyrene
Dibenz[ah]anthracene
Benzo[ghi]perylene
Total PCBs"*
-Volume weighted mean
"number of samples
***78 congeners
VWM-
Conc
(nq/L)
2.11
7.80
1.35
8.92
21.91
1.37
3.44
5.89
3.34
2.28
2.01
2.11
1.24
2.41
2.03
concentration;
Minimum Maximum
Cone
(ng/L)
0.13
1.32
0.12
0.58
0.49
0.24
0.60
0.89
0.02
0.51
0.02
0.23
0.36
0.79
0.27
Total vol = 804.6 L
Cone
(ng/L)
47.76
178.45
30.30
207.97
911.75
15.61
25.30
265.37
33.76
30.16
185.10
23.17
29.07
18.10
36.36
% Particulate
Minimum
0.76
2.84
0.00
10.43
16.39
11.99
10.52
16.78
6.06
0.83
11.19
18.96
5.15
40.86
8.00
Maximum
76.01
76.83
99.85
97.08
98.38
94.70
91.93
92.63
98.18
96.78
99.16
98.96
99.17
99.54
89.90
N"
21
21
21
21
21
21
21
21
21
21
21
21
21
21
21
Table IV.4. Mean total (paniculate [filter + funnel] and dissolved) rain concentrations of potycyclic aromatic hydrocarbons and total
polychtorinated biphenyls, Chesapeake Bay, 1990-1991.
phase the following period. We interpret this as direct
evidence that both the magnitudes and the relative
importance of various scavenging mechanisms (e.g.,
gas phase aerosol versus scavenging mechanisms) are
highly variable.
Atmospheric Fluxes
Estimated dry aerosol fluxes for 14 PAHs, total PCBs
and PCB homolog groups were calculated using a
deposition velocity of 0.49 cm • s"1 and are listed in Table
IV.5. Dry aerosol fluxes for individual PAHs ranged
from <2 to about 21 ug«m~2/year. Dry aerosol fluxes of
PAH calculated from Isle Rqyale in Lake Superior were
comparable to those calculated for Chesapeake Bay.
Using a mass averaged dry deposition velocity of 0.99
on/s, McVeery and Hites (1988) calculated a dry aero-
solfluxofbenzo[ghi]peryleneoflOug«m"2/yearforLake
Superior, whereas in the Chesapeake Bay we estimated
the flux to be 14 ug«rrr2/year.
Total PCB dry aerosol fluxes could not be estimated
because aerosol-bound PCBs were present at concen-
trations below our detection limits. However, Yamasaki
et al. (1982) quantitatively related the vapor/aerosol
distribution of HOCs to temperature (T) and aerosol
concentration (TSP) by the following equation
log A (TSP)/F = m/T + b (6)
where A is the adsorbent retained (vapor) concentra-
tion (pg«nr3), F is the filter retained (aerosol) concen-
tration
-------
DrvB
Polycyclic
Aromatic Vd =
Hydrocarbon 0.26 cmfe
Ruorene
Phenanthrene
Anthracene
Ruoranthene
Pyrene
Benzo [a] anthracene
Chrysene
Benzo [b] fluoranthene
Benzo [k] fluoranthene
Benzo [e] pyrene
Benzo [a] pyrene
Indeno [123-cd] pyrene
Dibenzo [a] anthracene
Benzo [ghi] perylene
Total PCBS"
Note: Ruxes are in ng/m2/year and
- total flux = dry + wet
"78 congeners
1290
8800
690
11170
10630
4160
8460
11270
5910
6800
2840
7050
1320
7590
N/A
JX
Vd =
0.72 cmfe
3570
24370
1920
30930
29440
11520
23440
31210
16370
18820
7870
19530
3640
21010
N/A
WetRux
Total Rux-
Vd= Vd =
0.26 cm/s 0.72 cnVs
2910
10580
1580
17230
14710
1980
5850
9260
6330
2240
2800
2260
1400
2780
2700
4200
19380
2270
28400
25340
6140
14310
20530
12240
9040
5640
9310
2720
10370
include dissolved, paniculate and funnel; dry fluxes are aerosol
— high dry deposition flux:wet deposition flux;
average ratio = 4
6480
34950
3500
48160
44150
13500
29290
40470
22700
21060
10670
21790
5040
23790
only.
Dry.
Wet—
1
2
1
2
2
6
4
3
3
8
3
9
3
8
Table IV.5.
1991.
Mean dry and wet fluxes of polycydic aromatic hydrocarbons and total potychlorinated biphenyls. Chesapeake Bay. 1990-
aerosol concentration to be 16 pg»m~3, giving a dry flux
of 2.5 ug»nrVyr, depending on the dry deposition ve-
locity. Adding these values to the wet flux for total
PCBs of 2.7 ug»irrVyr gives a total PCB flux of5 ug»nv
2/ye to 6 |o.g»nrVyr and a dry flux:wet flux ratio of 0.5.
The tetrachloro- and pentachlorobiphenyls dominate
the total flux. The dichlorobiphenyls measured in
precipitation exclude congeners 8/5 due to blank inter-
ferences and hence the dry flux:wet flux ratio is not
reported.
Wet Fluxes
Estimated wet fluxes of the 16 PAHs and total PCBs at
the Elms site are listed in Table IV.5. Monthly wet fluxes
for each PAH, total PCBs, and the PCB homologs are
shown in Figures IV.49 through IV.70. Individual PAH
wet fluxes ranged from about 1.4 p.g»mz/year for
dibenz[a,h]anthracene to as high as 17.2 u.g« rrr/year for
fluoranthene. The total PCB wet flux of 2.7 |ig« m2/year
is similar to that reported for rural Minnesota where the
t-PCB wet flux was reported to be 1.4 |ig«m2/year
(Franz et al., 1991). Wet fluxes of several PAHs mea-
sured at the Elms site are slightly larger than those
reported in the Lake Superior region (McYeery and
Hites, 1988), presumably due to larger regional sources
near the Chesapeake Bay. For example, the phenan-
threne, pvrene, and benzo[ghi]perylene wet fluxes for
Lake Superior are 5.4, 2.3, and 1.3 |ig»mYyear, re-
4-53
-------
2- soo
4-J>
c
o
E 400
CM
300
c
13 200
-------
2* 2500
~c
o
E 2000
CM
E
*o5 150°
c
3 1000
LJ_
3: 500
^ 2500
-i—/
c
o
E 2000
CM
E
\ 1500
c
"~^
J 1000
3: 500
1 1 1 I I 1 I
r\i
Fnenonthrene \
_ Elms, 1990 i>
HH dissolved N
j | porticulote i
(xXNj funnel rinse
-
•
I
•
, • i i i i i i
i i i i i i i
_
-
-
R
5
- • • n R '
1 1 1 1 • . 1
J F M A M J J
Morr.'n
-
-
-
H S
n \
y \ 3
1 n n 3
• • •
1 1 ••'•,• ' ' ' 1 ' ' ' • 1 ' ' • '('••"
Prenont'nrene
Elrr,s,1991
HI dissolved
j | pcrticulate
K\\j funnel rinse
• \ . I ' i ' '
A S C N D
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel
7 = sampler down
Figure IV.50. Ptienanthrene wet depositional fluxes measured at the Elms site.
4-55
-------
400
_c
-4-I
c
o
E 300
CM
E
*\
c" 200
N '
X
^
LI-
'S 10°
>.
>
1
i i 1 1 1 1 i 1 1 1 1
Anthracene
" Elms.1990
HH dissolved
[ | particulate
KXx] funnel rinse
-
-
... j • •
400
^—
c 300
E
\
CM
E
\ 200
c
v— •*
X
cz
_ 100
"•^
^
i
-
-
rrn
\
\
\
\
\
\
I
1
1
J
R
\
n \
n \
6 \ \
n CT \ \
\ \ ^
n
1 I 1 _ ->-
, ' ' ' I • ' ' i ' ' ' ' 1 ' ' ' ' i ' ' ' ' I ' ' ' ' I ' ' ' i . j .... ( .... ( ....
i I 1 I i 1 I . I I I
Anthracene
Elms, 1991
N I I part culate
\ K\N funnel rinse
Xj
\
\
x,
CXI
II
II
•
r\l •
I . - 1 i 1
i i i i i i i i . | .... | .........
FMAMJJASOND
Month
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel
7 = sampler down
Figure IV.51. Anthracene wet depositional fluxes measured at the Elms site.
4-56
-------
c
o
E
10000 -
8000 -
"_ 6000 -
a5 1500^
1000
i i I t i t
Fluoranthene
- Elms.1990
BH dissolved
• I | particulate
KNX] funnel rinse
• V >- N
~,
\
s
\
^
1
1 1 1 1 1
.
a>
500
c
o
c
X.
1200 -
900 -
600 -
a; 300 -
Fluorcnthene
Elms,1991
I | paniculate
R\S3 funnel rinse
N D
Month
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = net quantifiable in funnel
4 = net detected in dissolved phase
5 = nc? detected on filter
6 = nor detected in funnel
7 = ssnpler down
Figure IV.52. Fluoranthene wet deposition^ fluxes measured at the Elms site.
4-57
-------
§ 9000
E
-------
1800
/^-x
£
"i 15°°
<^ 1200
E
j; 900
33
^ 300
180
_c
"c 150
o
£
^ 120
1 90
X
I 60
5: 30
Benz[o]anthracene
Elms, 1990
•• dissolved
[_ | particulate
KSSl funnel rinse
-
-
-
-
i I 1 I 1 ; 1
-
_
6
n
n
1.
1 I Q n 4, -?-
t i i i i
-
_
" n is
\ F\
1 1 1 1 .
J F M A M
1111111
Benz[a]anthracene ~
Elms, 1991
•Hj dissolved
I ] particulate
~~ KSNl funnel rinse
D i
J J A S 0 N D
Month
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel
7 = sampler down
Figure IV.54. Benz[a]anthracene wet depositional fluxes measured at the Elms site.
4-59
-------
c
o
E
en
c
4000
3000
2000
1000
1 1
Chrysene
Elms,1990
I | porticulate
KXSJ funnel rinse
400
c
o
E
« 300
200
00
F M A M J J A
"~1i i I
Chrysene
Elms.1991
I | porticulote
F3S3 funnel rinse
0
N
D
Month
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel
7 = sampler down
Figure IV.55. Chrysene wet depositional fluxes measured at the Elms site.
4-60
-------
f
.c
"c 4600
o
CM
C
\ 4500 )
^ 2000
D
U_
|j 1000
^
£
c 1500
E
CM
E
\ 1000
c
X
J3
!t 500
-------
5 4000
c
0
E
<^ 3000
E
c
^ 2000
X
1
U_
"o 1000
jlllllll
-------
600
-p 500
i;
c
o
400
CM
E
^ 300
c
J 200
"CD
S: 100
i i i i i
Benzo[e]pyrene
Elms, 1990
IHi dissolved
| | participate
KNNl funnel rinse
-
-
F nn
DUU
-p 500
"c
o
E 400
CM
E
/ 300
c
x
J 200
3: 1 00
ps
\
-
~
— ' PI n
n n F
• . L . '.
J F M f\ M
i i i i i i
_
-
^
^ \
r\i
7
1 1 . 1
i i i i i ii
Benzo[e]pyrene
Elms, 1991
m dissolved
I | partculate
KNNl funnel rinse
-
=a
-
] .
J J A S 0 N D
Month
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected
in dissolved phase
5 = not detected on filter
6 = not detected
in funnel
7 = not analyzed
8 = sampler down
Figure IV.58. Benzo[e]pyrene wet depositions! fluxes measured at the Elms site.
4-63
-------
x-^
£ 800
c
o
F
L.
-^ 600
V.
en
c
^ 400
X
1 .
U—
^ 200
fT 800
c
o
E
^ 600
E
c
^ 4CQ
X
13
L_
| 2CO
i 1 1 1 i ; i 1 ; 1 1 1
Benzo[a]pyrene
Elms, 1990 rn
" HI dissolved \;
| | particulate S
KNNI funnel rinse N
\
\
4 \
K \
o \j
ED
he,-/
i i i i i i i i : 1 1 i
Eeizc[a]pyrene
Ei-ns.1991
HI dissolved
I | particulate
K\\l funnel rinse
3
— _
1 R
1 1 a 1 ' , I!
1 1 i n n A
i i i i i , , i . . , j .. , ... , ....
JFMAMJJASOND
Month
1 = not quantifiable ii dissolved pfiase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phasa
5 = not detected on ftter
6 = not detected in finnel
7 = sampler down
Figure IV.59. Benzo[a]pyrene wet deposibonal fluxes measured at the Elms site.
4-64
-------
finn
WWW
0- 500
JZ.
"c
0
400
CM
E
/ 300
c
J 200
^
"Q)
^ 100
pnn
vUw
'P 500
JC
c
o
/
CM
E
^ 300
c
D 200
u_
3: 100
1 J 1 1 1 1 1 1 i 1 1 |
lndeno[l ,2,3-cd]pyrene
Elms, 1990
BH dissolved
| | particulate
K\N funnel rinse
-
-
I_ 3
n n •*
^
n _ n -->-
1 * * ' i ............ j . . . | . . . . | . . , .... ( ... ( . . ( . . , , ( . . . , | , . , .
> i i i i i i i ,11
IndencM ,2,3-cd]pyrene
Elms, ',391
HHI dissolved
I-. | | particulate
\ h^Nl funnel rinse
\^
P~ i
-
n
PI
fl ' n
1 1 . , . 1
JFMAMJJASOND
Month
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnel
7 = sampler down
Figure IV.60. lndeno[1,2,3-cd]pyrene wet depositional fluxes measured at the Elms site.
4-65
-------
c
o
E
600
500
400
3 200
100
600
Dibenz[a,h]cmthracene
Elms, 1990
H dissolved
I | particulate
KSNi funnel rinse
^ 500 -
~c
o
E ^oo -
c
x
~a>
200
:QO
4 J
DO
1 I 1 1
Dibe^zfa.hjanthracene
Elms,1991
j ! particulate
k\NI funnel rinse
fl
D'wm
Ll
• , ' • • ' J T—r—r i|j-r.i|i-TT...
J F M A M
I I ' I '
J J A
r i '
0
TI^
N
*i^
D
Month
1 = not quantifiable in dissolved phase
2 = not quantifiable on filter
3 = not quantifiable in funnel
4 = not detected in dissolved phase
5 = not detected on filter
6 = not detected in funnei
7 = sampler down
Figure IV.61. Dibenz{a,h]anthracene wet depositional fluxes rreasured at trve Elms site.
4-66
-------
600
-2s 500
"c
o
400
TE
"o» 30°
c
^^
x
J 200
"oj
5: 100
600
-p 500
"c
o
£ 400
CM
E
^ 300
c
x
J 200
u-
~
-------
c
o
E
cr>
.c
500
400
200
I t
c
o
E
CD
C
X
rs
500
^00
:00
Total PCB
Elms.1990
II particulate
ISSN funnel rinse
I ' ' ' ' I
1 I
Total PCB
Elms,1991
| J particulate
funnel rinse
M J J A
1 = not quantifiable in dissolved sample
2 = not quantifiable on filter
3 = not quantifiable in funnel
7 = sampler down
8 = field blank
Figure IV.63. Total PCB wet depositional fluxes measured at the Elms site.
4-68
-------
c
o
E
c
X
15
10
i r
Total Dichlorobiphenyls
Elms,1990
| | particulate
funnel
-C
-I—'
c
o 15
E
10
c
X
I ' ' ' ' I
I 1
Total Dichlorobiphenyls
Elms,1991
| | particulate
funnel
2,3
0 N D
1 = not quantifiable in dssolved sample
2 = not quantifiable on later
3 = not quantifiable in funnel
7 = sampler down
8 = field blank
Figure IV.64. Total dichlorobiphenyl wet depositional fluxes measured at the Elms site.
4-69
-------
200
c 150
E
CM
X
13
-------
o
E
CT>
c
180
150
120
90
x
,T 60
30
Total Tetrachlorobiphenyls
Elms,1990
| | particulote
NXN funnel rinse
c
o
E
X
Z5
120
90
60
30
Till I I
I I 1 1 I T
Total Tetrachlorobiphenyls
Elms,1991
dissolved
particulate
funnel rinse
0 N . D
1 = not quantifiable in dissolved sample
2 = not quantifiable on filter
3 = not quantifiable in funnel
7 = sampler down
8 = field blank
Figure IV.66. Total tetrachlorobiphenyl wet depositional fluxes measured at the Elms site.
4-71
-------
80
c
o
E 60
40
Q)
20
c
o
E
CM
E
en
c
X
iZ
"o>
80
60
40
20
Total Pentachlorobiphenyls
Elms,1990
[ | porticulate
funnel rinse
Total Pentachlorobiphenyls
3 Elms.1991
I I particulote
funnel rinse
M A M J J A
Month
1 = not quantifiable in dissolved sample
2 = not quantifiable on filter
3 = not quantifiable in funnel
7 = sampler down
8 - field blank
0 N D
Figure IV.67. Total pentachlorobiphenyl wet depositional fluxes measured at the Elms site.
4-72
-------
80
70
c 60
CM
50
40
c
^ 30
20
10
Total Hexachlorobiphenyls
Elms.1990
| | particulate
[XSN funnel rinse
c
O
£
a>
c
X.
Z5
50
40
30
20
10
Total Hexachbrobiphenyls
Elms, 1991
| | particulcte
NXN fjnnel r'nse
0
N
D
1 = not quantifiable in dissolved sample
2 = not quantifiable on filter
3 = not quantifiable in funnel
7 = sampler down
8 = field blank
Figure IV.68. Total hexachlorobiphenyl wet depositional fluxes measured at the Elms site.
4-73
-------
c
o
E
c
X
20
10
Total Heptachlorobiphenyls
Elms,1990
| | particuiate
t\XN funnel rinse
§ 30
20
10
Total Heptachlorobiphenyls
Elms,1991
j j particuiate
funnel rinse
1 = not quantifiable in dissolved sample
2 = not quantifiable on filter
3 = not quantifiable in funnel
7 = sampler down
8 = field blank
Figure IV.69. Total heptachlorobiphenyl wet depositional fluxes measured at the Elms site.
4-74
-------
c
o
E
\
(N
E
\
en
c
X
iZ
-4—'
CD
C
O
E
CN
CT>
C
X
_D
U_
15
10
Total Octcchlorobiphenyls
Elms,1990
| | particulate
funnel rinse
15
10
\ I I
i I
Total Octachlorobiphenyls
Elms,1991
I | particulate
NNN funnel rinse
0
N
D
1
2
3
7
8
not quantifiable in dissolved sample
not quantifiable on filter
not quantifiable in funnel
sampler down
field blank
Figure IV.70. Total octachlorobiphenyl wet depositions fluxes measured at the Elms site.
4-75
-------
spectively. Using our upper estimate of the dry depo-
sition velocity (0.76 cm/s), the ratio of the dry aerosol
flux to the wet flux ranges from 1 to 9 for the compounds
studied. McVeety and Hites (1988) estimated that the
dry to wet deposition ratio is 9:1 for PAHs in Lake
Superior.
Elemental Concentrations in Aerosol Particles
Concentrations
In this section, we present data on the spatial and
temporal concentrations of selected elemental constitu-
ents (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, S, Se, Zn) of
aerosol particles for the first year of the study and give
preliminary estimates of their dry deposition fluxes to
the bay's surface waters. Concentrations of the various
elements areplotted against Julian weekinFigures IV.71
to IV.74 all valid samples. In general, concentrations
rise and fall with source activity, precipitation,
andmeteorological and surface conditions. For ele-
ments carried on particles from anthropogenic sources,
concentrations rise during periods of low winds and
temperature inversions, whereinpollutants are trapped,
and fall during windy periods and during periods of
precipitation. The concentrations of elements associ-
ated with crustal material rise during dry windy peri-
ods and during earth disturbing activities, such as
plowing,andlandscapingandconstructionwork. Based
on compilation of average concentrations of elements in
the earth's crust (Turekian and Wedepohl, 1961), more
than 99% of the As, Cd, Pb, S, Se, and Zn, and >95% of
the Cu and Zn observed in aerosol particles in this study
were of noncrustal, origin. Aluminum, Fe, and Mn hav e
large (Al, 100%; Fe and Mn, each near 50%) crustal
components and, on average, about 20% of the Cu is
associated with crustal material. Some of the crustal
material may be associated with coal, which cannot be
distinguished from crustal material by elemental ratios.
As indicated in Figures FV.71 to IV.74, concentration vs.
time profiles of many of the anthropogenic elements are
similar, especially those for Cr, Se, V, and Zn. Concen-
trations for nearly all of the elements of anthropogenic
origin were elevated in August, September, and No-
vember, 1990 and in January and February, 1991. This
behavior probably reflects a combination of increased
emissions corresponding to peak air conditioning and
heating periods, low precipitation scavenging and
transport dynamics. Low concentrations observed in
June, July, October, and April were consistent with
elevated precipitation, as shown, for example, by Mn.
In week 12, large increases in the concentrations of Cd,
Cr, Se, Zn, V, Cu, Ni, Pb, and S were observed at Wye,
but not at Elms, and are attributed to a "field day"
activity at the Wye Institute during which motor vehicle
traffic near the site was abnormally high and many
vehicles parkednear the sampler. Data from this sample
were excluded from all subsequent analyses. Concen-
trations of particulate S were characteristically elevated
during the summer months when more photochemical
oxidants were available for the conversion of gaseous
sulfur. Concentrations of crustal elements, Al, Fe, and
Mn tended to be elevated in the spring and summer
months, which probably reflects agricultural and con-
struction activities. This behavior was consistent with
data reported for College Park, MD, in which average
summertime concentrations for ALFe, andMn reported
by Kitto (1987) substantially exceeded those reported
by McCarthy (1988) for winter months (see Table IV.8).
Average concentrations of Al, As, Cd, Cr, Cu, Fe, Mn,
Ni, Pb, S, Se, and Zn for samples collected at Wye and
Elms are listed in Table IV.6, along with their standard
deviations, average uncertainties, numbers of values
determined, and median, minimum, and maximum
values. The complete set of individual results are listed
in Appendices A2.5 and A2.6, respectively. In cases
where the measured concentration was near the instru-
mental detection limit (i.e., 4 for Cr at Wye; and 4 for Cd,
3 for Cr, 7 for Cu, 2 for Ni, and 1 for Pb at Elms) the
detection limit were divided by two and included in the
summary statistics in an attempt to minimize positive
bias that would result from excluding small values.
Relative uncertainties in the upper-limit-values trans-
formed for this purpose were taken to be 100%. We
attribute abnormally high concentrations of Al, S, and V
in Week 9 (6400+380,13,600+2000, and 26.5±2.2 ng'nv3,
respectively) to local activities at Wye, and exclude
these values from averages and flux calculations. Alu-
minum in sample Week 9 is 50-fold greater than the
mean Al concentration computed without this value;
including this value would nearly double the mean.
4-76
-------
o Elms site
Wye site o Haven beach
600
400
200
c
\
DD
C.
O
CD
r •>
o
CD
C/Q
c
0
0.6
0.5
0.4
0.3
0.2
0.1
Cd
10
20 30 40
Week in Sequence
50
60
Figure IV.71. Concentrations of elements in aerosol particles collected at the Wye Research and Elms Educational Institutes and Haven
Beach.
4-77
-------
o Elms site *• Wve site o Haven beach
C
O
5
4
3
2
1
60
50
40
30
20
10
.3 o
£
O 15
T
i04i9.5
116±10.6
o
o
^
CD
10
0
10
8
5
4
2
0
Se
Zn
o
10
20
5C
40
50
Week in Sequence
60
Figure IV.72. Concentrations of elements in aerosol particles collected at the Wye Research and Elms Educational Institutes and Haven
Beach.
4-78
-------
Elms Site
Wve site o Haven beach
E
\
00
c
o
JI3
CO
cj
c
c
o
o
'C
0)
. . T . . , , t Y i . . . . . . I . . . . I ... A ....
20
15
10
5
0
20
15
10
5
0
10000 c
8000
6000
4000
2000
0
Ni
Mm
15354 = 1485
T
10
20 30 40
Week in Sequence
50
60
Figure IV.73.
Beach.
Concentrations of elements in aerosol particles collected at the Wye Research and Elms Educational Institutes and Haven
4-79
-------
o Elms site
Wye site o Haven beach
£
c
c
o
13
CO
0)
o
C
O
o
o
£
>-.
o;
cu
500
400
300
200
100
0
12
10
8
6
4
2
0
Fe
I I I I I 1 1 • I I I I I I 1 I — ! I 1 ' ' 1 I ' ' ' ' ' ' ' • • ^ • • ' ' ' I • • I • • ' • Ci lilt......
Rain
f x '7
" .6...T 0.
Week in Sequence
6C
Figure IV.74. Concentrations of elements in aerosol particles collected at the Wye Research and Elms Educational Institutes and Haven
Beach.
4-80
-------
Al
As
Br
Cd
Cr
Cu
Fe
Mn
N?
Ni 1
Pb
S
Se
V
Zn
Average
163
0.622
323
0.133
0.663
2.33
144
2.82
2.89
4.01
4.50
3066
1.61
3.99
11.95
siqma
120
0.0302
129
0.082
0.360
2.05
103
1.69
2.64
8.50
2.82
1453
0.76
1.59
7.15
ave error1
14
0.061
027
0.016
023
025
6.6
0.10
027
0.35
0.57
520
0.16
0.34
128
n rnedon rnm rnBx
Elms Site
52
52
52
52
51
52
52
52
51
52
50
45
52
52
52
126
0582
3.15
0.123
0.623
1.97
113
251
2.19
1.96
4.12
2647
1.59
4.07
922
11.8
0.108
•0.699
0.003
0.070
0.008
ias
055
0.075
0.075
0350
736
0.310
1.10
325
566
156
6.17
0.435
1.41
8.66
465
12.7
112
612!
142
6324
3.80
8.35
35.8
2€24 removed; data shown in box include outliers indicated.
Al
As
Br
Cd
Cr
Cu 1
Cu2
Fe
Mn
Ni
Pb
s I
S3
Se
V 1
V3
Zn
121
0.690
3.04
0.131
0.79
2.82
2.35
117
3.09
3.30
413
2987
2669
1.53
3.68
324
13.5
62.7
0.340
1.40
0.0760
0.50
1.87
1.87
52.2
1.51
3.18
2.37
2220
1601
0.640
3.43
1.33
7.83
2W13 removed, 3W9 removed
1224
0.069
0252
0.018
0253
0.300
0275
5.44
0.16
0.310
0.548
452
440
0.160
0294
0260
1.51
Wye She
53
53
52
53
53
53
52
53
54
41
53
48
47
53
53
52
53
117
0598
2.79
0.116
0.644
1.84
1.80
103
3.06
1.92
420
2386
2372
1.42
326
324
122
24.8
0.337
0.064
0.0119
0.039
0.310
0.310
33
OSS
028
0.316
101
101
0.592
0.564
0564
4.70
303
156
8.4
0.431
228
27.0
924
283
82
13.6
13.6
13600 1
6783
3.47
26.5
7.0
482
data shown in boxes contain
outliers indicated
Table IV.6. Summary of concentrations of elements determined .
at the Wye and Elms sites, ng/m3.
Average concentrations listed in Table IV.6 are calcu-
lated both for the full data set (i.e., except for samples
discussed above) and for a reduced data set, in which a
concentration value was removed if the ratio, r, of its
concentration at Wye to its corresponding concentra-
tion at Elms met the following criteria:
r > (X + 3c?) (7)
or r < X/(X + 3o), (8)
where X and s were the average and standard devia-
tion of the ratios for the full data set. Ratios that were
removed to produce the reduced data summary are
indicated in Appendix A-2.7 and by the count, n, in
Table IV.6.
A statistical summary of the ratios, Wye/Elms, is
given in Table IV.7. A very large or very small ratio
indicates a disparity in the concentrations measured
at the two sites which must reflect either i) a local
disturbance, ii) contamination, or an invalid sample
oranalysis. Thus,comparisonof the fulland reduced
statistical summaries is provided to ascertain the
effect of outliers on site-to-site comparisons and on
subsequent flux estimates. However, the exclusion
of valid data is possible. For example, the minimum
Al concentration observed atElms, 11.8 ng»m'3, was
eliminated by the criteria even though airborne Al
concentrations as low as 12 ng»nv3 were observed
by Han (1992) in Beltsville. Thus, there may be no
valid reason to remove these data. As indicated in
Table IV.6, only a few outliers were identified, and
except for Ni at Elms, the differences in averages for
the full and reduced data set were less than ap-
proximately 10%. As indicated, one outlier was
removed for Ni at Ehns; all data for sample Week 12,
and data for Al Cd, and V in Week 9 at Wye.
As shown in Table IV.6, average concentrations
determined at Wye and Elms were quite similar,
diff eringby <13% for As, Br, Cd, Mn, Pb, S, Se, V, and
Zn; <23% for Cr, Cu, Ni, and Fe; and <35% for Al. As
indicated in Table IV.7, concentrations for all ele-
ments except V and possibly Al were larger at Wye
than at Elms, but not greatly so for most of the elements.
Averages of the Wye/Elms ratios for the full data set
ranged from 0.92 - 0.11 for V to 2.86 ± 0.89 for Cu; and
from 0.86 ± 0.10 for V to 1.46 ± 0.56 for Cu in the reduced
data set (where \mcertainties are the averages of the
uncertainties in the individual ratios). Median values
are far less dependent on either small or large values in
the fringes of the distribution, and, with the exception of
Cu, Ni, and S, were nearly identical for both the full and
reduced data sets (see Table FV.7). Medians (full data
set) for Al, Cu, Pb, 5e, V, Br, and Fe were <1 by 14%, 11%,
8%, 1%. 18%, 3V and 13% respectively; and respec-
4-81
-------
lively 9%, 9%, 7%, 29%, and 18% >1 for As, Cd, Cr, S, and
Zn. Thus, concentration variations between sites were
generally quite small.
The fact that the S concentrations at Wye often exceeded
those at Elms, might reflect its proximity to urban
plumes from Baltimore, MD and Washington, DC, and
local sources. The large spikes in Al at Elms might be
attributable to traffic on the unpaved road at this site.
Sulfur and V spikes suggest the influence of fuel-oil
combustion sources, such as oil-fired power plants, or
perhaps ship traffic. The relatively small differences in
the median concentrations for the majority of the ele-
ments at the two sites suggest that these atmospheric
pollutants have a strong regional contribution, or that
their major sources, such as the Baltimore, MD and
Washington, DC plumes, ubiquitous motor vehicle
emissions, and regionally dispersed sources tended to
influence the two sites similarly during most of the
week-long sampling periods.
Concentrations of airborne elements determined at the
Chesapeake Bay sites may be compared with average
concentrations determined at Beltsville and College
Park, MD, and Lewes, DE, listed in Table IV.8. The
Beltsville samples were collected in a large open grass-
covered field surrounded by trees, several km from the
nearest road or urban area in the Fall of 1990. The
College Park samples were collected in an urban envi-
ronment, during Summer months (1983-1985; Kitto,
1987) and in Winter months (1985-1986; McCarthy,
1988). The Lewes samples were collected in Cape
Henlopen Park, a semi-remote rural coastal environ-
ment, during July, August, and September of 1989
(Han, 1992). Concentrations averages reported for Al,
Cr, Cu, Fe, Mn, and Se were remarkably similar for the
Beltsville and Lewes sites. Those for As, Br, S, and V
were about 2-fold greater at Lewes than at Beltsville,
possible reflecting the influence of ship traffic. Concen-
trations measured at the more urban College Park site
were uniformly greater (generally by a factor of 2) than
those reported for Beltsville. Average concentrations
for As, Br, and Se in the Bay aerosol were quite similar
to those measured in the more limited Beltsville data
set However, the Chesapeake Bay site values were
from 1.5- to 2.5-fold less than the Beltsville averages for
Al Cr, Cu, Fe, Mn, and Zn. The Chesapeake Bay sites
average concentrations for S is nearly equal to the
average of Summer and Winter concentrations reported
for College Park.
Estimation of Dry Deposition
The dry deposition fluxes of particulate-borne elements
may be calculated for each sampling period as the
product of the atmospheric concentration of each ele-
ment and a deposition velocity (Vd) appropriate to wa-
Statistics lor toll data set
Average
Standard deviation
Average uncertainty
Median
n
Uncertainty of the median
Median uncertainty
Al
1
1.20
1.60
0.18
0.86
46
011
0.11
As
1.39
1.51
0.20
1.09
47
0.21
0.13
Cd
2.76
6.29
1.99
1.09
47
022
050
Cr Cu
1.81 2.86
2.88 4.74
1.54 2.08
1.07 0.89
46 45
0.74 0 17
0.54 0.16
Nl
1.65
2.64
0.60
0.68
47
0.09
0.16
Pb
t.56
3.09
C77
092
45
017
017
S
1 16
0.57
0.33
1.29
35
0.47
0.30
Se
1.07
0.40
016
0.99
47
012
014
Zn
1.30
0.66
051
1 18
47
0.22
0.18
V
092
0.46
0.11
0.82
46
0.097
0097
Br
1 14
0.65
0.14
0.97
46
0.12
0.11
Fe Mn
1.29 159
1.44 0.89
0.18 0.07
087 1.16
47 47
0.07 0.053
0.051 0.064
Statistics after removal of outliers ^ '
Average
Standard deviation
Average uncertainty
Median
n
^ Lower limit value included
0.89
0.54
0.12
085
44
1 18
OS2
0.18
1.07
46
1.12
0.67
0.25
1.02
43
1.22 146
071 1.6?
0.85 0.56
106 0.7S
41 40
1.36
159
034
0.45
33
107
367
353
380
41
1 15
0.36
0.30
0.99
32
1.11
0.38
0.16
1.04
45
1.27
O.S3
050
1 18
45
0.86
0.32
0.10
082
45
1.03
0.39
0.12
0.95
44
0.94 1.17
0.54 0.40
0.06 0.07
0.86 1.16
44 43
n average as 1/2 the value ±1/2 the value
Table IV.7.
Summary of concentration ratios, Wye/Elms.
4-82
-------
Al
S
Cd
Cf
Cu
Fe
Mn
Se
V
Zn
As
Br
Bflttsvtlto Oofleoe Pwfc Lmms
9/22-12/1990(8) Summer months, 1983-1985 (t Writer months. 1985-1986 (c) 7/24/89-9/8/89
Ave. ± slgma mm max n
230 - 222 1Z4 868 (23)
1680 ± 1425 384 4863 (24)
2.01 = 1.60 0.15 7.77 (24)
5.90 i 3.19 1.52 10.7 (9)
238 = 175 33.4 733 (24)
5.07 ± 5.55 U07 28.4 (23)
1.55 i 1.12 0.183 4.75 (24)
3.47 ± 3.74 0513 13.7 (20)
25.9 ± 24.2 2.41 9624 (24)
0.518 t 0.54 0.099 2.38 (19)
4.00 * 2.49 0.957 10.8 (24)
Ave. i Sigma mm max n
1230 ± 810 420 4140 ,31)
4000 ± 2380 900 11000 (30)
0.53 ± 022 029 0.86 (5)
5 i 2.8 1.5 132 29)
12 ± 5 4 18 (8)
830 ± 430 280 2200 OO)
20 ± 8 6 43 01)
2.1 ± 1 037 4.4 OO)
10 ± 10 1 56 01)
43 ± 17 18 100 (30)
1.01 ± 0.59 025 2L56 OO)
41 ± 26 11 140 <31)
Ave. r sigma min max n Ave. ± soma n
420 - 280 90 1400 (24)
2100 = 1100 910 5600 (24)
0.52 - 0.39 0.069 1.5 (18)
3.9 = 22 1.7 9.6 (24)
440 = 310 41 1600 (24)
14 z 7 6 36 (24)
2.4 = 1 12 5.7 (24)
9.1 - 4.6 32 21 (24)
41 = 17 18 94 (24)
0.87 = 0.4 0.39 1.7 (24)
28 r 23 92 120 (24)
272 ± 265 (91)
3771 ± 3225 (92)
2.06 ± 1.54 (92)
621 ± 5.06 (56)
203 ± 197 (92)
5.32 ± 4.66 (89)
1.99 ± 1.78 (92)
7.44 ± 6.05 (90)
17.4 ± 132 (92)
1.11 ± 1.16 (83)
10.7 ± 122 (91)
(a) Han. 1992
(b) Kffio, 1987
(c) McCarthy. 1988
Table IV.8.
Concentrations of airborne elements determined in Bettsvilte. MD, College Park, MD and Lewes, DE, ng/m'.
ter surfaces. In general, dry deposition rates over water
are expected to be smaller than over land, where turbu-
lence-inducing vegetation, terrain, and surface struc-
tures promote pollutant transport to the surface. De-
spite this, turbulence and deposition may be enhanced
at the land-water boundary, where temperature differ-
ences create updrafts. Deposition velocities depend
strongly on both particle diameter (D ) and atmo-
spheric stability. However, experimental measurements
of Vd are few, contain large uncertainties, and are often
reported without supporting meteorological data. Al-
though various methods may be used to extrapolate
limited Vd measurements to other meteorological con-
ditions (for example, Dolske and Sievering, 1979), herein,
we provide estimates of the annual fluxes using only the
average annual concentrations and deposition veloci-
ties.
Aerosol particles may be conveniently classified into
crustal components, which comprise wind blown dust
from natural and anthropogenic dust-making activi-
ties, and noncrustal components, which are typically
derived from high-temperature combustion sources.
Crustal components of the aerosol reside in larger par-
ticles, with mass median aerodynamic diameters
(MMAD) typically >1 (im, whereas anthropogenic
components reside in aerosol with MMADs typically
ranging from 0.2 to >0.5 um, depending on the proxim-
ity of major sources and the degree of atmospheric
processing. At Deep Creek Lake, a rural recreational
area in western Maryland, most of the mass of anthro-
pogenic elements most often occurred in aerosol with
modal aerodynamic diameters between 0.3 to 0.6 um
(Doddetal. 1991). Mass median aerodynamic diameters
often range from 2 to 3 \*m for aged continental aerosol
and are typically 12-15 |im for urban aerosol (Holsen et
al., 1992). A; indicated by the work of Sievering et al.
(1981) reported in Table IV.9, Vd s measured for ele-
ments with 33% crustal source (e.g., Fe and Mn) may be
five or six fold greater than those measured for an
element with predominately noncrustal source (e.g.,
Pb). In general, Vd is minimal for small particles (0.02 to
0.1 um) and increases for larger particles, becoming
equal to the gravitational settling velocity for particles
•with diameters >40 |jm (4.8 cm/s for D of 40 pirn).
4-83
-------
Investigator Stability
Sieverinaetal.. 1979
over Lake Michigan Tair15.8°
May 18-20. 1 977 Twater 7.3"
U 3.8 ±0.8 revs
Dolske and SJeverina, 1979
estimated trom diababc drag 3.6to52nVs
Vd * Cdd"(Uair - Uwater)
dT* +1.0 to +2.7
over Lake Michigan +2_8 to +3^ ^a
May -Sept.. 1977
Dekimyea and Pate). 1979
mixing box model variable1
April -October. 1977
over Lake Huron
Dedeurwaerder et al., 1983
vaseline - coated plates not reported
12 days. 1980-1981
Souther Bight, North Sea
Vd
Species (cm/s)
SO4 02 ±0.16
Pb 0.13
Fe 0.65
Mn 055
aerosol 0.47 ±3x
ible 0.72 ± 3x
0.51 ±3x
e 0.39 ±3x
aerosol 057 ±0.16
P (0.7910122)
(6 month ave.)
Cu 0.19 (5)
1.0 (2)
Zn 020(7)
023(2)
Pb 0.42 ± 0.01 (9)
Cd 0.04 (7)
0.10 (2)
Fe 1.35 ±0.05 (9)
Mn 0.49 (7)
0.77(2)
MMAD
(|un)
88%<1|im
82%<1um
47%<1nm
49%<1|im
0.1 to 2pm
0.1 to2|un
0.1 to2|im
0.1 to2(im
1|un
(28%<1|im)
0^8nm
020)im
0.66um
0.68to
0.75(im
0.52um
1.1um
125±
O.OSum
0.84um
0.98nm
1 Air and surface temperatures and wind speed not reported
Table IV.9.
Deposition velocities determined for aerosol particles over water.
The rate of pollutant transport to the Earth's surface
increases inversely with atmospheric stability. Stable
conditions exist when the air is warmer than the water
and the wind speed, U, is low. The atmosphere becomes
more unstable as the temperature difference, DT (=T -
Twattr), between the air and water decreases. The most
unstable conditions exist when the water is warmer
than the air above it. Under extremely stable conditions
(dT,+8.5°C;andU,3.8±0.8 m« s-1),Sieveringefa/.(1981)
reported Yds of 0.13 em's"1 for Pb (noncrustal resi-
dence) and 0.55 to 0.65 cm» s~l for Fe and Mn (elements
with large crustal components). Larger Vds are esti-
mated from these data by Dolske and Sievering (1979)
for less stable conditions. Monthly
average wind speeds and temperature
differentials derived for the Chesa-
peake Bay area from climatological
compilations (see Appendix A.2.9)
range from -3.3 to +0.83°C and 3.7 to
5.0 m«s-1,respectivery,suggestingthat
bay air is visually much less stable. For
these conditions of average U and dT,
Dolske and Sievering (1979) estimated
Vds of 0.47 and 0.72 cm-s'1.
Deposition velocity estimates from
"box-model" calculations for phos-
phorous containing particles deposit-
ing on Lake Huron over a 6-month
period (Delumyea and PeteL 1979)
ranged from 0.01 to l.Scm's'1 and
averaged 0.57±0.16 cm» s1. The size
distributions for phosphorous-con-
taining particles were often bimodal,
with concentrations peaking in par-
ticles with diameters between 0.3 and
0.5 urn, and 2.9 and >4.6 \un; suggest-
ing "fine" and coarse components, as
is the case for Fe and Mn, which have
nearly equal noncrustal and crustal
components. The fact that the average
Vd reported for the Lake Huron study,
(i.e., 0.56 cm • s"J), was nearly identical
to the values reported by Sievering et
al. (1981) for Fe and Mn (0.65 and 0.55
cm* s'1), is problematical, as the latter
should be minimum values, in accordance with the
extremely stable conditions accompanying the Lake
Michigan study. This demonstrates the difficulties in
using these data for the Chesapeake Bay. Excluding
Cd, for which Vds appear to be inconsistently low, Vds
determined from a 12-day study in the North Sea using
vaseline-coated plates (Dedeurwaerder et al., 1983)
averaged 0.26±0.16 cm* s'1 for noncrustal elements in
aerosol with MMAD <0.75 urn and, 1.18±0.08 cm* s'1
for elements with both crustal and noncrustal compo-
nents in aerosol with an MMAD of 1.2 urn. The data of
Dedeurwaerder et al. (1983) are in logical agreement
with those of Sievering et al. (1981) in that the mean Vd
4-84
-------
for their noncrustal elements, (0.26 cm* s'1), for a vari-
ety of stability conditions, is two-fold larger than the
latter's value for Pb (i.e., 0.13 cm* s'1) which was de-
termined under extremely stable conditions.
Herein, we take the Vd of 0.26 cm* s'1 derived from the
data of Dedeurwaerder etal. (1983) to apply to
noncrustal components of the Chesapeake Bay aerosol,
noting that the value applied by Dolske and Sievering
(1979) to Lake Michigan during conditions appropriate
to the bay was substantially larger, i.e., 0.72 cm* s"1.
Combining the data of Dedeurwaerder et al. (1983) and
Delumyea and Petel (1979) for elements with roughly
equal crustal and noncrustal components we obtain an
average of 0.84 cm* s'1, from which we infer a value of
1.4 em's'1 for totally crustal elements. To estimate
atmospheric fluxes to the Chesapeake Bay, we deter-
mine the fraction of each element associated with crustal
and noncrustal components and derive a weighted
deposition velocity, Vd, accordingly. Annual fluxes, F.
(kg/yr), for each element, i, are calculated from
F. = C, • Vd, • 315 (9)
where, C is the annual average concentrations of ele-
ment i (ng*m~3), P is in ug*m"2* yr, Vd' in an*s-1, and
315 is a conversion factor.
Results of the calculation are reported in Table IV.10,
wherein we list both low and high estimates of the
atmospheric fluxes. Low estimates are based on
noncrustal and crustal VjS of 026 and 1.4 cm*s-1, re-
spectively and high estimates are based on respective
Vd s of 0.72 and 4 on's'1. The former is that of Dolske
and Sievering (1979), the latter is the limiting value for
hygroscopic particles of diameters near 2 um under
conditions of turbulence-limited transfer (Slinn and
Slinn, 1980).
In Table IV.ll, we compare low and high estimates of
the atmospheric fluxes determined for the Chesapeake
Bay with those used by Gate (1975) for southern Lake
Michigan. The lower Vds generally agree with Gate's,
except for VjS for Cd and Pb, which we believe are
overestimated by Gate. As indicated in Table IV.ll,dry
deposition flux estimates for all but Cd and earlier
estimates of Pb are comparable to those reported for
Lake Michigan, which receives pollutants from heavy
industrial and urban sources in Gary, IN, and Chicago,
IL. Gate's estimate of the Cd dry flux to Lake Michigan
exceeds even our high estimate by nearly 2-fold. This is
probably due, in part, to the 2-fold larger Vd assumed by
Gate. Likewise, a nearly 2-fold smaller Vd for Ni leads
Average, ng/m ^
Elms Wve
Al
As
Br
Cd
Cr
Cu
Fe
Mn
Ni
Pb
51
Se
V
Zn
163
0.622
3.23
0.133
0.663
2.33
144
2.82
2.89
4.50
3066 "
1.61
3.99
11.95
121
0.690
3.04
0.131
0.79
2.35
117
3.09
3.30
4.13
2669
1.53
3.24
13.5
Dry Deposition flux, kg/yr
Crustal component, % (Low estimates) (High estimates)
Elms Wve Elms Wve Elms Wve
100.00%
0.57%
0.19%
0.16%
21.98%
2.68%
51.18%
50.94%
2.96%
0.65%
0.02%
0.01%
4.96%
1.04%
Upper limit values were included in averages.
Deposition velocities assumed: noncrustal, 0.26 - 0
Bay surface area, 1 1 ,000 km 2.
100.00%
0.38%
0.15%
0.12%
13.70%
1.97%
46.77%
34.52%
2.60%
0.70%
0.02%
0.01%
4.53%
0.69%
72 cm/s: crussl.
1072137
581
2949
121
1428
2453
549127
10715
3093
4224
2768693
1455
4725
11486
1 .4 cm/s.
797820
637
2765
119
1328
2383
416867
8855
3464
3890
2410696
1381
3758
12731
2257130
1594
8139
334
3316
6519
1198160
23387
8192
11570
7664325
4028
12219
31262
1679621
1753
7638
329
3204
6397
914908
19855
9218
10646
6673123
3823
9763
34849
Table IV.10.
Data summary and annual flux estimates tv the Chesapeake Bay.
4-85
-------
to a low estimate for this element for Lake Michigan.
The much smaller areal Pb flux for the Bay reflects the
phase out of leaded gasoline. The Bay is shallow (mean
depth is only 6m) but its surface area (1.1 x 1010 m2) is
comparabletothatofLakeMichigan(Z9xl010m2). Thus
its potential for atmospheric contamination may be
significantly grater than that of Lake Michigan.
Average wet fluxes concurrently determined by
Scudlark et aL (in Baker et al, 1992) for the three Bay sites
are listed in the last column of Table IV. 11. As indicated,
dry fluxes were substantial, accounting for a minimum
of approximately 80% of the total atmospheric fluxes for
crustal elements Al and Fe; -50% for As, Cr, Cu, and Ni;
-40% for Mn, Pb, and Zn; and -19 for Cd. Gatz (1975)
obtained values near 50% for all of these elements and
Strachan and Eisenriech's (1988) value for Pb was 19%,
possibly suggesting regional differences in source
strengths or in scavenging processes.
Dry deposition estimates, however, remain uncertain.
Keeler ef al. (1992) observed that concentrations of par-
ticulate-bome elements were typically greater in air
over Lake Michigan than in air over adjacent land site.
If this were true for the Chesapeake Bay, then our land-
based measurements may underestimate Chesapeake
Bay air loadings and deposition fluxes. Furthermore,
recent evidence (Holsen et aL, 1992) suggest that large
particles (ie., aerodynamic diameter >10 to 100 jun)
may control the deposition of anthropogenic and crustal
elements. In our study, we considered only particles
<10 nm. If the large particle hypothesis is true, then dry
deposition to water might be severely underestimated.
Finally, the underlying physics suggests that dry depo-
sition to water surfaces occurs episodically, i.e., during
periods of high turbulence and great atmospheric insta-
bility. The disparity between deposition velocities for
different wind speeds is so great that the deposition
associated with a wind speed of 20 m • s'1 for 10 minutes
a day would be equivalent to the deposition associated
with an entire week at an average wind speed of 5 m»
s'1. Thus, a small fraction of periods of high turbulence
could lead to substantially enhance deposition relative
to the estimates made herein.
Trace Elements in Precipitation
Concentrations
The weekly measured trace element concentrations in
precipitation collected at both sites are summarized in
Figures IV.75 through IV.96. As a general observation,
Mean V a, cnVs
This work
Low High
Al
As
Br
Cd
Cr
Cu
Fe
Mn
Ni
Pb
S
Se
V
Zn
1.4
0.27
0.26
0.26
0.47
0.28
0.85
0.76
0.29
0.27
0.26
0.26
0.31
0.27
4.00
0.74
0.73
0.72
1.31
0.78
2.43
2.15
080
0.74
0.72
0.72
0.87
0.75
Gate1
1.30
• 0.22
(0.45)
0.50
(0.50)
1.10
0.56
(0.45)
030
0.29
OE2
Dry Deposition Flux, ug/m 2/yr Bay Wet Flux
This work
Low Hah
64030
54
270
11
110
290
34030
700
330
370
230000
130
3=0
1030
180030
150
750
32
300
810
97030
2030
910
_ 1030
640030
350
1100
2900
1 Estimates from data of Gatz (1 975), 2Dolske and Sevenng (1979): and
(1988).
Lake Michigan Church et al. (1 992)
liq/m^Vr
22000,21000
35
58
130
800,690
47200, 52000
890,2100
210
3900,17000 2, 360 3
360
2000, 6900 2
Strachan and Eisenretch
13600
49
48
88
260
10400
1190
257
556
214
1335
Table IV.11.
Deposition velocities and annual flux estimates lor the Chesapeake Bay.
4-86
-------
Aluminum - Wye
550
500
450-
400-
350-
300
250
concentration (ug/L)
200-
150-
100-
50--
10 15 20 25 30 35
Julian week 1990
40
45
IT TV
50
550
concentration (ug/L)
500 -
450-
400-
350-
300-
250-
200-
150-
100-
50-
0
1
i i i
5
ffr
i TT i
10
i i i i i i i i i i i i i i i i i i i i i i i
15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.75. Weekly integrated aluminum concentrations in precipitation from the Wye CBADS site.
4-87
-------
Aluminum - Elms
460
400
350
300
250
200
160
100
50
concentration (ug/L)
|.T|Th
15 10 15 20 26 30 36 40 45 50
Julian week 1990
A CA _
4OO -
.4 AA
4OO •
3OQ
9OO
OCA -
«ou
AAA -
zoo -
4 CA -
TOO
TOO
CA .
6O
0_
concentration (
T f T?!T T
TTTI i TTTTjT
1 5 10
ug/L)
f T!T -f If T
15 20 26 30 35 40 45 50
Julian week 1991
Figure IV.76. Weekly integrated aluminum concentrations in precipitation from the Elms CBADS site.
4-i
-------
Arsenic - Wye
0.25
concentration (ug/L)
0.15
0.1
0.05
I,
,
I
I, I
I,
15 10 15 20 25 30 35 40 45 50
Julian week 1990
0.25
concentration (ug/L)
0.2-
0.15-
0.1 -
0.05-
15 10 15 20 25 30 35
Julian week 1991
40
i i n i i (I r
45 50
Figure IV.77. Weekly integrated arsenic concentrations in precipitation from the Wye CBADS site.
4-89
-------
Arsenic - Elms
concentration (ug/L)
u.iz -
.1
.08 -
.06 -
.04
.02
n -
1
III
10 15 20 25 30 35 40 45 50
Julian week 1990
0.12
concentration (ug/L)
0.1 -
0.08-
0.06-
0.04-
0.02-
i i i i n i i i i i i i i i i i i i i i i i i i i
15 10 15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.78. Weekly integrated arsenic concentrations in precipitation from the Elms CBADS site.
4-90
-------
Cadmium - Wye
0.3
0.26
0.2
0.16
0.1
0.05
oonoantratlon (ug/L)
0.3
concentration (ug/L)
0.26
o.e
0.16
0.1
0.05 +•
u
16 101620268086404660
Julian week 1990
16 10 16 20 26 80 86 40 46 60
Julian week 1991
Figure IV.79. Weekly integrated cadmium concentrations in precipitation from the Wye CBADS site.
4-91
-------
Cadmium - Elms
concentration (ug/L)
u.»-
00 _
.0
0«p
.7
.O"
0£ _
.O
O.4
.3
.2
04 _
.1
o-
1 ll
nll.iiiii.TTTfl
1 6
10
15 20 25 30 36
Julian week 1990
40 46 60
0.9
concentration (ug/L)
0.8
0.7
0.6
0.6
0.4
16 20 25 30 35
Julian week 1991
40 45
50
Figure IV.80. Weekly integrated cadmium concentrations in precipitation from the Elms CBADS site.
4-92
-------
Chromium - Wye
concentration (ug/L)
ll
•
, ••••• , • , ,-•••• , ••-
10 IS 20
Julian week 1990
so
concentration (ug/L)
e-
5
4
3-
2-
1 -
0
!-.-•-.- — — T^ . T~ T-T"*-r~ . T . i i i i . i—
t I I I I I i I I i ! I I Ii I i I ! I I I I I I I I I I f I I I I I I I I I | I | I T
10 15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.81. Weekly integrated chromimum concentrations in precipitation trom the Wye CBADS site.
4-93
-------
Chromium - Elms
1.2
concentration (ug/L)
0.8
0.6
0.4
0.2
,l
-r*nr
• -•• , -- , •-.-••
10 15 20 25 30 35 40
Julian week 1990
45 50
1.2
concentration (ug/L)
1 -
0.8-
0.6-
0.4
0.2-
Dill
10 15 20 25 30 35
Julian week 1991
40 45 5O
Figure IV.82. Weekly integrated chromium concentrations in precipitation from the Elms CBADS site.
4-94
-------
Copper - Wye
concentration (ug/L)
2.5
2-
1.5
1
0.5
it
15 10 15 20 25 30 35 40 45 50
Julian week 1990
concentration (ug/L)
2.5
0.5
2 -
1.5
1 -
iJjL
IL
A
1111111111111111111111
15 10 15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.83. Weekly integrated copper concentrations in precipitation from the Wye CBADS site.
4-95
-------
Copper - Elms
concentration (ug/L)
0 'i i i i i i i i i it i i i i i i i i i I'l
J
HIM i
iiLUi
...I)
iTTTTf I f'Tl'
16 10 16 20 26 30 36 40 46 60
Julian week 1990
concentration (ug/L)
Ml -I
fr¥
1
Ij
16 10 16 20 26 30 36
Julian week 1991
40 46 50
Figure IV.84. Weekly integrated copper concentrations in precipitation from the Elms CBADS site.
4-96
-------
Iron - Wye
400-
300
concentration (ug/L)
200
100-
rWrm
rf Trf T
i i i i i i i i i i i ..... i i i i i i i i i i
15 10 15 20 25 30 35 40 46 50
Julian week 1990
400
concentration (ug/L)
300-
200-
100-
rr
llll.ll lilL I
ITTTTTTITI I I I I I I I I I I I I I I I I I I I I I I I I
15 10 15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.85. Weekly integrated iron concentrations in precipitation from the Wye CBADS site.
4-97
-------
Iron - Elms
250
concentration (ug/L)
200
150
100
50
0-V-r
•ll .l.j.ll
m
rfTTTT1
15 10 15 20 25 30 35 40 45 50
Julian week 1990
250
concentration (ug/L)
200-
150-
100-
50-
0 TTTi iTTTTiTTTiTTTTTTTTTTTTTTill i i i i—i i i i i i . i i i i i i i i i
15 10 15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.86. Weekly integrated iron concentrations in precipitation from trie Elms CBADS site.
4-98
-------
Manganese - Wye
concentration (ug/L)
40
35
30
25
15-
10
0 i i i i i i ; i i i i
1 5 10
l l I I l l l l I I I I I I
15 20 25 30
TlTTTfTliTflfiTT.TfTfilTi
35
40
45
50
Julian week 1990
45
concentration (ug/L)
40-
35-
30-
25-
20-
15-
10-
5--
4^-f^
fT"T?TTTTf?ifTiTTT.Ti HIM ii
15 10 15 20 25 30 35
Julian week 1991
40 45 50
Figure IV.87. Weekly integrated manganese concentrations in precipitation from the Wye CBADS site.
4-99
-------
Manganese - Elms
25-
20-
15-
10-
5-
o-
25-
20-
15-
10-
5-
o-
concentration (ug/L)
• III . Ll 1 • II 1 •
i i i i i i i i i T i i~i i i i i i i i i i i i i i i i i > i i i i > i i i i i i i i i i i i i i i i i
15 10 15 20 25 30 35 40 45 50
Julian week 1990
concentration (ug/L)
—
—
^jJ
_ .. —
-
_ . —
H
,,ll
I,
- - - - - -----
-
__
..II.
15 10 15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.88. Weekly integrated manganese concentrations in precipitation from the Elms CBADS site.
4-100
-------
Nickel - Wye
concentration (ug/L)
1.8-
.6 "
1.4-
.2 -1
1 -
.8 -
0.6-
0.4-
0.2-
o-
1 1
— . - ...... _ • • "
III T Mi
l l l l l l l i i i l l l l l l l l 1 l l l 1 l 1 l l TTT T I TT TTTT I T
15 10 15 20 25 30 35 40 45
Julian week 1990
concentration (ug/L)
2-]
1.8-
1.6-
1.4-
1.2-
0.8-
0.6-
0.4-
0.2-
o-
— ... ... . ... .
------ - - - -- . _ .
. _
-
l|| L l Illl Iff
i TT 1 1 1 TT T TTTT TlTT IT II 1 II Mill
15 10 15 20 25 30 35 40 45
Julian week 1991
1 "I
50
---
i i i i i
50
Figure IV.89. Weekly integrated nickel concentrations in precipitation from the Wye CBADS site.
4-101
-------
concentration (ug/L)
3 -
2.5-
2-
1.5-
1 -
0.5-
Nickel - Elms
i i i i i r i i T ! i i i i i i
5 10 15
concentration (ug/L)
"
2.5-
2-
1.5-
1 -
0.5 J
---
i i i i i i i i i i
1 5 10
-
l-l
T i T i
15
lILji
II
1 III.! 1 •••II
• 1 1 1 1 1 1 1 1 1 § 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
20 25 30 35 40 45 50
Julian week 1990
1
~-
i,l
_ . . ._.
l.lll,
-
T III i 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
20 25 30 35 40 45 50
Julian week 1991
Figure IV.90. Weekly integrated nickel concentrations in precipitation from the Elms CBADS site.
4-102
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Lead - Wye
concentration (ug/L)
W I I I I I II ~T'"I~r~I I I I II I
10
16 20 26 30 *6
Julian week 1990
46 60
concentatlon (ug/L)
2.5
2
1.5
0.5
1
1
16 10 16 2O 26 SO 86 40 46 60
Julian week 1991
Figure IV.91. Weekly integrated lead concentrations in precipitation from the Wye CBADS site.
4-103
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Lead - Elms
concentation (ug/L)
1.6- —
O-'TT
10 15 20 25 30 35 40 45 50
Julian week 1990
concentation (ug/L)
o -
4.5-
4-
3.5-
3-
2.5-
2-
1.5-
„
— —
—
-
—
- -
_ . .
1 I
0.5-
nil
—
- —
-
\ 1
TTT i i T T i : i i
- - - - —
- - - -
. _
- -
—
- --
ill
T i TT
-
I
T
-
--
,l
TT
_ _
- -
- -
-
||
i T
1 5 10 15 20 25
_
—
-- — - - — -
Ii
I
30 35 40 45 50
Julian week 1991
Figure IV.92. Weekly integrated lead concentrations in precipitation from the Elms CBADS site.
4-104
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Selenium -
concentration (ug/L)
.7
0.6-
.5 -
.4 -
0.3-
0.2-
0.1 -
0 i i i i i i i i i i i i i i i i i i i i i i
15 10 15 20
Julian
concentration (ug/L)
.7 -
0.6-
0.5-
0.4 J
0.3 J
0.2-
0.1 -
1
_- - —
1 liilll
1
-
-
i i i i i i i i i i i i i i i i i >
15 10 15 20
Julian
-
Wye
ll
25 30 35
week 1990
—
_.._
I
—
— ~~ - - -.
1 I • II!
25 30 35
week 1991
-
1
40
40
1
II
1 1 1 I 1 T 1 T
45 50
— ...
...
—
45 50
1
i
-
-
Figure IV.93. Weekly integrated selenium concentrations in precipitation from the Wye CBADS site.
4-105
-------
Selenium - Elms
concentration (ug/L)
0.8 H
0.6
0.4 H
0.2
1,1
.1
1,1 , .11
15 10 15 20 25 30 35 40 45 50
Julian week 1990
concentration (ug/L)
0.8-}
0.6 H
0.44
0.2
0 TT i i i i
15
rf-
iill
i T i TT i T i TTT i T i i i i i i i i i i i i i i i i i i i i i i i i i i
10 15 20 25 30 35 40 45 50
Julian week 1991
Figure IV.94. Weekly integrated selenium concentrations in precipitation from the Elms CBADS site.
4-106
-------
14
12 -
10 -
-
-
-
-
J
~
12-
10-
8-
6-
4-
;
0
Zinc - Wye
concentration (ug/L)
"" I II
Ihl. ilh.iiiiii.
15 10 15 20 25 30 35 40 45 50
Julian week 1990
concentration (ug/L)
III IL llllll I III ll I
TTT i i i TTT TiTTTT T i TT 7 TT > T MM i i i i i M M M M
15 10 15 20 25 30 35 40 45 50
Julian week 1991
-
Figure IV.95. Weekly integrated zinc concentrations in precipitation from the Wye CBADS site.
4-107
-------
concentration (ug/L)
4 C
TO ~
4 n —
TO
5_
Zinc - Elms
T i i i t i i i i i i i i i t i
15 10 15
concentration (ug/L)
20
is-
le-
s'
0_
In .1
1 1 1 1 I 1 t
1 5
10
1 ..
T i TT
15
.ill .Ll.
I II • I»H
i i i i i i i i i i i i i i • i i > i t t ( i i i i i . i t i i i
20 25 30 35 40 45 50
Julian week 1990
1
..I
..ni .
-
20 25 30 35 40 45 50
Julian week 1991
Figure IV.96. Weekly integrated zinc concentrations in precipitation from the Elms CBADS site.
4-108
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many elements (e.g., As, Cu, Cr) exhibit a seasonality, char-
acterized by maximum concentrations during the summer.
This behavior parallels observed trends in the acid compo-
nents (H+, S&\, NQ3) in the northeast U.S., which has been
attributed primarily to photochemically enhanced rates of
acid precursor oxidation during summer (Lindberg, 1981).
However, for atmospherically-derived trace elements, other
meteorological and physical processes are probably more
important than chemical reactivity in contributing to the
observed seasonality. These processes would include seasonal
differences iru a) storm trajectory, favoring atmospheric
transport from concentrated mid-west U.S. emission regions
during summer (Church and Scudlark, 1992),
b) micrometeorology, whereby summer convective precipi-
tation events effectively scavenge a larger portion of the
boundary layer (often 50-60,000 ft.) compared with typical
winter frontal storms, and c) precipitation amount, typically
lower in summer storms, which often yields samples with
higher concentrations (as previously discussed). In fact, all
of the "spikes" which appear in the weekly concentration
record correspond to low volume precipitation events.
Although source attribution and elucidating scavenging
mechanisms are important factors, they are not within the
scope of this study. Thus, it is not possible to distinguish the
degree to which each of the above three factors is responsible
for the observed intra-annual trends.
In this study, we assume that the precipitation concen-
trations and wet fluxes measured at the land-based sites
are representative of those over the Chesapeake Bay
surface. As discussed earlier in this section, atmo-
spheric aerosol concentrations and fluxes (and presum-
ably precipitation by which they are scavenged) over
water can be significantly different than those mea-
sured over land. Despite these caveats, for practical and
logistical purposes, it was not possible to conduct our
routine sampling at stations over the water. However,
during this phase of the CBADS program we were
afforded a unique opportunity to sample a precipitation
event (23 October 1990) onboard ship in the Chesapeake
Bay at a station off the Potomac River (76°17.58'W x
37°39.65'N) coincidentally with several land-based sites,
using identical sampling and analysis protocols (Table
IV.12).
While any conclusions based on this comparison of only
one isolated set of samples would be tenuous at best, an
interesting pattern is evident:
(a) Crustally-derived elements (Al, Fe, and to some
extent Mn and Cr) exhibited lower concentrations
over water than land. This seems reasonable for
crustal elements which are typically associated with
Chesapeake Bay
(Shipboard)
Wye CBADS
Elms CBADS
Beltsville, MD
Lewes, DE
Al
1.9
3.8
2.5
1.9
1.3
Cd
0.013
0.007
0.001
0.007
0.067
Cr
0.025
0.199
0.081
0.140
0.032
Cu
0.09
0.18
0.10 "
0.13
0.17
Fe
1.4
2.7
3.2
3.6
0.8
Mn
0.07
2.65
0.34
0.14
0.10
Ni
0.66
0.29
0.14
0.05
0.10
Pb
0.27
0.17
0.13
0.09
0.13
Zn
0.16
0.77
0.23
0.56
0.19
Table IV.12.
Comparative precipitation concentrations (ng/L) at five Mid-Atlantic sites (volume-weighted average).
4-109
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ground-based, locally dominant emissions of large
(>2.5 pm) particles which tend to dry deposit close
to their source.
(b) The precipitation concentrations of some (Cd, Ni,
Pb),butnot all anthropogenically-derived elements,
were higher over water than land.
More extensive sampling is obviously required to test
the hypothesis that the deposition of some trace ele-
ments over water differs from that which is observed
over land.
Wirf Deposition
Monthly-integrated atmospheric wet fluxes, which ap-
pear in Figures IV.97 through IV.107, were directly
calculated for each site based on the total measured
precipitation amount (gauge) and the monthly volume-
weighted average trace element concentration.
The total monthly precipitation amount is utilized to
calculate wet deposition whether or not the volume was
sufficient for analysis. Thus, this calculation inherently
assumes that the trace element concentrations in the
events not analyzed (predominantly low precipitation
events) are equal to the monthly average concentration.
In reality, this assumption probably results in a some-
what conservatively-estimated atmospheric wet flux
rate, since low volume events typically exhibited higher
than average concentrations (Lim et al., 1991).
The data in Figures IV.97 through IV.107 reveal the
following general trends. The atmospheric fluxes for
crustal elements (Al, Fe and Mn) showed dramatic
peaks in wet deposition at both sites in March (and to a
lesser extent in June/July, 1991), although these peaks
were not associated with the same events or weekly
samples. It is also interesting to note that the peaks
evident in wet deposition danot parallel corresponding
peaks in aerosol concentrations. This inconsistency
suggests that the aerosol and precipitation composi-
tions may reflect different sources when the boundary
layer is not well-mixed. It is also possible that peaks in
transport and deposition revealed by episodic precipi-
tation events are less resolved with weekly-integrated
aerosol measurements. Furthermore, the Al/Fe ratios
at Wye (1.25) and Elms (1.40) were somewhat less than
would be predicted from a pure crustal source (1.69)
(Turekian and Whedepohl, 1961), indicating either a)
the preferential scavenging of Al, which is unlikely, or
b) the presence of secondary anthropogenic sources
having a lower Al/Fe ratio. Coal flyash (Al/Fe= 1.0;
Bertine and Goldberg, 1971) is one likely candidate.
Theatmospheric fluxes of anumber of anthropogenically
derived elements (e.g., As, Cd, Cr) exhibited a season-
ality whereby maximum fluxes were observed during
summer (Church and Scudlark, 1992). This trend re-
flects seasonal variability in emission rates as well as
meteorology (precipitation amount, storm type and
trajectory). For all elements examined, the atmospheric
Element
Al
As
Cd
Cr
Cu
Fe
Mn
Ni
Pb
Se
Zn
WYE
%
Total Crustal3
17,554 100
52 6
51
128 16
275 4
14,003 74
1,514 13
272 5
554
287
1,448 1
ELMS
%
Total Crustal3
9,557 100
45 4
36
48 23
244 2
6,844 82
864 12
241 3
557
140
1,121 1
Flux Ratio
(Wye/Elms)
1.84
1.44
1.42
2.66
1.13
2.05
1.75
1.13
0.99
2.05
1.29
•less than 1%
a Al normalized
Table IV.13. Annual wet deposition (6/90 - 7/91) at two
Maryland CBADS sites (Mg/mVyear).
4-110
-------
8,000
6,000
4.000 -
2,000
ALUMINUM
Wye
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Deo Jan Feb Mar Apr May Jun
I 1990 I 1991 I
Elms
8,000
6,000
4,000 -
2,000
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Peb Mar Apr May Jun
I 1990 I 1991 I
Figure IV.97. Monthly average wet deposition of aluminum at two Maryland CBADS sites.
4-111
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ARSENIC
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Elms
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV.98. Monthly average wet deposition of arsenic at two Maryland CBADS sites.
4-112
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CADMIUM
Wye
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb liar Apr May Jun
1990 I 1991
Elms
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV.99. Monthly average wet deposition of cadmium at two Maryland CBADS sites.
4-113
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CHROMIUM
Wye
deposition (ug/m2/month)
10
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
I 1990 I 1991
Elms
50
deposition (ug/m2/month)
40 -
30 -
20
10-
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV.100. Monthly average wet deposition of chromium at two Maryland CBADS sites.
4-114
-------
COPPER
Wye
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
I 1990 I 1991
Elms
deposition (ug/m2/month)
20 -
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV. 101. Momnly average wet deposition of copper at two Maryland CBADS sites.
4-115
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IRON
Wye
4,000
3.000
2,000
1,000
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nor Dec Jan Peb liar Apr May Jun
I 1900 I 1891
Elms
4,000
3,000
2.000
1,000 -
deposition (ug/m2/month)
Jun Jul Aug Sep Oct NCTV Dec Jan Feb Mar Apr May Jun
I 1990 I 1991
Figure IV.102. Monthly average wet deposition of iron at two Maryland CBADS sites.
4-116
-------
LEAD
Wye
120
deposition (ug/m2/month)
40
20
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
I 1990 I 1991 I
Elms
120
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV.103. Monthly average wet deposition of lead at two Maryland CBADS sites.
4-117
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600
MANGANESE
Wye
deposition (ug/m2/month)
100
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991 I
Elms
600
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV.104. Monthly average wet deposition of manganese at two Maryand CBADS sites.
4-118
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NICKEL
Wye
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991 I
Elms
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV.105. Monthly average wet deposition of nickel at two Maryland CBADS sites.
4-119
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SELENIUM
Wye
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991 I
Elms
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
1990 I 1991
Figure IV.106. Monthly average wet deposition of selenium at two Maryland CBADS sites.
4-120
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ZINC
Wye
450
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
I 1990 I 1991
Elms
450
deposition (ug/m2/month)
Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
I 1990 I 1991
Figure IV.107. Monthly average wet deposition of zinc at two Maryland CBADS sites.
4-121
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wet deposition was higher at the Wye site than at the
Elms site (Table IV.13) despite lower precipitation
amounts (90 cm vs. 116 cm, respectively). This spatial
trend probably reflects the combined influence of a) the
Baltimore, MD and Washington, D.C. emission plumes,
and b) regional agricultural land use and farming
practices, which contribute to elevated atmospheric
fluxes of elements with a significant crustal source (Al,
Fe, Mn, and Cr).
Using Al as a crustal normalizer, we can factor out the
crustal component to the observed fluxes based on
reported soil elemental ratios (Turekian and Wedepohl,
1961).
Except for Al, Fe, Mn and Cr, the crustal contribution to
the observed fluxes is relatively minor (Table IV.13).
The spatial variability in annual wet fluxes, expressed
as the Wye/Elms ratio varies from 0.99 (Pb) to 2.66 (Cr)
(Table IV.13). Taking into account the fact mat the
annual precipitation at the Wye site was below average
while the Elms precipitation was above average, the
spatial difference in wet deposition could be magnified
under more typical meteorological conditions. On a
monthly time scale, the inter-site variability can be as
much as a factor of 10, and is even larger on a weekly or
event basis (see Table IV.12).
In terms of temporal variability, the average monthly
wet deposition flux for a given element at each site was
also highly variable, deviating by as much as a factor of
50 during the 13 month data record. As is the case with
spatial variability, the temporal variability increased
with a decreasing time scale (weekly or event). Thus, the
atmospheric wet flux of elements to Chesapeake Bay appears
to be a very heterogeneous process with respect to space and
time, requiring employment of multiple sites over a long time
frame to accurately assess.
Due to the paucity of other reliable measurements, it is
difficult to put the CBADS fluxes in perspective either
spatially or with respect to long-term trends. However,
the following precipitation trace element data have
been reported in the Chesapeake Bay region which can
be used as a basis of comparison:
a) Lewes, DE (Church and Scudlark, 1992) - The aver-
age wet fluxes for the period 1982-89 were reported
at the mid-Atlantic coast, based on identical collec-
tion, processing and analysis methods as the CBADS
Network. Other than the Great Lakes (GLAD) data,
this represents the only long-term continual record
of trace elements in precipitation in the U.S.
b) Lower Chesapeake Bay (Wade and Wong, 1982) -
Collections were conducted using unspecified
techniques at four sites in the lower bay (Virginia)
from December 1980-February 1982. To derive wet
fluxes, we arithmetically averaged the reported
concentration data from the four sites, and assumed
an average precipitation amount of 100 cm/yr.
c) Upper Chesapeake Bay (Conkwright et al., 1982) -
Sampling was conducted from April 1981 through
April 1982 at six upper bay (Maryland) sites, two of
which were in close proximity to the CBADS Wye
and Elms sites. Collections were conducted using
an ACM collector with an acid-washed bucket liner
coupled with other trace metals "clean" observances.
Wet fluxes were calculated from the arithmetic
average concentrations from the six sites, assuming
average annual precipitation of 100 cm/yr.
d) BeltsvUle, MD (Scudlark, Church and Conko, un-
published) - In conjunction with an independent
source attribution study, precipitation was sampled
from July-November, 1990, on the grounds of an
abandoned airstrip at the USDA Experimental Sta-
tion. These somewhat limited measurements were
extrapolated to derive annual fluxes. However, by
employing collection and analysis methods identi-
cal to the CBA.DS Network, one major source of
variability was eliminated in attempting to exam-
ine spatial/ temporal trer ds. Wet fluxes were calcu-
lated from t; arithmetic average concentrations,
assuming annual precipitation of 100 cm/yr.
These wet fluxes are summarized in Figure IV.108 (it
should be noted that not all elements were analyzed in all
the studies). In general, the CBADS fluxes were consistent
with those measured "upwind" at Beltsville, suggesting
4-122
-------
« i!
i i
oa
u
2 ~
S °
5 ^
s r
* S
a Ok
- Ck.
W P
Q S
S 5
0
I
Figure IV.108. Variability in the wet deposition of selected trace elements at various sites in the Chesapeake Bay region.
4-123
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that the bay inherits a dominant regional source from
more distant sources. For most anthropogenically-de-
rived elements (notably Pb, Ni, Zn, Cd and Cu), the long-
term average fluxes measured at Lewes were somewhat
higher thanmosemeasuredaxitemrx>rarilyinthe CBADS
Network. For Pb, this is not an unanticipated result, due
to the phasing out of alkyl-Fb additives in gasoline over
this period. In fact, the eight-fold decrease in the precipi-
tation Pb concentration observed over the past decade at
Lewes (Church and Scudlark, 1992) closely parallels the
estimated decrease in the atmospheric Pbburden over this
period (Shen, 1991).
For the other elements of interest, due to the temporal
incongruity in the data, it is not possible to discern if the
discrepancies between the Lewes and CBADS wet fluxes
represented a spatial or temporal trend. This inconsis-
tency can only be resolved by comparison of the CBADS
data to Lewes data for an identical time period (samples
from the Lewes site since January 1,1990 have been
collected and archived but analyses are pending fund-
ing). However, it is possible that enhanced deposition
at Lewes results from unique chemical climatology in
the marine coastal regime, which would be consistent
with the hypothesis suggested by the shipboard sample
comparison previously discussed (Table IV.12).
Except for Al, Fe and Mn, wet fluxes calculated from the
early 1980's EPA studies were 1-2 orders of magnitude
higher than the CBADS data. If these differences are real
(and do not simply reflect sampling/analysis artifacts), it
would suggest that precipitation trace element concentra-
tions have decreased dramatically over the past decade.
However, this hypothesis is not supported by our own
trace element record for this period at Lewes, which does
not indicate a decrease (except for lead).
The total atmospheric loading of trace elements to
Chesapeake Bay can be apportioned into wet and dry
components using the data collected in this study. The
data indicate that with the exception of the crustally-
derived elements, wet deposition is a major atmospheric
scavenging mechanism for the input of trace elements to
Chesapeake Bay. Qualitatively, the proportion of dry
deposition for crustal elements (AL, Fe) appears greater
than for wet deposition, while the wet deposition propor-
tion for noncrustal elements (Mn, Pb, Se, Cd) appears
greater than dry. However, the range of dry deposition
estimated particularly for noncrustal elements is consid-
erable which currently prevents accurate quantitative
apportionment of wet versus dry atmospheric fluxes.
Furthermore, the wet/dry flux apportionment for As
derived in this study agrees well with an independent
estimate based on a direct comparison of wet-only and
bulk (wet + dry) collections, which concluded that wet
flux comprised 45-71% of the total (Scudlark and Church,
1988).
4-124
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SECTION V
CONCLUSIONS
Common Trends and Interpretations
Great temporal variability was observed in the concen-
trations of organic contaminants and elemental con-
stituents of aerosol particles and rain. Large spatial
variations were also observed for trace elements in rain
but not for elemental constituents in aerosol particles
collected in week-long samples. The relative homoge-
neity of the latter suggests that surface air above the bay
is influenced by regional sources or by ubiquitous
sources of trace elements dispersed about the study
area. Spatial variation in organic contaminants was not
evaluated in this study. The great spatial variations in
trace element constituents of rain are presumed to
reflect spatial inhomogeneities in transport and scav-
enging processes for air parcels influencing the Chesa-
peake Bay. Differences in the temporal profiles for trace
elements in rain and aerosol particles suggest that sur-
face air above the Chesapeake Bay often differs from air
aloft. Thus, in-cloud processes scavenge aerosol from
different sources or source regions than do the below-
cloud scavenging processes. Air masses influencing the
bay have both continental and marine sources that
cause short-term temporal variations in meteorological
scavenging regimes. Longer term temporal variations
in inorganic pollutants in both aerosol particles and rain
reflect seasonal fossil fuel usage, peaking in the winter
heating and summer cooling seasons (i.e., for elements
such as As, Se, and V); peak photochemical activity in
summer months for S; and agricultural and construc-
tion activities in the spring and summer months for
crustal elements such as Al, Fe, and Mn.
Atmospheric Deposition to Chesapeake Maryland
Waters
The atmospheric deposition of contaminants to the
Maryland tidewaters of the Chesapeake Bay is summa-
rized in Table V.I from the data provided in this report.
The substantial uncertainty inherent in the calculation
of dry deposition results primarily from estimated un-
certainties in dry deposition velocities. The total atmo-
spheric loading of contaminants to Chesapeake Bay can
be apportioned into wet and dry components using the
data collected synoptically in this study. While the wet
and dry fluxes appear to be roughly comparable, the
dry deposition flux is still quite uncertain. Dry deposi-
tion depends on the size distribution of aerosol particles
and/or the structure of turbulence. In addition, the
importance of large particle deposition cannot be accu-
rately assessed from the data collected in this study.
Mathematical models of dry deposition mechanisms
suggest that dry deposition occurs episodically during
highly unstable periods. Dry deposition velocities esti-
mated for a wind speed of 20 m/s are nearly 200-fold
greater than those velocities f or 5 m/ s. Clearly, fluctua-
tions in wind speed and pollutant concentration should
be measured on very short temporal scales (e.g., on the
scale of minutes) to answer these questions.
Qualitatively, theproportion of dry depositionfor crustal
elements (e.g., Al, Fe) appears greater than for wet
deposition, while the wet deposition proportion for
non-crustal elements (e.g., Mn, Pb, Se, Cd) appears
greater than the dry. However, the range of dry depo-
sition estimates, particularly for non-crustal elements,
is considerable and currently prevents accurate quanti-
tative apportionment of wet versus dry atmospheric
fluxes. However, for arsenic the range reported here
agrees with previously reported estimates of wet/dry
apportionment at Lewes, Delaware (Church and
Scudlark, 1992), based on wet measurements similar to
those used here and dry flux modeling. Furthermore,
the wet/ dry flux apportionment for As agrees well with
an independent estimate based on a comparison of wet-
only and bulk (wet + dry) collections. They concluded
that wet flux comprised 45-71% of the total (Scudlark
and Church, 1988), which compares well with the range
of 39-64% estimated here for the Chesapeake Bay.
The proportion of atmospheric fluxes to fluvial fluxes-
from other point and non-point fluvial sources must
await better quality fluvial data. The utility of this
atmospheric deposition data for prioritizing the reduc-
tion of loadings of toxic substances to the bay will only
come about after low-level contaminant assays of equal
quality control are applied to fluvial routes of contami-
nant entry.
5-1
-------
Compound
A. Organic Compounds
Wet(l)
(Mg/m2/yr)
Dry (2)
(ug/m2/yr)
Total (3)
Gig/m2/yr)
Annual Loading (4)
(kg/yr)
(1) Polycyclic aromatic hydrocarbons
Huorene
Fnenanthrene
Anthracene
Fluoranthene
Pyrene
Benzo(a)anthracene
Chrysene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Benzo(e)pyrene
Benzo(a)pyrene
Indeno(123-cd)pyrene
Dibenz(ah)anthracene
Benzo(ghi)perylene
(2) PCB homologs
dichloro-
trichloro
tetrachloro
pentachloro
hexachloro
heptachloro
octachloro
total PCBs"
B. Trace Elements
Aluminum
Arsenic
Cadmium
Chromium
Copper
Iron
Manganese
Nickel
Lead
Selenium
Zinc
3
11
2
17
15
2
6
9
6
2
3
2
1
3
-
053
0.92
054
034
0.19
0.09
2.7
13,600
49
48
88
250
. 10,400
1,190
257
556
214
1,335
5
27
3
38
35
10
22
31
18
15
8
16
4
17
0.85
034
0.6
033
0.21
0.1
0.03
25
120,000
100
21
200
400
65,000
1300
540
690
240
2,000
±
±
±
±
±
±.
±
±
±
i
±
±.
i.
±
±
±
±
±
±
±
±
±
±
+_
±
+
±
+
±
+
±
±
±
1
8
0.6
10
9
4
7
10
5
6
3
6
1
7
0.4
02
03
02
0.1
0.05
0.02
12
57,000
50
10
%
190
31,000
640
250
320
110
960
8
38
5
55
50
12
28
40
24
17
11
18
5
20
0.9
0.9
IS
0.9
0.6
03
0.1
5
134,000
150
69
290
660
7300
2500
800
1,250
450
3300
42
200
27
290
265
64
148
210
127
90
58
95
27
106
5
5
8
5
3
2
0.6
27
710,000
790
370
1300
3300
400,000
13,000
4,200
6,600
2,400
18,000
i
±
±
i
±
±.
±
i
±
±
i
±
i-
i
±
±
±.
±
±
±
±
±
±
±
±
±
±
±
+
±
±
±
+_
6
41
3
52
50
20
40
53
28
32
13
33
6
36
2
1
2
1
05
03
0.1
6
300,000
270
50
500
1,000
160,000
3300
1300
1,700
600
5,100
(1) Wet deposition average fluxes, volume weighted from a) biweekly collections at the western shore site (organics), and
b) weekly collections averaged again at both eastern and western shore sites (trace elements).
(2) Dry deposition average fluxes, averaged for a)daily (Tuesday) sampling at only the western shore site (organics), and
b) weekly integrated collections averaged at both me eastern and western shore sites (trace elements). The error represents
the largest uncertainty which is the assumed dry deposition velocities (see text for details).
Simple sum of wet and dry fluxes. The error is that stated for dry deposition.
(3)
(4)
Annual loading is the total flux to that portion of the Chesapeake Bay below the fall line of all tributaries and north of
the Maryland-Virginia border (5.3x10 rrr).
Table V.1. Summary of atmospheric fluxes during year 1 (7/90 - 6/91) for the Chesapeake Bay Atmospheric Deposition
Study. The data are averages over the annual period.
5-2
-------
Future Research Initiatives
Recommendations for future research priorities for the
Chesapeake Bay Atmospheric Deposition Study Pro-
gram are offered. First, there needs to be a better
assessment of the organic contaminant and dry and wet
trace element deposition fluxes. Reducing the uncer-
tainty in atmospheric flux estimates can only come from
synoptic sampling at more sites, some actually over the
water, and the sampling of single meteorological events.
For these events, some meteorology and air mass trajec-
tory analysis would be necessary, together with some
chemical source assessment Because some of the varia-
tion, no doubt, stems from differential transport and
scavenging regimes altered that might be in their char-
acteristics near and over large coastal waters bodies,
sampling in the vertical would be necessary. All these
would be considered process-oriented studies that
would be required beyond simple pollutant concentra-
tion and flux monitoring.
As such, the objectives of future studies could be to:
a) determine the long-term temporal (inter-annual)
variability in precipitation and aerosol concentra-
tions and fluxes,
b) compare atmospheric fluxes to other geochemi-
cally / ecologically important inputs such as ground
water, fluvial, and watershed inputs that currently
must use data of limited quality and quantity in
space and time,
c) investigate atmospheric scavenging mechanisms
and their relationship to local meteorology (i.e., a
modeling-based sampling strategy).
d) identify atmospheric sources by geographic region
and/or emission type, including the influence-of
localized urban emissions on bay-wide deposition,
e) estimate the indirect atmospheric loading (via
watershed runoff from the drainage basin) to Chesa-
peake Bay. This requires the derivation of "trans-
mission/retention factors" for each trace element
or organic contaminant under differing land use
regimes, as well as additional wet flux measure-
ments in important Chesapeake Bay watersheds,
f) determine if atmospheric fluxes at the land-based
sites are truly representative of fluxes observed
over bay waters or over the watershed, and
g) improve estimates of dry deposition, including
improved deposition measurement elucidating the
role of large particles and episodic turbulent condi-
tionsmcarryingairbornecontaminantstotheChesa-
peake Bay.
Objectives (a) and (b) are addressed in Years 2 and 3 of
the expanded study under current EPA funding, with
objectives (c) and (d) being the specific focus of the
planned CBADS Year 3 intensive-phase experiments.
Achieving objectives (e), (f), and (g) will require ancil-
lary studies presently being considered/proposed un-
der funding from this program and EPA. Finally, the
utility of this atmospheric data for mitigation of toxic
contaminant inputs to the bay will occur only after low-
level contaminant assays of quality equal to those deter-
mined herein are obtained for other routes of contami-
nant entry.
5-3
-------
-------
ACKNOWLEDGEMENTS
This study was supported by a grant from the Maryland
Power Plant Research Program that is administered by
the Maryland Department of Natural Resources. The
encouragement and support of Dr. Paul Miller, Direc-
tor, is gratefully appreciated.
We wish to thank Dr. Russell Brinsfield at the Univer-
sity of Maryland Wye Research and Education Station,
and Mr. Rob Chapman at St. Mary's County Board of
Education, Elms Environmental Educational Center,
for permission to deploy sampling equipment at their
sites. We are grateful for the cooperation of the Mary-
land Department of the Environment in sharing pre-
cipitation chemistry data for the Elms site.
University of Maryland Center for Environmental and
Estuarine Studies Contribution Number 92-094.
-------
-------
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