EPA-600/3-77-038
April 1977
Ecological Research Series
. ,
','; ;•'"' : • -" •"-1 -'• * '• • ?iCTWct-f'!« ;4'tifttf fif"-;1>": *4l *-' -'"
INPUT OF PHOSPHORUS TO
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/3-77-038
April 1977
ATMOSPHERIC INPUTS OF PHOSPHORUS TO
SOUTHERN LAKE HURON, APRIL-OCTOBER 1975
by
Richard G. Delumyea and Resy L. Petel
Great Lakes Research Division
The University of Michigan
Ann Arbor, Michigan 48109
Grant R803086
Project Officer
Michael D. Mullin
Large Lakes Research Station
Environmental Research Laboratory-Duluth
Grosse lie, Michigan 48138
ENVIRONMENTAL RESEARCH LABORATORY—DULUTH
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
DULUTH, MINNESOTA 55804
..i:V!ft
M.
N. J. 08817
iAL PROTECTION AGENCY
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DISCLAIMER
This report has been reviewed by the Environmental Research Laboratory-
Duluth, U.S. Environmental Protection Agency, and approved for publication.
Approval does not signify that the contents necessarily reflect the views and
policies of the U.S. Environmental Protection Agency, nor does mention of
trade names on commerical products constitute endorsement or recommendation
for use.
ii
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FOREWORD
Our nation's freshwaters are vital for all animals and plants, yet our
diverse uses of water for recreations, food, energy, transportation, and
industry physically and chemically alter lakes, rivers, and streams. Such
alterations threaten terrestrial organisms, as well as those living in water.
The Environmental Research Laboratory in Duluth, Minnesota develops methods,
conducts laboratory and field studies, and extrapolates research findings
—to determine how physical and chemical pollution affects aquatic
life
—to assess the effects of ecosystems on pollutants
—to predict effects of pollutants on large lakes through use of
models
—to measure bioaccumulation of pollutants in aquatic organisms
that are consumed by other animals, including man.
This report evaluates the relative contributions of wetfall and dryfall
to the total atmospheric input of phosphorus to the southern portion of Lake
Huron. Airborne and other non-point sources can account for a significant
amount of pollutants coming into an ecosystem. These must be considered
when assessing the total impact of a pollutant on a body of water.
Donald I. Mount, Ph.D.
Director
Environmental Research Laboratory
Duluth, Minnesota
iii
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ABSTRACT
The input of phosphorus has been demonstrated to be seasonally dependent.
Of the total input, approximately half is potentially available, and one-
fourth is immediately available. Inputs due to wet and dry deposition are
roughly equal in magnitude. The major source appears to be agriculture with
at least 10% due to combustion sources. A model for particulate deposition
was used to determine the deposition velocity of phosphorus containing par-
ticles. The value of 0.6 cm/sec is considered applicable to other components
whose mean diameter is lym.
iv
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CONTENTS
Foreword ill
Abstract iv
Figures vi
Tables vii
Acknowledgments viii
Section:
1. Introduction 1
Objectives 1
Definitions 2
2. Conclusions and Recommendations 3
3. Procedures and Methods 5
Equipment 5
Sampling 6
Sample Preparation and Chemical Analysis 7
Meteorological Data 9
4. Results and Discussion 14
Total Fallout 14
Wet Deposition 16
Total Aerosol Loading 19
Aircraft Sampling 22
Aerosol Samples 25
Particle Size Distribution of Phosphorus 28
Determination of Deposition Velocity 29
5. Total and Relative Inputs of Phosphorus from Wet and Dry
Deposition 46
Wet Deposition 46
Dry Fallout 47
Total Deposition 47
Literature Cited 49
Appendix 51
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FIGURES
Number Page
1 Location of sampling devices aboard the ROGER R. SIMONS .... 6
2 Location of sampling and meteorological stations 8
3 Wind speed, direction and aerosol concentration roses 11
4 Monthly variation of available phosphorus in integrated
fallout samples 16
5 Comparison of rainfall, concentration of reactive phosphorus
in rain and total available phosphorus collected in inte-
grated samples, April-October 1975 18
6 Relationship between total aerosol concentration, soluble
and available phosphorus 21
7 Flight paths for aircraft sampling, 15-17 September 1975 ... 23
8 Plots of backscatter vs. altitude 26
9 Monthly aerosol total available phosphorus concentration ... 29
10 Size distribution of phosphorus in aerosol samples collected
from April through September 1975 38
11 Plot of aerosol available phosphorus for each station,
April-October 1975 39
12 Deposition (C/Co) vs. wind speed
13 Schematic representation of mixing box model for particle
deposition ......................... 43
14 Deposition velocity, Vd, vs. wind speed ............ 44
VI
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TABLES
Number Page
1 Comparison of R/V ROGER R. SIMONS and National Weather Service
data on wind direction 10
2 Integrated fallout samples-volume collected and available
phosphorus content, 1975 15
3 Comparison of observed and calculated rainfall 17
4 Phosphorus content of event rain samples, June-October 1975 . 19
5 HiVol loadings, June-October 1975 20
6 Aircraft particulate sample summary 24
7 Analysis of aerosol samples for soluble, reactive, and
bound phosphorus content 27
8 Average monthly aerosol phosphorus concentration . 28
9 Aerosol concentration of soluble and reactive phosphorus by
station for the months April-October 1975 30
10 Size distribution of phosphorus-containing particles, April-
September 1975 37
11 Calculation of deposition velocity at various wind speeds . . 44
12 Wet, dry and total available phosphorus deposition for the
months of April-October 1975 46
vii
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ACKNOWLEDGMENTS
This work was supported by the U.S. Environmental Protection Agency as
part of a grant (No. R-803-086) to Claire L. Schelske, Project Director, at
the Great Lakes Research Division of the University of Michigan. The support
and assistance of these two organizations are gratefully acknowledged.
The authors also wish to extend their thanks to the following persons
for assisting with the establishment of the sampling stations: W. J. Levering,
Gordon Brown and John Ohmstead, Inverhuron Provincial Park; Richard Murdie
and Jack Wick, Point Clark Boat Club; Dan Mansel and M. Blake Evans, Point
Farms Provincial Park; B. E. Snead and Tom Castle for permission to use the
Bayfield Marina; Frank J. Moore, St. Joseph; W. H. Carlton and Don Matheson,
Ipperwash Provincial Park; J. Janks, Paul R. Rearick and Dennis Swanson,
Lakeport State Park; the Board of County Road Commissioners of Sanilac County,
Dale Wheeler and Walter Erb and Gilbert Orris at Sanilac County Parks #2 and
#1; and the Board of County Road Commissioners of Huron County, Lester Ender
for permission to use Wagener and Lighthouse County Parks.
Our thanks are also extended to James V. Murphy, Captain of the R/V
ROGER R. SIMONS, and his crew for their help in collecting over-the-lake sam-
ples; to Chas. Fitzsimmons of the EPA-National Environmental Research Center,
Las Vegas, Nevada, and his crew for collecting the aircraft samples; and to
C. Robert Snider of the U.S. Weather Service Forecast Office, Detroit Metro-
politan Airport, for supplying the meteorological data.
The dedicated work of Barbara Kure, Isaac Walden and Jane Matthews in
collecting the samples under sometimes gruelling conditions accounted for
the success of the sampling scheme. Our thanks are also extended to Jill
Goodell, who performed the majority of the chemical analyses. Finally, the
helpful suggestions of and stimulating discussions with John Robbins, Great
Lakes Research Division, and Donald Stedman, Atmospheric and Oceanic Sciences,
University of Michigan, must be acknowledged as valuable aids to the program.
viii
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SECTION 1
INTRODUCTION
Upon completion of the Port Huron water tunnel, the southern portion of
Lake Huron will serve as the principal water supply for the Metropolitan
Detroit/Windsor and Port Huron/Sarnia areas. The quality of this water is
therefore important, and any adverse changes which may occur must be antici-
pated and, if possible, prevented. To do so, a knowledge of chemical species
which can affect water quality is necessary.
Phosphorus has been determined to be the limiting nutrient in the Great
Lakes system (Schelske & Stoermer 1971, 1972; Schelske et al. 1972; Miller
et al. 1974) and therefore inputs and fates of phosphorus should be routinely
monitored. It has been estimated that atmospheric inputs may account for up
to 50% of the phosphorus and nitrogen entering Lake Superior (Elder 1975).
In a study of the dissolved, suspended and scavenged phosphorus in precipi-
tation in the southern portion of Lake Michigan, Murphy (1974) concluded that
wet deposition alone accounts for 20-33% of the available phosphorus entering
the lake. If the input due to dry fallout had been considered, this value
would have been significantly higher.
It should be noted that all of the phosphorus entering the lake from the
air must pass through the layer of maximum biological activity (euphotic zone).
This is not true of river or lakewater inputs. Further, since dissolved phos-
phorus in rain provides an immediate but intermittent source of nutrient to
the biomass whereas dry fallout provides a continuous source, the effect of
each type of atmospheric input must be evaluated.
OBJECTIVES
The principal objective of this investigation was to determine the total
input of phosphorus to the southern portion of Lake Huron from the atmosphere.
This was achieved through the monthly collection and analysis of total inte-
grated fallout samples from 11 shore-based sampling stations. The relative
inputs of wet and dry fallout were determined by collection and analysis of
event rain samples and filtered particulate samples from the shore-based and
shipboard stations.
The majority of the work, however, involved the determination of the in-
put to the lake from dry fallout. This area has received little attention in
the past, due in part to the difficulty involved in collecting meaningful
data. To accomplish this objective, aerosol samples were collected from
shore-based, shipboard and aircraft-mounted sampling equipment. This inten-
sive investigation has resulted in a significant increase in the knowledge of
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dry deposition over lake surfaces.
DEFINITIONS
Total Soluble Phosphorus is defined as the amount of phosphorus (as
orthophosphate, PO^""^)in neutral unbuffered samples. For aerosol samples,
it is the amount of phosphorus (as POi^"3) obtained from complete extraction
of a filter with distilled water. Total Reactive Phosphorus refers to the
amount of phosphorus (as POi+~3) extracted with pH=2 sulfuric acid from a sam-
ple which has been previously extracted with distilled water. Total Available
Phosphorus is the sum of the soluble and reactive phosphorus. In the inte-
grated fallout samples, total available phosphorus was determined by analysis
of the acidified sample after filtration through glass fiber mats to remove
turbidity due to undissolved particles. Since these samples were pre-acidi-
fied, total soluble phosphorus values could not be obtained; therefore, for
comparison of aerosol and integrated fallout samples, total available phos-
phorus values were used. Total Phosphorus values were obtained by digestion
of samples in a persulfate/sulfuric acid medium and this term refers to the
sum of all phosphorus in the sample, including soluble, reactive, inorganic-
and organic-bound phosphorus. Samples are referred to by the method of
collection, e.g., Andersen, HiVol and Gelman refer to aerosol samples collec-
ed by Andersen cascade impactors, high volume samplers, and Gelman Air Sam-
pling Kits, respectively.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
This one-year duration study has differentiated between wet and dry
atmospheric inputs and has determined 3 types of phosphorus entering the lake,
based on potential impact on the lake. This approach has been shown to be
superior to the collection of total integrated fallout samples that are sub-
ject to contamination from local sources and do not accurately reflect the
input over the open lake. Due to chemical changes in fallout samples which
occur during the collection period, the actual form in which the chemical
species would have entered the lake is not known. Using integrated fallout
collectors, the rate of available phosphorus input to the lake was determined
to be 6.5 ng/cm2/dy, which is approximately one-third of the total atmospheric
input to the lake. This is significantly higher than the sum of the wet (2.2
ng/cm2/dy) and the dry input (1.7 ng/cm2/dy). For both wet and dry inputs,
approximately 1/4 of the total input of phosphorus is immediately soluble and
half is potentially available. During periods of reduced biological activity,
the sum of wet and dry depositions accounts for 73% of the amount observed
from integrated fallout collectors, however. Both types of phosphorus input
are seasonally dependent, being highest in the spring and fall. On the basis
of this and from total atmospheric loading and the particle size distribution
of the phosphorus-containing particles, it has been concluded that a majority
of the phosphorus inputs is due to agricultural activity. A significant
portion (10% or more) may be attributed to combustion sources derived from
combustion of fossil fuels. A simple mixing box model was employed in the
study of particulate deposition. From this model, a value of 0.6 cm/sec for
the deposition velocity of the phosphorus-containing particles was obtained.
This value can now be used to test more sophisticated models.
From the work reported here, several recommendations can be made. While
they are suggestions as to how the present study could have been improved,
they should be applied to future studies as well. Shipboard collection of
samples for atmospheric studies was found to be expensive and inefficient.
Contamination from the ship and its exhaust hampered aerosol collection, and
"bad" weather forced the ship to remain in port when wet deposition was occur-
ring. In its place, a permanently anchored platform with a source of electric
power should be established and adequate protection taken against contamination.
In the long run, this should result in a more favorable cost-to-benefit ratio.
Any attempt to determine annual inputs must cover at least two consecutive 12-
month periods. The vertical distribution of aerosol concentration must be
determined in order to properly evaluate the mixing box model. This was
attempted in the present study but was unsuccessful. The next study should
include the determination of this parameter. The validity of total fallout
measurements has already been questioned. In the future, the independent
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measurement of wet and dry deposition should be employed. In addition to
providing more realistic input data, this will permit evaluation of the im-
pact of any input through analysis of the chemical form of the species. Per-
haps most important, a standard set of definitions should be established to
classify the effective form of each species according to potential availabil-
ity—for example, the soluble, reactive and total phosphorus determined in
the present study.
In summary, the input of phosphorus to Lake Huron from the atmosphere
has been shown to be significant. The amount entering through dry deposition
has been shown to be larger than previously anticipated. For other elements
(e.g. selenium and lead) this may be the predominant input mode. For this
reason, additional research is needed on the long-range transport and depo-
sition of particulate matter. Such work should be expanded tc consider a
large number of elements and classes of compounds whose potential impact on
the lake must be known.
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SECTION 3
PROCEDURES AND METHODS
EQUIPMENT
Gelman Air Sampling Kits (Bendix Environmental Science Division, 1400
Taylor Ave., Baltimore, MD, catalog No. 25004) were modified for field use
by removal of the external flowmeter, attachment of locks and chains and the
installation of timing devices. Several flowmeters were calibrated as a func-
tion of vacuum pressure against an absolutely (gravimetrically) calibrated
wet test meter. Before and after each sample was obtained, flow rate and
pressure values were recorded and the actual flow rate determined from the
calibration curve for the flowmeter used. The Gelman pumps were used to col-
lect aerosol samples on 37-mm glass fiber filters (Gelman Instrument Co., 660
S. Wagner St., Ann Arbor, MI) for nutrient analysis and on 25-mm Whatman 41
filters (Reeve Angel, 9 Bridewell Place, Clifton, NJ) for later analysis for
trace metals. A vacuum increase of 5-10 cm of mercury was usually observed
after sampling at approximately 42 £pm for 8 hr due to buildup on the filter.
Filter holders were placed inside downward-facing plastic rain shields to
prevent contamination of the samples by precipitation.
The Gelman pumps were also used to draw air through downward-facing
Andersen cascade impactors (Andersen 1966). Discs of 4-mil Durethane ®
plastic were cut from sheets with a stainless steel cutter and were placed on
stainless steel backup plates in the impactor. A Whatman 41 backup filter in
an in-line filter holder was attached to the end of the impactor. A flow
rate of approximately 28 £pm was used, and samples were collected for 24-hr
periods. The principle of cascade impactors has been well reviewed (Lee and
Goranson 1972; Andersen 1966) and will not be discussed.
High volume air samplers (General Metal Works, 8368 Bridgetown Rd.,
Cleves, OH) were used to collect aerosol particles on 8" x 10" glass fiber
mats. The mats were weighed to constant weight before and after collecting
a sample to determine the total weight gained through aspiration of a known
volume of air. From this, the total concentrations of particulate matter in
the air were determined. These samplers were run at 1416 £pm for 8-12 and
sometimes 24-hr periods. Sections of the filter mat were also cut with a
37-mm diameter stainless steel cutter and chemically analyzed for phosphorus
content.
Integrated fallout collectors were placed at each station for the period
between aerosol sample collection, generally 24-30 days. These collectors
consisted of a 1-gal Nalgene® bottle with the bottom one inch cut off, in-
verted and attached to an upright 1-gal bottle. A polyethylene sleeve was
placed around the contact and secured with fiber-reinforced tape. A 17.5
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mesh nylon screen was placed over the opening to reduce contamination from
large objects (leaves, insects, etc.)- Immediately prior to placement, 50 ml
of pH=2 sulfuric acid was added to the container as a biocide and preservative.
The unit was then placed in a wood-and-metal holder and hoisted to the top
of a 5-m mast.
Event rain samples were collected in 0.4-m2 rain buckets lined with poly-
ethylene bags. The buckets were placed out when rain was anticipated and
removed as soon after the event as possible (usually less than 8 hr). If the
total volume collected exceeded 500 ml, the contents of the bag were agitated
to mix the sample and a portion transferred to a polyethylene bottle. No
attempt was made to determine the volume collected.
SAMPLING
The research vessel ROGER R. SIMONS was scheduled to anchor on station
in Lake Huron for one 24-hr period each month from April through October 1975.
While on station only one generator was run, to reduce the possibility of con-
tamination. During this period, one 24-hr HiVol sample, two simultaneous
24-hr Andersen samples (one for future trace metal analysis, one for analysis
for phosphorus) and three consecutive pairs of 8-hr Gelman samples (one set
on Whatman 41 for metal analysis, the other set on glass fiber for phosphate)
were collected. Samplers were located on the ship as shown in Figure 1.
Figure 1. Location of sampling devices aboard the ROGER R.
SIMONS. Gelman filter samples were collected from the mast,
a HiVol sampler was located on the bow deck, and Andersen
impactors were elevated on a short mast at the bow. The
ship was bow-anchored with aft-pointing stacks.
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The 5-day land sampling period each month was coordinated so that there
was at least one full day of aerosol sampling prior to and following the col-
lection of samples from the SIMONS. Eleven sites were selected, five on the
Michigan shore, six on the Canadian. The stations, located at approximately
32-km intervals, are listed in the appendix and shown on the map in Figure 2.
Each site selected has the best combination of the following requirements:
a source of electric power, proximity to the lake shore, remoteness from
potential local sources (especially fuel-oil heated homes and agricultural
land) and minimum chance of vandalism. A 5-m mast was erected at each site,
and samplers were raised to the top of the mast by means of a rope-and-pulley
assembly.
The 11 land stations collected two sets of samples, one for trace metal
analysis, the other for phosphorus determination. On the odd numbered sam-
pling periods, phosphorus samples were collected at Lakeport, Sanilac County
Park #1 and Lighthouse County Park, Mich., and at Ipperwash Provincial Park,
Bayfield and Point Clark, Ont. The other stations, Sanilac County Park #2
and Wagner County Park in Michigan and St. Joseph, Point Farms Provincial
Park and Inverhuron Provincial Park in Ontario, collected samples for future
trace metal analysis. During the remaining periods, the opposite sample was
collected at each station, producing an oscillating grid of samples for each
type of analysis. The samplers were run for 8-hr periods followed by a 4-hr
down-time during which flow rate and vacuum pressure were recorded and new
filters installed. The pumps were activated by a timing device to run from
1000 to 1800 hr and from 2200 to 0600 hr the following day. In the 5-day
sampling period, seven samples were collected from each station. Part of the
first day was used assembling the stations and most of the last day was spent
dismantling the aerosol equipment and placing up the integrated fallout col-
lectors.
A high volume sampler placed at Lighthouse County Park collected consec-
utive 12-hr samples during the sampling period. An Andersen impactor was
operated at the Point Farms Provincial Park station for back-to-back 24-hr
periods.
Exposed glass fiber and Whatman 41 filters were transferred to labelled
50 x 12 mm plastic disposable petri dishes which were then sealed in plastic
bags. Andersen discs were transferred to labelled 100 x 10 mm plastic petri
dishes and also sealed in plastic bags. High volume samples, previously
weighed to constant weight, were wrapped in plastic, placed in a plastic bag
and put into a labelled manila envelope. All samples were handled with Tef-
lon dy -coated forceps to avoid contamination.
SAMPLE PREPARATION AND CHEMICAL ANALYSIS
Phosphorus was measured as orthophosphate using a molybdenum-antimony-
ascorbate procedure (Murphy and Riley 1962). This standard heteropoly acid
method was automated with a Technicon ® AutoAnalyzer (II). A volume of ap-
proximately 1.6 ml was analyzed for each sample. Blank solutions and stan-
dards containing pH=2 sulfuric acid were run during the analysis of the water
and acid filter extracts, event rains and integrated fallout samples. The
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Figure 2. Location of sampling and meteorological stations.
Two-letter codes designate sampling stations on the Lake
Huron shore and three-letter codes indicate weather stations.
persulfate digestion procedure was a modification of the method of Menzel and
Corwin (1965), and digestion blanks and standards were analyzed with the
digested samples.
Prior to use, all glassware was soaked in 10% sulfuric acid for a mini-
mum of 2 hr and multiply rinsed with distilled water. Singly distilled water
was used in the preparation of all reagents, for extraction of the filters
and dilution of samples. The concentration of phosphorus in the water was
routinely monitored. For extraction, a glass fiber filter was placed in a
60-ml suction flask. Ten 2-ml volumes of distilled water were aspirated
through the filter under slightly negative pressure. The filtrate was quanti-
tatively transferred to a 25-ml volumetric flask containing 2 drops of con-
centrated sulfuric acid and diluted to volume with distilled water. The
extraction was then repeated using ten 2-ml aliquots of pH=2 sulfuric acid.
This filtrate was transferred to a 25-ml volumetric flask (no acid present)
and diluted to volume with pH=2 solution. Approximately 19 ml of each of
these extracts were transferred to 16 x 150 mm Pyrex d) test tubes for trans-
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portation and storage. At least three unexposed filters were treated as above
each month to serve as blanks.
A stainless steel cutter was used to cut 37-mm diameter discs from the
previously weighed high volume mats, and duplicate discs from each filter
were treated as above. Unexposed high volume mats were similarly treated to
determine blank values.
Persulfate/acid digestions were performed on various samples to deter-
mine total phosphorus concentrations. A filter was placed in a 250-ml beaker,
10 ml of distilled water and 10 drops of concentrated sulfuric acid added
and the sample heated to approximately 80°C. Five ml of 5% ammonium persul-
fate were added and the sample evaporated to dense white fumes (almost to dry-
ness). The sample was allowed to cool, 20 ml of distilled water added, fil-
tered through a fine porosity sintered glass funnel and diluted to 25 ml in
a volumetric flask.
Monthly integrated rain samples were acidified during collection and
therefore water soluble phosphorus values were not obtained. After measure-
ment of the total volume collected, the samples were filtered through glass
fiber filters to obtain total available phosphorus values; portions were
filtered through pre-soaked 0.4 pm Millipore filters to determine total dis-
solved phosphorus, and 25.0 ml of the original sample were digested to deter-
mine total phosphorus content.
Event rains were analyzed "as is" without filtration or acidification.
It was later realized that for the sake of comparison, the rain samples should
have been acidified to determine whether additional (but not water soluble)
phosphorus would be available for uptake.
METEOROLOGICAL DATA
Meteorological data were supplied by the National Weather Service Fore-
cast Office at Detroit Metropolitan Airport, Detroit, Mich. Teletype outputs
of the Service A reports, consisting of hourly observations of temperature,
dew point, wind speed, wind direction, precipitation, and cloud cover, were
provided for all Michigan and Ontario weather stations.
Using these data, resultant wind speed and direction vectors were cal-
culated for the 4 hr preceding and the 8 hr of sampling for each of 12 meteo-
rological stations, shown in Figure 2. Although some of the stations were
removed from the shores of southern Lake Huron, the overall wind speeds and
directions were used to provide an indication of the flow of large air masses
in the southern Lake Huron basin. Meteorological data were also obtained on
the SIMONS when it was stationed on the lake for sampling. Of the 13 periods
where such data were available, comparison of the direction of the average
12-hr vector for all stations with the direction observed on the SIMONS
(Table 1) showed that only once did they differ by more than 90° (in that one
case they were 152° apart, however). Discounting this set, the average dif-
ference at 90% confidence was 42 + 16° (n = 12). A composite wind speed and
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TABLE 1. COMPARISON OF R/V ROGER R. SIMONS AND NATIONAL
WEATHER SERVICE DATA ON WIND DIRECTION
Date
1975
4/16
4/16-17
4/17
5/13
5/13-14
5/14
6/12
6/12-13
7/09-10
7/10
7/16
7/16-17
7/17
Wind
RS
3.5
3.5
3.5
9.3
7.8
3.8
20.9
18.4
6.2
12.8
15.2
12.5
5.4
speed, km/hr
NWS
9.6
4.8
9.0
8.0
6.4
9.1
16.3
13.8
12.2
6.9
9.4
5.3
4.6
Wind
RS
226
350
126
335
143
186
230
230
208
(128)
201
208
237
direction,
NWS
237
263
160
267
221
214
217
218
292
280
200
191
203
DEC
AAngle*
47
87
34
68
78
28
13
12
88
152
1
17
34
*Eliminating highest value, 90% confidence limit is 42° ±
16.0° variation (n = 12); and using all values, the value
is 51° ± 21.9° variation (n = 13).
direction vector was obtained for the 12-hr period (interval + sampling) by
taking the average wind speed and direction from all stations. This vector
is shown for each sampling period in Figures 3a through 3g.
10
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WIND
SPEED
I0
0 20 40 60 80 100 120 140
AEROSOL CONG.
WIND I0
SPEED 5
o
• * "". *
, . . .
AEROSOL CONC.
(a) April sampling period.
(b) May sampling period.
Figure 3. Wind speed, direction, and aerosol concentration roses. Ar-
rows indicate wind direction; concentration of total available phosphorus
measured during that period is indicated at the perimeter of the circle.
The lack of correlation between total available phosphorus concentration
and wind speed is shown below each wind rose.
11
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WIND I0
SPEED 5
ft
i
„» *
i
X
I
AEROSOL CONG.
(c) June sampling period.
WIND
SPEED
10
* »
u
" "B io is 20
AEROSOL CONG.
(d) July sampling period.
WIND
SPEED
i 4 6 8 10
AEROSOL CONG.
(e) August sampling period.
Figure 3 continued.
12
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«.Q3
WIND
SPEED
§10 J5 20 25 30
AEROSOL CONG.
(f) September sampling period.
Figure 3 continued.
WIND
SPEED
10
- ~t 10 15 20 25—30
AEROSOL CONG.
(g) October sampling period.
13
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SECTION 4
RESULTS AND DISCUSSION
TOTAL FALLOUT
The integrated fallout samples provided a means for determining the to-
tal input of phosphorus. They contained both wet and dry deposition which
had occurred over a fixed area at a particular point during a given period.
Analysis of the phosphorus content of these shore-based samples provided an
upper-limit estimate of the phosphorus input to the lake surface from the
atmosphere. In determining these inputs, the mean value of the 11 stations
at a 90% confidence limit was used. The 90% confidence limit was selected
as the indicator of statistical reliability and will be indicated whenever
possible.
Since the samplers contained sulfuric acid as a preservative and biocide,
the water soluble portion of the phosphorus in the sample was not determined;
however, total available phosphorus was determined on aliquots of the acidi-
fied sample after filtration through glass-fiber and/or Millipore filters to
remove suspended particulate matter. The efficiency of this filtration was
verified by digestion of part of the filtrate and subsequent comparison of
the phosphorus content of the digested and undigested filtrate, which showed
that no additional phosphorus was present in the digested sample. Due to
complications in the digesting procedure, total phosphorus values were obtained
only for August-December integrated samples. Comparison of available and
total phosphorus in the integrated samples indicated that 32 ± 18% (n = 24)
of the total phosphorus in these late fall samples was present as available.
The volume and available phosphorus concentration of each sample is
listed in Table 2. To correct for potential volume losses, the amount of
available phosphorus (volume x concentration) was calculated for each sample
and the mean monthly value at 90% confidence used to determine the deposition
rate for each sampling period, as discussed below.
Average phosphorus contents of the samples were plotted (Fig. 4) to
illustrate the seasonal variation of total available phosphorus input from
the atmosphere. This input peaked in the late spring and rose again in the
early fall in a pattern that roughly corresponds to agricultural activity in
the Lake Huron basin. The May-June samples also showed marked evidence of
biological activity despite the screen and biocide. Most of the samples for
this period were dark green or yellow, and microscopic examination showed
algal growth, pollen, and even small insect larvae. A significant amount of
the phosphorus input during this period was therefore associated with biologi-
cal activity.
14
-------
TABLE 2. INTEGRATED FALLOUT SAMPLES—VOLUME COLLECTED (ml) AND AVAILABLE PHOSPHORUS CONTENT (ppb), 1975
Station
code
LT
WG
SI
S2
LP
IW
SJ
B4
PF
PC
IN
4/18-5/12
Vol
710
460
185
1190
1595
1415
1143
1155
970
565
225
847
[P]
15.78
12.66
69.08
5.42
4.18
3.24
7.71
2.23
41.87
35.69
22.26
33.3
5/16-6/9
Vol
1810
1820
2510
995
1160
2130
885
530
480
410
1273
[P]
200.60
54.26
22.36
37.67
8.20
5.89
3.73
28.83
69.53
730.3
116.1
6/13-7/7
Vol
670
175
325
175
610
170
620
660
475
300
418
[P]
10.22
124.51
9.03
124.55
114.99
124.57
4.74
7.31
124.66
3.96
64.9
7/11-8/8
Vol
1360
460
780
1050
2527
1180
260
1140
360
190
931
[P]
3.79
5.33
31,22
1.76
2.17
4.05
26.98
2.74
16.94
10.6
8/12-9/15
Vol
730
1135
1215
900
740
130
450
1105
3180
2560
1215
[P]
2.81
110,2
0.44
110.7
21,0
112.1
1.24
12,9
47.7
0.9
42.0
9/19-10/8
Vol
425
208
200
250
345
320
215
200
90
430
268
[P]
3.25
122.7
2.60
120.3
77.8
18.4
0.50
2.00
1.55
2.21
35.1
-------
APRIL MAY JUNE JULY
MONTHS
AUGUST SEPT
OCT
Figure 4. Monthly variation of available phosphorus
in integrated fallout samples. The boxes indicate
the 90% confidence limits for each monthly sample
set.
To determine whether the samplers were sampling the actual amount of pre-
cipitation which fell during the sampling period, the volume collected was
converted to an average rainfall in inches. This number was compared to the
amount of precipitation recorded at four weather service stations on the
Michigan shore of Lake Huron. As shown in Table 3, the correlation was good
in the spring but deteriorated during the hotter months due to evaporation
losses. The input of available phosphorus from the atmosphere was expected
to follow the amount of rainfall for each period. Comparison of the total
available phosphorus content of the integrated fallout samples with the
actual rainfall reported by the U.S. Weather Service for that period (Fig. 5)
showed that this was not the case, however. This was substantiated by the
seasonal variation in the phosphorus content of event rain samples.
WET DEPOSITION
Event rain samples were collected during each sampling trip to determine
the phosphorus content of rain. Comparison of remote and urban samples showed
16
-------
TABLE 3. COMPARISON OF OBSERVED AND CALCULATED RAIN-
FALL
Sampling
period
4/18-5/12/75
5/16-6/9
6/13-7/7
7/11-8/8
8/12-9/15
9/19-10/8
Calculated*
rainfall, cm
5.21
7.59
2.49
5.56
7.24
1.60
Observed**
rainfall, cm
5.49
8.03
5.18
8.33
8.41
3.35
%
calc/obs
95.
95.
48.
67.
86.
48.
*Rainfall, in = average volume, cnr
collector area, cmz
volume
167.5 cm*
**Average of Weather Service data from Saginaw,
Seebawing, Harbor Beach and Sandusky, Mich.,
weather stations.
the effect of industrial inputs of phosphorus to the atmosphere. During June,
event rain samples were taken on the SIMONS which was docked approximately
5 km downstream from the mouth of the St. Clair River in an area of industrial
development. The mean value for total soluble phosphorus for five samples
collected at the remote stations during this period was 7.1 ppb; in the Port
Huron/Sarnia sample it was 15.7 ppb. In October, a value of 1.96 ppb was
observed in the remote samples (3) whereas a sample taken at North Street,
a suburb of Port Huron, contained 36.6 ppb of soluble phosphorus.
Analysis of the event rain samples collected provided a means of deter-
mining the contribution of wet deposition to the total atmospheric phos-
phorus input to the lake. No rain events occurred during the sampling periods
in April or May. The data for the remaining months, shown in Figure 5 and
Table 4, indicated that a definite seasonal trend existed which was not that
of the total fallout samples. The mean value of total soluble phosphorus, in
parts-per-billion, 90% confidence limit and number of samples collected for
the months of June through October are: 7.09+3.05, (5); 8.65, (1); 4.89 +
3.65, (4); 0.95+0.13, (4); and 1.96+4.00, (3), respectively. Although
these values represent only the soluble fraction of the available phosphorus,
it is still possible to estimate the contribution of precipitation to the
integrated fallout samples. This value would be a lower limit, and the
actual contribution is expected to be approximately double this value (Murphy
1974).
17
-------
u
9
8
7
6
5
4
3
2
1
n
•
•
.
m
"
'
'RAINFALL
INCHES
/A
/ \ SOLUBLE P
/
/
\ IN RAIN.PPB
\
\
AVAILABLE P IN\
INTEGRATED X.
SAMPLES, .ug/,o \
-
\
\
I
i
i
i
i
\ t
\ \
— -^—
\
M '
iy--
APRIL MAY
JUNE
JULY
AUGUST SEPTEMBER OCTOBER
Figure 5. Comparison of rainfall, concentration of
reactive phosphorus in rain and total available
phosphorus collected in integrated samples, April-
October 1975. Units for the scale are indicated on
the figure.
18
-------
TABLE 4. PHOSPHORUS CONTENT OF EVENT RAIN SAM-
PLES, JUNE-OCTOBER 1975
Station
code
IN
IN
IN
LT
RS
RS
PH
IN
PH
LP
LP
IN
SJ
LT
LT
IN
IW
IW
IN
LP
NS
Date
6/11
6/12
6/12-13
6/11
6/12
6/12-13
6/11-12
7/10
7/10
8/20-21
8/21
8/20-21
8/21
9/18
9/18-19
9/18
9/18
10/8-9
10/9
10/8-9
10/8
Time
?
1000-1800
1800-1000
?
1750-1815
2300-0800
2000-0000
0930-1730
0830-0930
2000-0808
0810-2010
1800-1800
0715-2045
1230-1814
1814-0600
1330-1745
?
2300-2100
1400-1730
1945-0620
1345-2200
[P]
ppb
6.51
12.19
4.31
4.92
3.99
7.86
15.69
8.65
11.03
7.72
7.25
1.28
3.32
1.01
0.27
0.95
1.03
0.26
0.95
4.67
36.57
[P]
Average
7.09
+ 3.05
15.69
8.65
11.03
4.89
+ 3.65
0.95
± °-13
1.96
+ 4.00
36.57
TOTAL AEROSOL LOADING
HIVol samples were collected at the Lighthouse County Park station near
Huron City, Mich., and on board the SIMONS. Starting in June, these samples
were used to determine the total particulate concentration in the air (total
loading) by weighing the filter mats to constant weight before and after
sampling. The values for total loading in yg/m3 are listed in Table 5 with
station and monthly averages. These average values have been plotted against
month (Fig. 6) to indicate the seasonal variation of total loading. As with
the integrated fallout samples, September showed an elevated load of partic-
ulate matter in the air. Unfortunately, no data were available for the
spring months.
These total loadings have been used to determine whether a particulate
concentration gradient exists across the lake. If the deposition of particu-
19
-------
TABLE 5. HiVOL LOADINGS, JUNE-OCTOBER 1975
Sta
LT
LT
LT
LT
WRS
WRS
WRS
LT
LT
LT
LT
LT
LT
LT
RS
RS
LT
LT
LT
LT
LT
LT
PH
LT
LT
LT
LT
LT
LT
LT
LT
RS
RS
RS
LT
LT
LT
LT
LT
LT
LT
Date
6/8-10
6/10-11
6/11-12
6/12-13
6/12
6/12-13
6/13
7/7-8
7/8
7/8-9
7/9
7/9-10
7/10
7/10-11
7/9
7/9-10
8/18-19
8/19
8/20
8/20-21
8/21
8/21-22
8/22
9/14-15
9/15-16
9/16
9/16-17
9/17
9/17-18
9/18
9/18-19
9/15
9/15-16
9/16
10/8-9
10/9
10/9-10
10/10
10/10-11
10/11
10/11-12
yg/m3
18.4
25.8
19.7
39.0
19.1
27.3
20.3
51.3
31.8
9.8
19.7
7.2
5.1
7.6
11.4
1.1
8.8
6.8
11.25
17.6
13.7
23.9
36.7
69.5
50.3
73.1
64.7
49.9
39.9
24.1
53.9
61.8
56.0
31.0
32.7
45.2
62.4
12.9
16.9
Station Monthly
avg . avg .
25.7
24.2 + 5.4
22.2
18.9
16.1+ 9.9
6.27
11.60 11.6 + 4.0
23.
51.0
52.7 + 8.1
57.2
33.5 33.5 + 15.1
20
-------
120
110
100
90
60
70
60
50
40
30
20
10
TOTAL AVAILABLE
PHOSPHORUS
TOT. SOLUBLE
PHOSPHORUS
APRIL MAY JUNE JULY
MONTHS
AUGUST SEPT OCT
Figure 6. Relationship between total aerosol concen-
tration, soluble and available phosphorus.
late matter is sufficiently rapid, the concentration of particulate matter
over the lake should be less than that in the air over the upwind shore.
Although the number of samples was small and the locations of the samplers
different, it appears that such a gradient does exist. The June samples were
collected during a period when the wind was from the southwest (^218°). The
small difference between land and lake samples was due to the proximity to
the Michigan shore of the SIMONS, which was anchored 5 km from the shore due
to bad weather. Nevertheless, the values obtained from the SIMONS were lower
than the land-based samples (27.3 vs. 39.0 yg/m3). In July, the SIMONS was
on station at mid-lake and was again downwind from the Michigan shore. Aero-
sol concentrations for 9 July were 19.7 and 11.4 yg/m3 for the land and lake
samples, respectively. During the following period a strong rain occurred,
reducing the total aerosol concentration. Again the value from the Michigan
shore (7.2 yg/m3) was higher than that at mid-lake (1.1 yg/m3). In September,
however, total aerosol loadings were slightly higher in samples taken from
the SIMONS (52.2 yg/m3) relative to the land-based samples (57.2 yg/m3).
During this period, the wind was from the south (191-203°) and had little
cross-lake direction so a comparison was not possible.
21
-------
AIRCRAFT SAMPLING
During the week of 15-19 September, the Environmental Protection Agency,
Las Vegas, Nev., provided an aircraft for use in the study. The aircraft, a
B-26, was equipped with a DME, Bendix ozone, TECO nitric oxide, temperature,
dewpoint, nephelometer, altitude and Dasiki ozone monitors and a particulate
sampling system. The aircraft was used to determine the mixing layer height
from nephelometer data taken during spirals, to collect particulate samples
at three heights to determine the altitude profile of aerosol particles, and
to track a given parcel of air by sampling particulate matter at various
points along the wind trajectory at a given height. Flight paths are depicted
on a map of southern Lake Huron in Figure 7. Data records for the nephelo-
meter were produced every 5 sec. A summary of the particulate samples col-
lected is given in Table 6.
The first sampling mission was flown 15 September (Fig. 7a). The air-
craft rendezvoused, with the SIMONS at 1312 hr. A spiral from 2743 m to 244 m
MSL at a descent rate of 2.54 m/sec was performed over the ship. A 93 km/hr
crosswind pattern at 670 m MSL was then begun at 1334:20 using the ship as
the center point. The wind was reported by the Weather Service to be from
240°. Wind streaks on the lake surface seemed to confirm this. Wind speed
was estimated from aircraft drift to be about 56 km/hr. Filter No. 1 ran
from first rendezvous with the ship to the end of the first crosswind pattern.
This filter includes the spiral and the crosswind pattern.
At the end of the first crosswind pattern, a second spiral was performed
over the ship from 2743 m to 244 m MSL. Filter No. 2 was run during the sec-
ond spiral. Assuming a 56 km/hr wind, the air parcel sampled during the first
crosswind pattern was calculated to have moved approximately 46 km east of
the first pattern. The second crosswind pattern was then flown parallel to
the first but 46 km downwind. Filter No. 3 was run during all of pattern two.
A third and final spiral was performed over the ship from 2743 m to 244 m MSL
before returning to Selfridge Air National Guard Station to refuel and re-
calibrate.
Weather conditions prevented sampling missions on all but Monday and
Wednesday. Mission One on Wednesday, 17 September (Fig. 7b), attempted to
measure the altitude profile of phosphate concentrations. A box pattern with
sides of approximately 64 km was flown over the lake at three altitudes, col-
lecting a filter sample at each altitude. Although a light wind was blowing
from the east during this mission, the box pattern should block out the effects
of pollutant transport. Filters were collected at 610 m, 488 m, and 366 m
MSL. The lake surface is approximately 180 m MSL.
Mission Two on 17 September (Fig. 7c) attempted to measure the effect of
particle transport and fallout over the lake. Unfortunately, the wind was not
blowing by then, and the air pump failed near the beginning of the second fil-
ter. The first filter ran during two passes between Grand Bend and Point
Clark, Ont., for 59 min at 488 m MSL. The second filter ran for only 2.25
min, from a point near Lexington, Mich., to a point about 13 km north of
Lexington. If the wind had been blowing, the second crosswind pattern would
22
-------
I WIND
f 9 KNOT
I 100-
I PORT
I SAM LA
t
LEXINGJONTir
r"~~ \ 1659:30
> BEGIN FILTER
TWO
MAG. NORTH
Figure 7. Flight paths for aircraft sampling, 15-17 September 1975.
23
-------
TABLE 6. AIRCRAFT PARTICULATE SAMPLE SUMMARY
Sampling
Date time
9/15/75 1311
1409
1429
9/17/75 1115
1202
1247
1550
1659
: 00-1403
: 00-1425
:35-1505
:00-1158
: 00-1243
: 00-1329
: 00-1649
: 30-1701
:00
:35
:00
:00
:00
:00
:00
:45
Vol.
a3
3.54
1.01
1.95
2.74
2.56
2.50
2.92
0.13
Tot. sol,
P, ng/m3
1.50
2.20
1.64
7.30
8.47
9.93
1.28
6.93
Tot. react.
P, ng/m3
21.45
2.67
4.22
5.28
5.84
—
5.84
8.28-
Tot.
P,
3
7
6
7
7
7
2
2
bound
ng/m3
.54
.64
.21
.59
.03
.72
.05
.27
Tot. P
ng/m3
26.
10.
12.
20.
21.
17.
9.
17.
40
53
07
17
39
65
17
48
% Avail.
total P
86.9
27.4
48.6
62.4
66.9
>56.3
77.6
87.0
Remarks
Includes first spiral pluc
first crosswind pattern
Second spiral only
Second crosswind pattern
Box pattern at 610 ci MSL
Box pattern at 488 m MSL
Box pattern at 366 m MSL
Along Canadian shoreline
at 488 m MSL
Along U.S. shoreline at
488 m MSL
-------
have been performed at a distance downwind from the first pattern according
to the estimated transport speed. The decision to sample along the western
shoreline was made after it was apparent that the wind was too light to mea-
sure transport effects.
Figure 8 shows the nephelometric data from the three spirals plotted
against height. From these data, the mean height of the mixing layer is
approximately 1200 m above the lake surface. This value agrees with that of
1200-1300 m obtained from rawinsonde data by Portelli (In press) for the mean
afternoon maximum mixing heights in summer over the southern portion of Canada,
including the Great Lakes. The value of 1200 m will be used in the calcula-
tion deposition velocities discussed below.
In this study, eight filter samples were collected. The first attempt
at obtaining a horizontal gradient was confused by the inclusion of spirals
while the filter samples were being collected; thus the fixed altitude require-
ment was not met. Mission Two of the 17 September sampling failed to establish
a horizontal gradient since no sample was collected at a second point and
since the wind speed was almost zero. Thus the altitude profile samples taken
on 17 September were the only "good" samples. Unfortunately these did not
include a sample above the mixing height for comparison. Intervals of 122 m
also appear to be too small to establish a significant gradient. Values for
all filter samples were higher than land-based and shipboard samples by a
factor of about 4, averaging somewhere near 160 ng/m3 using the volume data
supplied by NERC. The only explanations for this exceedingly high difference
are that either the samples were contaminated from the aircraft (or during
handling) or that the reported volume aspirated is wrong. The latter is
supported by the agreement between aircraft and land-based samples for per-
cent soluble and available phosphorus. In either case, the particulate sam-
ples cannot be considered valid. It should be noted, however, that the
feasibility of the use of an aircraft as a workable platform for particulate
sampling has been established. The continued investigation of height profiles
is necessary, and this work has established criteria for such future work.
AEROSOL SAMPLES
To determine the availability of phosphorus to the lake, airborne par-
ticulate samples were analyzed for three fractions—water soluble, acid (pH=2)
soluble, and bound phosphorus. Results of the analysis of samples collected
in September are shown in Table 7. Of the total phosphorus in the aerosol,
28.7% is immediately available to the biomass, 48.2% of the aerosol phos-
phorus is potentially available for use in the short term, and over half of
the phosphorus entering the lake from dry deposition is not soluble in either
water or pH=2 sulfuric acid. This fraction must be present as either inorganic
salts (insoluble metal phosphates) or as organically bound phosphorus. While
this phosphorus is not immediately available and probably settles to the bot-
tom, it may eventually be released to the lake water through some aging pro-
cess at the sediment-water interface (Bannerman et al. 1975). Clearly, this
fraction should be investigated further to determine its chemical and physical
composition and its potential release.
25
-------
ON
2700
252O
2340
2160
1980
1800
1620
1440
1260
E
— IO6O
2 900
720
540
360
180
0
», 2700
•*
f
' I I3I&45 KZO
« . 2340
{
\ 2160
'» 1980
&
^ 1800
« ^ i
• K IA9A
« » ,
I1 ^ . 1440
* * > 1260
" i *»
i ' e
« i « "1080
* e 900
» « ^
*, ' 720
• > 540
t *' 360
LAKE SURFACE - 175m. ' '' ,eo
b
2700
,*» 1409:05 2520
4 2340
,*«* 2160
Jf I960
•' 1800
I"
• X .
1 1 1620
V
*\ 1440
> i
'« ^1260
i* H
* « 5 1080
"l %
J. 900
' . 720
i
, * « 540
V
« , 360
LAKE SURFACE ~ 175m W42:'5
' _•- '_ ' 1 • ' 1 1 • 1 1 u O
1517^50
I
X •
.,' *
I *
1 }*
I
^L
/
--..
Jt
* i
1 B
t* «
* \
*' I
. .'
1 ^
153250 •*;
I
I „
LAKE SURFACE ~ 175m. » *
SCATTER COEFFICIENT
ttl 02 0.3 0.4 05 0.6 07 OB 0.9 1.0 I.I 1.2 1.3
SCATTER COEFFICIENT
ai 0.20.30.4050.6070809 1.0 I.I 1.2 1.3
SCATTER COEFFICIENT
(a) (b)
Figure 8. Plots of backscatter vs. altitude.
(c)
-------
TABLE 7. ANALYSIS OF AEROSOL SAMPLES FOR SOLUBLE, REACTIVE AND BOUND
PHOSPHORUS CONTENT REPORTED IN ng/m3
1
Sample
SJ1
SJ3
SJ7
BY 2
BY4
BY 6
PF1
PF5
PC6
LP3
LP5
LP7
IW2
IW4
IW6
* Avg.
** Avg.
[P]
Sol
17.47
5.01
14.53
5.10
4.00
7.29
4.10
8.37
6.36
3.35
7.95
14.06
33.3
2.99
9.58
= 28.7 + 7.7%
= 48.2 + 7.4%
[P]
React.
10.90
4.89
4.14
9.79
14.73
4.71
2.63
9.82
2.23
4.23
3.90
2.05
4.34
2.58
at 90%
at 90%
[P]
Bound
33.05
25.21
17.90
19.93
11.66
11.78
19.25
16.40
10.60
11.12
3.73
7.48
16.02
6.57
confidence
confidence
Total
P
61.42
35.11
36.57
38.66
23.66
18.51
37 . 44
26.76
16.18
23.30
21.69
12.86
23.35
18.73
(n = 14) .
(n = 13).
ZSol.*
28.4
14.3
39.8
10.3
30.8
22.2
22.4
23.7
20.7
34.1
64.8
25.9
12.8
51.1
Avail.**
46.2
28.2
51.1
48.4
51.6
36.4
48.6
34.5
61 . 5
81.8
41.8
31.4
64.9
The seasonal variation of soluble, reactive and total available phosphorus
in the aerosol is shown in Table 8 and in Figures 6 and 9. Individual sample
concentrations are listed by month in Table 9. The seasonal variation of the
aerosol phosphorus is similar to both the integrated fallout samples (Fig. 4)
and the total aerosol loading. The rise in phosphorus input from all atmos-
pheric sources in the spring and fall was previously suggested to be due to
agricultural activity. The variation in the percent soluble of available
phosphorus, also listed in Table 8, tends to support this view. It may be
that the addition of orthophosphate-enriched fertilizers increases the amount
of water-soluble phosphorus, and the higher percentages observed in the spring
and fall are due to increased aerosol injection of agricultural soil.
To determine whether any relationship existed between wind direction and
aerosol phosphorus content, wind roses shown in Figure 3 were constructed.
No correlation was observed between total aerosol, available phosphorus and
wind speed or wind direction. Since aerosol particles can travel distances
of over 300 km before deposition, meteorological data taken in the lake basin
may not accurately reflect meteorological conditions at the source of the
aerosol. It is likely, however, that a longer term study with more data would
be able to determine the relationship between wind direction and aerosol con-
centration.
27
-------
TABLE 8. AVERAGE MONTHLY AEROSOL PHOSPHORUS CONCENTRATION
Sampling
period
(1975)
4/14-18
5/12-16
6/9-13
7/7-11
8/18-22
9/15-19
10/8-12
Total soluble
phosphorus,
ng/m3
54.73
56.90
12.57
1.83
4.31
13.97
8.01
Total reactive
phosphorus,
ng/m3
50.34
29.15
6.53
5.76
3.74
5.13
3.55
Total available*
phosphorus,
ng/m3
105.07 + 19.0
86.05 + 16.6
19.11 + 3.5
7.59 + 2.1
8.05 + 1.9
19.10 + 2U
11.56 + 2.1
% Soluble
of available
52.1
66.0
65.8
24.1
53.5
73.1
69.3
90% confidence limit.
PARTICLE SIZE DISTRIBUTION OF PHOSPHORUS
Aerosol particles can be divided into three size categories which rough-
ly correspond to source modes. The fraction <0.1 y has been attributed to
gas phase reactions and particles formed from condensation of vapors produced
in combustion processes. For example, aviation and automotive fuels contain
organophosphorus additives to reduce corrosion; open-hearth furnace fumes
have been found to contain 0.3% of phosphorus pentoxide. The size range 0.1-
1.0 p is generally associated with continental erosion and to a lesser extent
with sea spray and the smaller fractions of fly ash. Soil has been estimated
to contain in the area of 650 ppm phosphorus by weight (Bowen 1966, p. 196).
Application of phosphate-enriched fertilizers increased this value consider-
ably. The particles in the size range of 1.0-10 p are usually derived from
sea spray (not a significant contribution from the freshwater Great Lakes,
however), fly ash, biological injection (spores, bacteria) and the larger
fraction of continental dust. The fly ash from iron and steel production
contains an average of 1.2% P205. Fly ash from oil-fired boilers has been
estimated to contain 0.9% phosphorus, as P205 (Athanassiadis 1969). Pursglove
(1957) has estimated that by 1980 the electric utility industry alone will
produce 45 million tons of fly ash containing 400,000 tons of phosphorus pent-
oxide each year. The fraction of this fly ash which will enter the air is
not known. Incineration of refuse would also contribute to this size fraction.
Murphy (1974) concluded that the atmospheric inputs of phosphorus from the
fertilizer industry, soil, and the combustion of fuel are predominant. If
the size distribution of phosphorus in the aerosol is known, it is possible
to estimate the general origin of the particles. Knowledge of the size dis-
tribution is also useful in evaluating the accuracy of such parameters as the
residence time and hence deposition velocity.
Due to the relatively small amounts of phosphorus anticipated on each
stage, the 24-hr Andersen samples were collectively digested by stage for
each month. As a result, the minimum sampling time was 72 hr. Backup filters
28
-------
120
390
a:
80
V)
o
£70
ui
si60
3 50
10%) fraction of phosphorus was contained
on the particle <0.1 y. Table 10 lists the phosphorus distribution of par-
ticles >0.1 y by size range, and the data are plotted in Figure 10. The mass
median diameter is approximately 1 y, with at least 28.5% of the phosphorus
found on particles less than 0.5 y. The particle size distribution is bimodal
for all months, the peak of the lower mode appearing to shift to the 0.3-0.5
y range during May, June and July from the range of 0.5-0.9 in April, August
and September. No seasonal trend can be observed from these data, however.
From the mass median diameter, it appears that a significant fraction is due
to continental erosion. This supports the conclusion that spring and fall
rises in phosphorus content of the aerosol and total fallout samples are
related to the agricultural injection of soil particles. A significant pro-
portion (at least 10%) also originates from combustion sources.
DETERMINATION OF DEPOSITION VELOCITY
The concentration of total available phosphorus in the aerosol samples
collected at each station is shown in Figure 11. It was qualitatively observed
29
-------
TABLE 9. AEROSOL CONCENTRATION OF SOLUBLE AND REACTIVE PHOSPHORUS BY STA-
TION FOR THE MONTHS APRIL-OCTOBER 1975
AEROSOL INPUT—APRIL
Filter
nuir.ber
LT1
LT3
LT5
LT7
WG2
WG4
WG6
S13
SI5
S17
S22
LP1
LP3
LP5
LP7
IW2
IW4
SJ1
SJ3
SJ5
BY 2
BY4
BY 6
PF1
PF3
PF5
PC2
PC4
PC6
INI
IN3
INS
RSI
RS2
RS3
Total soluble
phosphorus, ng/m3
29.95
64.43
38.71
64.18
60.56
65.28
75.15
20.15
17.45
23 . 40
10.44
17 . 41
43 . 35
9.32
24.23
90.75
67.75
68.71
82.12
177.52
103.20
157.55
100.70
58.76
56.18
54.13
77.05
107.79
70.28
18.75
11.11
18.28
12.71
8.76
9.44
Total reactive
phosphorus, ng/m
54.45
74.24
64.61
70.37
55.01
54.46
69.51
33.69
26.80
24,61
31.19
26.06
35.13
30.55
47.05
113 . 41
54.41
29.69
98.45
93.72
88.62
93.78
62.64
26.11
114.71
29.74
24.41
41.82
26.59
•31. *"*
20.57
33.41
30.30
23.72
23.76
Total available
phosphorus, ng/m3
84.40
138.67
103.31
134.55
115 . 57
119.74
144.66
53.84
44 . 24
48.01
41.63
43. 47
78.48
39.88
71.23
204.15
122.16
98.40
180.57
271.24
191.82
251.33
163.34
84.87
170.89
83.88
101.45
149.61
96.87
53.05
31.68
51.70
43.01
32.49
33.21
30
-------
TABLE 9 (continued). AEROSOL INPUT—MAY
Filter
number
LT1
LT3
LT5
LT7
WG4
WG6
Sll
S13
S15
S17
S22
S24
S26
LP1
LP3
LP5
LP7
IW1
IW3
IW5
IW7
SJ2
SJ4
SJ6
BY1
BY5
BY7
PF2
PF4
PF6
PC3
PCS
PC7
INI
IN2
IN4
IN6
RSI
RS2
RS3
Total soluble
phosphorus, ng/m
9.90
33.63
51.61
164.64
17.71
135.29
46.94
44.60
104.55
89.34
54.38
94.44
27.55
45.58
122.68
42.38
81.20
48.06
11.23
18.03
36.86
51.35
68.64
64.66
18.47
77.46
54.10
17.99
57.12
49.24
54.52
39.45
20.87
178.27
23.23
73.81
83.64
19.76
25.45
17.34
Total reactive
phosphorus, ng/m
25.65
57.57
156.80
53 . 67
80.88
60.64
42.87
9.28
36.73
6.31
9.55
116.36
14.30
12.09
61.27
15.25
7.50
5.41
4.68
8.01
5.11
41.01
46.84
18.12
2.95
24.41
12.11
2.67
45.40
11.95
12.88
25.25
21.58
46.29
21.92
20.98
19.68
0.16
0.16
1.89
1
Total available
phosphorus, ng/m'
35.54
91.20
208.41
218.31
98.59
195.93
89.81
53.88
141.28
95.65
63.92
210.80
41.85
57.67
183.96
57.63
88.70
53.47
15.91
26.05
41.97
92.36
115.49
82.78
21.42
101.86
66.21
20.66
102.52
61.19
67.40
64.70
42.45
224.56
45.15
94.79
103.33
19.93
25.61
19.23
31
-------
TABLE 9 (continued). AEROSOL INPUT—JUNE
--.-.- - -
Filter
numb e r
LT1
LT3
LT5
LT7
WG2
WG4
WG6
Sll
S13
S15
S17
522
S24
S26
LP1
LP3
LP5
LP7
IW1
IW3
IW5
IW7
SJ2
SJ4
SJ6
BY1
BY3
BY 5
BY 7
PF2
PF4
PF6
PCI
PC3
PCS
PC7
IN2
IN4
IN 6
RS2
RS3
Total soluble
phosphorus, ng/m
4.30
2.01
7.21
25.25
5.70
7.51
26.15
23.97
13.69
23.43
39.42
10.32
16.92
22.68
30.37
19.42
10.46
31.50
1.91
15.66
37.22
28.02
8.60
6.66
9.20
5.66
7.41
9.01
14.01
6.24
5.02
7.46
3.36
3.14
2.01
19.49
5.00
Total reactive
phosphorus, ng/m3
4.14
2.76
0.53
4.36
11.43
7.31
2.98
10.82
5.79
4.93
3.37
2.06
6.21
6.28
6.95
3.95
3.17
4.50
38.02
2.26
14.13
5.77
5.84
6.50
15.26
7.92
1.10
7.78
11.58
8.68
6.11
5.17
5.28
'3.81
7.66
7.50
5.67
4.58
2.72
3.10
Total available
phosphorus, ng/m3
8.43
4.78
0.43
11.57
36.68
13.01
10.49
36.98
29.76
18.62
26.80
41.47
16.53
23.20
29.63
34.31
22.60
14.96
69.52
4.17
29.79
42.99
33.86
15.10
21.92
17.12
6.76
15.19
20.59
22.69
12.35
10.19
12.74
7.17
10.80
9.51
25.16
9.58
2.50
2.82
32
-------
TABLE 9 (continued) . AEROSOL INPUT—JULY
Filter
number
LT1
LT3
LT5
LT7
WG2
WG4
WG6
S12
S14
S21
S23
S25
S27
LP1
LP3
LP5
LP7
IW2
IW4
IW6
SJ1
SJ3
SJ5
BY2
BY4
BY 6
PF1
PF3
PF5
PF7
PC2
PC4
PC6
IN3
IN5
IN7
RSI
RS2
Total soluble
phosphorus, ng/m3
6.03
0.04
1.56
1.15
1.73
3.38
4.08
13.12
6.42
1.50
3.22
2.64
6.98
0.30
1.92
3.93
6.66
3.11
3.11
0.49
0.21
Total reactive
phosphorus, ng/m3
6.15
3.18
3.17
11.86
2.25
7.04
0.31
5.96
16.49
0.87
2.75
3.61
2.10
6.79
8.25
8.05
2.50
5.78
2.10
2.60
2.45
2.66
3.43
20.03
23.66
3.50
5.69
4.90
7.06
0.80
3.45
6.56
12.56
6.67
8.50
3.39
1.83
5.59
Total available
phosphorus, ng/m3
12.18
3.22
3.17*
11.86*
3.82
8.18
2.04
9.33
20.57
13.99
2.75*
3.61*
2.10*
13.21
9.75
8 . 05*
2.50*
9.00
2.10*
5.24
9.43
2.96
5.35
23.96
23.66*
3.50*
12.34
4.90*
10.17
0.80*
6.56
6.56*
13.05
6.88
8.50*
3.39*
1.83*
* Soluble phosphorus value below detection limit.
33
-------
TABLE 9 (continued). AEROSOL INPUT—AUGUST
•
Filter
number
LT1
LT3
LT7
WG2
WG4
WG6
S13
S15
S17
S26
LP1
LP3
LP5
LP7
IW2
IW4
IW6
SJ1
SJ3
SJ5
SJ7
BY 2
BY4
BY 6
PF1
PF3
PF5
PF7
PC2
PC4
PC6
INI
1N3
INS
IN7
RSI
Total soluble
phosphorus, ng/m3
2.11
1.77
5.64
0.95
3.87
8.04
1.29
3.99
7.91
3.02
0.37
6.83
16.83
0.32
7.69
18.92
2.57
4.91
13.24
2.90
1.28
5.90
1.23
4.68
5.39
1.90
4.30
1.17
6.47
1.71
8.09
Total reactive
phosphorus, ng/m3
1.22
1.76
7.06
10.62
4.10
2.84
0.64
0,21
2.15
3.21
0.96
3.68
3.51
0.58
2.31
1.15
12.20
4.39
5.13
2.93
11.82
18.43
4.35
1.24
4.60
8.38
1.65
0.58
3.25
0.82
0.85
2.66
2.19
3.04
Total available
phosphorus, ng/m3
3.33
1.77**
7.40
8.01
14.49
12.14
4.13
4.63
8.12
5.17
3.21*
1.32
10.51
20.34
0.89
2.31*
8.84
31.12
6.95
10.04
16.17
14.73
19.71
10.25
2.46
9.28
13.77
3.55
0.58*
3.25*
5.12
0.85*
3.83
8.66
1.71**
11.13
* Soluble phosphorus value below detection limit.
** Reactive phosphorus value below detection limit.
34
-------
TABLE 9 (continued). AEROSOL INPUT—SEPTEMBER
, .
Filter
number
LT1
LT3
LT5
LT7
WG2
WG4
WG6
Sll
S13
S15
S17
S22
S24
S26
LP1
LP3
LP5
LP7
IN2
IN4
IN6
PCI
PC3
PC5
PC7
PF2
PF4
PF6
BY1
BY3
BY5
BY 7
SJ2
SJ4
SJ6
IW1
IW3
IW5
IW7
RSI
RS2
RS3
Total soluble
phosphorus, ng/m
11.27
19.94
19.18
7.21
22.88
23.38
13.53
10.63
11.66
15.63
3.54
14.21
20.85
6.25
19.85
11.05
16.50
7.83
18.43
13.41
10.16
13.81
19.59
17.19
11.71
16.93
14.79
9.00
12.17
10.92
19.77
2.88
28.91
34.47
9.79
7.35
9.96
16.78
4.53
9.14
9.57
10.23
Total reactive
phosphorus, ng/m
6.61
9.36
8.97
1.33
10.55
7.77
6.14
10.64
6.13
5.53
1.55
4.59
5.89
3.95
10.66
2.87
7.75
5.81
7.88
1.69
1.05
6.85
2.82
3.51
1.21
1.58
3.47
2.19
8.12
2.76
3.11
0.48
3.30
4.34
1.60
10.09
4.42
6.86
1.50
7.42
6.10
6.77
Total available
phosphorus, ng/m3
17.88
29.30
28.15
8.54
33.43
31.15
19.67
21.27
17.79
21.16
5.09
18.80
26.74
10.20
30.51
13.92
24.25
13.64
26.31
15.10
11.21
20.66
22.41
20.70
12.92
18.51
18.26
11.19
20.29
13.68
22.88
3.36
32.21
38.81
11.39
17.44
14.38
23.64
6.03
16.56
15.67
17.00
35
-------
TABLE 9 (continued). AEROSOL INPUT—OCTOBER
, , „ ,
Filter
number
LT2
LT6
S12
S14
WG1
WG5
WG7
S21
S23
S25
S27
LP2
LP4
LP6
IW1
IW3
IW5
IW7
SJ2
SJ4
BY1
BY3
BY5
BY7
PF2
PF4
PF6
PCI
PC3
PCS
PC7
1N2
IN4
IN6
Total soluble
phosphorus, ng/m
8.83
0.06
3.98
15.73
7.72
2.14
3.18
8.41
7.65
5.21
0.86
10.68
19.04
3.04
11.02
23.27
6.33
2.39
7.71
18.96
7.44
6.68
9.99
3.34
9.12
15.64
1.04
9.39
7.32
6.25
3,66
10.78
14.90
0.68
Total reactive
phosphorus, ng/m3
4.32
0.66
7.02
6.31
4.39
3.30
4.62
1.76
4.19
2.30
3.65
6.30
1.66
3.48
3.68
4.23
1.84
2.96
7.05
4.41
0.87
3.10
1.56
4.61
6.63
0.73
11.14
1.17
1.73
0.88
7.05
3.17
Total available
phosphorus, ng/m3
13.15
0.72
22.75
14.03
6.53
6.48
13.03
9.41
9.40
3.16
14.33
25.34
4.70
14.50
26.95
10.61
4.23
10.67
26.01
11.85
7.55
13.09
4.90
13.73
22.27
1.77
20.53
8.49
7.98
4.54
17.83
18 . 07
0.68*»
** Reactive phosphorus value below detection limit .
36
-------
TABLE 10. SIZE DISTRIBUTION OF PHOSPHORUS-CONTAINING PARTICLES, APRIL-
SEPTEMBER 1975
Sample
month
April
May
June
July
August
September
AVERAGE
Percent
>4.6y
23.6
6.6
28.9
1.2
15.0
8.0
13.9
2.9-4
27.
11.
6.
12.
21.
15.
15.
.6p
5
4
2
6
0
4
7
1.6-2
7.
19.
5.
24.
11.
17.
14.
.9u
9
4
2
4
0
1
2
0.9-1.6u
8.6
9.2
12.5
18.3
10.5
12.5
11.9
0.5-0.9u
21.3
11.0
13.6
8.6
19.3
20.9
15.8
0.3-0.5u
6.0
24.5
24.3
17.8
7.6
14.2
15.7
0.1-0.3
5.2
18.0
9.3
17.1
15.6
11.8
12.8
>lu
67.5
46.6
52.8
56.5
57.6
53.1
55.7
<0.5y
11.2
42.2
33.6
34.9
23.2
26.0
28.5
that in almost all cases the stations located on the downwind shore collected
a lower amount of aerosol than those on the upwind shore of Lake Huron. This
observation is best illustrated by the month of June (Fig. 11). During the
sampling period, the wind originated in the east and blew across the lake for
four consecutive periods, turned south with no crosswind component for one
period and then blew from the east for the last two sampling periods. Thus
there were four periods during which the Canadian shore was upwind and two
periods when the American shore was upwind. Except for the last Canadian up-
wind samples when the wind was swinging southward, the downwind stations
observed a lower phosphorus content in the air, establishing that a definite
cross-lake concentration gradient existed for the aerosol. To attempt to
quantify this observation, one station on each shore was selected on a line
parallel to the wind direction, and these samples collected at those stations
were compared. In five cases (the first three Canadian upwind and the two
American shore upwind) the ratio of downwind-to-upwind phosphorus contents of
the aerosol, C/Co, was in the range of 0.4-0.8, even though rain occurred
during two of these periods. Further, C/Co was independent of the magnitude
of the concentrations, which ranged from an average of 13.4 to 33.2 pg/m3.
It was observed that the total average phosphorus was higher during the periods
when the wind blew from the Canadian shore; however, this observation cannot
be used to draw a definite conclusion on the effect of wind direction since
this was not observed in most other months.
Although the effect of wind direction could not be determined, the effect
of wind speed was found to be significant. When the ratio C/Co was plotted
against wind speed (Fig. 12), it was observed that the ratio increased with
increasing wind speed. In other words, the faster the wind blew, the smaller
the fraction of the aerosol that fell out. Due to the decreased residence
times of the aerosol over the lake at higher wind speeds, this effect is
reasonable. These values of C/Co were then used to calculate deposition ve-
locities for each period, using a simple mixing box model.
The assumptions made in the model used (Fig. 13) are: 1) a constant mix-
ing height; 2) a complete sink at the bottom; 3) complete mixing of the compo-
nents of the box; and 4) particles falling at some constant velocity. Under
37
-------
30
15
0
30
15
O
UJ
UJ
"> „
CD 0
O
CL
*?
30
APRIL
2345678
12345678
JULY
I 2345678
AUGUST
I 2345678
SEPTEMBER
1234567
ANDERSEN STAGE
1234567
ANDERSEN STAGE
Figure 10. Size distribution of phosphorus in aerosol sam-
ples collected from April through September 1975. The size
ranges for stages 1-7 are: >4.6 y, 2.9-4.6 y, 1.6-2.9 y,
0.9-1.6 y, 0.5-0.9 y, 0.3-0.5 y, and 0.1-0.3 y, respectively.
these conditions, the equation for the deposition is
log(C/Co) = -kt = - ^ t
or
Vd = log(C/Co)
where
Vd = deposition velocity
H = height of mixing layer
t = time between measurement of C and Co
C = downwind concentration
Co = upwind concentration
C and Co have been experimentally determined, H was determined from the air-
craft data, and t can be determined by dividing the cross-lake distance by
the wind speed. The only unknown, therefore, is the deposition velocity, Vd.
38
-------
APRIL
TOTAL AVAILABLE PHOSPHORUS
AVERAGE- 105.1 ncf/m3
3. /^j"N340.l°-5.'
(a)
7L28
MAY
TOTAL AVAILABLE PHOSPHORUS
AVERAGE = 66.0 ng/m3
(b)
Figure 11. Plot of aerosol available phosphorus for each station, April-October 1975. Concentration
is given in ng/m3. The wind direction in degrees from north and wind speed in mph are indicated in
the upper left corners for each sampling period.
-------
JUNE
TOTAL AVAILABLE PHOSPHORUS
AVERAGE = 19.1 nc/rn3
2.
63O3.0-0.05 J
X9.5I
ijll.57 X[ 2O.59
X £42.99
26.80;<
10.19
10.49 X2I.92
X X
12.74
S.S8 V7'12
X X
29.63X,
5./tj--N;«u.a°-7.ii
o
34.31 k"/
'/•/-hK37.7°-O.G4 ./
0 /
^-X0.43
X 10.80
XI8.62 XI5.I9
X
(c)
Figure 11 continued.
JULY
TOTAL AVAILABLE PHOSPHORUS
AVERAGE = 7.6 n
(d)
-------
AUGUST
TOTAL AVAILABLE PHOSPHORUS
AVERAGE = O.I ng/m3
.31
6- /-1~N 357.4°-6.21
SEPTEMBER
TOTAL AVAILABLE PHOSPHORUS
AVERAGE = 19.1 ncj/m3
3. /TA.3!.2°-3.53 /
^-^ /ll.21
I9.67X
"t I'
V f
\ X k\l.3
J0.20X X
LX
(e)
22.08
£4.2 5 >
23.64
12.92
3.36
13.64
Figure 11 continued.
-------
OCTOBER
TOTAL AVAILABLE PHOSPHORUS
AVERAGE = 11.6 nrj
2^<^h\ SOC.80-6.30
V—/ * 17.8 3
^13.15
X( >$I3.73
3.98SC
ly X ^tlO.67
\ y
\431^S
'• X^N 256.5°- 6.80
<20.53
4.70
9.4 OX
L/;ta61
7.^71.3^3.9,
^J jf.
4.54
3.
4.23
(g)
Figure II continued.
The calculation of deposition velocity at the various wind speeds is
shown in Table 11. When the effect of residence time is removed from the
C/Co relationship, it is observed that while the fraction deposited decreases
with increasing wind speed, the deposition velocity of those particles actu-
ally increases (Fig. 14). The above results are consistent with the wind
tunnel experiments of Sehmel and Sutter (1974). They observed that with
monodisperse spherical particles of uranine (density =1.5 g/cm3) at temper-
atures from 15-22°C at wind speeds from 2.2 to 13.8 m/sec, the deposition
velocity for particles greater than 1 y increases with increasing wind speed
over water surfaces. They observed that at any given wind speed, total
deposition was a function of the concentration of particles above the surface
(the more in the air, the more falls out), which agrees with our observation
that C/Co is independent of the magnitude of the concentrations involved.
The data for deposition over Lake Huron are the first field verification of
42
-------
o
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
O.I
WIND SPEED, M/SEC.
Figure 12. Deposition (C/Co) as a function of wind
speed for total available phosphorus concentration,
southern Lake Huron, June 1975.
H
/
c
0
/
/'
\
— u v<
f
/
c
/
/
MIXING BOX MODEL log(Co/C)»- -t
Vj U
Figure 13. Schematic representation of mix-
ing box model for particle deposition.
43
-------
TABLE 11. CALCULATION OF DEPOSITION VELOCITY, Vd,
AT VARIOUS WIND SPEEDS
Wind speed, m/s
C/Co
Vd*, cni/s
1.5
2.0
3.6
4.2
4.9
Vd = (log Co/C)
0.48
0.53
0.67
0.60
0.74
S = (log Co/C) 2 y
0.50
0.57
0.63
0.94
0.65
1.0
0.9
0.8
0.7
0.6
O.S
OA
WIND SPEED, m/sec
Figure 14. Deposition velocity, Vd,
as a function of wind speed for total
available phosphorus concentration,
southern Lake Huron, June 1975.
44
-------
the work of Sehmel and Sutter, and in view of the number of variables involved
in the samples, including heterogeneous particle size range, irregularly
shaped particles, uncontrolled meteorological conditions, thermal gradients,
particle density, etc. not present in the wind-tunnel data, the differences
in actual deposition velocity between the two studies are not unreasonable.
The field work gives a deposition velocity of the phosphorus-containing
particles whose mean diameter is 1 u to be 0.6 cm/sec, which is considerably
higher than the value of 0.01 cm/sec from the wind-tunnel data.
45
-------
SECTION 5
TOTAL AND RELATIVE INPUTS OF PHOSPHORUS FROM
WET AND DRY DEPOSITION
From the above data, total and relative inputs of phosphorus to southern
Lake Huron can be determined by comparison of the average deposition rates
of wet, dry and total fallout (Table 12). The total deposition was determined
by dividing the content of the total integrated samples by sampling time and
surface area. Wet deposition was determined by multiplying the event rain
concentration by the. monthly volume of rain and dividing by the sampling peri-
od. Dry fallout was determined from the aerosol concentration and the depo-
sition velocity.
WET DEPOSITION
Inputs due to wet deposition must be considered speculative due to the
lack of a sufficient number of samples and incomplete analysis. The input of
available phosphorus due to rainout and washout is estimated to be 76 metric
tons, and the total phosphorus may be twice that value. Little emphasis was
placed on this contribution during the present study; nevertheless, the val-
ues for rain concentration are comparable to other studies. Further, the
estimated input of phosphorus agrees well with the value reported by Murphy
TABLE 12. WET, DRY, AND TOTAL AVAILABLE PHOSPHORUS DEPOSITION FOR
THE MONTHS OF APRIL-OCTOBER 1975
Sampling
period
4/18-5/12
5/16-6/9
6/13-7/7
7/11-8/8
8/12-9/15
9/19-10/8
Wet
deposition*
-
1.7 + 0.72
1.5 + 1.1
1.1 + 0.49
0.12 + 0.13
Dry
deposition
5.0 + 0.93
2.7 + 0.50
0.69 + 0.31
0.41 + 0.19
0.71 + 0.12
0.80 + 0.12
Total
observed
5.2 + 5.8
23.1 + 4.6
5.3 + 3.7
1.0 + 0.22
11.5 + 2.8
2.9 + 2.2
% Wet
-
-
32
148(?)
9.6
4.2
% Dry
96
12
13
41
6.2
28
Average 1.1 ng/cm2/dy 1.7 ng/cm2/dy 6.5 ng/cm2/dy 15% 33%
Soluble portion of available phosphorus only.
46
-------
and Doskey (1975) for the input of phosphorus from precipitation to Lake
Michigan. They estimate 1000 metric tons enter that lake in this manner.
Correcting for the difference in surface area, the Lake Huron data would pre-
dict 900 metric tons. The greater input to Lake Michigan is undoubtedly due
to the greater population density in the Lake Michigan Basin.
DRY FALLOUT
The average concentration of phosphorus in the aerosol was found to
range from 0 to 369 ng/m3 with an 8-month average of approximately 76 ng/m3.
Some typical values for the aerosol phosphorus concentration in other areas
are: Los Angeles 1430 ng/m3, Cincinnati 220 ng/m3 (Athanassiadis 1969),
southern Atlantic Ocean 20 ng/m3*. Thus the value for the air over southern
Lake Huron is considered low and typical of rural areas. Based on the data
for aerosol phosphorus, the average deposition rate is 1.7 ng/cm2/dy of
available phosphorus. On a yearly basis, 59 metric tons of available phos-
phorus and almost 123 metric tons of total phosphorus enter southern Lake
Huron from dry fallout.
The average total aerosol concentration, based on HiVol samples, is
27.6 yg/m3. Rural values have been determined to vary from less than 20 to
150 yg/m3 in other areas, with the usual value near the higher end of this
range. Thus, based on aerosol concentration, the air over Lake Huron is rel-
atively "clean." Using the HiVol data, total dry deposition has been calcu-
lated to be 0.60-2.7 yg/cm2/dy with an average of 1.4 yg/cm2/dy. This value
agrees with a preliminary value of 1.7 yg/cm2/dy obtained by Whelpdale (1974)
based on samples collected in July 1968. Using the value of 1.4 yg/cm2/dy,
this amounts to an annual input of 49,000 metric tons of dry fallout to
southern Lake Huron (surface area = 9.5 x 1013 cm2).
TOTAL DEPOSITION
If all contributions to the total available phosphorus input are con-
sidered, a deposition rate of 6.5 ng/cm2/dy was observed. Using this depo-
sition rate, 225 metric tons of available phosphorus eatered southern Lake
Huron on a yearly basis. If only total available phosphorus inputs are con-
sidered, wet deposition accounts for approximately 34% of the amount observed
in the integrated samples. Dry deposition accounts for 26% of the input to
the lake surface. Thus at least 60% of the total available phosphorus can be
accounted for by these two modes. Biological events and other local phenomena
which can elevate the phosphorus content of the integrated samples accounts
for most of the discrepancy. If the May-June integrated samples, which showed
marked evidence of biological input, are eliminated, the wet-plus-dry inputs
account for over 73% of the total available phosphorus observed. Such local
events definitely result in an input to the lake but are local and restricted
to nearshore regions. Thus the extrapolation of the deposition observed in
integrated samples to a total lake input will be systematically high. This
is especially true if one considers total phosphorus rather than total avail-
able phosphorus. Analysis of September-December 1975 samples showed that
*
D.F.S. Natusch, Univ. of Illinois at Urbana-Champaign, pers. comm. 1975.
47
-------
available phosphorus was 32 4; 16% of the total phosphorus observed. On a
yearly input basis, 675 metric tons of phosphorus would.be predicted to enter
southern Lake Huron from the atmosphere, of which 152 metric tons can be
accounted for from wet deposition and 123 metric tons from dry input. Thus
only 41% of the total phosphorus input predicted from the integrated samples
can be verified. Again, this discrepancy is believed to be due to biological
and other local contamination of the integrated samples.
These values differ significantly from the only other work on atmospheric
inputs to Lake Huron (Acres Consulting Services Ltd. 1975). The study areas
differed somewhat in that the Acres work included an extra 3.7 x 1013 cm2 of
open lake and the 2.8 x 1013 cm2 of Saginaw Bay. Probably as a result of in-
clusion of the relatively industrialized Saginaw Bay area, the value for total
loading due to dry deposition was significantly higher (87,000 metric tons,
corrected to southern Lake Huron area, as compared to 49,000 metric tons).
The effect of industrial activity on the phosphorus content of rain and the
total loading has been previously discussed. On the other hand, total phos-
phorus values obtained by analysis of integrated fallout samples gave a sig-
nificantly lower estimated input (90 metric tons). The samples used to pro-
ject this yearly input were collected during the period from October 1973 to
July 1974. The winter months would be expected to predict lower inputs since
the scavenging efficiency of snow is much less than that of rain (Murphy and
Doskey 1975). The aerosol concentration in the air would also be expected to
be lower due to snow cover.
48
-------
LITERATURE CITED
Acres Consulting Services Ltd. 1975. Atmospheric loading of the upper Great
Lakes. Canada Centre Inland Waters, Burlington, Ont., Vol. 2. 126 p.
Andersen, A. A. 1966. A sampler for respiratory health hazard assessment.
Am. Ind. Hyg. Assoc. J. 27: 160-165.
Athanassiadis, Y. C. 1969. Preliminary air pollution survey of phosphorus
and its compounds. A literature review. U.S. Public Health Service,
Raleigh, North Carolina, Pub. No. APTD 60-45.
Bannerman, R. T., D. E. Armstrong, R. F. Harris and G. C. Holdren. 1975.
Phosphorus uptake and release by Lake Ontario sediments. U.S. Environ-
mental Protection Agency, Grosse lie, Michigan, Rep. No. EPA-660/3-75-
006.
Bowen, H. J. M. 1966. Trace elements in biochemistry. London: Academic
Press. 196 p.
Elder, F. C. 1975. International Joint Commission Program for Atmospheric
Loading of the Upper Great Lakes. Paper presented at Second Interagency
Committee on Marine Science and Engineering Conference on the Great
Lakes, Argonne, 111.
Lee, R. E., Jr. and S. Goranson. 1972. Cascade impactor network. National
Environmental Research Center, Research Triangle Park, North Carolina,
Pub. No. AP-108 (PB 213377/5).
Menzel, D. W. and N. Corwin. 1965. The measurement of total phosphorus in
sea water based on the liberation of organically bound fractions by
persulfate oxidation. Limnol. Oceanogr. 10: 280-282.
Miller, W. E., T. E. Maloney and J. C. Green. 1974. Algal productivity in
49 lake waters. Water Res. 8: 667-679.
Murphy, J. and J. P. Riley. 1962. Modified single solution method for the
determination of phosphate in natural waters. Anal. Chim. Acta. 27:
31-36.
Murphy, T. J. 1974. Sources of phosphorus inputs from the atmosphere and
their significance to oligotrophic lakes. Univ. Illinois, Water
Resources Research Center, Urbana, Rep. No. 92.
49
-------
and P. V. Doskey. 1975. Inputs of phosphorus from precipitation
to Lake Michigan. U.S. Environmental Protection Agency, Grosse lie,
Michigan, Rep. No. EPA-600/3-75-005.
Portelli, R. In press. Mixing heights, wind speeds and air pollution poten-
tial for Canada. Atmosphere.
Pursglove, J., Jr. 1967. Fly ash in 1980. Coal Age, Aug. 1967, pp. 84-85.
Schelske, C. L. and E. F. Stoermer. 1971. Eutrophication, silica depletion
and predicted changes in algal quality in Lake Michigan. Science 173:
423-424.
and . 1972. Phosphorus, silica, and eutrophication of
Lake Michigan, p. 157-171. In G. E. Likens (Ed.), Nutrients and eutro-
phication. Lawrence, Kansas: Allen Press.
, L. E. Feldt, M. A. Santiago and E. F. Stoermer. 1972. Nutrient
enrichment and its effect on phytoplankton production and species compo-
sition of Lake Superior. Proc. 15th Conf. Great Lakes Res., pp. 149-165.
Sehmel, G. A. and S. L. Sutter. 1974. Particle deposition rates on a water
surface as a function of particle diameter and air velocity. J.
Recherches Atmospherique 8: 911-920.
Whelpdale, D. M. 1974. Particulate residence time. Water, Air and Soil
Pollution 3: 293-300.
50
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APPENDIX—SAMPLING STATION LOCATIONS
Lighthouse County Park (LT). Permission to use this facility was granted
by the Board of County Road Commissioners of Huron County, Mr. Lester Ender,
Chairman. The park is located near Huron City, Mich., approximately 0.8 km
from M-25 directly on the lake shore. A 5-m mast was attached to a lightpole
in a grassy clearing removed from obstructions, approximately 150-200 m from
the shore. Little automobile traffic was observed in this area of the park.
The sampler was relocated twice, once due to objections to the noise and once
due to contamination from a nearby building. The station was located at 44°
01.4' N and 82° 47.3' W.
Wagener County Park (WG). This park, 6.4 km south of Harbor Beach, Mich.,
on M-25, was also under the supervision of the Huron County Road Commission.
The park is a day-use area and a season trailer park with no tenting, there-
fore campfires were not a problem. The sampling area was located at the end
of the park at the shoreline, where the 5-m mast was attached to a power pole.
A number of tall trees were located near the sampler and may have interrupted
normal air flow. The soil is rock and sand. The station was at 43° 47.7' N
and 82° 38.0' W.
Sanilac County Park //I (SI). Mr. Dale Wheeler, Board of County Road
Commissioners of Sanilac County granted permission to use this park and
Sanilac #2. The park is 4 km north of Forester, Mich., on M-25 and is a day-
use and season trailer park, a park manager is in permanent residence at the
park. The 5-m mast was anchored to a wooden post on the edge of the beach
area. Power was supplied from a building nearby. The beach area is designated
for picnics only, and although charcoal grills were located within 25 m of the
sampler they were not observed to be in use during any of the sampling trips.
The latitude and longitude of this station were 43° 30.7' N and 82° 35.6' W.
Sanilac County Park #2 (S2). This day-use only park is located about
6.4 km north of Lexington, Mich., on M-25. The mast was anchored to a stair-
way leading from the 5-m bluff to the beach. The sampler was removed from
all obstruction and 50 m from the caretaker's summer residence. The location
of this station was 43° 17.7' N and 82° 32.8' W.
Lakeport Station Park (LP). Permission to use this park was granted by
Mr. Paul Rearick, Michigan Department of Natural Resources, and the park
manager Mr. J. Janks. The park is located at the town of Lakeport, Mich., on
M-25. The mast was attached to a pumphouse approximately 100 m from the shore
in the day-use area. A stand of trees was located between the sampler and
the shore; soil was grass-covered and the main road, M-25, was located 250 m
51
-------
from the station across an open field which was a potential source of contam-
ination. The latitude and longitude of the station were 43° 04.8' N and 82°
30.0' W.
Ipperwash Provincial Park (IW or IP). Permission to use the three pro-
vincial parks was granted by Mr. W. H. Charlton, Regional Director of the
Ministry of Natural Resources, Ontario, and the individual park managers.
The park extends along the shore at Kettle Point about 2.4 km west of Ont-21
near Ravenswood, Ont. The 5-m mast was located in a 100 x 50 m clearing,
attached to a 2.5-m tall pumphouse. The clearing is on a 5-m bluff behind a
low stand of pine trees, and the soil is mainly sandy and grass-covered. The
location of this station was 43° 13.0' N and 82° 00.9' W.
St. Joseph Shores on Lake Huron (SJ). This station was located on private
property owned by Mr. Frank Moore, Zurich, Ont. It was located 2.4 km south
of the St. Joseph intersection on Ont-21, on a point well past the end of a
private paved drive and at least 200 m from the only residence in the imme-
diate area. The sampler was attached 5 m up a 50—m tower used for television
reception. The tower itself was located on a 10-m cliff at the edge of the
lakeshore at the end of a well-groomed lawn. The latitude and longitude were
43° 24.5' N and 81° 43.1' W.
Bayfield Marina (BY). Permission to use this facility was granted by
Mr. B. E. Snead, Small Craft Harbour Branch, Environment Canada, and by Mr.
Tom Castle, the marina operator. The marina is located at the mouth of a
river at Bayfield, Ont. Due to the need for electric power, the mast was
attached to the side of a service building approximately 3 m tall. A dirt
road leading from the main road into the marina was approximately 5 m away
but not well travelled. The sampler was 100 m from the lakeshore, located
at approximately 43° 34.1' N and 81° 42.7' W.
Point Farms Provincial Park (PF). The park is 7 km north of Coderich,
Ont., on Ont-21. The mast was attached to a comfort station on the beach,
about 0.8 km from the main road. The beach area is at the bottom of a tree-
covered 20-m bluff and the sampler was 30 m from the lakeshore. The area
was designated as day-use and no campfires were permitted in the area. The
latitude and longitude of this station were 43° 48.4' N and 81° 43.6' W.
Point Clark Boat Club (PC). The board of directors of this private
boat club granted permission to establish a sampling station on their pro-
perty. The sampler was attached 5 m up a power pole with an angle brace and
eye hook. It was directly on the lakeshore on a point of land removed from
all structures. The nearest residences were summer camps approximately 300
m away. The only road was a access ramp to the water owned by the private
club and not heavily travelled. A potential source of contamination was a
nearby marine fuel storage tank (150 gal). The station was located at 44°
04.8' N and 81° 46.0' W.
Inverhuron Provincial Park (IN). The park is located at Douglas Point
about 3 km west of Tiverton, Ont. The 5-m mast was attached to a comfort
station located at lake level in a sandy beach at the south end of the park.
The area was day-use only and removed from the camping area. A nearby parking
52
-------
lot was a potential source of contamination, but was seldom in use. The
proximity of this station to the Bruce Nuclear Power Development raised the
question of contamination from the oil-fired power plant which supplements
the reactor facility. No evidence for this contamination has been observed,
however. This station was located at 44° 17.7' N and 81° 36.3' W.
53
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/3-77-038
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
ATMOSPHERIC INPUT OF PHOSPHORUS TO SOUTHERN LAKE
HURON, APRIL-OCTOBER, 1975.
5. REPORT DATE
April 1977 issuing date
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
Richard G. Delumyea and Resy L. Petel
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Great Lakes Research Division
Institute of Science § Technology Building
University of Michigan
Ann Arbor, Michigan 48109
10. PROGRAM ELEMENT NO.
1BA026
11. CONTRACT/GRANT NO.
803086
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Research Laboratory-Duluth
Office of Research and Development
U.S. Environmental Protection Agency
Duluth, Minnesota 55804
13. TYPE OF REPORT AND PERIOD COVERED
Final; April-October 1975
14. SPONSORING AGENCY CODE
EPA/600/03
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The input of phosphorus has been demonstrated to be seasonally dependent. Of
the total input, approximately half is potentially available, and one-fourth is
immediately available. Inputs due to wet and dry deposition are roughly equal in
magnitude. The major source appears to be agriculture with at least 10% due to
combustion sources. A model for particulate deposition was used to determine the
deposition velocity of phosphorus containing particles. The value of 0.6 cm/sec
is considered applicable to other components whose mean diameter is 1 ym.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
Phosphorus
Precipitation (chemistry)
Dryfall
Wetfall
Eutrophication
Rainfall
Lake Huron
08/H
13. DISTRIBUTION STATEMENT
RELEASE. TO PUBLIC
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
62
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
54
* U.S. GOVERNMENT PRINTING OFFICE: 1977-7 57-056/5608
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