United States
Environmental Protection
Agency
Environmental Research
Laboratory
Duluth MN 55804
Research and Development
EPA-600/S3-84-101 Dec. 1984
&EPA Project Summary
Atmospheric Transport of
Toxaphene to
Lake Michigan
C. P. Rice, P. J. Samson, and G. Noguchi
Atmospheric levels of toxaphene were
monitored during the summer and fall
of 1981 at four locations: Greenville,
Mississippi, St. Louis, Missouri, Bridg-
man, Michigan, and Beaver Island,
Michigan. Each collection was conduct-
ed by continuously sampling air during
the first two weeks of the months of
August, September, October, and No-
vember. The collected toxaphene was
analyzed on a capillary equipped elec-
tron capture gas chromatograph. The
average concentrations over the entire
sampling period for each site were 7.39
ng/m3in Greenville, 1.18 ng/m3inSt.
Louis, and 0.27 ng/m3 for Lake Michi-
gan (Bridgman and Beaver Island com-
bined). The summer versus fall fluctua-
tions in amount of toxaphene at each
site was 0.44 ng/m3 versus 0.26 ng/m3
for Bridgman; 1.73 ng/m3 versus 0.63
ng/m3 for St. Louis; and 9.05 ng/m3
versus 4.34 ng/m3 for Greenville. The
maximum monthly average occurred in
September for all of these collections.
Diagnostic modeling to describe pos-
sible air transport of toxaphene showed
that at all receptor locations the air
transport corridor for toxaphene was
associated with southerly winds. The
strength of this corridor increased from
northern to southern measurement
sites. A flux estimate for toxaphene
deposition to the lake surface ranged
from 3,360 to 6,720 kg/yr.
This Project Summary was developed
by EPA's Environmental Research Lab-
oratory, Duluth. MN. to announce key
findings of the research project that is
fully documented in a separate report of
the same title (see Project Report order-
ing information at back).
For this study, atmospheric levels of
toxaphene were monitored simultaneous-
ly during the summer and fall of 1981 at
four locations: Greenville, Mississippi; St.
Louis, Missouri; Bridgman, Michigan;
and Beaver Island, Michigan.
The sampling intervals at each site
were adjusted to occur simultaneously in
an attempt to determine possible atmos-
pheric links between the sites and a
southern input source for toxaphene.
Backward air trajectories were construct-
ed for each location during the sample-
collection periods. These trajectories,
coupled with the observed atmospheric
concentrations of toxaphene, were used
to construct probability contours for the
likeliest toxaphene delivery corridors into
each of the sites.
Collection was conducted by continu-
ously sampling air during the first two
weeks of each of the following months of
1981: August, September, October, and
November. Beaver Island samples were
collected only during the second and third
time interval. Samples were collected
using both high- and low-volume air
samplers. The high-volume sampler em-
ployed a General Metals suction pump
drawing air at a rate of 0.6 to 1.1 mVmin
through a sampling train having a glass
fiber filter followed by two to three
polyurethane foam plugs (9 cm diam. x
6.5 cm long). The high-volume system
was used in St. Louis, Bridgman, and
Beaver Island and operated for periods of
2 to 4 days for each sample collection.
Three samples were collected for each
2-week period. The low-volume air samp-
ler consisted of a low-volume suction
pump (flow rates of 7 to 10 L/min) which
was connected to a series of 2 to 3
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polyurethane foam plugs (3.5 cm diam. x
10.5 cm long). The low-volume system
was used at the Greenville sampling site.
During this study, one sampler was
operated continuously over the entire 4-
month period to secure an integrated
collection.
The collected toxaphene was removed
from the plugs and filters using Soxhlet
extraction with petroleum ether. The
toxaphene was analyzed on a fused silica
capillary equipped electron capture gas
chromatograph. Sample extracts were
subjected to a minimum of cleanup and
fractionation prior to analysis in order to
avoid changes in the chromatographic
appearance of the toxaphene mixtures.
The extracts were treated with sulfuric
acid for cleanup and then injected directly
into the gas chromatograph. Individual
peaks in the samples were compared to
peaks in a standard of toxaphene obtained
from EPA. The peak matching method
was relative retention time using either
p,p'-DDE or octachloronapthalene as the
reference standard. To avoid misidenti-
fication of peaks, a narrow window for
peak matching was selected, and peak
regions suspected of interferences, e.g.,
PCBs and chlordanes, were not included
in the matching routine.
With the capillary column selected and
the sensitivity provided by the instrument,
between 26 to 60 peaks were selected for
matching against the samples. Although
approximately 200 peaks were identified
in the standard, many were screened out
for various reasons, e.g., poor baseline
resolution, low detector response, or
inteference from PCBs or chlordanes.
A percentage of the number of peaks
matched versus the number of peaks
sought was calculated. This provided an
estimate of the similarity of the material
measured to the standard used. The
mean percent matches for each of the
sampled regions were 36% for Lake
Michigan, 38% for St. Louis, and 51 % for
Greenville. One interpretation of the
results posited that the composition of
toxaphene nearest the source would
have the best match; Greenville, located
in an area of high toxaphene usage,
seemed to fit this concept.
While most of the toxaphene was
recovered from the foam plugs, less than
5% was on the filters, indicating little or
no particulate-phase toxaphene in the
air. The average concentrations over the
entire sampling period for each site were
7.39 ng/m3 in Greenville, 1.18 ng/m3in
St. Louis, and 0.27 ng/m3 for Lake
Michigan (Bridgman and Beaver Island
combined). These results indicate a defi-
nite decline in concentration of toxaphene
moving from south to north. Also, the
amount of toxaphene at each site varied
seasonally, i.e., the levels measured
higher in the two summer collections
than in the two fall collections. For
Bridgman, these values were 0.44 ng/m3
for the summer and 0.26 ng/m3 for the
fall; for St. Louis these respective values
were 1.73 ng/m3 versusO.63 ng/m3; and
for Greenville they were 9.05 ng/m3
versus 4.34 ng/m3. The maximum aver-
age level of toxaphene for all sites was
measured in the second 1981 sampling
period (25 August through 3 September).
The changing pattern for toxaphene in air
over the sampling period appears to be
one of an initial increase in early August
to a maximum in early September, and
then a gradual decrease in October and
November. This cycle agrees with similar
observations of changing levels of toxa-
phene in air measured in the Mississippi
delta by other researchers in 1974.
Diagnostic modeling to describe possi-
ble air transport of toxaphene showed
that at all receptor locations the air
transport corridors for toxaphene were
associated with southerly winds. The
preferred corridors of transport of higher
concentrations increased from northern
to southern measurement sites, presum-
ably in response to the larger range of
concentrations in the south. This analysis
does not prove which source region(s)
contributed to the observed concentra-
tions, partly because so little is known
about the magnitude of the source
strenghts. However, the methodology
developed for this analysis can identify
the probable corridors of transport deliver-
ing the material to the receptor. The
methodology is well suited for analysis of
data which, because of low concentra-
tions in the atmosphere, must be collected
over long time periods (longer than a day).
With a sufficient number of samples,
intra-period fluctuations in contribution
to the sample will be removed and
meaningful transport characteristics will
be discerned.
A flux estimate for toxaphene deposi-
tion to Lake Michigan was calculated. An
event rain sample collected at Beaver
Island during one of the 1981 air collec-
tion periods was used in this calculation.
The toxaphene measured in this sample
gave a washout coefficient of 1,355 for
this sample. This was higher than the
range of values (16 - 861) reported in
1981 by other researchers; therefore, the
current study used values of 500 to 1,000
for the wet flux estimate. For the air
concentration for this flux calculation.
this study used measured values am
assumed that the Beaver Island result
represented northern Lake Michigan am
that the Bridgman site represented south
ern Lake Michigan. To estimate winte
levels, the summer average was reducei
by one-fourth. This resulted in an esti
mateoftheyear-round level of toxaphem
in air over Lake Michigan to be 0.11
ng/m3. The wet llux, which was calcu
lated using the above derived values
ranged from 3,000 to 6,000 kg of toxa
phene per year. To derive a dry flu:
estimate, we chose a deposition velocit
range of 0.12 to 0.24 cm/sec and usei
our measured whole lake air concentra
tion. Using these values, the calculate!
dry flux was 360 to 720 kg of toxaphem
deposited per year. Together, these ac
counted for a total estimate of 3,360 ti
6,720 kg/yr for toxaphene flux to Laki
Michigan in 1981.
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C. P. Rice, P. J. Samson, andG. Noguchiare with the University of Michigan, Ann
Arbor, Ml 48109.
M. D. Mullin is the EPA Project Officer (see below).
The complete report, entitled "Atmospheric Transport of Toxaphene to Lake
Michigan," (Order No. PB 85-121 143; Cost: $10.00, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Duluth. MN 55804
U S GOVERNMENT PRINTING OFFICE, 1984 — 559-016/7859
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Center for Environmental Research
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