Gschwend%20thesis.pdf

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compound concentrations in air to seawater concentrations of the Cz- and
C3-benzenes may be a valid indicator for the longer-term direction of flux.
Oyster Pond, Quashnet River, and Sippewissett Marsh.
Inland water samples were analyzed for their volatile content. Five
samples of Oyster Pond water were acquired in August and September, 1978.
This pond is located very near CD and is separated from the coastal seawater
by a narrow stretch of land (figure 3-1). The pond is a collecting basin
for groundwater and runoff, and releases about 3 X 106 liters of water to
the Sound near CD per day (Emery, 1972). Motorboats are not allowed on
Oyster Pond.
The concentrations of o-xylene in Oyster Pond were consistently found
to be lower than those in CD (figure 4-6). Assuming that sinks such as
biodegradation or loss to the sediments are no more important in the pond
than they are at CD, these .data suggest that the atmosphere. was not an im-
portant source of C2- and C3-benzenes to CD at this time. . Since o-xylene
is more soluble in freshwater than in seawater, the concentrations in
freshwater should be higher than in seawater given an atmospheric source
at equilibrium with both (Sutton and Calder, 1975; Appendix IV).
After rain, the Oyster Pond concentration of o-xylene increased (30%),
while at CD the concentration decreased (25%). This observation indicates
that the atmosphere is the source of this aromatic compound to Oyster Pond
but not to CD. It also supports the conclusion from the year-round data
that rain does not lead to delivery of aromatic hydrocarbons to CD.