Gschwend%20thesis.pdf

-174-
2 A=lcm
z = lO
-2
em corresponding to a wind velocity of 4.5 m/sec
3
V = 200 cm
then DA/zV = 3 x
-6
10 / sec
(Kanwisher, 1963)
depth at CD ca. 2 meters.
and af ter i hour C exp (-DA! zV) x (t) = 0.99C
0 0
af ter i day
= 0.78C 0
af ter 3 day
= 0.46C 0
af ter i week = O. 16C 0
Thus, if 30 ng o-xylene/kg were added to a 5 ng o-xylene/kg background,
degassing would reduce an observed concentratiòn of 35 ng o-xylene/kg
to 10 ng o-xylene/kg within 1 week. This reduction would be even faster
if wind speeds were greater or if other sinks such as mixing with cleaner
wa ter also were available.
SUMRY
Several independent approaches have been taken in an effort to assess
the transport öf C2- and C3-bè zenes to coastal seawater.
The data suggest that the atmosphere was not an important route of
delivery of these aromatic compounds to the seawater in the summer. The
highest concentrations of C2- and C3-benzenes ever observed at CD were
associated with motorboat traffic on a summer weekend. Two other lines of
evidence suggest that the air was not a source of these compounds to coastal
seawater in the period from late spring through fall. First, the inhomogeeity
of concentrations in surface seawater from Vineyard Sound indicated that