Arctic seawater concentrations o
f two currently usedpesticides, endosul
fan and
fchars/gamma.gi
f" BORDER=0 >-HCH, were collated
from avariety o
f cruises undertaken throughout the 1990s up to 2000
for di
fferent regions o
f the Arctic Ocean. Sur
face seawaterconcentrations
for
fchars/alpha.gi
f" BORDER=0>- and
fchars/beta2.gi
f" BORDER=0 ALIGN="middle">-endosul
fan ranged
from <0.1-8.8 (mean 2.3) pg/L and 0.1-7.8 (mean 1.5) pg/L, while
fchars/gamma.gi
f" BORDER=0 >-HCHconcentrations were ~100
fold higher than
fchars/alpha.gi
f" BORDER=0>-endosul
fan,ranging between <0.70 and 894 (mean 250) pg/L.Geographical distributions
for
fchars/alpha.gi
f" BORDER=0>-endosul
fan revealed thehighest concentrations in the western Arctic, speci
fically inthe Bering and Chukchi Seas with lowest levels towardthe central Arctic Ocean. In contrast,
fchars/gamma.gi
f" BORDER=0 >-HCH revealed higherconcentrations toward the central Arctic Ocean, withadditional high concentrations in the coastal regions nearBarrow, Alaska and the White Sea in northwest Russia,respectively. A
fugacity approach was employed to assessthe net direction o
f air-water trans
fer o
f these twopesticides, using coupled seawater and air concentrations.For
fchars/alpha.gi
f" BORDER=0>-endosul
fan, water-air
fugacity ratios (FR) were all<1 indicating net deposition to all regions o
f the Arctic Ocean,with the lowest values (0.1-0.2) evident in the CanadianArchipelago. Given the uncertainty in the temperature-adjusted Henry's Law constant (
factor ~10), it is plausiblethat equilibrium may have been reached
for this compoundin the western
fringes o
f the Arctic Ocean where the highestwater concentrations were observed. Similarly, FRvalues
for
fchars/gamma.gi
f" BORDER=0 >-HCH were generally <1 and in agreementwith other separate studies, although, like
fchars/alpha.gi
f" BORDER=0>-endosul
fan,net deposition predominated over the Canadian Archipelago.In the central and eastern regions o
f the Arctic Ocean,as well as in the two coastal areas o
f this study, the
fugacityratios
for
fchars/gamma.gi
f" BORDER=0 >-HCH where ~1 indicating conditions approachingequilibrium. The elevated water concentrations andhigher FRs in these coastal areas support the assessmentthat riverine/coastal sources are important
for thischemical, but less so
for
fchars/alpha.gi
f" BORDER=0>-endosul
fan
for which air towater trans
fer during the ice-
free summer months is likelyto be the major contemporary source to the Arctic. It isrecommended that archived extracts o
f river water bereanalyzed
for
fchars/alpha.gi
f" BORDER=0>-endosul
fan to con
firm this.