Distribution of Chlorinated Hydrocarbon Pesticides and PCBs in the ...

trips in Table 4.2 and detailed in Appendix B. Compounds of
all classes of organochlorines (HCH, HCB, BDT, PCBs and
cyclodienes) were quantifiable in filtered snow melt. The
alpha and gamma isomers of HCH were the most abundant
dissolved compounds. There were however, very large
differences in the amount of HCH present on each trip and
differences in the ratios of the a1pha:gamma isomers. Total
HCH decreased from 2100 ng/L in May to 1250 ng/L in
August/September. In June 1987, sample concentrations were
480 ng/L, principally as a result of lower a HCH levels. The
ratio of a1pha:gamma isomers varied from 2,3 to 5.5 to 1.5
respectively over the three trips. Concentrations of HCH
associated with particulates were less than 1.0 ng/L in all
samples.
PCBs (as Arochlor 1254) were the next most abundant
dissolved component. Seasonally, concentrations were lower
in August/September relative to May and June (79 ng/L vs 125
and 177 ng/L respectively). PCBs were quantifiable on
particulates in May and June (54 and 7 ng/L respectively) and
below detection (