Residues of Currently
and Never Used Organochlorine
Pesticides in Agricultural Soils from Zhejiang Province, China
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Abstract
Studies on residues of currently and never used organochlorine
pesticides (OCPs) facilitate the assessment of the contamination level,
distribution, sources, transportation, and trend of these selected
OCPs in China. In this work we investigated the concentration levels
of endosulfans and chlordane, which are currently used, and the never
used aldrin and dieldrin in the province of Zhejiang, a rainy, and
hilly tea-growing province in eastern China. The average/mean residue
levels of OCPs was in the order ∑endosulfan > ∑chlordane
> aldrin > dieldrin. The residue level was in good agreement
with
the usage of OCPs in Zhejiang. The spatial distribution showed that
the residues of OCPs in soils from the mountain area were always higher
than those in soils from the plains. The distribution characteristics
were related to usage for current-use OCPs and temperature for never
used OCPs. The isomeric ratios and enantiomeric fractions are useful
tools to identify the degradation preference of contaminants. The
wide range of ratios between <i>trans</i>-chlordane (TC)
and <i>cis</i>-chlordane (CC) indicated that the degradation
of the two isomers of chlordane was different at different sites.
Nonracemic residues of TC and CC were observed in most soils; this
is significant since the enantiomers have different toxicities