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Fig. 17.20 Frequencies of herbicide and insecticide detection in shallow groundwater beneath
10 different land-use settings (Kolpin et al.
1998
). Reprinted with permission from Kolpin et al.
(
1998
). Copyright 1998 American Chemical Society
Differences in transport and persistence among the pesticides included in
Fig.
17.19
may be explained by variations in the physical and chemical properties
of the compounds. Kolpin et al. (
1998
) related the frequencies of herbicide and
insecticide detection in shallow groundwater to land surface use. Although pes-
ticides were found in groundwater beneath different land uses, variations were
observed in the frequencies of herbicides and insecticides. For example, urban
category ranked seventh in herbicide frequency, but second in frequency of
insecticide detection (Fig.
17.20
).
Later, Gilliom (
2007
) reported another 10-year study by the US Geological
Survey (NAWQA) which provides a national-scale view of pesticide occurrence in
streams and groundwater. Water samples were analyzed for 75 pesticides and 8
degradates currently in use, and bed sediments and fish tissue were analyzed for 32
organochlorine pesticides whose use has been discontinued. In one-third of deeper
wells from aquifers used for water supply, at least one pesticide compound was
