Environmental Engineering Reference
In-Depth Information
Fig. 3
Detections of chlorpyrifos and 95th centile concentrations in U.S. surface water, 1992-
2010 (data from Martin et al.
2011
)
Frequencies of detection and 95th centile concentrations decreased more than
five-fold between 1992 and 2010 (Fig.
3
). Detections in 1992-2001 ranged from
10.2 to 53.1%, while 2002-2010 detections ranged from 7.0 to 11.2%. The 95th
centile concentrations ranged from 0.007 to 0.056 μg L
−1
in 1992-2001 and 0.006-
0.008 μg L
−1
in 2002-2010. Localized intensive studies of CPY in surface waters
also indicated the dramatic decrease in detection of CPY between 2001 and 2002,
for example in Texas (Banks et al.
2005
).
Farm Resource Regions (USDA-ERS
2000
) with the greatest percent detections
(Table
3
) and the greatest 95th centile concentrations (Table
4
) were the Fruitful
Rim region and the Basin and Range region. Farms in the Basin and Range and
Fruitful Rim FRRs include cattle, wheat, sorghum, fruit, vegetable, nursery and cot-
ton farms in the western third of the U.S. and southern Texas, Florida, and south-
eastern Georgia and South Carolina (Martin et al.
2011
).
The greatest frequency of detections (Table
3
) and 95th centile concentrations
(Table
4
) occurred in undeveloped and agricultural land-use classes. The two land-
use classes with the most urban land (urban and mixed) had the smallest frequency
of detections and 95th centile concentrations, consistent with the cessation of
CPY-based product sales for most homeowner uses in December 2001 (Johnson
et al.
2011
).
Databases in California and Washington were also examined to identify addi-
tional data on concentrations of CPY in surface waters. The California Department
of Pesticide Regulation Surface Water Database (CA-SWD) was developed in 1997
to collect and provide information on pesticides in California surface waters (CDPR
2012a
). Samples were taken from rivers, creeks, urban streams, agricultural drains,
the San Francisco Bay delta region, and runoff of urban storm-water from August
Search WWH ::
Custom Search