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Concentrations and loads of suspended sediment-associated pesticides in the San Joaquin River, California and tributaries during storm events

January 1, 2009

Current-use pesticides associated with suspended sediments were measured in the San Joaquin River, California and its tributaries during two storm events in 2008. Nineteen pesticides were detected: eight herbicides, nine insecticides, one fungicide and one insecticide synergist. Concentrations for the herbicides (0.1 to 3000 ng/g; median of 6.1 ng/g) were generally greater than those for the insecticides (0.2 to 51 ng/g; median of 1.5 ng/g). Concentrations in the tributaries were usually greater than in the mainstem San Joaquin River and the west side tributaries were higher than the east side tributaries. Estimated instantaneous loads ranged from 1.3 to 320 g/day for herbicides and 0.03 to 53 g/day for insecticides. The greatest instantaneous loads came from the Merced River on the east side. Instantaneous loads were greater for the first storm of 2008 than the second storm in the tributaries while the instantaneous loads within the San Joaquin River were greater during the second storm. Pesticide detections generally reflected pesticide application, but other factors such as physical-chemical properties and timing of application were also important to pesticide loads.

Publication Year 2009
Title Concentrations and loads of suspended sediment-associated pesticides in the San Joaquin River, California and tributaries during storm events
DOI 10.1016/j.scitotenv.2009.09.040
Authors M.L. Hladik, Joseph L. Domagalski, K.M. Kuivila
Publication Type Article
Publication Subtype Journal Article
Series Title Science of the Total Environment
Index ID 70035731
Record Source USGS Publications Warehouse
USGS Organization California Water Science Center; Toxic Substances Hydrology Program