title: Temporal and spatial trends in sediment contaminants associated with toxicity in California watersheds.
abstract: California's Stream Pollution Trends program (SPoT) assesses long-term water quality trends, using 100 base-of-the-watershed sampling sites. Annual statewide sediment surveys from 2008 to 2012 identified consistent levels of statewide toxicity (19%), using the freshwater amphipod Hyalella azteca. Significant contaminant trends included a decrease in PCBs, stable concentrations of metals and PAHs, and a statewide increase in detections and concentrations of pyrethroid pesticides. The pyrethroid pesticide bifenthrin was detected in 69% of samples (n = 410). Detection of toxicity increased in a subset of samples tested at a more environmentally relevant test temperature (15 °C), and the magnitude of toxicity was much greater, indicating pyrethroid pesticides as a probable cause. Pyrethroid toxicity thresholds (LC50) were exceeded in 83% of samples with high toxicity. Principal components analysis related pyrethroids, metals and total organic carbon to urban land use.
authors.affiliation: University of California, Davis, USA. Electronic address: csiegler@ucdavis.edu.
authors.forename: Katie
authors.initials: K
authors.lastname: Siegler
authors.affiliation: University of California, Davis, USA.
authors.forename: Bryn M
authors.initials: BM
authors.lastname: Phillips
authors.affiliation: University of California, Davis, USA.
authors.forename: Brian S
authors.initials: BS
authors.lastname: Anderson
authors.affiliation: University of California, Davis, USA.
authors.forename: Jennifer P
authors.initials: JP
authors.lastname: Voorhees
authors.affiliation: University of California, Davis, USA.
authors.forename: Ron S
authors.initials: RS
authors.lastname: Tjeerdema
mesh_terms: D033304:Amphipoda / Q000187:drug effects / Q000254:growth & development; D000818:Animals; D002140:California; D019015:Geologic Sediments / Q000032:analysis*; D010575:Pesticides / Q000032:analysis / Q000633:toxicity; D011722:Pyrethrins / Q000032:analysis / Q000633:toxicity; D045483:Rivers / Q000737:chemistry; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
chemical_list: D010575:Pesticides; D011722:Pyrethrins; D014874:Water Pollutants, Chemical; C099952:bifenthrin
keywords: California; Pyrethroids; Sediment; Spatial–temporal; Toxicity