001 I Street

San Jose, CA, United States

001 I Street

San Jose, CA, United States

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Zhang X.,001 I Street | Zhang M.,001 I Street | Zhang M.,University of California at Davis
Science of the Total Environment | Year: 2011

Quantifying effectiveness of agricultural BMPs at the watershed scale is a challenging issue, requiring robust algorithms to simulate not only the agricultural production system but also pollutant transport and fate. This research addresses the challenge to simulate performances of BMPs in reducing organophosphates (OPs) runoff at the watershed scale. The SWAT model is calibrated and validated following a sensitivity analysis combining Latin Hypercube sampling and One-factor-At-a-Time simulation. The calibrated model is then applied in the Orestimba Creek Watershed to simulate BMPs including buffer strips, sediment ponds, vegetated ditches, use reduction, and their combinations. BMP simulation suggested that sediment ponds trap 54-85% of sediment from field runoff, but less than 10% of dissolved diazinon and chlorpyrifos. Use reduction can reduce pesticide load in a close-to-linear fashion. Effectiveness of vegetated ditches and buffers depends on their physical dimension and vegetation cover. Combining individual BMPs provides enhanced mitigation effects. The combination of vegetated ditches, buffer strips and use reduction decreases diazinon and chlorpyrifos load by over 94%. This study has suggested that the SWAT model reasonably predicts BMP effectiveness at the watershed scale. Results will assist decision making in implementing BMPs to reduce pesticide loads in surface runoff. © 2011.


Phillips B.M.,University of California at Davis | Anderson B.S.,University of California at Davis | Siegler K.,University of California at Davis | Voorhees J.P.,University of California at Davis | And 2 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2016

Agricultural use of organophosphate pesticides are responsible for surface water toxicity in California and has led to a number of impaired water body listings under section 303(d) of the Clean Water Act. Integrated passive-treatment systems can reduce pesticide loading in row crop runoff, but they are only partially effective for the more soluble organophosphates. The Landguard™ enzyme has been effectively proven as an on-farm management practice for the removal of chlorpyrifos and diazinon in furrow runoff, but it has not been used in larger-scale treatment because of concerns regarding the potential impact on in-stream macroinvertebrates after chronic use. A first-order agricultural creek was treated with the Landguard enzyme for 30 days approximately 450 m upstream of its intersection with the Salinas River. Toxicity and pesticide chemistry were measured in the creek during treatment as well as in the river both upstream and downstream of the creek input before and after treatment. Benthic macroinvertebrates were also surveyed in the river before and after enzyme treatment. Low concentrations of organophosphate pesticides were detected in the creek, but Landguard removed detected concentrations of chlorpyrifos. Toxicity detected in the creek was likely caused by pyrethroid pesticides, and no toxicity was detected in river samples. There were no differences in habitat or macroinvertebrate assemblages between upstream and downstream samples or between pre- and post-treatment samples. These results indicate that chronic treatment of the creek with Landguard enzyme had no impact on macroinvertebrate community structure in the river. © 2015 Springer Science+Business Media New York.


PubMed | 001 I Street and University of California at Davis
Type: Journal Article | Journal: Archives of environmental contamination and toxicology | Year: 2016

Agricultural use of organophosphate pesticides are responsible for surface water toxicity in California and has led to a number of impaired water body listings under section303(d) of the Clean Water Act. Integrated passive-treatment systems can reduce pesticide loading in row crop runoff, but they are only partially effective for the more soluble organophosphates. The Landguard enzyme has been effectively proven as an on-farm management practice for the removal of chlorpyrifos and diazinon in furrow runoff, but it has not been used in larger-scale treatment because of concerns regarding the potential impact on in-stream macroinvertebrates after chronic use. A first-order agricultural creek was treated with the Landguard enzyme for 30days approximately 450m upstream of its intersection with the Salinas River. Toxicity and pesticide chemistry were measured in the creek during treatment as well as in the river both upstream and downstream of the creek input before and after treatment. Benthic macroinvertebrates were also surveyed in the river before and after enzyme treatment. Low concentrations of organophosphate pesticides were detected in the creek, but Landguard removed detected concentrations of chlorpyrifos. Toxicity detected in the creek was likely caused by pyrethroid pesticides, and no toxicity was detected in river samples. There were no differences in habitat or macroinvertebrate assemblages between upstream and downstream samples or between pre- and post-treatment samples. These results indicate that chronic treatment of the creek with Landguard enzyme had no impact on macroinvertebrate community structure in the river.


Hu X.C.,Harvard University | Andrews D.Q.,Environmental Working Group | Lindstrom A.B.,U.S. Environmental Protection Agency | Bruton T.A.,University of California at Berkeley | And 9 more authors.
Environmental Science and Technology Letters | Year: 2016

Drinking water contamination with poly- and perfluoroalkyl substances (PFASs) poses risks to the developmental, immune, metabolic, and endocrine health of consumers. We present a spatial analysis of 2013-2015 national drinking water PFAS concentrations from the U.S. Environmental Protection Agency's (US EPA) third Unregulated Contaminant Monitoring Rule (UCMR3) program. The number of industrial sites that manufacture or use these compounds, the number of military fire training areas, and the number of wastewater treatment plants are all significant predictors of PFAS detection frequencies and concentrations in public water supplies. Among samples with detectable PFAS levels, each additional military site within a watershed's eight-digit hydrologic unit is associated with a 20% increase in PFHxS, a 10% increase in both PFHpA and PFOA, and a 35% increase in PFOS. The number of civilian airports with personnel trained in the use of aqueous film-forming foams is significantly associated with the detection of PFASs above the minimal reporting level. We find drinking water supplies for 6 million U.S. residents exceed US EPA's lifetime health advisory (70 ng/L) for PFOS and PFOA. Lower analytical reporting limits and additional sampling of smaller utilities serving <10000 individuals and private wells would greatly assist in further identifying PFAS contamination sources. © 2016 American Chemical Society.


Wilhoit L.R.,001 I Street
ACS Symposium Series | Year: 2012

Most biological opinions related to pesticides and endangered species assume worst-case scenarios for pesticide use, largely due to a lack of reliable pesticide use data. California maintains a large database of pesticide use data with 38 years of detailed and accurate data on each production agricultural pesticide application and summary information on other, mostly non-agricultural applications. These data can be used to develop more realistic assessments of the effects of pesticides on endangered species. © 2012 American Chemical Society.

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