title: Pesticides on residential outdoor surfaces: environmental impacts and aquatic toxicity.
abstract: BACKGROUND
  Pesticides are routinely applied to residential impervious outdoor surfaces for structural pest control. This residential usage has been linked to the occurrence of toxic levels of pesticides in urban water bodies. It is believed that run-off water transports particles that have sorbed hydrophobic pesticides. However, concentrations of particle-bound pesticides have not been directly measured on impervious surfaces, and the role of these particles as a source of contamination is unknown.
  
  
  RESULTS
  Pesticides were detected in 99.4% of samples, with >75% of samples containing at least five pesticides. Assuming all particles were transferred with run-off, the run-off amount of pesticide during each rainfall would be >5 mg. We also used the US EPA Storm Water Management Model and estimated that 43 and 65% of the pesticides would be washed off during two rainfall events, with run-off concentrations ranging from 10.0 to 54.6 ng L(-1) and from 13.3 to 109.1 ng L(-1) respectively. The model-predicted pesticide run-off concentrations were similar to the levels monitored in urban run-off and sediments. Most (78%) particle samples contained aggregate toxicities above the Hyalella azteca LC50 .
  
  
  CONCLUSIONS
  The results suggest that loose particles on residential impervious surfaces are not only carriers but also an important source of hydrophobic pesticides in urban run-off and contribute to downstream aquatic toxicities. © 2015 Society of Chemical Industry.
authors.affiliation: Department of Environmental Sciences, University of California, Riverside, CA, USA.|California Department of Pesticide Regulation, Sacramento, CA, USA.
authors.forename: Weiying
authors.initials: W
authors.lastname: Jiang
authors.affiliation: California Department of Pesticide Regulation, Sacramento, CA, USA.
authors.forename: Yuzhou
authors.initials: Y
authors.lastname: Luo
authors.affiliation: Department of Environmental Sciences, University of California, Riverside, CA, USA.|Department of Physical and Environmental Sciences, Texas A&M University, Corpus Christi, TX, USA.
authors.forename: Jeremy L
authors.initials: JL
authors.lastname: Conkle
authors.affiliation: Department of Environmental Sciences, University of California, Riverside, CA, USA.|Department of Environmental Science and Energy, College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen, Guangdong, China.
authors.forename: Juying
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Environmental Sciences, University of California, Riverside, CA, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Gan
mesh_terms: D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis*; D010575:Pesticides / Q000009:adverse effects / Q000032:analysis*; D012111:Residence Characteristics / Q000706:statistics & numerical data; D014874:Water Pollutants, Chemical / Q000009:adverse effects / Q000032:analysis*
chemical_list: D010575:Pesticides; D014874:Water Pollutants, Chemical
keywords: impervious surface; particle; pesticide; residential; run-off; toxicity