title: Mass Balance of Fipronil and Total Toxicity of Fipronil-Related Compounds in Process Streams during Conventional Wastewater and Wetland Treatment.
abstract: Attenuation of the pesticide fipronil and its major degradates was determined during conventional wastewater treatment and wetland treatment. Analysis of flow-weighted composite samples by liquid and gas chromatography-tandem mass spectrometry showed fipronil occurrence at 12-31 ng/L in raw sewage, primary effluent, secondary effluent, chlorinated effluent, and wetland effluent. Mean daily loads of total fipronil related compounds in raw sewage and in plant effluent after chlorination were statistically indistinguishable (p = 0.29; n = 10), whereas fipronil itself was partially removed (25 ± 3%; p = 0.00025; n = 10); the associated loss in toxicity was balanced by the formation of toxic fipronil degradates, showing conventional treatment to be unfit for reducing overall toxicity. In contrast to these findings at the municipal wastewater treatment, both parental fipronil and the sum of fipronil-related compounds were removed in the wetland with efficiencies of 44 ± 4% and 47 ± 13%, respectively. Total fipronil concentrations in plant effluent (28 ± 6 ng/L as fipronil) were within an order of magnitude of half-maximal effective concentrations (EC50) of nontarget invertebrates. This is the first systematic assessment of the fate of fipronil and its major degradates during full-scale conventional wastewater and constructed wetland treatment.
authors.affiliation: The Biodesign Institute, Center for Environmental Security and Global Security Initiative, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Supowit
authors.affiliation: The Biodesign Institute, Center for Environmental Security and Global Security Initiative, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Akash M
authors.initials: AM
authors.lastname: Sadaria
authors.affiliation: The Biodesign Institute, Center for Environmental Security and Global Security Initiative, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Reyes
authors.affiliation: The Biodesign Institute, Center for Environmental Security and Global Security Initiative, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Rolf U
authors.initials: RU
authors.lastname: Halden
mesh_terms: D000818:Animals; D007448:Invertebrates; D010575:Pesticides / Q000032:analysis; D011720:Pyrazoles / Q000032:analysis* / Q000737:chemistry / Q000633:toxicity; D012722:Sewage / Q000737:chemistry; D062065:Wastewater / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D010575:Pesticides; D011720:Pyrazoles; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical; C082360:fipronil