title: Insecticide concentrations in stream sediments of soy production regions of South America.
abstract: Concentrations of 17 insecticides were measured in sediments collected from 53 streams in soy production regions of South America (Argentina in 2011-2014, Paraguay and Brazil in 2013) during peak application periods. Although environmental regulations are quite different in each country, commonly used insecticides were detected at high frequencies in all regions. Maximum concentrations (and detection frequencies) for each sampling event ranged from: 1.2-7.4 ng/g dw chlorpyrifos (56-100%); 0.9-8.3 ng/g dw cypermethrin (20-100%); 0.42-16.6 ng/g dw lambda-cyhalothrin (60-100%); and, 0.49-2.1 ng/g dw endosulfan (13-100%). Other pyrethroids were detected less frequently. Banned organochlorines were most frequently detected in Brazil. In all countries, cypermethrin and/or lambda-cyhalothrin toxic units (TUs), based on Hyalella azteca LC50 bioassays, were occasionally>0.5 (indicating likely acute toxicity), while TUs for other insecticides were <0.5. All samples with total insecticide TU>1 were collected from streams with riparian buffer width<20 m. A multiple regression analysis that included five landscape and habitat predictor variables for the Brazilian streams examined indicated that buffer width was the most important predictor variable in explaining total insecticide TU values. While Brazil and Paraguay require forested stream buffers, there were no such regulations in the Argentine pampas, where buffer widths were smaller. Multiple insecticides were found in almost all stream sediment samples in intensive soy production regions, with pyrethroids most often occurring at acutely toxic concentrations, and the greatest potential for insecticide toxicity occurring in streams with minimum buffer width<20 m.
authors.affiliation: University of California, Berkeley, Department of Environmental Science, Policy & Management, Berkeley, CA 94720-3114, USA. Electronic address: lisahunt@berkeley.edu.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hunt
authors.affiliation: ILPLA (CONICET-CCT La Plata) - UNLP Instituto de Limnología "Dr. Raúl A. Ringuelet", Boulevard 120 y 62, La Plata, 1900, Buenos Aires, Argentina. Electronic address: bonetto@ilpla.edu.ar.
authors.forename: Carlos
authors.initials: C
authors.lastname: Bonetto
authors.affiliation: University of California, Berkeley, Department of Environmental Science, Policy & Management, Berkeley, CA 94720-3114, USA. Electronic address: resh@berkeley.edu.
authors.forename: Vincent H
authors.initials: VH
authors.lastname: Resh
authors.affiliation: Laboratório de Avaliação e Promoção da Saúde Ambiental, IOC, FIOCRUZ, Av. Brasil 4365 Manguinhos, Rio de Janeiro, RJ 21045-900, Brazil. Electronic address: dbuss@ioc.fiocruz.br.
authors.forename: Daniel Forsin
authors.initials: DF
authors.lastname: Buss
authors.affiliation: ILPLA (CONICET-CCT La Plata) - UNLP Instituto de Limnología "Dr. Raúl A. Ringuelet", Boulevard 120 y 62, La Plata, 1900, Buenos Aires, Argentina. Electronic address: fsilvialaura@hotmail.com.
authors.forename: Silvia
authors.initials: S
authors.lastname: Fanelli
authors.affiliation: ILPLA (CONICET-CCT La Plata) - UNLP Instituto de Limnología "Dr. Raúl A. Ringuelet", Boulevard 120 y 62, La Plata, 1900, Buenos Aires, Argentina. Electronic address: marrochinatalia@yahoo.com.ar.
authors.forename: Natalia
authors.initials: N
authors.lastname: Marrochi
authors.affiliation: Center for Fisheries, Aquaculture and Aquatic Sciences, Department of Zoology, Southern Illinois University, Carbondale, IL 62901, USA. Electronic address: mlydy@siu.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lydy
mesh_terms: D000383:Agriculture; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry; D007306:Insecticides / Q000032:analysis*; D013020:South America; D013025:Glycine max; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data
chemical_list: D007306:Insecticides; D014874:Water Pollutants, Chemical
keywords: Aquatic toxicity; Insecticides; Pyrethroids; South America; Soybean production; Stream buffers