title: Factors influencing the occurrence and distribution of neonicotinoid insecticides in surface waters of southern Ontario, Canada.
abstract: The widespread use of neonicotinoid insecticides and recent increased regulatory scrutiny requires the generation of monitoring data with sufficient scope and resolution to provide decision makers with a better understanding of occurrence and distribution in the environment. This study presents a wide-scale investigation of neonicotinoid insecticides used across the range of agricultural activities from fifteen surface water sites in southern Ontario. Using statistical analysis, the correlation of individual compounds with land use was investigated, and the relationship between neonicotinoid occurrence and hydrologic parameters in calibrated water courses was also assessed. Of the five neonicotinoids studied, imidacloprid, clothianidin and thiamethoxam exhibited detection rates above 90% at over half the sites sampled over a three year period (2012-2014). At two sites in southwestern Ontario, the Canadian Federal freshwater guideline value for imidacloprid (230 ng/L) was exceeded in roughly 75% of the samples collected. For some watersheds, there were correlations between the occurrence of neonicotinoids and precipitation and/or stream discharge. Some watersheds exhibited seasonal maxima in concentrations of neonicotinoids in spring and fall, particularly for those areas where row crop agriculture is predominant; these seasonal patterns were absent in some areas characterized by a broad range of agricultural activities.
authors.affiliation: Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, Ontario, L7S 1A1, Canada. Electronic address: john.struger@canada.ca.
authors.forename: John
authors.initials: J
authors.lastname: Struger
authors.affiliation: Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, Ontario, L7S 1A1, Canada.
authors.forename: Josey
authors.initials: J
authors.lastname: Grabuski
authors.affiliation: Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, Ontario, L7S 1A1, Canada.
authors.forename: Steve
authors.initials: S
authors.lastname: Cagampan
authors.affiliation: Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, Ontario, L7S 1A1, Canada.
authors.forename: Ed
authors.initials: E
authors.lastname: Sverko
authors.affiliation: Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, Ontario, L7S 1A1, Canada.
authors.forename: Daryl
authors.initials: D
authors.lastname: McGoldrick
authors.affiliation: Water Science and Technology Directorate, Environment and Climate Change Canada, 867 Lakeshore Road, Burlington, Ontario, L7S 1A1, Canada.
authors.forename: Christopher H
authors.initials: CH
authors.lastname: Marvin
mesh_terms: D000383:Agriculture; D006146:Guanidines / Q000032:analysis* / Q000737:chemistry; D007093:Imidazoles / Q000032:analysis* / Q000737:chemistry; D007306:Insecticides / Q000032:analysis* / Q000737:chemistry; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000032:analysis* / Q000737:chemistry; D009864:Ontario; D010078:Oxazines / Q000032:analysis* / Q000737:chemistry; D045483:Rivers / Q000737:chemistry*; D012621:Seasons; D012995:Solubility; D000077922:Thiamethoxam; D013844:Thiazoles / Q000032:analysis* / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry; D014887:Weather
chemical_list: D006146:Guanidines; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D013844:Thiazoles; D014874:Water Pollutants, Chemical; C480342:clothianidin; C082359:imidacloprid; D000077922:Thiamethoxam
keywords: Clothianidin; Imidacloprid; Neonicotinoid insecticides; Surface water; Thiamethoxam; Water quality guidelines