Pesticides in the air, atmospheric deposits, and surface waters of Canada

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dc.contributor.authorMessing, Paul
dc.contributor.examiningcommitteeWaite, Don (Soil Science) Bullock, Paul (Soil Science) Tomy, Gregg (Environment & Geography) Diamond, Miriam (University of Toronto)en_US
dc.contributor.supervisorFarenhorst, Annemieke (Soil Science)en_US
dc.date.accessioned2015-01-08T17:15:17Z
dc.date.available2015-01-08T17:15:17Z
dc.date.issued2015-01-08
dc.degree.disciplineSoil Scienceen_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.abstractIn Canada, more than 35 million kilograms of pesticide active ingredients are applied annually on agricultural land with about 84% of this mass applied in the Canadian Prairies Provinces. Pesticide residues may become airborne through post-volatilization losses from land, water or vegetative surfaces, via wind-eroded soil, and by spray drift during pesticide application. Once in the air, pesticides may be dispersed and transported as parent molecules or as degradation products. Currently used and legacy pesticide air concentrations were measured in the agricultural region of the Prairie Provinces and the northern subarctic and arctic regions of Canada in 2005 and 2007. More intensive air sampling was conducted across the province of Manitoba in 2008 and 2009. Separate wet versus dry atmospheric deposition samples and wetland water samples were also taken in these years. In general, pesticides were detected in the monitored environmental media as mixtures with the frequency and concentrations detected being largest for pesticides that were applied on-site. Although the most commonly used herbicides in western Canadian agriculture were frequently present in the air in the regions where they are applied, they appeared infrequently and at low levels in the Canadian Subarctic, Arctic, and remote sites far from agricultural pesticide applications. Results also indicated that the concentrations of legacy pesticides such as lindane (γ-HCH) and its manufacturing by-product prior to 1971 (α-HCH) continued to decrease over time in the Canadian environment. Air concentrations of pesticides in agricultural regions, and subsequent wet and dry atmospheric deposition, contaminated surface water following periods of pesticide application. Dry deposition contributed 12–51% of the total deposition. Calculations were performed to predict wetland water column pesticide concentrations based on total atmospheric deposits alone. The estimated concentrations were closest to actual concentrations for MCPA and predictions were also reasonable for a range of other herbicides, but a source other than atmospheric deposition was clearly relevant to the detection of clopyralid in the wetland water-column. Individual herbicide concentrations did not exceed Canadian water quality guidelines for the protection of aquatic life.en_US
dc.description.noteFebruary 2015en_US
dc.identifier.urihttp://hdl.handle.net/1993/30175
dc.language.isoengen_US
dc.rightsopen accessen_US
dc.subjectPesticidesen_US
dc.subjectWetlandsen_US
dc.subjectagricultureen_US
dc.subjectArcticen_US
dc.subjectherbicidesen_US
dc.subjectlegacy compoundsen_US
dc.subjectManitobaen_US
dc.subjectpotholeen_US
dc.subjectwet depositionen_US
dc.subjectdry depositionen_US
dc.subjectPassive samplingen_US
dc.subjectAiren_US
dc.subjectBulk depositionen_US
dc.titlePesticides in the air, atmospheric deposits, and surface waters of Canadaen_US
dc.typedoctoral thesisen_US
local.subject.manitobayesen_US
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