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Dissipation and mobility of atrazine, simazine, diazinon and chlorpyrifos in the Ryder soil of the Lower Fraser Valley, British Columbia

University of British Columbia

Research was undertaken to determine the dissipation and mobility of four commonly used pesticides (simazine, atrazine, diazinon and chlorpyrifos) under the environmental conditions encountered in the Lower Fraser Valley of British Columbia. The pesticides studied were chosen based upon their widespread usage, their method of application which often involves direct deposition onto the soil, and the fact that all four compounds can be extracted and analyzed for simultaneously. In addition, previous work had shown that three of the four pesticides may be found as contaminants in groundwater in the Lower Fraser area. The research was conducted in field plots with a Ryder Series silt loam soil, similar in properties to the soils commonly used for raspberry production. The primary objective of the research was to aid in determining the potential for movement of these compounds into ground water when applied at the recommended rates and using methods similar to those used in standard agricultural practice. The results show that diazinon and chlorpyrifos dissipate very quickly, with half lives of 1-4 days under the conditions of this study, and that these two compounds display virtually no potential for vertical movement. Atrazine and simazine dissipate at a much slower rate, with half lives of 45-80 days, and show a significant potential for vertical movement, having been detected in all samples at depths of 30-40 cm. Maximum concentrations at depth were detected 231 days after spray application where the quantities of atrazine and simazine, in the 30-35 cm depth, represented as much as 9.5% and nearly 13%, respectively, of the amounts originally applied to the soil surface. In addition to the parent compounds, two degradation products of atrazine and/or simazine were detected throughout the soil profile, from 0-40 cm, towards the end of the experiment. From the research it may be concluded that contamination of ground water with diazinon or chlorpyrifos can, in most cases, be attributed to point sources while contamination with atrazine or simazine may be via either point or non-point sources.

Thesis/Dissertation

application/pdf

2009-02-06

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http://hdl.handle.net/2429/4244

Soil Science

University of British Columbia

UBCV

DSpace