R. Raina¹, Wayne Belzer² and Keith Jones²

¹Department of Chemistry and Biochemistry, and Trace Analysis Facility, University of Regina, 3737 Wascana Parkway, Regina, SK, Canada, S4S 0A2. ²Aquatic and Atmospheric Sciences Division, Environment Canada, Vancouver, British Columbia, Canada, V6C 3S5

Abstract

Two N-trihalomethylthio fungicides were detected in the atmosphere in the Lower Fraser Valley agricultural region of Canada. Captan was detected in both the particle and gas phase with a dominant particle phase fraction observed in both 2005 and 2006 (only total captan atmospheric concentrations were available for 2004). This provides the first evidence of particle transport as a significant atmospheric transport pathway for captan in an agricultural region in Canada. Weekly captan air concentrations reached maximum levels of 13.2 ng m^-3 in June 2006, while for folpet total atmospheric levels were lower with maximum reaching 1.7 ng m^-3 in August 2004 and generally <1 ng m³ in 2005 and 2006. Folpet is detected in the atmosphere although not previously reported in usage inventories. In the three years examined (2004–2006) captan concentrations observed a seasonal maximum in atmospheric concentrations during spring to early summer coinciding with expected peak usage period on crops in the Lower Fraser Valley agricultural region located in British Columbia, Canada. No usage data is available in Canada beyond 2003 but these seasonal trends show that captan remains a dominant pesticide used in this agricultural region with no decline in atmospheric concentrations during 2004–2006.