Pesticides in the atmosphere across Canadian agricultural regions.

The Canadian Atmospheric Network for Currently Used Pesticides (CANCUP) was the first comprehensive, nationwide air surveillance study of pesticides in Canada. This paper presentsthe atmospheric occurrence and distribution of pesticides including organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), acid herbicides (AHs), and neutral herbicides (NHs) during the spring to summer of 2004 and 2005 across agricultural regions in Canada. Atmospheric concentrations of pesticides varied within years and time periods, and regional characteristics were observed including the following: (i) highest air concentrations of several herbicides (e.g., mecoprop, triallate, and ethalfluralin) were found at Bratt's Lake, SK, a site in the Canadian Prairies; (ii) the west-coast site at Abbotsford, BC, had the maximum concentrations of diazinon; (iii) the fruit and vegetable growing region in Vineland, ON, showed highest levels for several insecticides including chlorpyrifos, endosulfan, and azinphos-methyl; (iv) high concentrations of atrazine and metolachlor were measured at St. Anicet, QC, a corn-growing region; (v) the Kensington site in PEI, Canada's largest potato-producing province, exhibited highest level of dimethoate. Analysis of particle- and gas-phase fractions of air samples revealed that most pesticides including OCPs, OPPs, and NHs exist mainly in the gas phase, while AHs exhibit more diversity in particle-gas partitioning behavior. This study also demonstrated that stirred up soil dust does not account for pesticides that are detected in the particle phase. The estimated dry and wet deposition fluxes indicate considerable atmospheric inputs for some current-use pesticides (CUPs). This data set represents the first measurements for many pesticides in the atmosphere, precipitation, and soil for given agricultural regions across Canada.

Pesticides measured in air and precipitation in the Yamaska Basin (Québec): occurrence and concentrations in 2004.

Air and precipitation samples were collected and analyzed for 91 pesticides or metabolites from May to September 2004 at St. Damase, an agricultural site located in Yamaska basin in Québec, Canada. A broad range of pesticides was detected during this experiment where 40 different compounds were measured. Most of the samples showed more than 10 simultaneous pesticide detections and sometimes reaching 19 simultaneous detections. The most detected pesticides in air were trifluralin, metolachlor and captan, which were found in all the samples during the 5 months of measurements. For the detected compounds, the average concentrations ranged from 4 pg/m3 to 8 ng/m3. Some of the pesticides detected in air were found in precipitation samples as well showing that wet deposition can occur and have an impact on aquatic ecosystems. The most important pesticides detected were related to corn and soya cultivations, the two main cultures in this region highlighting that the major sources come from local applications. On the other hand, the detection of some pesticides in precipitation which were undetectable in air implies that some compounds may have a long range transport origin.

Some pesticides occurrence in air and precipitation in Québec, Canada.

Air and precipitation samples were collected in three stations located in Quebec between January 1993 and March 1996 to determine spatial and seasonal variations of several organochlorine pesticides and metabolites (alpha-HCH, gamma-HCH, HCB, gamma-chlordane, DDT, DDE, Mirex). alpha-HCH, gamma-HCH, and HCB were more or less measured in large amounts at all sites, whereas gamma-chlordane, DDT, and DDE concentrations were lower and Mirex was undetectable. Higher concentrations levels were observed in air during hot spring/summer periods except for HCB, indicating a probable temperature dependence. Ln concentrations vs reciprocal temperature plots and Henry's law determinations helped to highlight the contribution of soil and/or water volatilization of those compounds. Itwas observed that alpha-HCH came mainly from Atlantic Ocean volatilization at Mingan, whereas sources of gamma-chlordane and DDE were mostly due to volatilization from soils in southern Quebec. DDT may be present in the atmosphere by the way of transport from remote regions. Lindane sources were multiple: it may be found in the atmosphere bythe processes of transport and volatilization coming from soil or water. Finally, a negative correlation between HCB and air temperature implies that processes other than volatilization are involved in transport of this compound.