Atmospheric Transport and Transformation of Agricultural Pesticides
By Donna Fleury
Researchers at the University of Regina are helping the agricultural industry better understand the effects of pesticides on the environment and air quality in western Canada. New analytical tools and information are providing a better understanding of the atmospheric transport and transformation of agricultural pesticides and their relationship to environmental factors. As a result, industry will be able to develop improved management practices for pesticide use and to maintain crop production while having minimal impacts on the environment and human health.
“We started the first small project in 2003 with a long-term Environment Canada site at Bratt’s Lake just outside of Regina, Saskatchewan, and one in the Lower Fraser Valley (LFV) in B.C.,” explains Dr. Renata Raina, associate professor, Department of Chemistry and Biochemistry, University of Regina. “We wanted to look at insecticides and fungicides in particular, focusing on common products used in the Prairies such as organophosphorus insecticides and their degradation products (due to their greater toxicity concerns), as well as trihalomethylthio fungicides, which have higher usage in LFV.”
The monitoring sites selected were characteristic high pesticide usage sites, but with different types of crops and products used. “The Bratt’s Lake site was selected partly because Saskatchewan has the highest provincial pesticide usage across the country, particularly in the southern grain cropping regions,” says Raina. “We also selected the LFV site because they grow quite different crops and the climate is quite different. We expect the way pesticides degrade to be different between the regions.” Raina adds that pesticide usage data is challenging to access, with a 2003 Canadian usage inventory being the most recent. The way inventory information is collected varies, but is primarily based on usage sales by distributors.
When Raina started the project, there were few tools available and only a few compounds had been studied across Canada. Prior to joining the University of Regina, she worked at Environment Canada in the ’90s. She had done some studies on past use legacy pesticides and gradually shifted her research focus to currently used pesticides. “With this project, we wanted to look at things that others hadn’t looked at before, partly because this type of work is very expensive and until recently no one had the full capability to do the air sample analysis needed. The levels of pesticides in air samples are much lower than in a soil or vegetative sample, so new analytical tools had to be developed to enable us to do the analysis required.”
To assist with the research, Raina established the Trace Analysis Facility at the University of Regina in 2006. “This facility is an ultra clean lab equipped with the necessary analytical tools capable of analyzing air samples for pesticides and more importantly their degradation products, which is more challenging than the active ingredients,” explains Raina. “The chemical characteristics of these breakdown products are different and the levels are often even lower than the parent compound they originate from.” Raina believes they have now developed enough tools to successfully analyze the major chemical classes or specific pesticides that characterize atmospheric transport in those particular agricultural regions.
In April 2011, Raina was awarded a five-year NSERC Discovery grant to study the levels of a wide range of pesticides in the western Canadian agricultural regions of the LFV, the Okanagan Valley and the Prairies. “In this new project we will have nine sites across the three regions, with in-kind support from our collaborators including Metro Vancouver, Environment Canada, Agriculture and Agri-Food Canada, B.C. Ministry of Environment and other provincial and federal government departments,” says Raina. “We are still developing new chromatography-mass spectrometry methods for analyzing pesticides, and will be expanding our analysis from a small number of pesticides of less than 100 to closer to 300, many with completely different properties. There are currently over 500 pesticides registered for usage in North America.”
Pesticides have the ability to travel in the atmosphere in both the gas or particle phase and can travel thousands of kilometers from their application region. “We are trying to develop a new tool by looking at air concentrations to determine if the pesticides are from more of a regional source or a long-range atmospheric transport,” explains Raina.
“In this study, we will be measuring atmospheric levels of pesticides and their degradation products and monitoring their seasonal and annual trends, movement and relating this to available usage information. This information is a valuable tool in examining how actual pesticide usage is changing with environmental factors, economic factors and crop production.”
Because pesticides can move very long distances in the atmosphere, it was important to look at the possibility of transport from the US to Canada or vice versa. “Therefore, we are collaborating with selected high usage regions in the US to track the potential contributions from long-range trans-boundary atmospheric transport to Canada, and from region to region,” says Raina. “We felt it was also important to compare our Canadian agriculture regions to the high usage regions in the US.”
During the study, Raina and her team will be analyzing weekly air samples from the western Canadian and US monitoring sites. They are still finalizing the most suitable US locations with similar cropping and pesticide practices as the Canadian study locations to be able to track air parcel movement into Canada. One monitoring site is in collaboration with the University of North Dakota and Washington State is another likely location.
“The new methods, tools and information developed through this research will assist industry and farmers in developing and selecting better pesticides and improving management practices,” says Raina. “We also expect that the monitoring information will assist researchers with future model development, which will have a broad application across industry. This information is also essential in guiding Canada in making future pesticide management choices to maintain crop production while having minimal impacts on the environment and human health.” Preliminary information from the new study is expected in 2012 and throughout the project with release of data through peer-reviewed journals.