Importance of Deposition Measurements in Agro-Ecosystems A Perspective from Canadian Prairie Crops

E. Poscher, M.P. Schellenberg, J.M. Clarke, H. Cutforth, M.R. Fernandez, and T.N. McCaig
Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada
1 Airport Road, Box 1030, Swift Current, SK S9H 3X2, Canada

Our study examines differences in heavy metal and metalloid concentrations in soils and crops across Saskatchewan. Western Canada is known for production of animal and plant foods in an area largely free of industrial and other anthropogenic sources of pollution. Therefore incidents of higher-than-desired levels of heavy metals and metalloids in agricultural crops are surprising but have occurred, such as the cases of cadmium in durum wheat, flax, and sunflower, and, most recently in 2006, selenium in yellow peas. Sources of these heavy metals and metalloids have remained unknown. It is generally assumed that these heavy metals and metalloids were derived from the soil. Atmospheric deposition may be another possible source for elevated heavy metals and metalloids found in crops, as wind-borne particles, sea salt spray, volcanoes, forest fires, energy production, mining, smelting, refining, manufacturing processes, waste incineration, transportation, and other natural and anthropogenic processes emit heavy metals into the atmosphere. How much of these emissions reach our agro-ecosystems, our crops, and our food chain? Some 30 years ago, the FAO issued a statement saying that “80% of chronic diseases are related to pollution”, emphasizing the significance of pollutants to environmental and human health. Ever since this FAO statement, medical studies have shown that many chronic diseases may be metal-related, such as auto-immune diseases, allergies, autism, cancers, inter alia. The objective of our research study is to identify potential heavy metal point, area, and/or line sources in agricultural production systems by surveying the major food and feed crops including corresponding soil samples for possible heavy metal and metalloid accumulation across the province of Saskatchewan. The installation of four heavy metal monitoring stations in the Saskatchewan agroecosystem is envisioned to determine atmospheric deposition of heavy metals and metalloids onto agricultural soils and crops.