Enhancing the understanding and assessment of soil erosion and sedimentation through improvements to tracer techniques

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Soil erosion and sedimentation (SES) continue to be major environmental concerns in Canada and around the world. Soil erosion degrades soil quality, and the resulting sediment degrades water quality and air quality. Tracers have proven to be valuable tools in measuring SES, enhancing the understanding of these processes, and developing models for their assessment and prediction. Of these tracers, the fallout radionuclides (FRNs) 137Cs and 210Pb have been very effective in monitoring the redistribution of soil and sediment within agricultural fields, and in tracking and sourcing sediments within agricultural watersheds, a technique known as sediment fingerprinting. The general objective of the proposed research is to improve techniques used to assess SES using tracers. A coordinated and complementary group of research projects will examine the nature of spatial and temporal properties of soil and sediment in agricultural landscapes and watersheds, focusing on tracers used in the assessment of SES. The variability of sediment properties in waterways and water bodies will be studied in two watersheds, one in Manitoba and the other in New Brunswick. The variability of soil properties in landscapes will be studied in two cultivated fields associated with each of these watersheds. Innovative technologies and techniques, such as the use of portable gamma spectrometers to measure FRNs in the field and the use of new and new combinations of FRNs, will be evaluated for their ability to provide more effective soil and sediment sampling strategies and to provide a more effective means of interpolating SES results across landscapes and watersheds. Sampling strategies that employ a greater awareness of spatial and temporal variability and their causes (inherent/natural and induced/anthropogenic causes) are expected to lead to substantial decreases in the uncertainties associated with SES measurements. It is realistic to expect that the errors associated with SES measurements could be cut in half. The insights gained by examining the spatial and temporal variability of soils and sediments will enhance the understanding of soil erosion (soil loss and accumulation) and sedimentation (production, transport, behaviour and fate). More informed and more reliable measurements will increase confidence in SES assessments. Greater confidence is expected to lead to the development of more effective policies and programs, and to more widespread use of effective soil and water conservation practices, and, in doing so, enhance the sustainability of our land and water resources. In no small part, this impact will be achieved by training professionals at all levels in land and water resources research and management. The proposed research will provide training for two PhD students, two MSc students and eight undergraduate students.