Effect of antecedent hydrologic conditions and agricultural activity on riparian zone biogeochemistry

点击翻译按钮获取中文摘要

Riparian wetlands have been identified as important landforms that effectively reduce the loading of chemicals from agricultural lands, yet nitrate loading in ground water and surface water remains a problem. This is particularly evident in the Great Lakes Region, where the lakes continue to be impacted by agricultural practices. An improved understanding of when and why riparian wetlands do not attenuate nitrate is needed, particularly in the Great Lakes region, where the threat of increased climatic variability exists.   Much attention has been given to the physical characteristics of riparian wetlands and upland fields in assessing riparian zone function, but little attention has been given to temporal patterns in the fate and transport of nitrogen. Pre-event antecedent conditions may play an important role in governing temporal patterns in nitrogen dynamics through their effect on soil nitrogen transformations, runoff pathways, and the interaction of these two variables.   Using a mixture of field observations and laboratory experimentation, the objectives of this research are to: (1) identify and quantify the hydrologic and biogeochemical controls on nitrogen fate and transport in riparian soils; 2) characterize hydrologic controls on the fate and transfer of nitrogen in an agricultural riparian wetland in Southern Ontario when hydrochemical inputs to the wetland originate from dual sources (upland, upstream); and (3) quantify the effects of antecedent hydrologic conditions (AHC) on event-based nitrogen transfer.   The future combined impacts of land-use and climate change in agricultural watersheds on surface water quality cannot be overstated; the potential reduction in the natural services provided by riparian buffer wetlands must be understood in order to develop effective future management strategies. This work will be useful in environmental models and will also be of use to managers in their effective management of Canadian water resources.