The effects of multiple stressors on the biogeochemistry of lakes and catchments

这项建议的中心目标是评估人类活动如何相互作用导致湖泊、溪流和集水区的环境变化。我将利用现有的长期数据库来评估这一点，该数据库包括位于加拿大北部生态臭氧南部的一组8个湖泊、24个溪流及其集水区过去30年的气候、水文、化学和物理数据。*这个环境数据库是世界上最详细和最长期的记录之一。除了一些数据类型，如湖泊化学物质平衡，这是现存的最完整的数据集。这里考虑的压力来源是酸沉积、气候变化，以及较小程度的紫外线辐射。我将使用这些数据来检验一些假设，例如，控制生态系统酸化和酸化恢复的气候因素随后会影响营养(磷)水平，从而影响湖泊生产力。我还将调查不同气候变化情景下湖泊从酸化中恢复的速度。以及溶解有机质循环的变化，这可能会导致痕量金属有效性的变化。我将把重点放在开发模型上，使我们能够对生态系统的未来状态做出定量预测。我将使用现有的数据来修改现有的酸化模型，以包括氮的物种以及无机氮和有机氮之间的转化；这一改进将使对加拿大环境的临界酸负荷的估计更加准确。加拿大还将开发一个集水范围的溶解有机碳模型，该模型可被纳入用于评估环境压力影响的生物地球化学模型。

The central objective of this proposal is to evaluate how human activities interact with each other in causing environmental change in lakes, streams and catchments.  I will do this by utilizing an existing long-term database that includes climate, hydrologic, chemical and physical data measured over the past 30 years for a set of 8 lakes, 24 streams and their catchments that are located in the southern part of Canada's boreal ecozone.  This environmental database is one of the most detailed and long-term records in the world.  For some data types such as lake chemistry mass balances, it is the most complete dataset in existence.  The stressors that are considered here are acid deposition, climate change and, to a lesser extent, UV radiation.  I will use these data to test a number of hypotheses, for example, that climate factors that are controlling ecosystem acidification and recovery from acidification subsequently affect nutrient (phosphorus) levels and thus lake productivity.  I will also investigate rates that lakes recover from acidification under different climate change scenarios, and changes in dissolved organic matter cycles that may result in changes in trace metal availability.  There will be a strong focus on developing models that will allow us to make quantitative predictions about the future state of ecosystems.  I will use the available data to modify existing models of acidification to include nitrogen species and the transformations between inorganic and organic nitrogen; this refinement will allow much more accurate estimation of critical loads of acid to the Canadian environment.  I will also develop a catchment-scale model of dissolved organic carbon that can be incorporated into biogeochemical models that are used to assess impacts of environmental stresses.