The effects of multiple stressors on the biogeochemistry of lakes and their catchments: mass budgets, long-term trends and modeling

这项建议的主要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，其中包括过去35年来对位于加拿大北部生态臭氧南部的8个湖泊、24条溪流及其集水区测量的气候、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。对于一些数据类型，如湖泊化学物质平衡，它是现有的最完整的数据集。此外，我将利用过去3年测量的短期数据，对北部生态臭氧以南的Simcoe湖盆地的几个子流域进行测量，这些流域具有非常不同的化学成分。这里考虑的应激源是气候变化、营养物质、酸沉积和微量金属污染。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。我还将研究溶解有机物质循环的变化，这可能会导致温室气体产生和痕量金属可用性的变化。将把重点放在开发模型上，这些模型将使我们能够对生态系统的未来状态做出量化预测。我将使用现有的数据来修改现有的酸化模型，以包括氮物种以及无机氮和有机氮之间的转化；这种改进将使对加拿大环境的酸临界负荷的估计更加准确。

The major 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 35 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. In addition, I will utilize shorter-term data measured over the past 3 years for several sub-catchments of the Lake Simcoe basin that are south of the boreal ecozone and that have very different chemistry. The stressors that are considered here are climate change, nutrients, acid deposition and trace metal contamination. 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 changes in dissolved organic matter cycles that may result in changes in greenhouse gas production and 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.