Impacts of multiple interacting stressors on the environment: Investigating the fate, transport, and dynamic relationships between contaminant and nutrient cycles

导致淡水富营养化的水质问题是一个迅速加剧的全球关切，最近五大湖富营养化情况的增加已引起国际注意。元素循环、碳体系和代谢过程正在发生变化，我们对这些变化对大型湖泊系统的长期影响知之甚少。五大湖占北美淡水供应的85%以上，并且有过水质问题的历史，在20世纪70年代早期伊利湖的文化富营养化达到顶峰。磷酸盐的投入被认为是造成富营养化的一个关键因素，它刺激了环境政策的变化，导致富营养化的减少，一直持续到1990年代。然而，最近蓝藻繁殖的增加为伊利湖的再富营养化提供了证据。尽管许多协调努力试图将富营养化与磷动态联系起来，但越来越清楚的是，这个问题的严重性和复杂性已经超出了简单的磷酸盐限制机制。***目前，我们对污染物（甲烷、碳氢化合物、工业溶剂和废水）、天然有机物质（NOM）和营养物质（硝酸盐、磷酸盐和硫酸盐）的命运和迁移的理解取得了进展；然而，解释往往受到“静态”地球化学快照的限制，这限制了统一单个化学物种之间的动态关系及其随时间变化的行为。在养分的历史沉积、土壤和沉积物中碳、氮、硫、磷的循环以及它们与蓝藻生物量发展的时空关系方面存在知识空白。本研究将使用地球化学方法（组成和同位素）来提高我们对控制陆地和水生来源（生物和非生物）C/N/S/P可用性的基本过程与促进蓝藻生长的适应性代谢反应之间动态关系的理解。***了解C/N/S/P从点源和非点源排放者到其最终沉积点（或代谢摄取点）的命运和运输的潜在机制，将揭示驱动系统每个阶段初级生产的因果关系，并提供控制富营养化的战略目标。全面了解影响测量、监测和识别造成水质问题的污染源的关键化学和环境因素，将有助于制定更好的政策决策，并长期保护我们的淡水资源。

Water quality issues that lead to freshwater eutrophication are a rapidly intensifying global concern and the recent increase in eutrophic conditions in the Great Lakes has gained international attention. Elemental cycles, carbon regimes and metabolic processes are changing and we have little insight into the long-term effect these changes will have on large lake systems. The Great Lakes account for over 85% of North America's freshwater supply and have had a history of water quality problems that peaked in the early 1970's with cultural eutrophication in Lake Erie. Phosphate inputs were identified as a critical factor causing eutrophication that stimulated changes in environmental policies that led to a decline in eutrophication through to the 1990's. However, recent rises in cyanobacteria blooms provide evidence for the re-eutrophication of Lake Erie. Despite many coordinated efforts that attempt to link eutrophication to phosphorus dynamics, it is becoming clear that the magnitude and complexity of this issue has moved beyond a simple phosphate-limited mechanism.***Currently, progress has been made to improve our understanding of the fate and transport of contaminants (methane, hydrocarbons, industrial solvents and wastewater), natural organic matter (NOM), and nutrients (nitrates, phosphates, and sulfates); however, interpretations are often constrained by ‘static' geochemical snapshots that limit unifying the dynamic relationships between individual chemical species and their changing behavior over time. Knowledge gaps exist connecting the historical deposition of nutrients, the recycling of carbon, nitrogen, sulfur, and phosphorus in soil and sediments, and their relationship to cyanobacterial biomass development across temporal and spatial scales. This research will use geochemical approaches (compositional and isotopic) to improve our understanding of the dynamic relationships between the fundamental processes that control the availability of C/N/S/P from terrestrial and aquatic sources (biotic and abiotic), and the adaptive metabolic responses that promote cyanobacteria growth in different environmental conditions. ***An understanding of the underlying mechanisms responsible for the fate and transport of C/N/S/P from point and non-point source emitters through to their final point of deposition (or metabolic uptake) will expose the causal links that drive primary production at each stage of the system and provide strategic targets to control eutrophication. A comprehensive understanding of the key chemical and environmental factors that influence the measurement, monitoring, and identification of pollution sources responsible for water quality issues will lead to better policy decisions and long-term protection of our freshwater resources.