Landscape-scale effects of nitrogen on lake ecosystems: Accelerating a new paradigm for freshwater eutrophication.

氮对湖泊生态系统的景观尺度影响：加速淡水富营养化的新范例。

• 批准号: 155612-2013
• 负责人: Leavitt, Peter
• 金额: $ 4.37万
• 依托单位: University of Regina
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=631921
• 关键词: Landscape; scale; effects; nitrogen; lake

We hypothesize that increases in agricultural fertilization needed to feed 3 billion more people by 2050 will saturate soils with phosphorus (P) and create conditions in which subsequent influx of nitrogen (N) regulates water quality in developed regions. However, unlike during the Green Revolution, future N fertilization will be conducted with urea. Rarely used prior to 1960, urea now accounts for >50% of global N fertilizer, is ubiquitous in lakes worldwide, and has potentially detrimental but poorly understood effects on aquatic ecosystems. Given that ~1 billion people currently lack clean water, we seek to develop a rigorous theoretical basis to understand the consequences of these global changes for humans and freshwaters. Our program will develop a novel paradigm for future water quality degradation by conducting 3 integrated projects. First, we will combine explicit land-use models with detailed measurements of lake and stream parameters to produce a new biogeochemical model of how urea is created, destroyed and transported in aquatic ecosystems. Second, we will use ~60,000-L experiments and paleoecological (fossil) analyses as a surrogate for whole-ecosystem fertilization to identify chemical thresholds for N effects on P-rich lakes. Here, very large open- and closed-bottom enclosures in lakes of contrasting P content will be fertilized with N to define thresholds for N damage and quantify the role of sediments in regulating the response of surface waters. The relevance of thresholds to whole lakes will be tested by replicated fossil analysis of the past relationship between N influx and algal abundance in 20 lakes along a gradient of P content. Third, we will take advantage of a whole-catchment N diversion to demonstrate experimentally how elimination of N pollution from P-rich lakes regulates ecosystem production and toxicity. Here we will combine landscape-scale mass balances (N, P, C) with a unique 20-year ecological research program to determine definitively whether N diversion can return P-rich lakes to baseline conditions. These projects should resolve a 40-yr long scientific debate and provide managers, scientists, governments, and the public with a means to avoid future water-quality loss.

我们假设，到2050年，需要增加30亿人口所需的农业施肥会增加磷（P）的土壤，并创造条件，在这种情况下，随后氮（N）随后的氮（N）调节发达地区的水质。但是，与绿色革命期间不同，未来的N受精将与尿素进行。尿素在1960年之前很少使用，现在占全球N肥料的50％，在全球湖中无处不在，并且对水生生态系统的影响有可能有害但知之甚少。鉴于目前约有10亿人缺乏干净的水，我们试图建立一个严格的理论基础，以了解这些全球变化对人类和淡水的后果。我们的计划将通过进行3个集成项目来开发一种新颖的范式，以用于未来的水质退化。首先，我们将将明确的土地利用模型与湖泊和溪流参数的详细测量相结合，以生成在水生生态系统中如何创建，破坏和运输尿素的新生物地球化学模型。其次，我们将使用〜60,000-L实验和古生态学（化石）分析作为全生态系统施肥的替代物，以鉴定N对PICH湖的影响的化学阈值。在这里，将用N的湖泊湖中的非常大的开放式底部和闭合底部用n受精，以定义n损伤的阈值，并量化沉积物在调节地表水反应中的作用。阈值与整个湖泊的相关性将通过对沿P含量梯度的20个湖泊中N涌入和藻类丰度之间的过去关系进行复制的化石分析来测试。第三，我们将利用整个鼠标n转移的优势，以实验证明如何消除P-Pich湖泊的N污染如何调节生态系统的产生和毒性。在这里，我们将将景观规模的质量平衡（N，P，C）与独特的20年生态研究计划相结合，以确定n个转移是否可以将P-Pich湖泊返回到基线条件。这些项目应解决40年的科学辩论，并为经理，科学家，政府和公众提供避免未来水质损失的手段。