Degradation and destablization of lake ecosystems by anthropogenic nitrogen: a new paradigm for future lake eutrophication

人为氮造成的湖泊生态系统退化和不稳定：未来湖泊富营养化的新范式

• 批准号: 155612-2007
• 负责人: Leavitt, Peter
• 金额: $ 4.57万
• 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: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=362265
• 关键词: Degradation; destablization; lake; ecosystems; anthropogenic

Global human population has doubled since 1950, largely due to the green revolution in which a 10-fold increase in agricultural application of fertilizer has doubled food production. These farming practices have also raised soil phosphorus (P) content by 200% or more and have created conditions in many sentinel ecosystems in which agricultural soils are now saturated with P, will remain so for centuries, and supply freshwaters with excess P.  Under these conditions, supplies of nitrogen (N) and light energy (E) appear to regulate lake production, water quality degradation, and the development of toxic algal blooms.  Unfortunately, because N fertilization has also increased 15-fold since 1970, and because more than half of this N is added as urea, a chemical form of N which selectively promotes toxic cyanobacteria, there exists the possibility that continued agricultural development will lead to continental-scale outbreaks of toxic and possibly carcinogenic algae.  Given that ~1 billion people already lack clean water, we seek substantial funding to develop a predictive understanding of the consequences of these changes for humans and freshwaters throughout Canada and the world.          We propose to develop a new paradigm for future lake eutrophication based on three component projects.  First, we will add growth-saturating levels of urea-N to a P-rich experimental lake to test the hypothesis that this form of N preferentially stimulates both growth and toxicity of cyanobacteria.  Second, we will investigate how N diversion from a chain of P-rich, N-limited lakes may improve water quality and reduce outbreaks of toxic algae.  Finally, we will combine whole-lake and catchment-scale mass balances of N and P with high-resolution paleoecological analyses to determine how the physical structure of lakes (thermal stratification) may affect N control of eutrophication over a large landscape.  Together these components will provide managers, scientists and the public with a new understanding of the controls of future water-quality degradation.

自1950年以来，全球人口翻了一番，这在很大程度上是由于绿色革命，在这场革命中，农业化肥使用量增加了10倍，使粮食产量翻了一番。这些耕作措施还将土壤磷含量提高了200%或更多，并在许多前哨生态系统中创造了条件，在这些生态系统中，农业土壤中的磷现在已经饱和，并将保持几个世纪的这种状况，并为淡水提供过剩的磷。在这些条件下，氮(N)和光能(E)的供应似乎调节了湖泊的生产、水质退化和有毒藻华的发展。不幸的是，因为自1970年以来，氮肥的施肥量也增加了15倍，而且其中一半以上以尿素的形式添加，尿素是一种N的化学形式，它选择性地促进有毒蓝藻的生长。持续的农业发展有可能导致大陆范围内有毒甚至可能致癌的藻类暴发。鉴于约10亿人已经缺乏清洁水，我们寻求大量资金，以发展对这些变化对整个加拿大和世界淡水的影响的预测性理解。我们建议基于三个组成部分的项目，为未来的湖泊富营养化开发一个新的范式。第一，我们将在一个富磷的实验湖泊中添加饱和生长水平的尿素-N，以检验这种形式的N优先刺激蓝藻生长和毒性的假设。第二，我们将研究从富P、N有限的湖泊链中分流N如何改善水质和减少有毒藻类的爆发。最后，我们将结合全湖和流域尺度的N和P质量平衡与高分辨率古生态分析，以确定湖泊的物理结构(热成层)可能如何影响大片景观上N的富营养化控制。这些组成部分将为管理者、科学家和公众提供对未来水质退化控制的新理解。