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

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(P)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，农业土壤现在被磷饱和，这种状况将持续几个世纪，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生产、水质退化和有毒藻华的发展。不幸的是，由于自1970年以来，氮肥的施用量也增加了15倍，而且其中一半以上是以尿素的形式添加的，尿素是一种N的化学形式，可以选择性地促进有毒蓝藻的生长，因此持续的农业发展可能会导致大陆范围内爆发有毒的、可能致癌的藻类。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人类和淡水的后果的预测性理解。

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.