1 Tahrcountry Musings: Alarming Increase of Phosphorous in World’s freshwaters

Sunday, February 20, 2011

Alarming Increase of Phosphorous in World’s freshwaters

Warning bells have been rung by Stephen Carpenter of the University of Wisconsin, US and Elena Bennett from McGill University, Canada about rapid increase of phosphorous in world’s freshwaters.    This excess phosphorous in water causes eutrophication. Eutrophication makes the water non-potable. It also leads to blooms of cyanobacteria that are toxic to humans, livestock and fish.
 The researchers found that current levels exceed all planetary boundaries for phosphorous in freshwater.
The concept of planetary boundaries was first introduced by in 2009 by Rockström et al . They categorized a planetary boundary as a human-determined acceptable level of a key global variable.
The researchers say the current alarming level is despite the fact that in some areas of the world we have a phosphorous shortage.
Dr Carpenter says there are some simple solutions to prevent eutrophication. His prescriptions say "Don't apply phosphorous to soils that don't need it and develop technology for recycling phosphorous.
The authors signs off with following conclusions.
Human release of P to the environment is causing widespread eutrophication of surface freshwaters. Yet the global distribution of P is uneven, and soils of many regions remain P-deficient even as soils of other regions are P-saturated (MacDonald et al 2011). Heterogeneity complicates the task of managing to provide both food and high quality freshwater, surely one of the key challenges of environmental management in the 21st century. The planetary boundary for freshwater eutrophication has been crossed while potential boundaries for ocean anoxic events and depletion of phosphate rock reserves loom in the future. The solution to this problem is widespread adoption of better practices for conserving P in agricultural ecosystems, so that P is cycled effectively among soil, crops, livestock and people without contributing to eutrophication of surface waters. At the same time, P-deficient regions of the world should be supplemented by P from P-rich regions. Such subsidies could come in the form of recycled P in fertilizer (e.g. solid P-rich material from manure digestors) or P in food.

Reconsideration of the planetary boundary for phosphorus
Stephen R Carpenter and Elena M Bennett
Environ. Res. Lett. 6 (January-March 2011) 014009

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