World’s freshwaters contain too much phosphorous

Nadya Anscombe in Environmental Research Web: New policies are needed to decrease the overuse of phosphorous, and allocate the element where it is most needed, according to researchers who have analysed levels in freshwater across the globe. While it's essential for plant growth and agriculture, an excess of phosphorous in water causes eutrophication, which makes water non-potable, leads to blooms of cyanobacteria that are toxic to humans and livestock, depletes oxygen and kills fish.

Stephen Carpenter of the University of Wisconsin, US and Elena Bennett from McGill University, Canada, have found that current conditions exceed all planetary boundaries for phosphorous in freshwater.

In 2009 Rockström et al introduced the concept of planetary boundaries to define a safe operating space for humanity on Earth. They categorized a planetary boundary as a human-determined acceptable level of a key global variable.

"But the phosphorous boundary introduced by Rockström et al was based on oceanic conditions not freshwater," Carpenter told environmentalresearchweb. "The research found that the world was substantially below the oceanic planetary boundary, and this motivated us to look at freshwater. We were not surprised when we found that we are substantially past the boundary for freshwater."…

Cyanobacteria fouling freshwater, shot by Lamiot, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported