Research finds massive phosphorus buildup

Fertilizer's legacy: Taking a toll on land and water
The River Thames in central London, UK near the tidal limit at Teddington Lock. Credit: Helen Jarvie

The world's total human population has jumped to over 7.4 billion just this year. Feeding the human species takes a tremendous toll on our natural resources including water, soil and phosphorus—a chemical element in fertilizer essential for food production.

In modern agriculture, fertilizer often leaks into waterways such as rivers, lakes and oceans. The (P) in the runoff stimulates algae blooms and then, when algae die and decompose, dead zones develop and fish die off. But much of the "lost" phosphorus doesn't end up in water bodies—large amounts of P also accumulate in the landscape. Until now, scientists have not had a good handle on the magnitude of this accumulation.

For the first time, an international group of scientists, including researchers from Arizona State University, has come up with a way to estimate on a large scale how phosphorus flows through an environment over many decades. By doing so, researchers are gaining a better understanding of how and where phosphorus accumulates.

"After we understand how human activity affects the accumulation of phosphorus in the environment, we can then focus our research efforts on reducing its long-term impact, even on figuring out how to recycle it. This will help secure food and water supplies for future generations," said James Elser, research scientist with the ASU School of Life Sciences and School of Sustainability, and co-author of the study.

Fertilizer's legacy: Taking a toll on land and water
The Yangtze River at Qutang Gorge, China. Credit: Jianbo Shen

The study's findings appear in today's issue of Nature Geoscience.

The researchers studied three river basins where food and water security are directly linked to phosphorus. The analysis included the Thames River basin in the U.K., the Maumee River Basin in the mid-western section of the U.S. and the Yangtze River Basin in China.

The study areas ranged in size from approximately 5,000 to 700,000 square miles. Historical records dating back 70 years were used to measure the human impact on the flows of phosphorus into and out of each catchment through trade, , human waste and agricultural runoff, comparing these flows to losses of P from each river's discharge. The results showed that massive amounts of phosphorus have accumulated in the landscape—a form of "legacy P" that may affect aquatic ecosystems for decades or even centuries.

Fertilizer's legacy: Taking a toll on land and water
Agricultural fields near Maumee River, USA. Credit: Tom Bruulsema

The study's novel analyses illustrate the challenges researchers face in figuring how to manage the storage, exploitation and reactivation of phosphorus that is already present in our environment.

"Somewhat of a surprise is that in populated landscapes, there is a huge amount of phosphorus in food waste, such as animal bones, and in sewage sludge removed during wastewater treatment," said Stephen Powers, postdoctoral researcher with Washington State University and lead author of the paper. "Until recently these waste flows have been largely ignored in watershed studies that involve phosphorus."

Of the three sites, only one showed clear improvement over several decades—the Thames River in the U.K. Powers said the U.K. is using less fertilizer to grow food and that both historically and currently, it is a world leader in modern . By following the U.K.'s lead, Powers said other countries might improve their ability to manage phosphorus.

Elser and Powers said the next step is to develop strategies that will reduce the impact of this "legacy P." The pair added that it is important to create new technologies and policies that recycle phosphorus for re-use as fertilizer, rather than allowing it to escape and build up in the landscape.


Explore further

The history of China as told through phosphorus

More information: Stephen M. Powers et al. Long-term accumulation and transport of anthropogenic phosphorus in three river basins, Nature Geoscience (2016). DOI: 10.1038/ngeo2693
Journal information: Nature Geoscience

Citation: Research finds massive phosphorus buildup (2016, April 11) retrieved 23 July 2019 from https://phys.org/news/2016-04-massive-phosphorus-buildup.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
535 shares

Feedback to editors

User comments

Apr 11, 2016
Heterosexuals need to seriously think abut ways to restrain their breeding impulses, instead of choosing to ignore their own compulsive destructive reproductive habits and habitually looking outside of themselves for solutions to a multitude of serious problems that are directly rooted in their having bred us past the limits of the fragile thin layer of life here in Earth that we depend on for our sustenance and the survival of the species. The huge elephant in the room that everyone has studiously ignored for decades, as 150k species go extinct annually, temperatures soar, water reservoirs shrink, cancer rates skyrocket, and food availability / safety is threatened.

Apr 12, 2016
You should check South American precolumbian practice in waste management. They were really going over the limit. They were throwing their garbage right into the fields and then they were slowly burning the forests. And they were calling it "fertilizing". Check "terra preta".

On a side note: Are we on Mars yet?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more