Phosphorus storagePhosphorus is a nutrient in high demand by life. It’s a major component of f

Phosphorus storagePhosphorus is a nutrient in high demand by life. It’s a major component of fertilizers and a component of sewage, so there are huge supplies of it carried downstream by rivers. Phosphorus is also a nutrient for organisms that live in lakes, rivers, and the ocean, so too much phosphorus also causes blooms of algae, using up oxygen other organisms need and sometimes releasing toxins that can make people sick. Managing phosphorus therefore is a major environmental issue, particularly in heavy agricultural areas.In many areas, phosphorus usage has gone through a cycle. After phosphorus based fertilizers were developed in the early part of the 20th century, phosphorus usage skyrocketed in areas like Europe and the US. However, after environmental regulations were established and costs of fertilizers began increasing, phosphorus deployment decreased.To understand how this deployment cycle affected pollution in the oceans, scientists led by Dr. Powers from the Center for Environmental Research, Education, and Outreach in Washington conducted a survey of phosphorus flows recorded leaving three rivers and combined it with a survey of phosphorus usage in the river basin.The Thames River basin saw a rapid increase in phosphorus usage starting in the first half of the 20th century, but for the next 5 decades more phosphorus was used on the land than came out of the river. Around the year 1990, phosphorus usage in the Thames basin began declining, but interestingly phosphorus kept flowing out of the river. Total phosphorus in Thames River sediment did start to decline, but nowhere near as fast as phosphorus usage on land. Today, more phosphorus is leaving the Thames basin than is used as fertilizer.Records for the Maumee River in Ohio, which contributes directly to algal blooms in Lake Erie, show a similar effect. Phosphorus usage in the basin has been declining since the 1970s, but phosphorus flows in the river have been increasing the entire time, and today more phosphorus flows into the lake than is used in the basin.The measurements from these rivers suggest phosphorus has a long residence time in the river basins. It gets stored for some time, either in the sediments, soil, or in the groundwater, and releases gradually over time. Even dramatic cuts in phosphorus usage will take decades to translate to substantial cuts in nutrient pollution to lakes and oceans.The most extreme location found by the researchers is the Yangtze River (Cháng Jiāng) in China. Phosphorus usage in that basin has skyrocketed since 1990 and as of right now the flows from the river represent only about 40% of the total phosphorus usage in the basin. Even if phosphorus usage started dropping today, outflows down that river will likely increase for years to begin removing the nutrient already present in that river basin.-JBBImage credit: Chelyshttp://bit.ly/1Txx6zTReference/Original Paper:http://bit.ly/1UL1V9kMore:https://www.epa.gov/nutrientpollution/problem -- source link
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