A new study carried out by the American Geophysical Union revealed that phosphorus pollution as a result from human activities appeared to have seeped into Earth’s freshwater bodies from 2002 to 2010. The study published in the journal Water Resources Research showed that a large portion of phosphorus fertilizers were not completely absorbed by plants. According to the researchers, the mineral either accumulated in the soil or washed into rivers, lakes, and coastal seas.
The researchers explained that phosphorus is a common component of mineral and manure fertilizers due to its efficacy in increasing crop yield.
As part of the study, the research team pooled data on different agricultural activities between 2002 and 2010. The experts also examined how much fertilizer was applied per crop in each country.
Moreover, the scientists looked at protein consumption per capita per country in order to determine domestic and industrial phosphorus production.
The researchers observed that domestic sewage contributed most to the global phosphorus pollution at 54 percent, followed by agriculture at 38 percent, and industry at eight percent.
The findings revealed that the phosphorus load from agriculture increased by 27 percent over the study period, from 525 gigagrams (Gg) or 579,000 U.S. tons in 2002 to 666 Gg or 734,000 U.S. tons in 2010.
The results also showed that human activity released 1.47 teragrams or 1.62 million U.S. tons of phosphorus into the world’s freshwater bodies per year. According to the study, China contributed 30 percent of the freshwater phosphorus load, while India and the U.S. contributed eight percent and seven percent, respectively.
The scientists identified the most severely polluted freshwater areas, which included the Aral drainage basin, the Huang-He (Yellow) river in China, the Indus and Ganges rivers in India, and the Danube river in Europe.
The research team also noted that while Australia and northern Africa showed less pollution, the areas had significantly less water to accommodate their increasing phosphorus loads.
The scientists underscored the need for increased wastewater treatment coverage and phosphorus removal rates in order to reduce the loads from point sources.
Mesfin M. Mekonnen, Arjen Y. Hoekstra. GLOBAL ANTHROPOGENIC PHOSPHORUS LOADS TO FRESHWATER AND ASSOCIATED GREY WATER FOOTPRINTS AND WATER POLLUTION LEVELS: A HIGH-RESOLUTION GLOBAL STUDY. Water Resources Research, 2018; DOI: 10.1002/2017WR020448