To improve water quality, China will need to cut nitrogen pollution, researchers say

To boost the quality of its waterways, China will need a multisector effort to curb releases of nitrogen, a team of international researchers says (Nature 2019, DOI: 10.1038/s41586-019-1001-1). Led by Chaoqing Yu of Tsinghua University, the team used historic water-quality data and simulation of runoff from agriculture to determine that most Chinese provinces have exceeded the national limit of 1 mg/L of nitrogen since the mid-1980s. The country currently discharges between 11.4 million and 17.6 million metric tons of nitrogen annually to fresh water from croplands, livestock manure, and domestic and industrial wastewater, the researchers estimate. Most provinces could lower the amount of pollution from croplands by using controlled-release fertilizers, the researchers say. They also suggest piping disinfected household wastewater into existing farm irrigation systems to recycle nutrients. In addition, better livestock management could increase recycling of nitrogen from manure into crops, reducing pollution, and improving public health. If these strategies were adopted, however, Shanghai and Shanxi Provinces would still have to cut industrial nitrogen discharges to meet the water standard, the researchers say.