Zhang Xin, Zhang Yan, Bi Zhi-Lei, Shan Ze-Xuan, Ren Li-Jiang, Li Qi
Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Sciences, Northwest University, Xi'an 710127, China.
Huan Jing Ke Xue. 2020 Apr 8;41(4):1594-1606. doi: 10.13227/j.hjkx.201909078.
The nitrate pollution of surface water has attracted worldwide attention, and it is not optimistic in China. To identify the distribution, sources, and transformation mechanisms of nitrate in China's surface waters, the nitrate data of 71 major rivers from 7 regions were systematically collected. The spatial distribution of nitrate concentrations in surface water was analyzed, and the main nitrate pollution sources were revealed based on nitrogen and oxygen isotopes of nitrate. The results show that approximately 7.83% of rivers in China exceeded the Chinese drinking water standard for nitrate (45 mg·L). The concentrations of nitrate in Mudanjiang, Haihe River, and the estuary of Yangtze River was even more than 90 mg·L, which indicates a serious pollution phenomenon. The isotopic compositions of surface water in China ranged from -23.5‰ to 26.99‰ for N-NO and from -12.7‰ to 83.5‰ for O-NO. The main sources of nitrate are domestic sewage in Northeast, Central, and East China, while those are inorganic fertilizers and domestic sewage in Southwest and South China. The nitrate sources of surface water in Northwest and North China are complex, mainly from domestic sewage, inorganic fertilizer, and nitration of soil organic matter. Through correlation analysis, it is found that the nitrate concentrations of surface water have a positive relationship with population, wastewater discharge, agricultural nitrogen fertilizer application, and GDP per capita in China. It is urgent to solve the problem of pollution and prevent the further pollution of China's surface waters. The new "10-Point Water Plan" issued by the Chinese government solved the previous problems, but it will take decades to control and repair the polluted surface waters. In Northwest, North China, Southwest, and South China, not only the scale of sewage treatment plants in cities and counties should be increased but also the use of agricultural fertilizers should be controlled and managed by the government. Northeast, Central, and East China need to further control point source pollution and reduce the discharge of industrial wastewater and domestic sewage into rivers.
地表水的硝酸盐污染已引起全球关注，在中国的情况也不容乐观。为了查明中国地表水中硝酸盐的分布、来源及转化机制，系统收集了7个区域71条主要河流的硝酸盐数据。分析了地表水中硝酸盐浓度的空间分布，并基于硝酸盐的氮氧同位素揭示了主要硝酸盐污染源。结果表明，中国约7.83%的河流硝酸盐含量超过中国饮用水硝酸盐标准（45mg·L）。牡丹江、海河及长江河口的硝酸盐浓度甚至超过90mg·L，表明污染现象严重。中国地表水的同位素组成中，N-NO为-23.5‰至26.99‰，O-NO为-12.7‰至83.5‰。硝酸盐的主要来源在东北、中部和华东地区是生活污水，而在西南和华南地区是无机肥料和生活污水。西北和华北地区地表水的硝酸盐来源复杂，主要来自生活污水、无机肥料以及土壤有机质的硝化作用。通过相关性分析发现，中国地表水中硝酸盐浓度与人口、废水排放、农业氮肥施用量及人均GDP呈正相关。解决中国地表水的污染问题并防止其进一步污染迫在眉睫。中国政府发布的新“水十条”解决了之前的一些问题，但控制和修复受污染的地表水仍需数十年时间。在西北、华北、西南和华南地区，不仅要扩大市县污水处理厂规模，政府还应控制和管理农业肥料的使用。东北、中部和华东地区需要进一步控制点源污染，减少工业废水和生活污水排入河流。
