Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Sciences, Northwest University, Xi'an 710127, China.
Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Sciences, Northwest University, Xi'an 710127, China.
Sci Total Environ. 2021 May 20;770:144674. doi: 10.1016/j.scitotenv.2020.144674. Epub 2021 Jan 20.
Nitrate pollution of surface water has attracted global attention, and the issue is becoming increasingly significant in China. To identify the pollution status, sources, and potential non-carcinogenic health risks of nitrate in China's river water, nitrate data from 71 major rivers from 30 provinces were systematically collected. The spatial distribution of nitrate concentrations in river water was analyzed, and the main nitrate pollution sources were revealed based on the presence of nitrogen and oxygen isotopes of nitrate. The results show that approximately 7.83% of samples in China exceeded the national drinking water standard for nitrate (45 mg/L). The concentrations of nitrate in Mudan River (Linkou County), Haihe (Beijing), and Yangtze River estuary (Shanghai) exceed 90 mg/L, which indicates severe pollution. The characteristic values of δN and δO of river water in China range from -23.5‰ to 26.99‰ and - 12.7‰ to 83.5‰, indicate many sources including inorganic fertilizer, soil nitrogen, wastewater or manure. The primary sources of nitrate in river water of Northeast, Northwest, Southwest, and South China were manure, septic waste, inorganic fertilizer, and soil organic matter nitrification. Manure and septic waste were the major source of nitrate in Central, East, and North China. Correlation analysis revealed that the nitrate concentrations of surface water has a positive relationship with GDP, nitrogen fertilizer application usage, wastewater discharge, and population in China. Non-carcinogenic risk of nitrate was identified in 80% of the regions in China, and potential moderate non-carcinogenic risk areas are Shanghai, Beijing, and Shaanxi. It is urgent to solve the problem of pollution and prevent the further pollution of China's river water. Though the new "10-point Water Plan" issued by the Chinese government solved previous problems, it will take decades to control and repair polluted surface water.
地表水硝酸盐污染已引起全球关注，在中国，这一问题正变得日益严重。为了明确中国河水中硝酸盐的污染状况、来源及潜在的非致癌健康风险，系统采集了中国 30 个省 71 条主要河流的硝酸盐数据。分析了河水中硝酸盐浓度的空间分布，根据硝酸盐氮和氧同位素的存在揭示了主要的硝酸盐污染源。结果表明，中国约有 7.83%的样品硝酸盐浓度超过国家饮用水硝酸盐标准（45mg/L）。牡丹河（连江县）、海河（北京市）和长江口（上海市）的硝酸盐浓度超过 90mg/L，表明污染严重。中国河流水体的δN 和 δO 值特征值范围分别为-23.5‰26.99‰和-12.7‰83.5‰，表明存在无机肥、土壤氮、废水或粪肥等多种来源。中国东北、西北、西南和华南地区河水中硝酸盐的主要来源是粪肥、化粪池废物、无机肥和土壤有机质硝化；而中国中部、东部和北部地区河水中硝酸盐的主要来源是粪肥和化粪池废物。相关分析表明，中国地表水硝酸盐浓度与 GDP、氮肥施用量、废水排放量和人口呈正相关。中国 80%的地区存在硝酸盐非致癌风险，有潜在的中度非致癌风险地区是上海、北京和陕西。解决中国河流水体污染问题、防止进一步污染迫在眉睫。尽管中国政府发布的新“十点水计划”解决了以前的问题，但控制和修复受污染地表水仍需数十年时间。
