农业面源污染指标与地表水质量的相关性研究

The Relationship between Nonpoint Agricultural Pollutants and Surface Water Quality in China

【目的】揭示我国农业面源污染物排放对地表水质量的影响,为改善地表水质量提供理论依据。【方法】总结了1999—2018年我国主要面源污染指标排放量变化趋势,并采用水质指数(WQI)量化分析了同期地表水质量,最后对农业主要面源污染指标排放量及其未利用量与地表水WQI之间做了相关分析。【结果】4种主要农业面源污染指标——化肥施用量和畜禽养殖业产生的化学需氧量(COD)、总磷(TP)和铵态氮(NH4+-N)在1999—2018年均呈先上升后趋于平稳或有下降的趋势。与1999年相比,2018年时4种主要污染物依次增长37.1%、21.1%、28.4%和15.6%。河流水质在1999—2006年呈下降趋势,之后明显改善,2018年WQI较1999年增加了13.8%。湖泊和水库的水质年际波动较大,2018年WQI较1999年分别增加6.5%和2.4%。畜禽养殖业产生的COD、TP和NH4+-N未利用量与河流WQI呈显著的负相关关系,TP对河流WQI的影响最大,其次是NH4+-N,COD影响最小。【结论】近年来我国河流水质有所改善,但水库和湖泊水质仍不容乐观,降低化肥施用量以及畜禽养殖业污染物未利用量是改善地表水质量的关键途径。

【Objective】The purpose of this paper is to analyze the effects of contaminants originating from non-point agricultural pollution on surface water quality in China,in attempts to provide a baseline to help improve surface water management across the country.【Method】The analysis was based on surface water quality index(WQI)and four main nonpoint agricultural pollutants:chemical fertilizers,chemical oxygen demand related to poultry industry and livestock(COD),total phosphorus(TP)and ammonium nitrogen(NH4+-N),measured from 1999 to 2018 across the country.These data were used to analyze the correlation between WQI and each of the four pollutants.【Result】All four agricultural pollutants increased first and followed by decline or stabilization as time moved from 1999 to 2018.Compared with their contents in 1999,chemical fertilizer,COD,TP and ammonium in the surface water in 2018 increased by 37.1%,21.1%,28.4%and 15.6%,respectively.The water quality of most rivers had deteriorated until 2006,but it has seen significant improvement since then.The WQI of most rivers in 2018 improved by 13.8%compared to that in 1999.The water quality of lakes and reservoirs showed significant inter-annual fluctuation,and their WQI in 2018 increased by 6.5%and 2.4%,respectively,compared to that in 1999.It was found that COD,TP and NH4+-N originating from livestock and poultry industry were negatively correlated with WQI of rivers at significant level.Across the country,TP impacted river WQI most,followed by NH4+-N,with COD being the least.【Conclusion】Water quality in rivers across China has improved over the past few years,but the water quality of reservoirs and lakes remains largely unchanged.Reducing fertilizer application and disposal of wastes from livestock and poultry industry is critical to improving surface water quality and should be the main target in reducing agricultural pollution and improving surface water quality.