广东沿海城市农业面源氮磷污染排放特征及控制对策研究

Emission characteristics and control strategies of agricultural non-point source nitrogen and phosphorus pollution in coastal cities of Guangdong Province

国家对沿海城市提出了强化氮磷排放控制、因地制宜推进农业面源污染防治的要求,广东沿海城市是全省农业面源氮磷污染的重要控制区域,厘清沿海城市农业面源氮磷污染排放特征对后续氮磷排放控制具有重要作用。采用排污系数法、等标负荷法对2018—2022年广东沿海地区农业面源污染负荷及其时空变化特征进行了分析,结果表明:广东沿海城市农业面源污染负荷整体呈先减少后增加趋势,且呈现较强的区域差异。不同类型源氮磷污染负荷贡献率表现为畜禽养殖源(37%~52%)>水产养殖源(24%~35%)>农业种植源(21%~29%);珠三角沿海区域广州、珠海、中山、东莞、汕头等市污染贡献主要为水产养殖源,其余沿海城市污染贡献主要为畜禽养殖源;从单位地表水资源量和单位土地面积等标污染负荷来看,中山、珠海、茂名、湛江等市相对较高(等标相对排放系数均大于4 m^(3)/km^(2),等标污染指数均大于0.4),东莞、深圳两市相对较低(等标相对排放系数均小于1 m^(3)/km^(2),等标污染指数均小于0.1)。在此基础上,从强化政策规划引领、优化推进区域种养结合、完善农业面源监测监管体系、加大技术研发与推广应用力度4个方面提出沿海城市农业面源氮磷污染控制对策建议,助力深入打好农业农村污染治理攻坚战,推进美丽海湾保护与建设。

Requirements for strengthening nitrogen and phosphorus emission control and promoting agricultural non-point source pollution prevention and control according to local conditions in coastal cities has been put forward.Guangdong coastal cities are important control areas for agricultural non-point source nitrogen and phosphorus pollution in the province.Clarifying the characteristics of agricultural non-point source nitrogen and phosphorus pollution emissions in coastal cities plays an important role in subsequent nitrogen and phosphorus emission control.The pollution coefficient method,equal standard load method were used to analyze the agricultural non-point source pollution load,and its spatiotemporal variation characteristics in coastal cities of Guangdong Province from^(2)018 to 2022.The results showed that the overall agricultural non-point source pollution load in coastal cities of Guangdong Province decreased first and then increased,and there were strong regional differences.The contribution rate of emissions from different types of sources was as follows:livestock and poultry breeding sources(37%-52%)>aquaculture sources(24%-35%)>agricultural planting sources(21%-29%).The pollution contribution of coastal cities such as Guangzhou,Zhuhai,Zhongshan,Dongguan and Shantou in the Pearl River Delta was mainly from aquaculture sources,while the pollution contribution of other coastal cities was mainly from livestock and poultry breeding sources.From the perspective of standard pollution loads such as unit surface water resource and unit land area,Zhongshan,Zhuhai,Maoming,and Zhanjiang had relatively high levels(the equivalent relative emission coefficient greater than 4 m^(3)/km^(2),and the equivalent pollution index greater than 0.4),while Dongguan and Shenzhen had relatively low levels(the equivalent relative emission coefficient less than 1 m^(3)/km^(2),and the equivalent pollution index less than 0.1).On this basis,suggestions for countermeasures against agricultural non-point source nitrogen and phosphorus pollution in coastal cities were proposed from four aspects:strengthening policy planning guidance,optimizing the promotion of regional planting and breeding integration,improving the agricultural non-point source monitoring and supervision system,and increasing technological research and promotion and application.This paper will help to deepen the battle against agricultural and village pollution,and promote the protection and construction of beautiful bays.