巢湖圩区农田面源污染负荷估算及治理措施研究

Research on the estimation of non-point source pollution load and treatment measures of farmland in Chaohu polder area

农田面源污染是巢湖流域水环境污染的主要来源之一。以巢湖流域万亩大圩杨柳圩为研究对象,采用入河系数法对圩内污染负荷进行估算分析。结果表明:2020年圩内污染负荷入河总量COD为175.24 t/a,NH3-N为24.99 t/a,TP为3.24 t/a,TN为38.49 t/a,其中农田面源污染负荷入河量COD为50.59 t/a,NH3-N为10.91 t/a,TP为1.02 t/a,TN为19.83 t/a,分别占总入河量的28.91%、43.66%、31.48%和51.52%;除圩区化肥农药利用率较低之外,沟渠水动力条件差、灌排一体、水生植物群落失衡等也是造成面源污染的重要因素;同时由于圩内净化空间与调蓄空间不足,造成大量污染在汛期随雨水泵送至外河,对周边水质造成严重影响。鉴于此,因地制宜的提出了合理的治理思路与措施,可为平原圩区的农田面源污染治理工程设计提供参考。

Non-point source pollution of farmland is one of the main pollutions in Chaohu Lake Basin.Taking the 10,000 mu of Yangliu polder area in the Chaohu Lake basin as the study object,the river inflow coefficient method is used to estimate and analyze the pollution load in the polder area.The results show that in 2020 the total COD of the pollution load in the polder is 175.24 t/a,NH3-N is 24.99 t/a,TP is 3.24 t/a,and TN is 38.49 t/a,of which the non-point source pollution load of farmland is 50.59 t/a,NH3-N of 10.91 t/a,TP of 1.02 t/a,and TN of 19.83 t/a,accounting for 28.91%、43.66%、31.48%and 51.52%of the total river inflow,respectively.In addition to the low utilization rate of chemical fertilizers and pesticides in the polder area,poor hydrodynamic conditions of water flow in the ditches,integrated irrigation and drainage system,and imbalance of aquatic plant communities are also important factors causing non-point source pollution.Meanwhile,due to the lack of purification and storage space in the polder area,a large amount of pollution is pumped to the outer river with rainwater during the flood season,which has a serious impact on the surrounding water quality.In view of this,reasonable treatment plans and measures are put forward according to local conditions,which can provide a reference for the design of farmland non-point source pollution control projects in the plain polder area.