某地农田灌溉退水水质及对主要河流水质影响的分析

Analysis of Water Quality of Backwater of Farmland Irrigation and Its Influence on Examination Section

为调查农田灌溉退水水质及对主要河流水质的影响,以苏北某地为研究对象,对主要流域田间水体开展调查监测。调查布设25个监测点位,采用单因子浓度比较法、水质指数法进行综合分析和评价。结果表明:该地农田灌溉退水通道水质污染空间分布不均匀,但各主要污染因子浓度变化趋势较为一致;水质因子污染程度由高到低为TN>TP>NH4^(+)-N>COD,其中TN和TP是主要水质控制因子;雨季水质综合指数高于旱季,施肥期NH4^(+)-N,TP和TN质量浓度在降雨后比降雨前分别平均升高24.1%,13.4%和11.5%,COD质量浓度则降低20.3%;农田灌溉退水在一定程度上影响了与其相关联的考核断面水质,汛期影响较大,枯水期则影响较小。

In order to investigate the water quality of farmland irrigation and its influence on the water quality of major rivers,an area in northern Jiangsu province was taken as the research object to investigate and monitor the field water around major rivers.A total of 25 monitoring points were set up,and the single factor concentration comparison method and water quality index method were used for comprehensive analysis and evaluation.The results show that the spatial distribution of water pollutions in the drainage channel were not uniform,but the concentration of each major pollution was consistent;the influence degree of pollutions from high to low was TN>TP>NH4^(+)-N>COD,TN and TP were the main water quality control factors;the comprehensive water quality index in rainy season was higher than that in dry season;the mass concentrations of NH4^(+)-N,TP and TN in fertilization period increased by 24.1%,13.4%and 11.5%respectively after rainfall,while the mass concntrations of COD decreased by 20.3%;to some extent,the water retreat from farmland irrigation affects the water quality of the relevant assessment section,which is larger in flood season,but less in dry season.