西干渠水体污染时空分布特征和影响因素分析

Spatial and Temporal Distribution Characteristics and Influencing Factors of Water Pollution in the Xigan Canal

流域地表水体污染过程的时空差异是人类生产生活和水文过程共同产生的结果。该文以西干渠中上游地区作为研究区,通过分析2018年10月-2019年9月地表水监测数据,研究了西干渠不同区域水质的季节变化特征和空间差异。结果表明,西干渠上游和中游的地表水体污染表现出明显不同的时空差异:西干渠上游,化学需氧量、氨氮和总磷随时间变化总体上呈现出先上升后下降趋势,总磷在枯水期浓度高于丰水期,氨氮浓度在枯水期和平水期偏高;西干渠中游,化学需氧量、氨氮随时间变化表现为先上升后下降的变化趋势,各监测点位总磷浓度随时间变化呈现不同的变化趋势;西干渠下游支渠水体污染程度较轻,各监测点位随时间变化规律不明显,水质主要受农业面源污染和农村生活污水影响。研究表明:西干渠上游主要受居民生活污水排放影响较大,中游水质受生活污水和工业废水影响较大。西干渠上游至中游,地表水质自净化能力降低,污染物集聚增多。

The spatiotemporal difference of surface water pollution process is the result of human production and life and hydrological process.Taking the middle and upper reaches of the western main canal as the research area,the seasonal variation characteristics and spatial differences of water quality in different regions of the Xigan Canal were studied by analyzing the surface water monitoring data from October 2018 to September 2019.The results showed that the surface water pollution in the upper and middle reaches of the Xigan Canal showed obvious spatial and temporal differences:in the upper reaches of the Xigan Canal,the changes of chemical oxygen demand,ammonia nitrogen and total phosphorus showed a trend of first increase and then decrease.The concentration of total phosphorus in the dry season was higher than that in the wet season,and the concentration of ammonia nitrogen was higher in the dry season and the water season;in the middle reaches of the Xigan Canal,the chemical oxygen demand and ammonia nitrogen were at any time.The results showed that the total phosphorus concentration at each monitoring point showed a different change trend with time;the water pollution degree of the downstream branch channel of the Xigan Canal was light,and the change law of each monitoring point with time was not obvious,and the water quality was mainly affected by agricultural non-point source pollution and rural domestic sewage.The results show that the water quality in the upper reaches of the Xigan Canal is mainly affected by the discharge of domestic sewage,while the water quality of the middle reaches is greatly affected by domestic sewage and industrial wastewater.From the upper reaches to the middle reaches of the Xigan Canal,the self purification ability of surface water is decreasing,and the concentration of pollutants is increasing.