练江干流底质污染及水质响应关系研究

Analysis of sediment pollution and their impacts on water quality in main stream of Lianjiang river

选取2019年11月(枯水期)和2020年5月(丰水期)、8月(平水期)练江干流20个调查点位,取样分析了底质总磷、总氮、有机质、重金属(铜、锌、镉、铅和镍)共8项检测指标数据,发现练江底质各种污染物总体时空差异较明显.利用主成分分析法(PCA)对沉积物污染进行源解析,并结合水质总氮、总磷、总氨氮和化学需氧量绘制网络关系图,结果表明练江干流底质主要受到电子垃圾拆解业和印染产业污染,其主要污染物是铜、镉和镍这三种重金属.11号点位受贵屿电子垃圾拆解区域污染,污染程度最高,在丰水期和平水期尤为严重.底质氮磷与水质氮磷共现性好,因此有必要关注沉积物氮磷污染与水质的相互影响.沉积物有机质与水质化学需氧量负相关,主要由于沉积物相以颗粒态有机物为主,而水相以溶解态有机物为主.锌和镉可考虑作为练江流域沉积物污染源的指示污染物,分别指示印染行业与电子垃圾拆解业的污染.

The pollution in Lianjiang river was surveyed in November 2019(dry season),May 2020(high water season)and August 2020(normal water season),via analyzing 8 sediment quality indexes including total phosphorus,total nitrogen,organic matter,and 5 heavy metals(Cu,Zn,Cd,Pb and Ni)of 20 survey points along the main stream of Lianjiang river.The spatial and temporal differences of various pollutants in the sediment of Lianjiang river are obvious.The principal component analysis(PCA)was used to identify the pollution sources,while the correlation between sediment pollution with water quality indexes of total nitrogen,total phosphorus,total ammonium nitrogen and chemical oxygen demand was visualized with the network relationship diagram.The results show that Cu,Cd and Ni were the main pollutants in the sediments of Lianjiang river,which were most likely from the e-waste dismantling and the textile and dyeing industries.Site 11 receiving the waste discharge from the e-waste dismantling area in Guiyu,showed the highest pollution level,especially during the high and normal water seasons.The nitrogen and phosphorus contents in sediments correlated well with their concentrations in water columns,indicating an alarming interaction in nitrogen and phosphorus pollution between sediments and water columns.Sediment organic matter was negatively correlated with COD in water columns.The main reason is that the sediment phase is dominated by granular organic matter,while the water phase is dominated by dissolved organic matter.Zn and Cd,from textile and dyeing,and e-waste dismantling industries,respectively,may be used as the indicator pollutants of sediments in Lianjiang river basin to identify the pollution sources.