九洲江流域水环境重金属污染特征及来源解析

九洲江流域环境综合治理已被列为国家跨地区生态补充试点,开展流域重金属污染调查与研究,能为流域生态补偿和综合治理提供科学依据.为了研究九洲江流域水环境重金属浓度分布特征,在流域干流和支流选取了33个采样点,于2018年枯水期、丰水期和平水期分3次进行采样监测,测定13种重金属(Cu、Zn、Pb、Cd、Cr、Ni、Fe、Mn、Hg、As、Sb、Tl、Se)的含量.结果表明,13种重金属平均浓度从大到小排序为Fe>Mn> Zn> As> Sb> Pb> Cu> Cr> Ni> Tl> Se=Cd=Hg,Fe、Zn、Pb、Sb和As呈现出丰水期>枯水期>平水期浓度分布特征,Mn则是枯水期>平水期>丰水期,As、Sb、Pb和Mn呈现出干流>支流浓度分布特征,Fe和Zn则是支流>干流,干流As和Sb呈现出丰水期浓度明显升高的污染特征;九洲江流域干流和支流Fe和Mn污染较重,大部分点位均超过参照标准限值,是九洲江流域重金属的首要污染物,As在丰水期支流点位有超标,超标率为5.6%,Sb在枯水期、丰水期的干流和支流均有超标现象,超标率范围为6.7%—30%,其它重金属浓度均未超标.内梅罗综合指数法分析结果表明,S13温泉镇中屯河重金属污染最重,污染相对较重的前10位均为支流点位.相关性分析、主成分分析和聚类分析结果表明,Mn、Pb、Cu、Tl、Fe和Zn浓度主要受自然地质环境影响,As和Sb具有同源性,主要来源于化肥和农药的农业面源污染,Ni和Cr来源可能是自然环境和畜禽养殖和城镇污水处理厂排放共同影响的结果.

Characteristics and sources of heavy metal pollution in water environment of Jiuzhou River basin

Comprehensive environmental management of Jiuzhou River has been listed as a national cross regional ecological supplementary pilot project, and the investigation and research of heavy metal pollution in the basin can provide scientific basis for ecological compensation and comprehensive management of the basin. In order to study the distribution characteristics of heavy metal concentrations in the water environment of Jiuzhou River basin, 33 sampling sites were selected in the main streams and tributaries, and the contents of 13 heavy metals(Cu, Zn, Pb, Cd, Cr, Ni, Fe, Mn, Hg, As, Sb, Tl, Se) were determined in 2018 during dry, wet and temperate season. The results showed that the order of the average concentration of 13 heavy metals as followed: Fe>Mn>Zn>As>Sb>Pb>Cu>Cr>Ni>Tl>Se=Cd=Hg. The concentration distribution characteristics of Fe, Zn, As, Sb and Pb showed: wet season> dry season> temperate season, but the concentration distribution characteristic of Mn was dry season> temperate season> wet season. The concentration distribution characteristics of As, Sb, Pb and Mn showed: main streams> tributaries, but the concentration distribution characteristics of Fe and Zn were tributaries> main streams, the concentration distribution characteristics of Sb and As on the main streams increased markedly in wet season. Fe and Mn in the main stream and tributaries of Jiuzhou River basin were seriously polluted, and most of the points were beyond the limit of the reference standard, which were the primary heavy metal pollutants in Jiuzhou River basin. As exceeded the standard at the tributary points in the wet season, with an over-standard rate of 5.6%;Sb exceeded the standard in both the dry and wet season, with an over-standard rate ranging from 6.7% to 30%;other heavy metal concentrations did not exceed the standard. Heavy metal pollution of S13 was the most serious in 33 sampling sites, and the top 10 most polluted were tributary sampling sites according to Nemerow comprehensive pollution index method. The results of correlation, principal component and cluster analysis showed that Mn, Pb, Cu, Tl, Fe and Zn were mainly affected by the natural geological environment. As and Sb were mainly from agricultural non-point source pollution of chemical fertilizers and pesticides, and had homology. The sources of Ni and Cr might be the result of the joint influence of the natural environment, livestock breeding and urban sewage treatment plant discharge.