赤水河河水溶解态微量元素空间分布及来源分析

Analysis Spatial Distribution and Sources of Dissolved Trace Elements in the Water of Chishui River

为了解人为活动对小流域微量元素的影响,以赤水河流域22条主要支流为研究对象,采集表层水样,结合多元统计分析方法对水体中8种溶解态微量元素(Al、Cr、Fe、Sr、Mn、Cd、Li和As)的含量、空间分布规律及来源进行分析。结果表明:8种微量元素的中位值浓度顺序为Sr>Fe>Al>Li>As>Cr>Cd>Mn,元素浓度总体较低,与长江源区背景值相近,其中Sr浓度中位值最高,为540.2 ug/L。空间分析表明,微量元素含量较高的子流域集中于赤水河中、上游地区。因子分析表明,As和Li的来源主要受到城市污水和工业废水的影响,Mn和Cd的来源与农业生产活动输入有密切关系,Al、Cr、Sr、Fe的来源除了与岩石矿物风化和土壤侵蚀有关外,还受到城市废水输入的影响。通过聚类分析,赤水河子流域在空间上划分为4个区域:赤水河下游段(C1),赤水河中上游段(C2),赤水河源河和渭河(C3),盐津河(C4),溶解态微量元素水平大小排序为C4>C2>C3>C1。其中Sr、Fe、As和Li浓度在C4最高,Mn和Cd浓度在C3最高,Al、Cr则在C2达到最高浓度值。

Surface water samples were collected from 22 sampling sites in the main tributaries of Chishui river basin for dissolved trace elements analysis (Al,Fe,Sr,Mn,Cd,Li,and As). The spatial variations and source identification were determined using various multivariate statistical techniques,including correlation analysis,principal component analysis (PCA) and cluster analysis (CA). The results showed that the median concentrations of these elements were in the order of Sr > Fe > Al > Li > As > Cr > Cd > Mn. And the median concentrations of trace elements in study area were match well with the background values of Yangtze River,without significant trace elements pollution in Chishui River. Compared with other trace elements,the relatively high concentrations could be observed on Sr with a median concentration of 540. 2 ug/L. Spatial structure analysis showed the high content of trace elements were mainly in the upper and middle reaches of Chishui River basin. The results of factor analysis illustrated that As and Li were mainly from domestic sewage. Mn and Cd were attributed to the cultivation. The source of Al,Cr,Sr and Fe were associated with the rock weathering and domestic sewage. Based on the clustering analysis,four spatial regions were identified: C1 (lower reaches of Chishui River Basin),C2 (middle and upper reaches of Chishui River Basin),C3 (Chishui Heyuan River Basin and Weihe River Basin),C4 (Yanjin River Basin),The trace element concentration of four regions followed by C4>C2>C3>C1. The highest concentrations of Sr,Fe,As and Li occurred in C4;while Mn and Cd in C3,Al and Cr in C2.