Using multivariate statistical methods to assess the groundwater quality in an arsenic-contaminated area of Southwestern Taiwan
Using multivariate statistical methods to assess the groundwater quality in an arsenic-contaminated area of Southwestern Taiwan
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DOI：
10.1007/s10661-011-2406-y
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发表时间：
2012-10-01
影响因子：
3
通讯作者：
Jang, C. -S.
中科院分区：
文献类型：
--
作者：
Lu, K. -L.;Liu, C. -W.;Jang, C. -S.
地下水是台湾西南部的主要水资源，因此，长期监测水质是必不可少的。本研究旨在利用多元统计方法，即因子分析（FA），聚类分析（CA）和判别分析（DA），评估台湾浊水溪冲积扇和嘉南平原砷污染含水层的水化学特征。应用因子分析方法揭示了地下水水化学的控制过程。应用聚类分析对采集的水样进行水质空间分类。判别分析，然后应用于阐明与发生升高的As浓度（> 10 μ g L-1）在地下水中的关键参数。浊水溪冲积扇和嘉南平原的主要水型分别为Na-Ca-Cl和Na-Mg-Cl。无机砷（As），特别是As（III），占主导地位，在这两个地下水集水区，其水平是较高的嘉南平原比浊水溪冲积扇。通过FA，三个因素，即，盐渍化程度，As还原，铁（Fe）还原，确定和表示的阶乘组合物之间的一些差异无关。As还原和Fe还原因子的空间分布格局表明，氧化还原分带分别由As优势带和Fe优势带所划分。元胞自动机的结果表明，三个主要群体可以适当地解释通过FA提取的因素。通过对浊水溪冲积扇和嘉南平原的判别分析，确定了影响地下水含砷量分布的3个参数（Fe 2+、Fe 3+、NH 4+）和4个参数（Fe 2+、Fe 3+、NH 4+、Ca 2+）。分析结果表明，Fe矿物的还原溶解是As活化的先决条件，而氧化还原条件从Fe还原向As还原的转变导致了溶解As在该地区的积累。
Groundwater is a major water resource in Southwestern Taiwan; hence, long-term monitoring of water quality is essential. The study aims to assess the hydrochemical characteristics of water in the arsenic-contaminated aquifers of Choushui River alluvial fan and Chianan Plain, Taiwan using multivariate statistical methods, namely, factor analysis (FA), cluster analysis (CA), and discriminant analysis (DA). Factor analysis is applied to reveal the processes controlling the hydrochemistry of groundwater. Cluster analysis is applied to spatially categorize the collected water samples based on the water quality. Discriminant analysis is then applied to elucidate key parameters associated with the occurrence of elevated As concentration (> 10 mu g L-1) in groundwater. Major water types are characterized as Na-Ca-Cl and Na-Mg-Cl in the Choushui River alluvial fan and Chianan Plain, respectively. Inorganic species of arsenic (As), particularly As(III), prevail in these two groundwater catchments, and their levels are higher in the Chianan Plain than in the Choushui River alluvial fan. Through FA, three factors, namely, the degree of salination, As reduction, and iron (Fe) reduction, are determined and denoted irrespective of some differences between the factorial compositions. Spatial distribution patterns of factors As reduction and Fe reduction imply that the redox zonation is delineated by As- and Fe-dominance zones separately. The results of CA demonstrate that three main groups can be properly explained by the factors extracted via FA. Three- (Fe2+, Fe3+, and NH (4) (+) ) and four-parameters (Fe2+, Fe3+, NH (4) (+) , and Ca2+) derived from discriminant analysis for Choushui River alluvial fan and Chianan Plain are elucidated as key parameters affecting the distribution of As-contained groundwater. The analytical results indicate that the reductive dissolution of Fe minerals is prerequisite for the mobilization of As, whereas the shift of redox condition from Fe- to As-reducing leads to the accumulation of dissolved As in this area.