Factors responsible for high arsenic concentrations in two groundwater catchments in Taiwan

Wang, Sheng Wei; Liu, Chen‐Wuing; Jang, Cheng‐Shin

doi:10.1016/j.apgeochem.2006.11.011

Cited by 82 publications

(47 citation statements)

References 45 publications

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“…6a, b). Many other regional hydrochemical studies have also produced a first component with high loadings of elements associated to different salinization processes, such as ion-filtration processes (Usunoff and Guzman-Guzman 1989), infiltration of saline surface water (Adams et al 2001), and seawater intrusion or infiltration from salt manufacturing (Wang et al 2007). The significance of the other two components 2 and 3, in terms of regional processes, is not as important as that of the first component 1 as they explain a lower percentage of the variance.…”

Section: Identification Of Natural (Geogenic) and Anthropogenic Groupmentioning

confidence: 99%

Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia

Zhu

Wang

2015

Environ Monit Assess

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Understanding the source and recharge of ground waters is of great significance to our knowledge in hydrological cycles in arid environments over the world. Northern Xinjiang in northwestern China is a significant repository of information relating to the hydrological evolution and climatic changes in central Asia. In this study, two multivariate statistical techniques, hierarchical cluster analysis (HCA) and principal component analysis (PCA), were used to assess the ground water recharge and its governing factors, with the principal idea of exploring the above techniques to utilize all available hydrogeochemical variables in the quality assessment, which are not considered in the conventional techniques like Stiff and Piper diagrams. Q-mode HCA and R-mode PCA were combined to partition the water samples into seven major water clusters (C1-C7) and three principal components (PC1-PC3, PC1 salinity, PC2 hydroclimate, PC3 contaminant). The water samples C1 + C4 were classified as recharge area waters (Ca-HCO 3 water), C2 + C3 as transitional zone waters (Ca-Mg-HCO 3 -SO 4 water), and C5 + C6 + C7 as discharge area waters (Na-SO 4 water). Based on the Q-mode PCA scores, three groups of geochemical processes influencing recharge regimes were identified: geogenic (i.e., caused by natural geochemical processes), geomorphoclimatic (caused by topography and climate), and anthropogenic (caused by ground water contamination). It is proposed that differences in recharge mechanism and ground water evolution, and possible bedrock composition difference, are responsible for the chemical genesis of these waters. These will continue to influence the geochemistry of the northern Xinjiang drainage system for a long time due to its steady tectonics and arid climate. This study proved that the chemistry differentiation of ground water can effectively support the identification of ground water recharge and evolution patterns.

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Section: Identification Of Natural (Geogenic) and Anthropogenic Groupmentioning

confidence: 99%

Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia

Zhu

Wang

2015

Environ Monit Assess

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“…Elevated As levels in groundwater were found in two neighboring catchments including the Chianan Plain and the southern Choushui River alluvial fan in Taiwan [21,67,137,162,176]. The reduction potential in the Chianan Plain is stronger than that of the Choushui River alluvial fan, and the difference in reduction potentials between these two vicinal areas is believed to be the cause of the exceptional concentrations of As in groundwaters [177,178].…”

Section: Taiwanmentioning

confidence: 99%

Natural Arsenic in Global Groundwaters: Distribution and Geochemical Triggers for Mobilization

et al. 2016

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The elevated concentration of arsenic (As) in the groundwaters of many countries worldwide has received much attention during recent decades. This article presents an overview of the natural geochemical processes that mobilize As from aquifer sediments into groundwater and provides a concise description of the distribution of As in different global groundwater systems, with an emphasis on the highly vulnerable regions of Southeast Asia, the USA, Latin America, and Europe. Natural biogeochemical processes and anthropogenic activities may lead to the contamination of groundwaters by increased As concentrations. The primary source of As in groundwater is predominantly natural (geogenic) and mobilized through complex biogeochemical interactions within various aquifer solids and water. Sulfide minerals such as arsenopyrite and As-substituted pyrite, as well as other sulfide minerals, are susceptible to oxidation in the near-surface environment and quantitatively release significant quantities of As in the sediments. The geochemistry of As generally is a function of its multiple oxidation states, speciation, and redox transformation. The reductive dissolution of As-bearing Fe(III) oxides and sulfide oxidation are the most common and significant geochemical triggers that release As from aquifer sediments into groundwaters. The mobilization of As in groundwater is controlled by adsorption onto metal oxyhydroxides and clay minerals. According to recent estimates, more than 130 million people worldwide potentially are exposed to As in drinking water at levels above the World Health Organization's (WHO's) guideline value of 10 μg/L. Hence, community education to strengthen public awareness, the involvement and capacity building of local stakeholders in targeting As-safe aquifers, and direct action and implementation of best practices in identifying safe groundwater sources for the installation of safe drinking water wells through action and enforcement by local governments and international water sector professionals are urgent necessities for sustainable As mitigation on a global scale.

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“…For the Choushui River alluvial fan, a neighboring region of Chianan Plain, As-contaminated aquifers are also found and distributed in the coastal area, with around 70 % of monitoring wells exceeding the drinking water quality standard in Taiwan (0.01 mg L −1 ) (Liu et al, 2006;Taiwan Sugar Company, 2006). For these two catchments, although high As concentrations were observed at different depths, major characteristics of groundwater as well as the dominant release mechanism of As were similar, particularly at the BFD-endemic area (Wang et al, 2007;Lu et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Identifying sources and controlling factors of arsenic release in saline groundwater aquifers

Liu

Kao

et al. 2014

Hydrol. Earth Syst. Sci.

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Abstract. An integrated hydrogeochemical study was carried out to realize the occurrence of arsenic (As) in a saline aquifer. Saline groundwater was mostly concentrated in the uppermost aquifer, and non-saline water was in the lower aquifer in the study area. High As concentrations were found in both the uppermost and lower aquifers. No correlation among salinity, well depth and As concentration was observed. Various forms of Fe oxyhydroxides were identified in the magnetic fractions, which were concentrated by high gradient magnetic separation (HGMS) technique, revealing that the redox cycling of Fe occurred in the subsurface. High levels of Fe, HCO − 3 , DOC and NH + 4 concentrations accompanying alkaline pH in the As-rich groundwater were consistent with the mechanism triggered by the microbially mediated reductive dissolution of Fe oxyhydroxides. A proposed threshold value of 50 µg L −1 As concentration was used as an indicator for identification of active proceeding reductive dissolution of As-bearing Fe oxyhydroxides in the saline aquifer. Desorption behaviors of As were relevant to its valence in the sediments and the co-existence of anions. Experimental and numerical results showed that additions of Cl − and SO 2− 4 , which represent the main anions of saline water, had minor effect on leaching sedimentary As. Although bicarbonate addition resulted in less As desorption than that of phosphate on a molar basis, the contribution of bicarbonate to the total release of As was greater than phosphate due to the much higher concentration of bicarbonate in shallow groundwater and the associated microbial mediation. Collectively, the chemical effect of saline water on the As release to groundwater is mild in the coastal aquifer.

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Factors responsible for high arsenic concentrations in two groundwater catchments in Taiwan

Cited by 82 publications

References 45 publications

Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia

Statistical study to identify the key factors governing ground water recharge in the watersheds of the arid Central Asia

Natural Arsenic in Global Groundwaters: Distribution and Geochemical Triggers for Mobilization

Identifying sources and controlling factors of arsenic release in saline groundwater aquifers

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