TY - JOUR
T1 - Primary sink and source of geogenic arsenic in sedimentary aquifers in the southern Choushui River alluvial fan, Taiwan
AU - Lu, Kuang Liang
AU - Liu, Chen Wuing
AU - Wang, Sheng Wei
AU - Jang, Cheng Shin
AU - Lin, Kao Hung
AU - Liao, Vivian Hsiu Chuan
AU - Liao, Chung Min
AU - Chang, Fi John
N1 - Funding Information:
This work has been supported by the National Science Council of the Republic of China , Taiwan, under Contract No. NSC-93-2313-B-002-071. We thank Dr. Ron Fuge, Dr. David Polya and three anonymous reviewers for their constructive reviews. Ted Knoy is appreciated for his editorial assistance.
PY - 2010/5
Y1 - 2010/5
N2 - This work characterized the sink and source/mobility of As in the As-affected sedimentary aquifers of the southern Choushui River alluvial fan, central Taiwan. Major mineral phases and chemical components were determined by XRD and X-ray photoelectron spectroscopy (XPS). The partitioning of As and Fe among cores were determined by sequential extraction. Based on XPS results, the primary forms of Fe were hematite, goethite and magnetite. Sequential extraction data and the XRF analysis indicated that Fe oxyhydroxides and sulfides were likely to be the major sinks of As, particularly in the distal-fan. Furthermore, Fe oxyhydroxides retained higher As contents than As-bearing sulfides. The reductive dissolution of Fe oxyhydroxides, which accompanied high levels of HCO3- and NH4+ concentrations, was likely the principal release mechanism of As into groundwater in this area. The dual roles of Fe oxyhydroxides which are governed by the local redox condition act as a sink and source in the aquifer. Ionic replacement by PO43 - and HCO3- along with seasonal water table fluctuation, caused by monsoons and excessive pumping, contributed specific parts of As in the groundwater. The findings can be used to account for the inconsistency between Fe and As concentrations observed in groundwater.
AB - This work characterized the sink and source/mobility of As in the As-affected sedimentary aquifers of the southern Choushui River alluvial fan, central Taiwan. Major mineral phases and chemical components were determined by XRD and X-ray photoelectron spectroscopy (XPS). The partitioning of As and Fe among cores were determined by sequential extraction. Based on XPS results, the primary forms of Fe were hematite, goethite and magnetite. Sequential extraction data and the XRF analysis indicated that Fe oxyhydroxides and sulfides were likely to be the major sinks of As, particularly in the distal-fan. Furthermore, Fe oxyhydroxides retained higher As contents than As-bearing sulfides. The reductive dissolution of Fe oxyhydroxides, which accompanied high levels of HCO3- and NH4+ concentrations, was likely the principal release mechanism of As into groundwater in this area. The dual roles of Fe oxyhydroxides which are governed by the local redox condition act as a sink and source in the aquifer. Ionic replacement by PO43 - and HCO3- along with seasonal water table fluctuation, caused by monsoons and excessive pumping, contributed specific parts of As in the groundwater. The findings can be used to account for the inconsistency between Fe and As concentrations observed in groundwater.
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U2 - 10.1016/j.apgeochem.2010.02.001
DO - 10.1016/j.apgeochem.2010.02.001
M3 - Article
AN - SCOPUS:77950918183
VL - 25
SP - 684
EP - 695
JO - Applied Geochemistry
JF - Applied Geochemistry
SN - 0883-2927
IS - 5
ER -