Econ. Environ. Geol. 2005; 38(5): 547-561

Published online October 31, 2005

© THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY

Characteristics of Natural Arsenic Contamination in Groundwater and Its Occurrences

Joo Sung Ahn1*, Kyung-Seok Ko2, Jin-Soo Lee2 and Ju-Yong Kim3

1Groundwater and Geothermal Resources Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea
2Geological and Environmental Hazards Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea
3Department of Environmental Science and Engineering, Gwangju Institute of Science and Engineering, Gwangju 500-712, Korea

Correspondence to :

Joo Sung Ahn

jsahn@kigam.re.kr

Received: August 9, 2005; Accepted: September 6, 2005

Abstract

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a few previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about 28% of the shallow groundwaters exceeded the Bangladesh drinking water standard, 50 μg/L, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of SO42- and NO3-, and high contents of dissolved organic carbon (DOC) and NH4+ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciation during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about 1% of grounwaters have concentrations higher than 10 μg/L. However, it was revealed that 19.3% of mineral waters, and 7% of tube-well waters from Nonsan and Geumsan areas contained As concentrations above 10 μg/L. Also, percentages exceeding this value during detailed groundwater quality surveys were 36% and 22% from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.

Keywords Arsenic, Groundwater, Geochemistry, Occurrence

Article

Econ. Environ. Geol. 2005; 38(5): 547-561

Published online October 31, 2005

Copyright © THE KOREAN SOCIETY OF ECONOMIC AND ENVIRONMENTAL GEOLOGY.

Characteristics of Natural Arsenic Contamination in Groundwater and Its Occurrences

Joo Sung Ahn1*, Kyung-Seok Ko2, Jin-Soo Lee2 and Ju-Yong Kim3

1Groundwater and Geothermal Resources Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea
2Geological and Environmental Hazards Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Korea
3Department of Environmental Science and Engineering, Gwangju Institute of Science and Engineering, Gwangju 500-712, Korea

Correspondence to:

Joo Sung Ahn

jsahn@kigam.re.kr

Received: August 9, 2005; Accepted: September 6, 2005

Abstract

General characteristics of groundwater contamination by As were reviewed with several recent researches, and its occurrence in groundwater of Korea was investigated based on a few previous studies and a groundwater quality survey in Nonsan and Geumsan areas. In Bangladesh, which has been known as the most serious arsenic calamity country, about 28% of the shallow groundwaters exceeded the Bangladesh drinking water standard, 50 μg/L, and it was estimated that about 28 million people were exposed to concentrations greater than the standard. Groundwater was characterized by circum-neutral pH with a moderate to strong reducing conditions. Low concentrations of SO42- and NO3-, and high contents of dissolved organic carbon (DOC) and NH4+ were typical chemical characteristics. Total As concentrations were enriched in the Holocene alluvial aquifers with a dominance of As(III) species. It was generally agreed that reductive dissolution of Fe oxyhydroxides was the main mechanism for the release of As into groundwater coupling with the presence of organic matters and microbial activities as principal factors. A new model has also been suggested to explain how arsenic can naturally contaminate groundwaters far from the ultimate source with transport of As by active tectonic uplift and glaciation during Pleistocene, chemical weathering and deposition, and microbial reaction processes. In Korea, it has not been reported to be so serious As contamination, and from the national groundwater quality monitoring survey, only about 1% of grounwaters have concentrations higher than 10 μg/L. However, it was revealed that 19.3% of mineral waters, and 7% of tube-well waters from Nonsan and Geumsan areas contained As concentrations above 10 μg/L. Also, percentages exceeding this value during detailed groundwater quality surveys were 36% and 22% from Jeonnam and Ulsan areas, respectively, indicating As enrichment possibly by geological factors and local mineralization. Further systematic researches need to proceed in areas potential to As contamination such as mineralized, metasedimentary rock-based, alluvial, and acid sulfate soil areas. Prior to that, it is required to understand various geochemical and microbial processes, and groundwater flow characteristics affecting the behavior of As.

Keywords Arsenic, Groundwater, Geochemistry, Occurrence

    KSEEG
    Dec 31, 2024 Vol.57 No.6, pp. 665~835

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