TY - JOUR
T1 - Hydrogeochemical interpretation of South Korean groundwater monitoring data using Self-Organizing Maps
AU - Choi, Byoung Young
AU - Yun, Seong Taek
AU - Kim, Kyoung Ho
AU - Kim, Ji Wook
AU - Kim, Hyang Mi
AU - Koh, Yong Kwon
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea Grant (2012, University-Institute Cooperation Program) funded by the Korean Government ( Ministry of Science, ICT & Future Planning ). Additional supports were provided by the 2010 Eco-Technopia 21 Project from the KEITI (project title: Studies of geological and geochemical factors related to the behavior and leakage of carbon dioxide in geologic carbon storage: Suggestion of optimal methods for environmental impact assessment of carbon storage), the Radioactive Waste Management Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea Government Ministry of Knowledge Economy (No. 201017102002D ), and the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources (KIGAM) . Prof. Rodney Grapes helped improve early version of this manuscript. Constructive comments from two anonymous reviewers and Dr. HE Gäbler (Associate Editor) helped clarify and improve the manuscript.
PY - 2014/2
Y1 - 2014/2
N2 - The National Groundwater Monitoring Network (NGMN) of South Korea provides data since 1995 to monitor the water level and quality of groundwater on a national scale. Major ions such as Ca, Mg, Na, K, HCO3, Cl, SO4 and NO3 have been monitored since 2008 to assess groundwater quality. Hydrochemical data of bedrock groundwater samples collected from 299 monitoring stations in 2009 were examined using the Self-Organizing Map (SOM) approach. Based on hydrochemical characteristics, bedrock groundwater is clustered into two groups and six subgroups. Group I containing 70.2% of groundwater samples (and monitoring stations) is characterized by lower TDS values and NO3 concentrations than Group II, indicating that Group I waters are less affected by contamination. Subgroup I-1 (39.1%) represents Ca-HCO3-type groundwater with relatively low pH, TDS and concentrations of most ions compared with groundwater of Subgroups I-2-1 (26.1%) and I-2-2 (5.0%). Subgroup I-2-2 represents a moderately alkaline, F-rich, Na-HCO3-type groundwater. Group II records either anthropogenic or natural processes. Subgroup II-1 (16.1%) contains groundwater with low values of TDS, HCO3 and pH, and moderately high NO3 concentrations due to nitrification, while groundwater of Subgroups II-2-1 and II-2-2 is characteristically high in Ca and Mg. Subgroup II-2-1 is also very high in SO4 and HCO3 but very low in NO3, while Subgroup II-2-2 is substantially enriched in Cl and NO3. The hydrochemistry of groundwater of Subgroup II-2-1 likely results from dissolution of carbonates and gypsum in clastic sedimentary rocks and is affected by dissolution of pyrite and/or S-bearing fertilizers in crystalline rocks. The enrichment of NO3, Cl, Ca and Mg in groundwater of Subgroup II-2-2 is the result of substantial contamination from agrochemicals and manure. Thus, about 20.5% (Subgroups II-1 and II-2-2) of bedrock groundwater in South Korea records anthropogenic contamination. This study shows that the SOM approach can be successfully used to classify and characterize the groundwater in terms of hydrochemistry and quality on a regional scale.
AB - The National Groundwater Monitoring Network (NGMN) of South Korea provides data since 1995 to monitor the water level and quality of groundwater on a national scale. Major ions such as Ca, Mg, Na, K, HCO3, Cl, SO4 and NO3 have been monitored since 2008 to assess groundwater quality. Hydrochemical data of bedrock groundwater samples collected from 299 monitoring stations in 2009 were examined using the Self-Organizing Map (SOM) approach. Based on hydrochemical characteristics, bedrock groundwater is clustered into two groups and six subgroups. Group I containing 70.2% of groundwater samples (and monitoring stations) is characterized by lower TDS values and NO3 concentrations than Group II, indicating that Group I waters are less affected by contamination. Subgroup I-1 (39.1%) represents Ca-HCO3-type groundwater with relatively low pH, TDS and concentrations of most ions compared with groundwater of Subgroups I-2-1 (26.1%) and I-2-2 (5.0%). Subgroup I-2-2 represents a moderately alkaline, F-rich, Na-HCO3-type groundwater. Group II records either anthropogenic or natural processes. Subgroup II-1 (16.1%) contains groundwater with low values of TDS, HCO3 and pH, and moderately high NO3 concentrations due to nitrification, while groundwater of Subgroups II-2-1 and II-2-2 is characteristically high in Ca and Mg. Subgroup II-2-1 is also very high in SO4 and HCO3 but very low in NO3, while Subgroup II-2-2 is substantially enriched in Cl and NO3. The hydrochemistry of groundwater of Subgroup II-2-1 likely results from dissolution of carbonates and gypsum in clastic sedimentary rocks and is affected by dissolution of pyrite and/or S-bearing fertilizers in crystalline rocks. The enrichment of NO3, Cl, Ca and Mg in groundwater of Subgroup II-2-2 is the result of substantial contamination from agrochemicals and manure. Thus, about 20.5% (Subgroups II-1 and II-2-2) of bedrock groundwater in South Korea records anthropogenic contamination. This study shows that the SOM approach can be successfully used to classify and characterize the groundwater in terms of hydrochemistry and quality on a regional scale.
KW - Bedrock groundwater
KW - Classification and characterization
KW - Hydrochemistry
KW - National Groundwater Monitoring Network
KW - Self-Organizing Map (SOM) approach
KW - South Korea
UR - http://www.scopus.com/inward/record.url?scp=84891629835&partnerID=8YFLogxK
U2 - 10.1016/j.gexplo.2013.12.001
DO - 10.1016/j.gexplo.2013.12.001
M3 - Article
AN - SCOPUS:84891629835
SN - 0375-6742
VL - 137
SP - 73
EP - 84
JO - Journal of Geochemical Exploration
JF - Journal of Geochemical Exploration
ER -