Episodes 2022; 45(4): 403-415
Published online December 1, 2022
Copyright © International Union of Geological Sciences.
Chung-Mo Lee1, Yongcheol Kim1, MoonSu Kim2, Hyun-Koo Kim2, Se-Yeong Hamm3*
1 Groundwater Research Center, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 34132, South Korea
2 National Institute of Environmental Research, Incheon 22689, South Korea
3 Department of Geological Sciences, Pusan National University, Busan 46241, South Korea
Correspondence to:E-mail: email@example.com
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Shallow groundwater is vulnerable to major pollutants, such as nitrate-nitrogen (NO3-N). The pollution characteristics of NO3-N need to be understood to protect the quality of shallow groundwater. As already known, shallow groundwater contamination by NO3-N is closely linked to agricultural fertilizers, domestic animals, and sewage. Correspondingly, nonpoint pollution sources such as fertilizers and sewage should be characterized by land use type. In this study, shallow groundwater contamination was examined according to three land use types (forest-dominant, agricultural-dominant, and mixed areas). Principal component analysis was adopted to extract two chemical components (Cl and SO4) related to NO3-N among a total of 11 components. Cluster analysis was performed through a self-organizing map by applying three water quality clusters to the three land use areas. Finally, the origin of NO3-N contamination was evaluated based on the ratio of [NO3-N]/[Cl]. As a result, the forest-dominant area was characterized by a natural origin of NO3-N with a [NO3-N]/[Cl] ratio of 0.45; the agricultural-dominant area was indicated by NO3-N from nitrogen fertilizer with a [NO3-N]/[Cl] ratio of 0.56; and the mixed area was designated by NO3-N from sewage with a [NO3-N]/[Cl] ratio of 0.34.