Shallow groundwater in rural areas is primarily polluted by agricultural activities. Nitrate-nitrogen is an indicator of artificial pollution. In this study, the hydrochemical characteristics and nitrate-nitrogen pollution of shallow groundwater were examined in two agricultural villages (Hyogyo-ri and Sinan-ri) in Chungcheongnam-do Province, Korea. Physicochemical quality analysis of shallow groundwater and stream water in the field, and chemical analysis in the laboratory were conducted from July 2020 to October 2021. In Hygyo-ri and Sinan-ri villages, shallow groundwater mainly b elonged t o the C a-Cl, Ca-H CO3, Na-HCO3, and Na-Cl types, whereas stream water predominantly belonged to the Ca-HCO3 type. The nitrate-nitrogen concentration in shallow groundwater varied depending on the season, displaying an increased concentration of nitrate-nitrogen in the dry season compared to the rainy season. Stream water may be influenced by runoff into villages from the surrounding area, although both shallow groundwater and stream water are affected by artificial pollution. In addition, the nitrate-nitrogen concentration in stream water was lower than that in shallow groundwater.

Introduction
Study areas
Methods
Results
    Water chemistry of Hyogyo-ri village
    Water chemistry of Sinan-ri village
Discussion
Conclusions
Acknowledgement

• Se-Yeong Hamm(Geoscience Co., Busan 40858, Korea, Institute of Environmental Studies, Pusan National University, Busan 46241, Korea) Corresponding author
• HyunKoo Kim(Soil and Groundwater Research Division, National Institute of Environmental Research, Incheon 22689, Korea)
• MoonSu Kim(Soil and Groundwater Research Division, National Institute of Environmental Research, Incheon 22689, Korea)
• Ji-Min Hwang(School of Earth and Environmental Sciences, Seoul National University, Seoul 08826, Korea)
• Hang-Tak Jeon(Geoscience Co., Busan 40858, Korea)
• Sul-Min Yun(BK21 School of Earth and Environmental Systems, Department of Geological Sciences, Pusan National University, Busan 46241, Korea)