In this study, the concentrations of some of the important ionic contaminants in groundwaters of national monitoring network in Korea were identified, and their correlation to nitrate concentration was investigated. Approximately 80% of the groundwater samples were found to be as Ca²⁺-(Cl^-+NO₃^-) type groundwater with the concentration ranges [minimum to maximum values, median (mg/L)] of Ca²⁺[0.1~228.2, 19.7], Mg²⁺[0.1~53.2, 5.1], K⁺[0.1~50.8, 1.9], Na⁺[1.5~130.5, 18.1], NO₃^--N[0.1~73.4, 9.3], NH₄⁺-N[0.0~53.9, 0.3], Cl^-[3.1~482.6, 24.0], and SO₄^2-[2.8~101.6, 7.0]. The prevalence of Ca²⁺-(Cl^-+NO₃^-) type suggest that the composition of groundwaters were greatly influcenced by chemical fertilizers and animal manure, Correlation analyses indicated threre was positive correlation between NO₃^--N concentration and ionic species including Cl^-, Ca²⁺, Mg²⁺, and Na⁺. In particular, the correlation was strongest for Cl^- and NO₃^--N, suggesting that groundwaters largely impacted by agricultural and livestock breeding activities tend to contain high levels of Cl^-. 

Keywords: Groundwater, Livestock Region, Nitrate, Chloride, Piper diagram, SPSS