title: Hydrochemical and multivariate statistical interpretations of spatial controls of nitrate concentrations in a shallow alluvial aquifer around oxbow lakes (Osong area, central Korea).
abstract: Hydrochemical and multivariate statistical interpretations of 16 physicochemical parameters of 45 groundwater samples from a riverside alluvial aquifer underneath an agricultural area in Osong, central Korea, were performed in this study to understand the spatial controls of nitrate concentrations in terms of biogeochemical processes occurring near oxbow lakes within a fluvial plain. Nitrate concentrations in groundwater showed a large variability from 0.1 to 190.6 mg/L (mean=35.0 mg/L) with significantly lower values near oxbow lakes. The evaluation of hydrochemical data indicated that the groundwater chemistry (especially, degree of nitrate contamination) is mainly controlled by two competing processes: 1) agricultural contamination and 2) redox processes. In addition, results of factorial kriging, consisting of two steps (i.e., co-regionalization and factor analysis), reliably showed a spatial control of the concentrations of nitrate and other redox-sensitive species; in particular, significant denitrification was observed restrictedly near oxbow lakes. The results of this study indicate that sub-oxic conditions in an alluvial groundwater system are developed geologically and geochemically in and near oxbow lakes, which can effectively enhance the natural attenuation of nitrate before the groundwater discharges to nearby streams. This study also demonstrates the usefulness of multivariate statistical analysis in groundwater study as a supplementary tool for interpretation of complex hydrochemical data sets.
authors.affiliation: Department of Earth and Environmental Sciences and the Environmental Geosphere Research Lab (EGRL), Korea University, Seoul 136-701, Republic of Korea.
authors.forename: Kyoung-Ho
authors.initials: KH
authors.lastname: Kim
authors.forename: Seong-Taek
authors.initials: ST
authors.lastname: Yun
authors.forename: Byoung-Young
authors.initials: BY
authors.lastname: Choi
authors.forename: Gi-Tak
authors.initials: GT
authors.lastname: Chae
authors.forename: Yongsung
authors.initials: Y
authors.lastname: Joo
authors.forename: Kangjoo
authors.initials: K
authors.lastname: Kim
authors.forename: Hyoung-Soo
authors.initials: HS
authors.lastname: Kim
mesh_terms: D004784:Environmental Monitoring / Q000379:methods; D005618:Fresh Water / Q000737:chemistry*; D007723:Korea; D015233:Models, Statistical; D009566:Nitrates / Q000737:chemistry*; D014872:Water Movements; D014874:Water Pollutants, Chemical
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical