Evaluation of the processes affecting vertical water chemistry in an alluvial aquifer of Mankyeong Watershed, Korea, using multivariate statistical analyses

• Published in: Environmental earth sciences 2008-03, Vol.54 (2), p.335-345
• Main Authors: Choi, Byoung-Young, Kim, Hyeon-Jung, Kim, Kangjoo, Kim, Seok-Hwi, Jeong, Hwa-Jin, Park, Eungyu, Yun, Seong-Taek
• Format: Article
• Language: English
• Subjects: Alluvial aquifers; Alluvial groundwater; Aquifers; Chemical analysis; Chemical speciation; cluster analysis; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Exact sciences and technology; Factor analysis; Geochemistry; Geology; Groundwater; Hydrogeology; Hydrology. Hydrogeology; Iron sulfides; Mankyeong watershed; Mineralogy; Original Article; Redox reaction; Redox reactions; Samplers; Seawater; Silicates; Statistical analysis; Sulfate reduction; Water analysis; Water chemistry; Water geochemistry; Water quality; Water resources; Water sampling; Watersheds
• ISSN: 0943-0105; 1866-6280; 1432-0495; 1866-6299
• DOI: 10.1007/s00254-007-0820-9

Vertical variations of redox chemistry and groundwater quality were investigated in an alluvial aquifer beneath an agricultural area, in which deep groundwaters are free of NO₃, Fe, and Mn problems that are frequently encountered during the development of alluvial groundwaters. This study was performed to identify and evaluate vertical chemical processes attenuating these chemical species in the study area. For this study, the processes affecting groundwater chemistry were identified by factor analysis (FA) and the groundwater samples collected from six multilevel samplers were hierarchically classified into three different redox zones by cluster analysis (CA) based on the similarity of geochemical features. FA results indicated three major factors affecting the overall water chemistry: agricultural activities (factor 1), redox reactions (factor 2), and remnant seawater (factor 3). The groundwater quality in the study area was revealed to be controlled by a series of different redox reactions, resulting in different redox zones as a function of depth. It was also revealed that the low Fe and Mn levels in the groundwater of the deeper part are associated with sulfate reduction, which led to precipitation of Fe as iron sulfide and adsorption of Mn on it.