Abstract
In order to evaluate groundwater quality and geochemical reactions arising from mixing between seawater and dilute groundwater, we performed a hydrochemical investigation of alluvial groundwater in a limestone-rich coastal area of eastern South Korea. Two sites were chosen for comparison: an upstream site and a downstream site. Data of major ion chemistry and ratios of oxygen-hydrogen isotopes (δ18O, δD) revealed different major sources of groundwater salinity: recharge by sea-spray-affected precipitation in the upstream site, and seawater intrusion and diffusion zone fluctuation in the downstream site. The results of geochemical modelling showed that Ca2+ enrichment in the downstream area is caused by calcite dissolution enhanced by the ionic strength increase, as a result of seawater-groundwater mixing under open system conditions with a constant PCO2 value (about 10-1.5 atm). The results show that, for coastal alluvial groundwater residing on limestone, significant hydrochemical change (especially increased hardness) due to calcite dissolution enhanced by seawater mixing should be taken into account for better groundwater management. This process can be effectively evaluated using geochemical modelling.
Original language | English |
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Pages (from-to) | 1672-1683 |
Number of pages | 12 |
Journal | Hydrological Sciences Journal |
Volume | 57 |
Issue number | 8 |
DOIs | |
Publication status | Published - 2012 Nov |
Keywords
- calcite dissolution
- coastal shallow groundwater
- hydrogeochemical modelling
- limestone terrain
- seawater mixing
ASJC Scopus subject areas
- Water Science and Technology