[AHW20-P16] A preliminary study of redox conditions of groundwater in the coastal area of Indramayu, Indonesia
Keywords:coastal area, groundwater, redox conditions, sulfate reduction
The Cl⁄Br ratio of samples from the groundwater demonstrates rising salinity due to f seawater intrusion. The mixing ratio of seawater and groundwater was evaluated by setting the Cl- concentration of seawater to 19500 ppm and that of the unaffected groundwater to 16 ppm, with a maximum mixing ratio of 62%. The SO42- concentration of the groundwater affected by seawater was calculated and compared to the measured value. A measured SO42- concentration lower than the calculated value was associated with sulfate reduction and vice versa. Sulfate showed weak correlations with the DOC, Fe and Mn concentrations of the groundwater. Sulfate reduction showed a strong correlation to the sampling depth, with no reduction at depths below 20 m. Further work is required to better understand the relationship between the measured and the calculated SO42- concentrations, as well as the geology of the region.