| Abstrak/Abstract |
The EC distribution throughout the study area, are lower than permissible limit, especially in the southern part of the study area. EC values gradually increase to the northern part but there are still the values in acceptable range. The bad groundwater quality can mostly be found in central part because high concentrations of EC and subsequently TDS cover in this area. The concentrations of both parameters are locally higher than acceptable range of WHO guidelines. The high conductivity values are found with high salt concentration in a little area away from the shore line. Therefore main problem of the study area is locally the groundwater salinity in some places. The objectives of this research are needed to get more detailed data for mineralogy and the content of ions in water, and the characteristics of hydrochemical processes in coastal aquifer system. Therefore the determination of the origin of water salinity and groundwater mineralization from aquifer is the main goal of this research. To identify the major processes activated for controlling the groundwater chemistry an attempt had been made by collection a total of 27 water samples from every point by groundwater analysis and mineralogical investigation were conducted. The main sources of salinity are related to the dissolution of minerals by Gibbs plot, and cation exchange. Weathering of silicate minerals controls the major ion chemistry of Ca2+, Mg2+, Na+ and K+. Cl- ion is dominant due to the dissolution of halite (NaCl) and apatite (Ca5 (PO4)3Cl). HCO3 comes from the dominant effect of silicate weathering. The main water types are Ca-HCO3 and Na-Cl as secondary type. The results from XRD analysis match with water types. In most of water samples, Na/Cl ratio is >1. In addition, the decreasing trend with an increase in Cl- ion as ion exchange process. The result of Br/Cl versus Cl fell in mineralized salinity group. In Simpson ratio had been calculated that 70% of water samples are fresh water types, while 15 % of water are moderately contaminated and remaining 15% are injuriously contaminated water types. In general, water chemistry is guided by weathering process (ion exchange) with the influence of Cl ions of the study area. |
