REACTIVE PRECIPITATES CONTROLLING THE GROUNDWATER CHEMICAL COMPOSITION OF THE GROUNDWATER OF BIODIVERSITY EXPERIMENT FIELD

We used hydrogeochemical modeling using PHREEQC2.16.03 (Pankhurst & Appelo, 2009) to interpret the possible reactive precipitates in the groundwater. The package is designed to perform a wide variety of low temperature aqueous geochemical calculations based on an ion-association aqueous model. We measured the chemical composition (major cations and anions, trace elements, rare earth elements, and all physico-chemical composition) of the groundwater in all season of the year. The results of the PHREEQC are validated by X-ray diffraction. The hydrogeochemical modeling by using PHREEQC shows that calcite (CaCO3), dolomite (CaMg (CO3)2), quartz (SiO2), and siderite (FeCO3) are the reactive precipitates in the study area. We also interpreted which form of the ion is significant at different time from speciation result. We also found these minerals by using x-ray diffraction. Seasonal changes also resulted in changed in reactivity of the minerals as the environmental conditions (pH, redox potential and temperature) are changing. We have also characterized the spatial variation of the groundwater in terms of these minerals and chemical composition. The result of this work is important to study the element cycling in the ecosystem process of the experiment field.