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Spatial Characteristics of Coastal Groundwater in Padang City Based on Stable Isotope Analysis 180 and 2H
Last modified: 2022-12-22
Abstract
The development of the city of Padang in the coastal area has a vulnerability to the potential for sea water intrusion. This study was conducted to determine the characteristics of shallow groundwater on the coast of Padang City using the stable isotope approach of oxygen -18(18O) and hydrogen -2(2H) or deuterium. Both of these isotopes are stable isotopes that are abundant in nature. Water samples were taken at several locations with a depth of 5 m below the ground surface and 1 water sample was taken at sea with an elevation of 0. The average water sample was 270 m from the sea. Water samples were tested with a spectrophotometer instrument. The results of the spectrophotometer test resulted in the isotope ratio in units of per thousand or per mil. Then the results of the isotopes are plotted into a graph of the relative abundances of oxygen (18O) and deuterium (2H). The results of the analysis of the 18O and 2H isotopes showed that 2 water samples tended to be near the meteoric line and 1 water sample interacted or mixed with seawater. The mixing effect is probably caused by evaporation and interaction of rock oxides from the aquifer lithology in the form of loose (sand) deposits. Based on the value of electrical conductivity indicates brackish water.