Estimation of atmospheric carbon sequestration rate through carbonate rock dissolution in Karst Jonggrangan, Java Island, Indonesia (case study: the underground river of Anjani Cave)

Abstract

Karst has an important role in atmospheric CO2 sequestration through the karstification process. Through the karstification process, the total amount of carbon dioxide absorbed in Indonesia is estimated to reach 13482 Gg CO2/year. This research was conducted in the Karst Jonggrangan area, focused on the underground river of Anjani cave. The objectives of this study were: (1) to determine how much the dissolution rate of CaCO3 minerals was, and (2) to calculate the atmospheric carbon sequestration rate through the carbonate dissolution process that occurred in the Anjani underground river. This research was carried out between March 2018 and March 2019. The data used were time-series of discharge and hydrochemical data, as well as discharge properties of the Anjani underground river. The entire data was obtained through the installation of a water fluctuation recording device and field measurement of hydrochemical parameters and the discharge characteristics. The results showed that the rate of carbonate rock dissolution in Anjani underground river was 37.54 m3/year/km2, while the sequestration rate of atmospheric carbon dioxide reached 97.43 tons/km2/year. The temporal variation in carbon dioxide absorption and dissolution rates was influenced by total discharge, dissolved CO2, and HCO3 − content in the water, temperature, and pH.