9:15 AM - 9:30 AM
[AHW28-02] Estimation of Carbon Dioxide Fixation by Alkaline Salt Lakes, A Case Study of Boon Tsagaan Lake, Mongolia
Keywords:Alkaline Lake, Carbon Cycle, Carbon Fixation, Mass Blance
Throughout Earth's history, the weathering of rocks has played a role in removing atmospheric CO2. In particular, silicate minerals containing Mg and Ca release divalent cations upon dissolution and have the property of absorbing atmospheric CO2. The absorbed CO2 precipitates as carbonate minerals at the terminus of the watershed (primarily in oceans and lakes), as shown in Equation (1):
CaSiO3+CO2→CaCO3+SiO2 (1)
The amount of CO2 fixed by biologically induced carbonate precipitation through the weathering of silicate minerals in the ocean is estimated to reach 0.13–0.17 Gt/year (Zhang et al., 2021). Considering that annual carbon emissions from human activities are approximately 40 Gt, carbonate precipitation through the rock weathering process in the ocean corresponds to about 0.4% of human-induced carbon emissions. While the formation of carbonate minerals through biological processes in the ocean has been extensively studied, research on carbonate mineral formation and carbon fixation in lakes remains relatively limited.
In the interior of continents, many salt lakes exist that have inflowing rivers but lack outflowing ones. Among these, salt lakes that are not affected by acidic substances tend to become alkaline and are referred to as alkaline salt lakes. In these lakes, salts are supplied from inflowing rivers, but due to the absence of outflowing rivers, water levels are maintained through evaporation, leading to the concentration of salts within the lake. As a result, inorganic mineral formation occurs. Studies by Fukushi et al. (2020) and Zeyen et al. (2021) have shown that the formation of calcium and magnesium carbonate minerals is a widespread phenomenon in alkaline salt lakes in continental interiors. In these lakes, the accumulation of ions from inflowing waters, combined with evaporation-driven concentration, leads to the precipitation of carbonates. Although it is known that CO2 is fixed through the carbonate precipitation process, there has not been sufficient quantitative investigation into the amount of carbonate formed per unit time or its contribution to the global carbon cycle.
This study aims to estimate the amount of CO2 fixed per unit time from a material balance perspective, focusing on Boon Tsagaan Lake (BTS Lake) in Mongolia.
CaSiO3+CO2→CaCO3+SiO2 (1)
The amount of CO2 fixed by biologically induced carbonate precipitation through the weathering of silicate minerals in the ocean is estimated to reach 0.13–0.17 Gt/year (Zhang et al., 2021). Considering that annual carbon emissions from human activities are approximately 40 Gt, carbonate precipitation through the rock weathering process in the ocean corresponds to about 0.4% of human-induced carbon emissions. While the formation of carbonate minerals through biological processes in the ocean has been extensively studied, research on carbonate mineral formation and carbon fixation in lakes remains relatively limited.
In the interior of continents, many salt lakes exist that have inflowing rivers but lack outflowing ones. Among these, salt lakes that are not affected by acidic substances tend to become alkaline and are referred to as alkaline salt lakes. In these lakes, salts are supplied from inflowing rivers, but due to the absence of outflowing rivers, water levels are maintained through evaporation, leading to the concentration of salts within the lake. As a result, inorganic mineral formation occurs. Studies by Fukushi et al. (2020) and Zeyen et al. (2021) have shown that the formation of calcium and magnesium carbonate minerals is a widespread phenomenon in alkaline salt lakes in continental interiors. In these lakes, the accumulation of ions from inflowing waters, combined with evaporation-driven concentration, leads to the precipitation of carbonates. Although it is known that CO2 is fixed through the carbonate precipitation process, there has not been sufficient quantitative investigation into the amount of carbonate formed per unit time or its contribution to the global carbon cycle.
This study aims to estimate the amount of CO2 fixed per unit time from a material balance perspective, focusing on Boon Tsagaan Lake (BTS Lake) in Mongolia.