LEI Junhao1,2, DONG Shaogang1,2, ZHANG Min1, GAO Donghui3, FENG Yanbo1, WANG Kun1
(1.School of Ecology and Environment, Inner Mongolia University, Hohhot 010021,China;
2.Inner Mongolia Key Laboratory of River and Lake Ecology, Hohhot 010021, China;
3.Inner Mongolia Academy of Ecological and Environmental Sciences, Hohhot 010021, China)
Abstract：Groundwater has an important impact on the global carbon cycle because of its wide distribution, huge water volume and high DIC content. However, the carbon cycle in groundwater mainly focuses on its discharge to surface water, and there are few reports on the migration and transformation processes of carbon in the whole groundwater system. To explore the role of groundwater system in the global carbon budget, taking the Hongjiannao basin as an example, this study constructs the carbon balance equation of groundwater system by using the principle of mass conservation and hydrogeochemical simulation method to analyze the supplement and discharge of carbon in groundwater. The results show that the groundwater system in Hongjiannao basin belongs to "carbon sink" with an annual carbon sink of 661.19-805.33t. Among them, the dissolution(dolomite)-precipitation(calcite) of carbonate rock is the main hydrochemical process affecting the carbon balance of groundwater; HCO3- in atmospheric precipitation and CO2 in vadose zone are the main recharge sources of DIC in groundwater in this area. According to the calculation result, the annual amount of carbon entering groundwater by water-rock interaction process is 451.05t; The total carbon content of groundwater recharge through precipitation infiltration, lateral recharge and farmland irrigation is 952.47-1039.24t; The amount of carbon discharged through drainage to lakes and groundwater exploitation is 684.96-742.36t.
Key words：water-rock interaction; groundwater; carbon balance; carbon cycle; carbon dioxide; Hongjiannao basin
EARTH AND ENVIRONMENT Vol.51, No.1, Tot No.351, 2023, Page 47
