环境地球化学国家重点实验室知识库

Carbonate rock chemical weathering carbon sinks reduce the rate of increase of the atmospheric CO₂ concentration and global warming. However, uncertainty still exists in the estimation results of carbonate rock chemical weathering carbon sink fluxes (CCSF), and the contributions of climate change and ecological restoration to the CCSF are not clear. To this end, we compiled published site data on ion concentrations in different watersheds in China and used a classical thermodynamic dissolution model to reassess the potential and spatial and temporal patterns of the CCSF in China from 1991 to 2020. We quantified the contributions of temperature (MAT), precipitation (MAP), evapotranspiration (ET), soil water (SM), and the normalized difference vegetation index (NDVI) to the CCSF. The results revealed that (1) China’s CCSF was 22.76 t CO₂ km⁻² yr⁻¹, which was higher than the global average (15.771CO₂ km⁻² yr⁻¹). The total carbonate rock chemical weathering carbon sink (CCS) was 4772.67×10⁴ t CO₂, contributing 14.91% of the global CCS through a carbonate rock area of 252.98×10⁴ km⁻². (2) China’s CCSF decreased gradually from southeast to northwest, with values of 33.14, 12.93, and 7.27 t CO₂ km⁻² yr⁻¹ in the southern karst, Qinghai-Tibetan karst, and northern karst regions, respectively. (3) The overall CCSF in China exhibited an increasing trend from 1991 to 2020, with a rate of increase of 0.16 t CO₂ km⁻² yr⁻¹. (4) The contributions of the MAP, MAT, ET, SM, and NDVI to the CCSF were 63.3%, 3.02%, 27.5%, 3.1%, and 3.05%, respectively. Among them, the increase in precipitation was the main contributor to the increase in the CCSF in China over the last 30 years, while the enhancement of ET offset part of the positive contribution of the increase in precipitation to the CCSF. In conclusion, the results of this study provide a systematic quantification of the magnitude, the patterns, and the influencing factors of CCS over a long time series in China. The results are of great significance and provide a reference for the diagnosis and gap analysis of the national and global carbon neutrality capacities.