地质科技通报 (Mar 2024)
Estimation of karst carbon sinks and analysis of their driving factors in Hubei Province from 2019 to 2021
Abstract
Objective Carbonate rocks have a significant carbon sink effect in water cycle. Since karst landforms are widely distributed in China, research on the potential of karst carbon sinks plays an important role in formulating regional strategies for increasing carbon sinks. Methods In this study, groundwater monitoring points in Hubei Province, which is located in the karst area of Southwest China, were selected. Quantitative calculations and method comparisons were performed based on the hydrochemical runoff method and the infiltration-equilibrium chemistry method. The spatial pattern and magnitude of karst carbon sinks in the hilly mountains of Hubei Province from 2019 to 2021 were evaluated via ArcGIS spatial analysis techniques. Additionally, the most suitable method for estimating karst carbon sinks at the regional scale were explored, the comprehensive analysis of the drivers of karst carbon sinks was performed, and the potential for increasing sinks were explored. Results The results showed that: (1) the intensity of carbon sinks estimated by the infiltration-equilibrium chemistry method were 2020>2019>2021. The total amount of karst carbon sinks in wet year (2020) was approximately 6 times of that in dry year (2019). The average annual carbon sink intensity in the three years was 12.84 t/(km2·a) and the annual total amount of carbon reached 163.89×104 t/a; (2) the infiltration-equilibrium chemistry method was more accurate in calculation results and simpler in data acquisition than the hydrochemical runoff method, and had a certain universality at both large and small spatial scales; (3) the change in carbon sinks was highly dynamic. The extent of changes in carbon sinks under climate change was mainly determined by runoff depth, with the intensity of carbon sinks increasing with runoff depth, while land use regulated the intensity of carbon sinks in karst processes; and (4) the karstification is strong in southwestern Hubei Province, so a pilot field of karst carbon sinks could be established within the area to quantitatively evaluate artificial interventions to increase carbon sinks. Conclusion This study not only provides an accurate and easy-to-use method for estimating karst carbon sinks, but also determines the magnitude and spatial pattern of karst carbon sinks in Hubei Province and figures out the coupling effect of the driving factors of carbon sink intensity, which demonstrates the complexity and anthropogenic control lability of karst carbon sinks. The results of this study provides a reliable scientific basis for the formulation of environmental protection policies and artificial sink increase measures.
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