中国岩溶2026，Vol.45Issue(3)：525-538,14.DOI:10.11932/karst2026y016
广西岩溶区2002-2022年岩溶无机碳汇时空分布特征与控制机制
Spatial and temporal distribution characteristics and control mechanisms of the karst inorganic carbon sink in the Guangxi karst region from 2002 to 2022
摘要
Abstract
Carbonate rock chemical weathering is a fundamental yet complex process within the global carbon cycle and constitutes an important long-term sink for atmospheric carbon dioxide(CO2).During carbonate dissolution,CO2 derived from the atmosphere and/or soil is consumed and transformed into Dissolved Inorganic Carbon(DIC),predominantly in the form of bicarbonate(HCO3-).This DIC is subsequently transported downstream through groundwater and surface runoff systems and may ultimately be stored in the ocean over long timescales.Because this process reduces atmospheric CO2 concentrations and,to some extent,mitigates the release of soil carbon to the atmosphere,carbonate weathering is widely regarded as an important natural mechanism for buffering anthropogenic climate warming.However,the magnitude of karst inorganic carbon sinks at the regional scale remains highly uncertain.This uncertainty is particularly pronounced in extensive karst regions,where strong spatial heterogeneity in lithological conditions,aquifer connectivity,recharge processes,and land-surface environments makes it difficult to upscale point-based hydrochemical observations to the regional level.Consequently,significant discrepancies persist in regional estimates of karst carbon sinks,and the relative contributions of climatic and environmental factors to DIC production and export have yet to be fully resolved.The Guangxi Zhuang Autonomous Region,located in southern China,is one of the most extensive and representative karst regions in the country.It is characterized by widespread carbonate rock outcrops,well-developed epikarst and subsurface drainage systems,and hydrogeochemical processes that are highly sensitive to monsoonal climatic forcing.The region has a subtropical humid monsoon climate,abundant precipitation,and diverse geomorphological settings,all of which provide favorable conditions for carbonate weathering and dissolved carbon export.At the same time,Guangxi exhibits marked regional variability in climate,hydrology,topography,and karst development,making it an ideal study area for reassessing karst inorganic carbon sinks and exploring their controlling mechanisms at the regional scale.Against this background,the present study systematically re-evaluates the karst inorganic carbon sink in Guangxi from 2002 to 2022 and employs the Geodetector model to investigate its controlling factors. This study employs multidisciplinary methodology,integrating field observations,remote sensing data,machine learning modeling,and spatial attribution analysis.First,in consideration of the geological and hydrogeological setting of the karst region in Guangxi,a relatively large dataset of measured groundwater DIC concentrations was compiled.High-resolution remote sensing data were also selected to characterize environmental conditions relevant to karst carbon processes.Based on these multi-source datasets,machine learning models were trained and validated to reconstruct the spatiotemporal distribution of DIC concentrations in karst groundwater across Guangxi from 2002 to 2022.Compared with conventional point-based observational approaches,this method enhances the regional representativeness of the estimates and helps compensate for the limited spatial and temporal coverage of measured data.Additionally,the incorporation of remotely sensed variables provides feasible proxy indicators for certain environmental conditions that are challenging to monitor continuously over extended periods.Second,the reconstructed DIC concentration fields were combined with long-term discharge data,and the karst inorganic carbon sink generated by carbonate weathering was recalculated using the classical and widely applied hydrochemical flux method,thereby providing a more accurate representation of both temporal fluctuations and spatial variability in dissolved carbon export.Finally,the Geodetector model was employed to quantify the explanatory power of potential influencing factors through both factor detection and interaction detection,with the aim of identifying the dominant controls on the spatial differentiation of the karst carbon sink in Guangxi. The results show that:(1)From 2002 to 2022,the cumulative karst inorganic carbon sink in Guangxi reached 5.03× 107 tCO2,with an annual average of 2.40 × 106 tCO2·a-1.(2)Interannual variability in the karst inorganic carbon sink was pronounced,with a marked increasing trend from 2003 to 2006,followed by an overall fluctuating upward trend thereafter.The maximum annual sink occurred in 2008,reaching 3.56×106 tCO2·a-1,whereas the minimum was recorded in 2009 at 1.44×106 tCO2·a-1,the former being approximately 2.5 times the latter.(3)The mean karst inorganic carbon sink intensity during the study period was 30.24 tCO2·km-2·a-1,with clear spatial heterogeneity.Higher values were mainly concentrated in central and northeastern Guangxi,whereas lower values occurred in the southwestern and southeastern parts of the region.(4)Geodetector analysis indicates that precipitation is the primary factor controlling the spatiotemporal variation of the karst inorganic carbon sink in Guangxi,consistent with the strong dependence of karst process on water availability.Further interaction detection reveals that the explanatory power of the interaction between any two factors is greater than that of any single factor,indicating that the formation and differentiation of the karst carbon sink exhibit significant nonlinear coupling characteristics.Among these interactions,the interaction between temperature and precipitation shows the highest explanatory power.关键词
岩溶无机碳汇评估/水化学径流法/地理探测器/时空分布/影响机制Key words
assessment of karst inorganic carbon sink/hydrochemical runoff method/geographical detector/spatial and temporal distribution/influence mechanism分类
天文与地球科学引用本文复制引用
田换杰,肖琼,孙平安,陈发家,张馨瑶..广西岩溶区2002-2022年岩溶无机碳汇时空分布特征与控制机制[J].中国岩溶,2026,45(3):525-538,14.基金项目
国家自然科学基金项目(42377069) （42377069）
广西重点研发计划项目(桂科AB25069498) （桂科AB25069498）
中国地质调查项目(DD20230547) （DD20230547）
中国-斯洛文尼亚岩溶地质"一带一路"联合实验室建设运行项目(YRPT2025021) （YRPT2025021）
山东省岩溶碳汇调查评价与监测试点项目(鲁勘字[2024]21号) （鲁勘字[2024]21号）
