土地利用对岩溶作用碳汇的影响研究综述

摘要

耦合水生光合作用的岩溶作用碳汇新模式的提出使得碳酸盐岩的风化过程成为寻找“陆地剩余碳汇”(residual land sink)的新方向。传统意义上，碳酸盐岩风化在全球碳循环模型中被认为是未快速响应地表环境变化的地质过程，然而最新一系列研究表明人类土地利用显著改变了这一地质循环过程。文章总结了岩溶作用碳汇对不同土地利用/覆被变化的具体响应，并对其机理进行了系统分析。发现土地利用与覆被变化影响岩溶作用碳循环过程主要源自土壤 CO 2浓度和径流量变化以及外源酸(硝酸和硫酸)的介入。证据显示在土地利用对岩溶作用碳汇的调控中土壤 CO 2浓度与径流量是复杂且相互制约的两个机制，人类活动产生的外源酸干扰在不同层面上的影响也不同。由于地表水生生态系统所产生的内源有机碳(AOC)的巨大稳碳能力(水生碳泵效应)在以往的研究中并没有与碳酸盐岩风化过程相联系，因而其对土地利用变化的响应过程和机理是岩溶碳循环研究的最新方向。基于土地利用调控碳酸盐岩风化过程的复杂性和多样性特点，综合考虑岩溶作用产生的 DIC(溶解无机碳)与 AOC 在不同土地利用情况下的相互关系以及定量分析各环境因素的具体效应成为了合理制定人为土地利用调控策略的必要前提，也是岩溶作用碳汇研究的未来发展方向。%Based on a new conceptual model of carbon cycle induced by the weathering carbonate rocks,the study of karst process is now having a new direction for researchers to find stable carbon sink in terrestrial carbon cycle ecosystem.The carbon cycle produced by the weathering of carbonate rocks used to be consid-ered as an unchanged carbon sink since pre-industrial times in global carbon model.However,a synthesis of recently published work reveals that Land Use/Cover Change (LUCC)due to human activities have altered these carbon fluxes.This paper is intended to review the observations concerning carbonate the response of rock weathering to LUCC,as well as a thorough analysis for their mechanisms.Recent findings show that the impact of LUCC on carbon cycle in karst process is complicated and this cycle is dependent on three as-pects,i.e.soil pCO 2 ,runoff fluctuation and the involvement of some inorganic acids,which may interact each other and control the magnitudes,variations of carbonate rock weathering under various LUCC.The effect of the first two aspects may present negative correlation,and the mechanisms of inorganic acids have different effects in the new model.Meanwhile,previous studies ignored the autochthonous organic carbon (AOC)produced in surface stream ecosystem which has great carbon sequestration capacity.The response process and mechanism to LUCC is a new direction of karst carbon cycle study.However,because of the complexity and diversity of the carbonate rock weathering under LUCC,it is difficult to determine the rela-tionship between DIC and AOC variations in various environmental conditions caused by LUCC.Therefore, how to probe into the mechanism of carbonate rock weathering and to establish a LUCC regulating strategy are important directions of future karst carbon cycle research.