| 喀斯特关键带水—土—气CO2分压垂直转化特征及影响因素 |
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| 引用本文： | 汪炎林,周忠发,薛冰清,李坡,田衷珲,张结,汤云涛.喀斯特关键带水—土—气CO2分压垂直转化特征及影响因素[J].地理学报,2020,75(5):1008-1021. |
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| 作者姓名： | 汪炎林 周忠发 薛冰清 李坡 田衷珲 张结 汤云涛 |
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| 作者单位： | 1.贵州师范大学 喀斯特研究院/地理与环境科学学院,贵阳 5500012.贵州省喀斯特山地生态环境国家重点实验室培育基地,贵阳 5500013.国家喀斯特石漠化防治工程技术研究中心,贵阳 5500014.贵州省喀斯特洞穴（旅游）资源开发利用工程技术研究中心,贵阳 550001 |
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| 基金项目： | 国家自然科学基金项目(41361081);国家自然科学基金项目(41661088);贵州师范大学博士科研项目(GZNUD[2017]6号);贵州省高层次创新型人才培养计划(黔科合平台人才)(2016-5674);国家遥感中心贵州分部平台建设(黔科合Z字)(2012-4003) |
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| 摘 要： | 喀斯特关键带是碳循环在岩石圈、大气圈、水圈和生物圈的主要综合作用区域,各层相互作用形成不同的反应体系,其中,CO2扮演了十分重要的作用。通过对双河洞洞穴上覆土壤及洞穴水及空气CO2浓度的监测,采用数理统计分析方法,根据碳酸平衡系统理论对CO2的垂直向转化特征进行系统分析。结果表明：CO2的垂直向转化过程受洞穴内外部气温变化、滴水pH及脱气沉积过程的影响,其供给来源、离子饱和状况在雨季和旱季存在明显差异;雨季时,大气降水在土壤中下渗速度较快,构成一个相对稳定的封闭环境,土壤、表层喀斯特带对渗透水CO2补充作用较弱,渗透水中CO2分压（即PCO2）变化范围在0.035~0.126 vol%,洞内水—气CO2分压（△lg PCO2 > 0）,洞穴水具有溶蚀性,此时表层喀斯特带下部中的CO2应为洞穴水CO2的主要来源;旱季时,由于降水量较小,渗透水有充分时间接受土壤与表层喀斯特带CO2补充,构成开放系统,渗透水变化范围为0.038 vol%~0.095 vol%,更有利于发生先期沉积过程（PCP）,此时洞内空气PCO2小于洞穴水（△lg PCO2 < 0）,促使滴水在洞内再次发生沉积、形成沉积物,此时土壤和表层喀斯特带均为洞穴水CO2的主要来源。
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| 关 键 词： | 喀斯特关键带 垂直转化 水—土—气PCO2 CO2来源 双河洞系 |
| 收稿时间： | 2018-12-04 |
| 修稿时间： | 2020-03-03 |
The vertical conversion characteristics and influence of the partial pressure of CO2 in the water-soil-atmosphere of critical karst zone |
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| WANG Yanlin,ZHOU Zhongfa,XUE Bingqing,LI Po,TIAN Zhonghui,ZHANG Jie,TANG Yuntao.The vertical conversion characteristics and influence of the partial pressure of CO2 in the water-soil-atmosphere of critical karst zone[J].Acta Geographica Sinica,2020,75(5):1008-1021. |
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| Authors: | WANG Yanlin ZHOU Zhongfa XUE Bingqing LI Po TIAN Zhonghui ZHANG Jie TANG Yuntao |
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| Institution: | 1.School of Karst Science/School of Geography & Environmental Science, Guizhou Normal University, Guiyang 550001, China2.The State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, Guiyang 550001, China3.The State Key Laboratory Incubation Base for Karst Mountain Ecology Environment of Guizhou Province, Guiyang 550001, China4.Guizhou Engineering and Technology Research Center for Development & Utilization of Cave Resources, Guiyang 550001, China |
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| Abstract: | The critical karst zone is the central area with the combined action of the carbon cycle in the lithosphere, atmosphere, hydrosphere, and biosphere, and the interaction among different layers forms distinctive reaction systems, where CO2 plays a vital role. Through monitoring the concentration of CO2 in the overlying soil of Shuanghe cave, cave water, and atmosphere, the vertical conversion characteristics of CO2 were systematically analyzed based on the carbonic acid equilibrium theory by adopting statistical analysis. The results show that the vertical conversion process of CO2 is influenced by the changes in temperature inside and outside the cave, pH value of the dripping water and the process of degassing precipitation, and the source of CO2 and ion saturation conditions, which are significantly different between the rainy and dry seasons. During the rainy season, the infiltration rate of atmospheric precipitation is high in the soil, forming a relatively stable enclosed environmental soil. The surface karst belt has weak activity in complementing CO2 in the infiltration water, and the partial pressure of CO2 (PCO2) in the infiltration water varies in the range of 0.035~0.126 vol%, and the partial pressure of CO2 in the water-atmosphere (△lg PCO2) inside the cave is above 0. The cave water is featured by the corrosion property, and CO2 in the lower part of the surface karst belt is the primary source of CO2 in the cave water, whereas during the dry season, due to a small amount of precipitation, the infiltration water has sufficient time to receive CO2 supplement from the soil and surface karst belt, forming an open system. The infiltration water changes in the range of 0.038~0.129 vol%, which is more conducive to the occurrence of the prior calcite precipitation (PCP). At this time, PCO2 in the atmosphere inside the cave is smaller than that in cave water (△lg PCO2 < 0), prompting the recurrence of degassing precipitation inside the cave. Also, both the soil and surface karst belt are the major sources of CO2 in the cave water. |
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| Keywords: | karst critical zone vertical conversion water-soil-atmosphere PCO2 source of CO2 Shuanghe cave system |
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