| 桂林凉风洞洞穴系统垂向碳迁移特征及其影响因素 |
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| 引用本文： | 丁梦凯,吴夏,曹建华,胡晓农,潘谋成,黄芬,任梦梦.桂林凉风洞洞穴系统垂向碳迁移特征及其影响因素[J].中国岩溶,2021,40(4):600-607. |
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| 作者姓名： | 丁梦凯 吴夏 曹建华 胡晓农 潘谋成 黄芬 任梦梦 |
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| 作者单位： | 1.北京师范大学地理科学学部自然资源学院/中国地质科学院岩溶地质研究所/自然资源部、广西岩溶动力学重点实验室 |
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| 基金项目： | 国家自然科学基金项目（41701235，41530316，41501222）；广西自然科学基金项目（2018GXNSFAA281320；2018GXNSFBA138042；2018GXNSFBA050004）；广西重大科技创新基地建设项目（2018-242-Z01）；中国地质科学院基本科研业务费（2020006） |
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| 摘 要： | 2017年11月至2018年11月，以桂林毛村凉风洞为研究对象，进行大气环境和洞穴环境野外监测，同时在洞穴上覆土壤30 cm和60 cm处开展试片溶蚀实验，并在洞穴内部进行试片溶蚀和滴水脱气监测，以测定垂向碳迁移主要过程中的CO2浓度和δ13C-CO2值。结果表明:（1）“大气—土壤—洞穴”垂向碳迁移系统能够与洞穴通风一起影响洞穴系统内部的CO2分布模式。洞口通风方向的转变取决于洞内温度与外界温度的差异，少雨的11月中旬到次年3月初通风方向为从洞外到洞内，此时垂向碳迁移能力弱，洞内CO2的分布由洞口通风主导；3月初至9月中旬，洞内外温差逐渐过渡并反转，洞口通风方向为从内向外，且降雨强度大，垂向碳迁移活跃并主导洞内CO2分布；（2）岩溶关键带土壤呼吸的强度决定了垂向碳迁移系统可迁移的碳量，洞内CO2分布的季节性变异本质上是外界环境在垂向碳迁移系统和洞穴模式上的响应；（3）洞穴上覆碳酸盐岩土下溶蚀实验表明土下溶蚀可削弱土壤碳源作用。土壤30 cm和60 cm处碳酸盐岩溶蚀速率分别为:0.48 mol?m-2?a-1和0.96 mol?m-2?a-1，而洞穴第一洞厅监测点的碳酸盐岩脱气速率为49.35 mol?m-2?a-1、第二洞厅内为9.07 mol?m-2?a-1，由垂向碳迁移系统运移到洞穴内部的溶解了土壤CO2的滴水脱气作用显著。
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| 关 键 词： | 开放型洞穴系统 垂向碳迁移 洞内温度 大气降水 岩溶关键带 通风模式 |
Characteristics and influencing factors of vertical carbon migration in the cave system of Liangfeng cave in Guilin |
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| DING Mengkai,WU Xi,CAO Jianhu,HU Xiaonong,PAN Moucheng,HUANG Fen,REN Mengmeng.Characteristics and influencing factors of vertical carbon migration in the cave system of Liangfeng cave in Guilin[J].Carsologica Sinica,2021,40(4):600-607. |
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| Authors: | DING Mengkai WU Xi CAO Jianhu HU Xiaonong PAN Moucheng HUANG Fen REN Mengmeng |
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| Institution: | 1.College of Natural Resources， Faculty of Geographical Science， Beijing Normal University/Institute of Karst Geology，CAGS/Key Laboratory of Karst Dynamics，MNR&GZAR2.Institute of Karst Geology，CAGS/Key Laboratory of Karst Dynamics，MNR&GZAR3.Institute of Groundwater and Earth Sciences， Jinan University |
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| Abstract: | In order to study the characteristics of vertical carbon migration in open karst cave system and its influencing factors. From November 2017 to November 2018， taking Liangfeng cave in the underground river basin of Maocun village， Guilin as the research object，we conducted real-time monitoring of the atmospheric environment and cave environment in the field. At the same time, a test piece dissolution experiment was carried out at 30 cm and 60 cm of the cave overlying soil ，and the test piece dissolution and drip degassing monitoring were carried out simultaneously in the cave so as to measure the CO2 concentration and δ13C—CO2 value in the main process of vertical carbon migration.The results show，（1）The "atmosphere-soil-cave" vertical carbon migration system can affect the CO2 distribution pattern inside the cave system together with cave ventilation. The change of the ventilation direction of the cave depends on the temperature difference between the inside and outside of the cave.The ventilation direction in the cold season with little rain was from outside the cave to the inside of the cave. At this time， the vertical carbon migration ability was weak， and the distribution of CO2 inside cave was dominated by the ventilation of cave entrance. From early March to mid-September， the temperature difference between inside and outside of the cave gradually transitioned and reversed. The ventilation direction of the cave entrance was from the inside to the outside， with high rainfall intensity. The vertical carbon migration was active and dominated the CO2 distribution in the cave； （2） The intensity of soil respiration in the karst critical zone determines the amount of carbon that can be transferred by the vertical carbon migration system. The seasonal variation of CO2 distribution in the cave was essentially the response of the external environment to the vertical carbon migration system and cave ventilation； （3） The dissolution experiment of carbonate rock on the overlying roof of the cave shows that the dissolution under the soil can weaken the role of soil carbon source. The dissolution rate of carbonate rock at 30 cm and 60 cm of soil are 0.48 mol·m-2·a-1 and 0.96 mol·m-2·a-1， respectively； while the carbonate rock precipitation-degassing rate at the monitoring point of the first cave hall was 49.35 mol·m-2·a-1 and 9.07 mol·m-2·a-1 in the second cave hall. The drip degrassing of dissolved soil CO2 transported by the vertical carbon migration system to the inside of the cave was significantly. |
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