| 斯洛文尼亚岩溶区草地生长季土壤CO2变化及其降雨效应 |
| 投稿时间：2023-12-14 修订日期：2024-02-28 点此下载全文 |
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| 基金项目:国家重点研发计划项目(编号: 2020YFE0204700)、国家自然科学基金项目(编号: 42261144672) |
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| 中文摘要:土壤CO2是岩溶作用的核心驱动因子，也是研究土壤呼吸及其与大气CO2源汇关系的核心指标。快速的岩溶动力学和碳循环过程及其对生态系统的敏感性，暗示其在现今全球碳循环中仍在发挥积极作用。本文以斯洛文尼亚第纳尔岩溶区典型草地土壤生态系统为例，开展不同深度土壤温度、水分和土壤CO2含量等指标高分辨率在线监测。监测工作在2021年6-9月草地生长季进行，每10 min记录一组数据。结果表明，土下20cm、30cm和50cm土温均值分别为19.69?C、18.54?C和17.42?C，暗示土温随深度增加逐渐变小。土下20cm、30cm和50cm水分含量均值分别为23.2%、21.7%和24.9 %。土壤水分变化主要受降雨控制，降雨强度越大，水分上升幅度越大。土下20cm、30cm和50cm土壤CO2变化范围分别为1884-6705 ppm、2088-5516ppm、2771-3606ppm，均值分别为3578ppm、3468ppm、3174ppm。无雨期间土壤水分显示出白天下降，夜晚基本保持不变的阶梯状下降趋势，受土壤水分控制，土壤CO2多日总体变化呈现锯齿状持续降低趋势。不同降雨条件下均出现土壤CO2向下迁移现象，从强降雨过程初期产生的土壤CO2含量快速下降看，表明雨水入渗产生的脉冲效应导致CO2快速向下迁移，进一步进入下伏岩溶含水层，可为碳酸盐岩溶蚀提供CO2驱动力，比较下降幅度与雨前CO2含量，暗示降雨过程中12%-33%的土壤CO2进入岩溶含水层并参与碳酸盐岩溶蚀。监测结果暗示岩溶作用是陆地生态系统碳循环的横向延伸，具有土壤CO2汇效应，也就是说，岩溶作用过程具有缓解土壤CO2向大气释放功能，即减源效应。因此，在研究岩溶区碳循环及其碳汇效应时，应把植被-土壤-碳酸盐岩溶蚀作为一个整体，从岩溶关键带角度，系统开展监测与研究，以期获得岩溶区碳循环过程的完整认识，揭示其碳汇效应，进一步评估岩溶区碳循环在全球碳循环的作用和应对气候变化中的地位。 |
| 中文关键词:土壤CO2，土壤水分，降雨过程，岩溶作用，减源效应，斯洛文尼亚 |
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| Soil CO2 change and rainfall effect in growing season in a karst grassland of Slovenia |
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| Abstract:Soil CO2 is a critical driving factor for karst processes and the core index for studying soil respiration and its relationship with atmospheric CO2 source-sink. The rapid dissolution kinetics of karst carbon cycle and its sensitivity to ecosystem suggest that karst carbon cycle is still playing an active role in the global carbon cycle. Taking the typical grassland soil ecosystem in Dinar karst, Slovenia as an example, high-resolution online monitoring of soil temperature, water content and soil CO2 concentration at different depths was carried out during the growing season from June to September in year 2021, the data were recorded in 10-minute time interval. Results showed that mean soil temperatures at depths of 20cm, 30cm and 50cm are 19.69?C, 18.54?C and 17.42?C respectively, implying soil temperature decreases gradually with increase of soil depth. Mean soil water contents at depths of 20cm, 30cm and 50cm are 23.2%, 21.7% and 24.9 % respectively. Soil moisture mainly was controlled by precipitation, i. e. the greater the rainfall intensity, the larger the moisture rises. The ranges of soil CO2 concentrations at depths of 20cm, 30cm and 50cm are 1884-6705 ppm, 2088-5516ppm and 2771-3606ppm respectively, with mean value of 3578ppm, 3468ppm and 3174ppm respectively. During the no-rain days, soil moisture presents a tendency of stair-stepped down, with decrease in day time and basically remain unchanged at night, and controlled by soil moisture, the multi-day changes of soil CO2 showed a jagged falling constantly. Soil CO2 down movement is observed during different rainfall conditions, soil CO2 concentration drops rapidly at the early stage of storm events, suggesting that pulse effect cause by rainfall infiltration is the main controlling factor to push CO2 move down quickly and enter to the underlying karst aquifer furtherly, thus providing critical driving force for carbonate rock dissolution. The value difference of CO2 decrease range and the pre-rain CO2 content suggested that 12%-33% of soil CO2 transported to karst aquifer and were involved in carbonate rock dissolution during the rainfall events. The monitoring results suggest that karst process is a lateral extension of carbon cycle in terrestrial ecosystems in karst area and has soil CO2 sink effect. It means that karst process has the function of alleviating the release of soil CO2 to the atmosphere, i.e. source reduction effect. Accordingly, Vegetation-soil-carbonate dissolution should be considered as a whole for studying the carbon cycle and carbon sink effect in karst area. Systematic monitoring and research should be carried out from the perspective of karst critical zone, so as to obtain a complete understanding of carbon cycle processes in karst area and reveal their carbon sink effects, thus further evaluating the role of karst carbon cycle in global carbon cycle and in coping with climate change as well. |
| keywords:Soil CO2,Soil moisture,Rainfall process,Karst processes,Source reduction effect,Slovenia |
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