岩溶区石漠化土壤CO2浓度和地表CO2通量研究

Study on Soil CO2 Concentration and Surface CO2 Flux in Karst Rocky Desertification Area

【目的】探讨我国南方喀斯特石漠化地区CO2浓度分布和时空排放规律及岩区土壤有机碳含量、土壤温度及土壤含水率等环境因子对CO2浓度及释放速率的影响。【方法】采用静态密闭箱-气相色谱法,对2017年1~12月重庆市南川石漠化治理示范区岩溶碳汇试验区坡改梯及对照区非坡改梯的土壤CO2浓度和地表CO2通量进行原位监测。【结果】非坡改梯地区土壤CO2浓度比坡改梯地区大,坡改梯和非坡改梯地区土壤CO2浓度大多数随着土壤深度增加呈下降趋势;非坡改梯地区地表CO2释放通量高于坡改梯地区;土壤CO2浓度及释放通量均随季节有明显变化,在一定范围内土壤温度及土壤含水率都与地表CO2释放通量呈显著正相关关系,在个别月份出现显著变化,表现为巨大的源与汇。【结论】土壤CO2浓度主要受土壤有机碳、土壤温度、土壤含水率、土壤微生物及人为因素共同影响,地表CO2通量变化与植被覆盖、人类活动及土壤CO2浓度密切相关。

【Objective】This paper aimed to investigate the distribution of CO2 concentration and its temporal and spatial emission laws in karst rocky desertification areas in southern China, and to explore the effects of environmental factors such as soil organic carbon content, soil temperature and soil water content on CO2 concentration and release rate in karst areas.【Method】The Static sealed chamber-gas chromatography method was used to monitor in situ the soil CO2 concentration and the surface CO2 flux in the terraced karst carbon sink experimental area and in the non-terraced karst carbon sink control area respectively in Nanchuan Rocky Desertification Control Demonstration Area in Chongqing from January to December of 2017.【Result】The soil CO2 concentration in the non-terraced area was higher than that in the terraced area, and the soil CO2 concentration in terraced area and non-terraced area decreased with the increase of soil depth;the surface CO2 emission flux in non-terraced area was higher than that in terraced area;both the soil CO2 concentration and the emission flux changed significantly with seasons. The soil temperature and soil water content showed significant positive correlations with the surface CO2 emission flux to some extent, and obvious changes occurred in some months, shown as huge sources and sinks.【Conclusion】Soil CO2 concentration is jointly affected by soil organic carbon, soil temperature, soil water content, soil microorganisms and human factors while the surface CO2 flux is closely related to vegetation coverage, human activities and soil CO2 concentration.