摘要
桂林毛村岩溶地下河流域位于桂林市东南30km的潮田毛村,流域面积约10km^2,为开展岩溶区、碎屑岩区土壤碳迁移对比研究,选择具代表性的林下棕色石灰土、红壤剖面各一个开展以月为观测周期的土壤呼吸排放CO_2速率、同位素动态变化及其土壤剖面不同层位CO_2浓度时空分布的动态观测,进而分析岩溶动力系统中土壤碳迁移特征及岩溶碳汇作用机制。结果显示:1)岩溶区石灰土的土壤呼吸排放CO_2速率明显低于碎屑岩区红壤的,岩溶区土壤呼吸速率的变化幅度为23.12～271.26mgC/m^2·h,碎屑岩土壤呼吸速率的变化幅度为51.60～326.28mgC/m^2·h;如以年平均值计算,则岩溶区土壤呼吸排放CO_2的量要比碎屑岩区红壤少25.12%;2)岩溶区石灰土土壤呼吸排放CO_2的δ^(13)C值比碎屑岩区红壤的偏重,岩溶区土壤呼吸排放CO_2的δ^(13)C值为-29.35‰～-18.26‰,平均为-22.68‰,碎屑岩区为-29.21‰～-22.60‰,平均为-26.21‰;3)岩溶区石灰土剖面中CO_2浓度出现双向梯度,且水热条件良好的季节双向梯度表现更明显,而碎屑岩区红壤剖面中则出现随土壤层深度的增加,土壤CO_2浓度增加的一向梯度;如以剖面中CO_2浓度的平均值计算,则岩溶区石灰土中CO_2浓度的变化幅度为0.05%～0.60%,年平均0.25%,而碎屑岩区红壤的变化幅度为0.05%～1.09%,年平均0.57%。这意味着岩溶区土-岩界面石灰岩的溶解消耗吸收土壤下层CO_2,即土壤中岩溶作用产生碳汇的过程。
Guilin Maocun karst underground river catchment is located in Maocnn Village,30km to the southeast of Guilin City ,covering an area of 10km^2. In order to carry out comparative study of soil carbon transfer in karst area and clasolite area,the soil profiles of brown limestone soil in typical karst area（25°11 ′38″N,110°31′35″E） and red soil in clasolite area （25 °11 ′35″N, 110°32′08″E） were selected. Both sites cover forest communities and the distance between them is about 1500m. The rate of CO2 emission from soil respiration in situ,isotope kinetic variation,and temporal and spatial distribution of CO2 concentration in different soil layers,were monitored and collected. The soil carbon transfer features in karst dynamic system and carbon sink mechanism were analyzed. The results showed that： （1）The rate of CO2 emission of soil respiration from limestone soil is apparently lower than that in red soil. The soil respiration rate in karst area varied from 23.12 -271.26mgC/m^2· h,with an average of 111.57mgC/m^2·h. The soil respiration rate in the clasolite area varied from 51. 60 - 326. 28mgC/m^2· h,with an average of 148.99mgC/m^2·h. Taking the averages into account,the CO2 emission from limestone soil respiration was 25.12% less than that in the red soil; （2）The δ^13C value of CO2 emission from soil respiration in karst area and in clasolite area was -29.35‰ - -18.26‰ and -29.21‰ - -22.60‰,respectively,with their respective mean values being -22.68‰ and -26.21‰. The δ^13C value of CO2 emission from soil respiration in the karst area is heavier with greater variations than that in the clasolite area; （3） The CO2 concentration in limestone soil profile had a bi-directional gradient, which could be more obvious in seasons with good hydro-thermal conditions. By contrast,the CO2 concentration in red soil profile had a uni-directional gradient,that is to say,the deeper the red soil layer,the higher the CO2 concentration. Taking into account the mean values o
出处
《第四纪研究》
CAS
CSCD
北大核心
2011年第3期431-437,共7页
Quaternary Sciences
基金
国家自然科学基金项目(批准号:40872213)
国地质调查局工作项目(批准号:1212010911062和S-2010.KP03-07-02)资助
