半干旱岩溶区土壤次生碳酸盐比例及对岩溶碳汇计算的影响  

Proportion of pedogenic carbonates and the impact on carbon sink calculation in karst area with semiarid environment

作　　者：黄奇波[1,2] 覃小群[2] 刘朋雨[2] 张连凯[2] 苏春田[1,2] 

机构地区：[1]中国地质大学环境学院,湖北武汉430074 [2]中国地质科学院岩溶地质研究所/国土资源部广西壮族自治区岩溶动力学重点实验室,广西桂林541004

出　　处：《中国岩溶》2016年第2期164-172,共9页Carsologica Sinica

基　　金：国家自然科学基金项目(41302211);中国地质调查项目(12120113005200)

摘　　要：定量评价半干旱岩溶区土壤次生碳酸盐比例和来源有助于认识土壤系统影响岩溶作用的机理。选取山西晋中盆地西南,吕梁山东侧的半干旱岩溶区马跑神泉小流域为研究对象,通过对林地、退耕地、灌丛地土壤剖面进行分层取样并测定碳酸盐含量及其δ^(13) C、CO_2浓度及其δ^(13) C值,分析其随深度的变化规律和控制因素;并结合研究区碳酸盐岩的δ^(13) C值计算3个剖面各层土壤次生碳酸盐所占比例。研究结果表明:3个土壤剖面的碳酸盐含量、CO_2浓度在0~50cm土层随深度增加而增加,在50~70cm土层随深度增加而减少;土壤碳酸盐δ^(13) C值、δ^(13) C_(CO_2)值在0~50cm土层随深度增加而偏负,在50~70cm土层随深度增加而偏重;土壤碳酸盐含量及其δ^(13) C值主要受次生碳酸盐比例控制,而土壤CO_2及其δ^(13) C_(CO_2)值在上层主要受大气CO_2和土壤有机质分解生成的CO_2共同影响,下层还受土-岩界面岩溶作用过程制约;退耕地、林地、灌丛剖面次生碳酸盐所占比例的均值分别为52%、42%和32%,证实北方半干旱岩溶区土壤中存在原生碳酸盐向次生碳酸盐转化过程。Abstract Quantitative evaluation of proportion and source of pedogemc carbonates m Karat area with semiarid environment have contributed to understand the mechanism of soil system affecting karst process, which has great significance in karst carbon cycle research. Soil samples were collected from soil profile of forest land, abandoned farmland and hrushland, in a typical small watershed in semi-arid area, southwest of Jinzhong basin, Shanxi Province, China, for analysis of content and δ13C of soil carbonates, content and δ13C of CO2 and δ13C of parent rocks, hence to explore their variation with depth and controlling factors, and quantify ratio of pedogenic carbonates in soil carbon. Results show that in the upper layer（0 to 50 cm）, the content of soil carbonates and CO2 increase with depth, while the δ13C of soil carbonates and CO2 decrease with depth. In the lower layer （50 70 cm）, the content of soil carbonates and CO2 decrease with depth, and the δ13C of soil carbonates and C（）z increase with depth. The content and δ13C of soil carbonates are mainly controlled by pedogenic carbonates proportion, while the content and 3uC of CO2 are mainly affected by at- mospheric CO2 and soil CO2 generated by organic matter decomposiuon in the upper layer, and impacted by karst process in soil - rock interface in the lower layer. The average proportion of pedogenic carbonates is 52%, 42%, 32% for abandoned farmland, forest land and brushland, respectively. This paper confirmed that the lithogenic carbonates can transform to pedogenic carbonates in north karst area with semiarid environment.

关 键 词：岩溶碳汇 碳酸盐 次生碳酸盐 δ^(13) C值 土壤CO_2 

分 类 号：P642.25[天文地球—工程地质学]