喀斯特漏斗坡地土壤有机碳特征、风化侵蚀及稀土元素分析  

Spatial distribution characteristics of soil organic carbon and analysis of the weathering erosion and REE in karst funnel slope

作　　者：冯晓静 张涛[1] 张晓娟 温月花 熊凯 李亚翠 季宏兵[1,2] FENG Xiao-jing;ZHANG Tao;ZHANG Xiao-juan;WEN Yue-hua;XIONG Kai;LI Ya-cui;JI Hong-bing(Key Laboratory of Metropolitan Eco-Environment Processes,College of Resource Environment and Tourism,Capital Normal University,Beijing 100048,China;School of Energy and Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]首都师范大学资源环境与旅游学院首都圈生态环境过程重点实验室,北京100048 [2]北京科技大学能源与环境工程学院,北京100083

出　　处：《地球化学》2019年第3期249-260,共12页Geochimica

基　　金：国家自然科学基金(41473122,41073096);国家重点基础研究发展计划项目(2013CB956702)

摘　　要：以西南喀斯特地区喀斯特漏斗坡地2个土壤剖面为研究对象,通过测定土壤部分物理化学属性、土壤有机碳含量分布特征、δ^13C值、几种土壤化学风化指标及稀土元素参数特征,探讨土壤侵蚀和沉积过程中土壤有机碳及其稳定碳同位素的动态变化及分布特征,同时利用土壤δ^13C值反演了C3/C4植被的变化历史。结果显示,山腰和山脚2个土壤剖面样品的土壤有机碳含量范围分别为4.17%~8.91%和2.37%~6.33%,山腰含量较高;δ^13C值变化范围分别为.18.9‰^-15.6‰和.22.1‰^-17.0‰,均随土壤深度的增加先增大后减小;利用土壤δ^13C值反演C3/C4植被的变化历史,2个剖面表现出相似的变化趋势;Na/K比值与ICIA的变化特征呈显著的负相关关系,R^2分别为0.67和0.98,表明该类红土中Na/K比值不仅能代表风化强度,且可能与侵蚀大小有关;常用的土壤风化发育指标表现为很好的协同作用,显示剖面土壤的形成是由基岩化学风化而成;稀土元素球粒陨石标准化之后显示Ce异常,Eu负异常,2个剖面δCe变化趋势基本一致,表明2个剖面经历了相似的风化迁移过程。Two different typical mountain slope soil profiles in karst areas were selected as a case to study the effect of soil erosion and deposition on dynamics of soil organic carbon (SOC) and inversion of the C3/C4 vegetation change history by determining certain properties. The δ^13C value of the soils and several soil chemical weathering indexes at different topographic positions were determined. The results show that SOC contents of two soil profiles are 4.17%–8.91% and 2.37%–6.33% in the mountainside and at the bottom, respectively, and the mountainside content is higher than that at the bottom. The δ^13C values range respectively, from -18.9‰ to -15.6‰ and -22.1‰ to -17.0‰, both of which increase with the gradient of profiles and then decrease. Inversion of C3/C4 vegetation change history from the the soil of the δ^13C values showes the two sections have a similar tendency. Variation in the values of the Na/K and chemical index of alteration (ICIA) show a significantly negative correlation. The correlation coefficient R^2 were 0.67 and 0.98. This showes that the values of Na/K can not only indicate the weathering intensity, but also the extent of erosion. Indexes based on macroelements of soil, which have good synergy, show the formation of profile soil evolves by bedrock chemical weathering. The element Ce was separated from the other REEs, and the chondrite-normalized REEs distribution patterns show significant Ce-anomalies and negative Eu-anonalies. The δCe trend of the two sections is basically the same, indicating that the two sections underwent a similar weathering migration process.

关 键 词：西南喀斯特 土壤有机碳 稳定碳同位素 C3/C4植物相对丰度 风化侵蚀 稀土元素 

分 类 号：P595[天文地球—地球化学]