湖北清江岩溶洞穴现代土壤有机碳同位素与生物标志物指标变化规律  

Variations of the Organic Carbon Isotope and Biomarker Indexes in Modern Soil from Karst Caves in the Qingjiang Valley,Hubei Province

作　　者：白晓[1] 黄俊华[2] 朱家平[1] 

机构地区：[1]南京地质矿产研究所,南京210016 [2]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074

出　　处：《地质科技情报》2014年第2期55-60,共6页Geological Science and Technology Information

基　　金：国家重点基础研究发展计划(2011CB808800);国家自然科学基金项目(41130207)

摘　　要：为进一步理解中国南方岩溶区现代土壤生物有机地球化学演化规律,对采自湖北清江流域典型岩溶洞穴上覆土壤开展了系统的分析。分别采用稳定同位素质谱仪(MAT-251)与气相色谱质谱仪(GC-MS)测试了样品中的有机碳同位素与生物标志物指标。其中有机碳同位素值(δ13Corg)在-28.3‰^-27.4‰之间变化,并随深度的增大呈逐渐正偏的趋势,指示了当地的植被类型自土壤层形成以来主要为C3植物。而可抽提有机质的总量、正构烷烃高碳数奇偶优势(CPIh值)、高碳数与低碳数含量比值(Rh/l值)、平均链长(ACL值)以及脂肪酸C16:1/C16:0等指标随土壤剖面深度的增大呈现逐渐降低的趋势,与土壤有机碳同位素的变化趋势基本一致,说明岩溶地区表层土壤中有机碳同位素和生物标志物均与土壤层内微生物活动的强弱密切相关。另一方面,也暗示了有机碳源是制约岩溶地区土壤微生物活动的重要因素之一。为进一步深入理解湖北清江和尚洞洞穴石笋记录提供了新的思路。In order to further investigate the organic geochemistry characteristics of surface soil in the karst region,we analyze the biomarker and organic carbon isotope in the the upper soil samples of the karst cave in the Qingjiang valley, Hubei Province by using the Gc-Ms and the MAT-251. The δ13 Corg values range from --28.3‰ to --27.4‰ indicating the C3 plants have been predominant in this region since the soil formed. The biomarker parameters,including carbon preference index（CPIh）, ratio of lower- to higher- molecular-weight homologues（Rh/1） and average chain length（ACL）, show comparable trends with depth, largely consistent with the organic carbon isotope. This phenomenon probably is restricted by microbial ac- tivities ,thus reflecting microbial degradation in the soil profile. The relative abundance ratio of the fatty acid of C,6：1and C16：0 has a significance correlation with the extractable organic matter. It shows the low concentration of carbon source could limit the microbial activity in the soil of Karst region. This study pro- vides the new idea of the stalagmite records in the Heshang cave, Qingjiang Valley, Hubei Province.

关 键 词：岩溶地区 有机碳同位素 生物标志物 土壤 微生物活动 

分 类 号：P531[天文地球—古生物学与地层学]