陈领 王小利 张青伟 段建军 李瑞东 罗安焕 陈佳

摘 要：本研究以黔中喀斯特区典型黄壤和石灰土为研究对象，通过100 d室内土壤有机碳矿化培养试验，结合13C同位素示踪技术，研究外源碳酸钙对土壤CO2总释放量的贡献及对土壤有机碳矿化的激发效应，为提高喀斯特地区土壤有机碳稳定性提供理论依据。结果显示，Ca13CO3在培养前期（1～10 d）可释放13CO2，后期（10～100 d）趋于稳定，Ca13CO3对黄壤和石灰土总CO2累积释放量具有一定的贡献，其贡献率达到25.47%和20.76%;外源Ca13CO3对黄壤和石灰土有机碳矿化均产生了负激发效应，培养100 d后土壤有机碳累积矿化量分别减少了76.05%和45.14%，激发效应主要受土壤类型的影响，黄壤有机碳矿化的负激发程度高于石灰土。

关键词：喀斯特;碳酸钙;有机碳矿化;碳同位素;CO2

Abstract：In this study，the typical yellow soil and lime soil in the karst area of central Guizhou were studied as the research object，and Througha 100-daymineralization cultivationof soil organic carbonindoors，，combined with 13C isotope tracing technology，the contribution of exogenous calcium carbonate to the total release of soil CO2 and its priming effect on soil organic carbon mineralization were conducted.It could provide a theoretical basis for improving the stability of soil organic carbon in karst areas.The results showed that Ca13CO3 can release 13CO2 in the early period of culture （1～10 d），and tends to be stable in the later period （10～100 d）.Ca13CO3 had a certain contribution to the total CO2 release of yellow soil and lime soil，and its contribution rate reached 25.47% and 20.76%;Exogenous Ca13CO3 had a negative priming effect on the organic carbon mineralization of yellow soil and lime soil.After 100-days cultivation，the cumulative mineralization of soil organic carbon was reduced by 76.05% and 45.14%，respectively.The priming effect was mainly affected by soil type mainly.The degree of negative excitation of organic carbon mineralization in yellow soil was higher than that in lime soil.

Keywords：Karst;Calcium carbonate;Organic carbon mineralization;Carbon isotope;CO2

土壤碳庫是陆地碳库的重要组成部分，包括土壤有机碳库和土壤无机碳库。全球土壤有机碳库储量估计为2000 Pg（以C计）[1];无机碳库量约947 Pg，以CaCO3占绝对优势[2]。贵州省处于中国西南部喀斯特区域中心，碳酸盐岩分布面积高达13×104 km2，碳酸盐岩出露面积较广，土层薄，水土流失严重[3-5]。碳酸盐岩中含有的无机碳以往被认为是一个“死库”，在土壤中很难转化。但近年来研究逐渐发现无机碳参与土壤有机碳（SOC）的转化，无机碳可通过各种途径转化进入大气[6]，石灰土性土壤在密闭培养过程中，其中的碳酸盐能释放出CO2。黄媛等[7]研究发现来源于外源碳酸钙的CO2释放量占总量的6.01%～34.05%;葛云辉[8]发现碳酸钙贡献的CO2为19.62%～ 48.44%;董燕婕[9]发现外源碳酸钙增加了碳释放累积量，释放的CO2中约有40%来自于无机碳。……