Carbon isotopic composition,turnover and origins of soil CO2 in a monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir,South China

作     者：DING Ping1,SHEN ChengDe1,2,WANG Ning1,YI WeiXi1,DING XingFang2,FU DongPo2,LIU KeXin2 & ZHAO Ping3 1Key Laboratory of Isotope Geochronology and Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China 2State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871,China 3South China Botanical Garden,Chinese Academy of Sciences,Guangzhou 510650,China 

出 版 物：《Science Bulletin》 (科学通报(英文版))

年 卷 期：2010年第55卷第23期

页      面：2551-2559页

学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学] 

基　　金：supported by the National Natural Science Foundation of China (40231015 and 40473002) the National Basic Research Program of China (2005CB422004) the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-SW-133) 

主　　题：Dinghushan Biosphere Reservoir soil CO2 turnover Bomb-14CO2 13C & 14C 

摘      要：Carbon isotopic compositions of soil CO2 in rainy season (July) from two natural soil profiles (DHLS & DHS) in the monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir (DBR),South China,are *** and origins of soil CO2 are preliminarily discussed in this *** show that the content of soil CO2 varies between 6120 and 18718 ppmv,and increases with increasing depth until 75 cm,and then it *** DHLS,soil CO2 δ 13C ranges from -24.71‰ to -24.03‰,showing a significant inverse correlation (R2=0.91) with the soil CO2 content in the same *** to a model related to soil CO2 δ 13C,the soil CO2 is mainly derived from the root respiration (80%) in *** in DHS,where soil CO2 δ 13C ranges from -25.19‰ to -22.82‰,soil CO2 is primarily originated from the decomposition of organic matter (51%–94%),excluding the surface layer (20 cm,90%).Radiocarbon data suggest that the carbon in soil CO2 is modern carbon in both DHLS and *** in 14C ages between the oldest and youngest soil CO2 in DHLS and DHS are 8 months and 14 months,respectively,indicating that soil CO2 in DHLS has a faster turnover rate than that in *** Δ14C values of soil CO2,which range between 100.0‰ and 107.2‰ and between 102.5‰ and 112.1‰ in DHLS and DHS,respectively,are obviously higher than those of current atmospheric CO2 and SOC in the same layer,suggesting that soil CO2 is likely an important reservoir for Bomb-14C in the atmosphere.