Modern stalagmite oxygen isotopic composition and its implications of climatic change from a high-elevation cave in the eastern Qinghai-Tibet Plateau over the past 50 years  

作　　者：YANG XunLin ZHANG PingZhong CHEN FaHu HUH Chih-an LI HongChun CHENG Hai Kathleen R. JOHNSON LIU JingHua AN ChunLei 

机构地区：[1]CAEP, Key Laboratory of Western China's Environmental System of Ministry of Education, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China [2]Institute of Earth Sciences, 'Academia Sinica', Taipei 115, China [3]Department of Earth Sciences, Cheng-Kung University, Tainan 700, China [4]Department of Geology and Geophysics, University of Minnesota, MN 55455, USA [5]Department of Earth Sciences, Oxford University, Parks Road, Oxford OX1 3PR, UK

出　　处：《Chinese Science Bulletin》2007年第9期1238-1247,共10页

基　　金：Supported by the National Natural Science Foundation of China (Grant No. 40471137);the Innovation Team Project of the National Natural Science Foundation of China (Grant No. 40421101);Doctor Station Foundation, Ministry of Education of China

摘　　要：An oxygen isotope record of a stalagmite from Huanglong Cave in the eastern Qinghai-Tibet Plateau dated with 230Th and 210Pb methods provides variations of the Asian monsoon with an average resolu-tion of 1 year over the past 50 years. This study shows that the δ18O of dripwater in the cave represents the annual mean δ18O of local meteoric precipitation and the stalagmites were deposited in isotopic equilibrium. A comparison of the stalagmite δ18O record with instrumentally meteorological data indi-cates that shifts of the δ18O are largely controlled by the amount effect of meteoric precipitation con-veyed through the southwest monsoon(the Indian monsoon) and less affected by temperature. Therefore,the variations of δ18O record reflect the changes in monsoon precipitation on inter-annual time scales under the influence of the southwest monsoon. Like many other stalagmite δ18O records in the Asian monsoon regions,the δ18O record of the stalagmite from Huanglong Cave also reveals a gradually enriched trend during the past 50 years,i.e. relatively enriched in 18O. This trend may indicate the decline of the Asian monsoon intensity which is consistent with the decrease of monsoon indices. The weakening of the modern Asian monsoon well matched with the temperature changes in strato-sphere,which may illustrate that the weakening of the monsoon mainly results from the lowering of solar radiation.An oxygen isotope record of a stalagmite from Huanglong Cave in the eastern Qinghai-Tibet Plateau dated with ^230Th and ^210Pb methods provides variations of the Asian monsoon with an average resolution of 1 year over the past 50 years. This study shows that the δ^18O of dripwater in the cave represents the annual mean 6180 of local meteoric precipitation and the stalagmites were deposited in isotopic equilibrium. A comparison of the stalagmite δ^18O record with instrumentally meteorological data indi- cates that shifts of the δ^18O are largely controlled by the amount effect of meteoric precipitation conveyed through the southwest monsoon （the Indian monsoon） and less affected by temperature. Therefore, the variations of δ^18O record reflect the changes in monsoon precipitation on inter-annual time scales under the influence of the southwest monsoon. Like many other stalagmite δ^18O records in the Asian monsoon regions, the δ^18O record of the stalagmite from Husnglong Cave also reveals s gradually enriched trend during the past 50 years, i.e. relatively enriched in 180. This trend may indicate the decline of the Asian monsoon intensity which is consistent with the decrease of monsoon indices. The weakening of the modern Asian monsoon well matched with the temperature changes in stratosphere, which may illustrate that the weakening of the monsoon mainly results from the lowering of solar radiation.

关 键 词：青藏高原 高海拔溶洞 现代石笋 氧同位素成分 气候变化 

分 类 号：P467[天文地球—大气科学及气象学] P931.5