Isotopic composition of precipitation over Arid Northwestern China and its implications for the water vapor origin  

西北干旱地区大气降水δ^(18)O的特征及水汽来源(英文)

作　　者：柳鉴容 宋献方 孙晓敏 袁国富 刘鑫 王仕琴 

机构地区：[1]Key Laboratory of Water Cycle and Related Land Surface Processes,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China [2]Graduate University of Chinese Academy of Sciences,Beijing 100039,China [3]CERN Sub-center of Water,Beijing 100101,China

出　　处：《Journal of Geographical Sciences》2009年第2期164-174,共11页地理学报（英文版）

基　　金：National Natural Science Foundation of China,No.40830636; No.40671034;Foundation of Isotopes in Precipitation of Chinese Ecosystem Research Network

摘　　要：In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation(CHNIP).During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ18O.The established local meteoric water line δD=7.42δ18O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region.The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions.The monthly δ18O values were characterized by a positive correlation with surface air temperature(δ18O(‰) =0.33 T(℃)-13.12).The amount effect visualized during summer period(δ18O(‰) =-0.04P(mm)-3.44) though not appeared at a whole yearly-scale.Spatial distributions of δ18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China.The quan-titative simulation of δ18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops.Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor.Multiple linear regression equations and a δ18O-T relation have been gained by using meteorological parameters and δ18O data to evaluate physical controls on the long-term data.The established δ18O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation （CHNIP）. During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ^18O. The established local meteoric water line δD=7.42δ^18O＋1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region. The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions. The monthly δ^18O values were characterized by a positive correlation with surface air temperature （δ^18O （‰） =0.33 T （℃）-13.12）. The amount effect visualized during summer period （δ^18O （‰） = -0.04P （mm）-3.44） though not appeared at a whole yearly-scale. Spatial distributions of δ^18O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China. The quantitative simulation of δ^18O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops. Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor. Multiple linear regression equations and a δ^18O-T relation have been gained by using meteorological parameters and δ^18O data to evaluate physical controls on the long-term data. The established δ^18OT relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.

关 键 词：Arid Northwestern China （ANC） Δ^18O PRECIPITATION water vapor origin 

分 类 号：P588.121[天文地球—岩石学] P457.6[天文地球—地质学]