不同水汽来源对湖南长沙地区降水中δD、δ^(18)O的影响  

Influences of Different Moisture Sources on δD and δ^(18)O in Precipitation in Changsha,Hunan Province

作　　者：吴华武[1] 章新平[1] 关华德[1,2] 孙广禄[1] 黄一民[1] 张婷婷[1] 

机构地区：[1]湖南师范大学资源与环境科学学院 [2]School of Environment,National Centre for Groundwater Research and Training,Finders University

出　　处：《自然资源学报》2012年第8期1404-1414,共11页Journal of Natural Resources

基　　金：国家自然科学基金项目(40871094;41171035);教育部高等学校博士点专项科研基金项目(20094306110006);湖南省重点学科项目(2011001);湖南省教育厅重点项目(09A056);中国科学院青藏高原环境变化与地表过程重点实验室开放基金项目(2011004);湖南省研究生创新项目基金(CX2011B191)

摘　　要：根据2010年在长沙地区进行降水收集和气象要素观测的资料,分析了该地区降水中δ18O与温度、降水量之间的关系,揭示了降水中δD、δ18O的变化特征,讨论了水汽输送对降水中δ18O变化的影响。结果表明,在天气尺度下,长沙地区大气降水中δ18O与降水量、温度之间存在显著的负相关关系,即该地区降水中δ18O的变化具有显著的降水量效应及反温度效应。对长沙地区的降雪样和降雨样进行线性回归,得出大降水事件和降雪的大气降水线具有较大斜率和截距。随着降水量的减小,大气降水线方程的斜率和截距也逐渐减小,这主要由于小降水事件的雨滴在降落过程中受到二次蒸发强烈,同位素分馏强烈。利用HYSPLIT模式追踪该地区气流的轨迹发现,在季风降水期间(5—9月),δ18O值偏低的水汽主要来自孟加拉湾、南海洋面与西太平洋海区;在非季风降水期间(10—4月),δ18O值偏高的水汽主要来自西风带携带的水汽和局地水汽环流。Based on the collected precipitation samples and observed meteorological data during 2010 in Changsha,we analyzed the relation between δ^18 in precipitation and temperature and precipitation amount,revealing the variations characteristic of δD and δ^18 in precipitation,and discussed the influence of moisture transport on the variations of δ^18 in precipitation.The results indicated that under the synoptic timescales,there was significant negative correlation between δ^18 in precipitation and precipitation amount and temperature in Changsha.That is,the variations of δ^18 in precipitation had significant precipitation amount effects and anti-temperature effects.We analyzed the snow samples and rain samples in Changsha by the linear regression,and obtained that the meteoric water line of large precipitation events and snowfall had large slope and interception.With the decrease in rainfall,the slope and interception of the meteoric water line also gradually decreased.It was mainly due to secondary evaporation that resulted in isotopic fractionation of light rainfall.We tracked the trajectory of air flow by HYSPLIT mode in Changsha and found that the moisture sources of the lower value of δ^18 mainly came from the Bay of Bengal,the South China Sea and Western Pacific region in the monsoon rainfall（May-September）;the moisture sources of the higher value of δ^18 mainly came from moisture carried by the westerly wind belt and the local water vapor circulation during non-monsoon rainfall（October-April）.

关 键 词：δD Δ18O 降水 HYSPLIT模式 水汽来源 长沙地区 

分 类 号：P426.6[天文地球—大气科学及气象学]