洞庭湖流域夏季旱涝与降水同位素丰度的关系  

THE RELATIONS BETWEEN SUMMER DROUGHTS/FLOODS AND OXYGEN STABLE ISOTOPE COMPOSITION OF PRECIPITATION IN DONGTING LAKE BASIN

作　　者：刘仲藜 章新平[1,2] 肖卓勇 贺新光[1,2] 饶志国 关华德 LIU Zhongli;ZHANG Xinping;XIAO Zhuoyong;HE Xinguang;RAO Zhiguo;GUAN Huade(College of Geographic Science,Hunan Normal Universityy Changsha 410081,Hunan;Hunan Key Laboratory of Geospatial Big Data Mining and Application,Changsha 410081,Hunan;College of Science and Engineering,Flinders University,Adelaide SA 5001,Australia)

机构地区：[1]湖南师范大学地理科学学院,湖南长沙410081 [2]湖南师范大学地理空间大数据挖掘与应用湖南省重点实验室,湖南长沙410081 [3]College of Science and Engineering,Flinders University,Adelaide SA 5001,Australia

出　　处：《第四纪研究》2022年第2期472-486,共15页Quaternary Sciences

基　　金：国家自然科学基金项目(批准号:41571021);湖南省人影办自立项科研经费项目(批准号:201901)共同资助。

摘　　要：稳定同位素在自然界中含量稀少,对环境变化极为敏感并能够记录环境变化。水稳定同位素技术被广泛地应用于水文气象、气象诊断和古气候恢复等领域。目前关于中国南方降水中氧稳定同位素的代表性问题一直存在争议,实测同位素数据的时间跨度短、取样不连续以及各站点的空间分布不均匀都对研究产生不利影响。文章利用实测的和isoGSM2模拟的水稳定同位素数据,分析了在月、季节和年时间尺度下洞庭湖流域夏季降水量与降水稳定同位素(δ^(18)O_(p))丰度的关系以及它们可能的影响因素,并利用多元线性逐步回归的方法计算了各影响因素的相对贡献。结果表明,洞庭湖流域夏季加权平均δ^(18)O_(p)与年加权平均δ^(18)O_(p)的波动趋势基本一致,均与夏季降水量存在显著负相关,流域在夏旱(涝)年时,夏季加权平均δ^(18)O_(p)显著偏正(负)0.48‰(0.66‰),说明流域夏季存在显著的降水量效应。湘江河水中氧同位素(δ18Or)在一定程度上也存在降水量效应,在夏涝年时,δ18Or波动幅度较大并显著偏负。在逐年夏季的统计关系上,西太副高位置偏南偏西(偏北偏东)利于降水中氧同位素偏正(负),说明流域存在环流效应。在年代际时间尺度上(9年滑动平均),夏季降水量是年加权平均δ^(18)O_(p)最主要的影响因素,可以解释年加权平均δ^(18)O_(p)变化的75%左右。Lianhua洞石笋中δ18O与龙山站夏季降水量也表现出反向变化,雨除强度为-0.30‰/100 mm。可以认为,氧同位素在洞庭湖流域可以作为降水量的代用指标。以上研究结果对东亚季风区古气候重建具有积极意义,还需要更多的研究去确定局地影响因素与大尺度影响因素对降水中氧同位素比率的相对贡献。Stable isotopes are scarce in the environment,but they respond very sensitively to the environmental evolution and record it in different geological archives.Tracing methods derived from the stable isotope composition of water have been widely applied in researches on hydrometeorology,weather diagnosis,and palaeoclimate reconstruction.The investigated area,Dongting Lake basin(24.4°~30.9°N,107.3°~114.7°E),is located in central-southern China,surrounded by mountains with a plain in its center and north.The Dongting Lake basin has a subtropical monsoon climate,which is alternately dominated by SWM and SEM in summer(JJA).It is an ideal region to study the evolution of the East Asian Summer Monsoon(EASM).The main rainy season of the basin is spring(MAM)and summer.In recent years,the isotopologues of oxygen stable isotope composition of precipitation in Southern China have been controversial,partly because the global observation sites,without widespread enough,collected data for a short period(several years or even several months).In this paper,there are three sources of the observed stable isotopic composition of atmospheric precipitation(δ^(18)O_(p))in Changsha,which are(1)from GNIP Changsha Station(28°07'12″N,113°02'24″E)(from January 1988 to December 1992),(2)cited from Yang et al.(2011)(from June 2006 to March 2009),and(3)measured daily data from Site1(28°11'29.76″N,112°56'27.78″E)(from January 2010 to December 2019).The measured daily stable isotopic composition of the Xiangjiang River water(δ^(18)O_(r))was derived from Site2(28°12'10.08″N,112°57'33.12″E)(from January 2010 to December 2019).Based on the observed and simulated data(from isoGSM2)on stable isotope composition of water,the relationship between summer precipitation(JJA P)and oxygen stable isotope composition(δ^(18)O)is determined in the Dongting Lake Basin under monthly,seasonal and annual timescales.Their possible influencing factors are demonstrated,and the contribution rate of different factors is analyzed by multiple linea

关 键 词：洞庭湖流域 夏季降水 降水稳定同位素 水汽输送 

分 类 号：P467[天文地球—大气科学及气象学] P597.2