内蒙古夏季大气降水同位素特征及影响因素

为探明内蒙古地区夏季大气降水中δD和δ¹⁸O组成特征及其对气象因子变化的响应关系，于2017~2019年夏季采集了内蒙古阿拉善左旗、呼和浩特市市区、正蓝旗、克什克腾旗（达里湖）、通辽科尔沁左翼中旗和呼伦贝尔新巴尔虎右旗（呼伦湖）等6个区域共计82次大气降水样品，结合来自全球降水同位素观测网（GNIP）的包头、张掖等6个区域大气降水样品中δD和δ¹⁸O数据，分析了内蒙古地区大气降水中δD和δ¹⁸O变化的区域差异及其主要影响因素，结果表明：内蒙古局地大气降水中δD和δ¹⁸O值存在自西向东不断偏负的趋势，其中呼伦贝尔新巴尔虎右旗大气降水中δD和δ¹⁸O值最偏负；相对地，西部阿拉善左旗大气降水中δD和δ¹⁸O值最偏正；内蒙古地区局地大气降水线斜率和截距同样表现出自西向东逐渐偏正的变化趋势，显示二次蒸发作用的影响逐渐下降，且局地蒸发水汽团对西部地区大气降水影响明显，如位于西风环流影响区的阿拉善左旗等区域局地蒸发气团占到8月部分单次大气降水来源水汽团的100%，而7月份，东亚夏季风环流对内蒙古局地大气降水的影响最为明显；整体上，虽然区域大气湿度变化引起的二次蒸发是影响内蒙古局地大气降水过程的一个关键因素，不过大气降水量对夏季大气降水稳定同位素组成的影响最明显.即西风环流影响区大气湿度变化对氘盈余指数d值的影响程度明显强于东亚夏季风区大气湿度变化的影响，而东亚夏季风环流影响区大气降水量对d值的影响程度则相对明显.

Characteristics and influence factors for the hydrogen and oxygen isotopic of precipitation in inner mongolia

In order to study hydrogen and oxygen stable isotopes (δD,δ¹⁸O) composition characteristics of summer atmospheric precipitation in Inner Mongolia,and responding to meteorological factors,a total of 82atmospheric precipitation samples in6regions were collected in the summer of 2017~2019,including Inner Mongolia Alxa Left Banner,Hohhot City Urban Area,Zhenglan Banner,Keshiketeng Banner (Dali Lake),Tongliao Horqin Left-wing Middle Banner,and Hulunbuir New Barhu Right Banner (Hulun Lake).This paper analyzed the regional differences and their main influencing factors inδD andδ¹⁸O changes of atmospheric precipitation in Inner Mongolia,combining theδD andδ¹⁸O data from 6regional atmospheric precipitation samples in Baotou’s and Zhangye’s the Global Precipitation Isotope Observation Network (GNIP).The results showed that:TheδD andδ¹⁸O of the local atmospheric precipitation in Inner Mongolia tended to be negative from west to east.Among them,theδD andδ¹⁸O of the atmospheric precipitation in the Hulunbuir,New Barhu Right Banner were the most negative;in contrast,theδD andδ¹⁸O of the atmospheric precipitation in the western Alxa Left Banner were the most positive;The slope and intercept of the local atmospheric precipitation line in Inner Mongolia also showed a positive trend from west to east,indicating that the influence of secondary evaporation had decreased and the local evaporation water vapor mass had a significant impact on atmospheric precipitation in the western region.For example,the local evaporation air masses in Alxa Left Banner that was located in the area affected by the westerly circulation account for 100%of the water vapour masses in some single atmospheric precipitation sources in August.But the East Asian summer monsoon circulation had the most impact on the local atmospheric precipitation in Inner Mongolia in July.Although the secondary evaporation caused by regional atmospheric humidity changes was a key factor affecting the local atmospheric precipitation process in Inner Mongolia,atmospheric precipitation had the most important influence on the stable isotope composition of summer atmospheric precipitation.That was,the influence of atmospheric humidity changes on the deuterium surplus index d-excess was stronger than the influence of atmospheric temperature changes in the East Asian summer monsoon region,while the influence of atmospheric precipitation on the d-excess in the East Asian summer monsoon circulation area was relatively significant.