摘要
根据长沙地区于2014年11月12日~2015年4月13日监测的大气水汽中δ18O和δ2H及观测的气象要素,分析了长沙近地面水汽中δ18O和δ2H变化特征以及与温度、绝对湿度、降水量的关系.结果表明：1长沙大气水汽中δ18O和δ2H季节变化显著,在冬季表现为高值.冬季大气水汽中δ18O和δ2H与绝对湿度存在正相关关系.δ18O和δ2H在监测期间存在较大波动,尤其是有降水事件发生时.降水事件对长沙大气水汽中δ18O和δ2H的变化影响显著,水汽稳定同位素的低值与降水事件有关.2不同天气条件下长沙大气水汽中δ18O和δ2H的日变化实质上与绝对湿度有关,而绝对湿度的大小又主要受控于局地的蒸散发和大气湍流的强度.单次降水过程中大气水汽δ18O和δ2H存在显著的类似于降水中稳定同位素的＂降雨量效应＂.3长沙大气水汽中δ18O和δ2H总是低于降水中δ18O和δ2H,逐日变化基本一致,它们之间的平均差值分别为8.6‰和66.82‰.4长沙冬半年大气水汽线方程为δ2H=7.18δ18O＋10.58,水汽线的斜率和截距总是小于同时段大气水线的斜率和截距,春季水汽线的斜率和截距明显高于冬季水汽线的斜率和截距.
Based on the monitored atmospheric water vapor stable isotopes and observed meteorological elements at Changsha during the period from November 12,2014 to April 13,2015,the variations of water vapor stable isotopes and the relationships between isotope ratios and temperature,absolute humidity,precipitation amount were analyzed in this paper. The results indicated that： 1 Seasonal variations of δ18O and δ2H in atmospheric water vapor at Changsha were remarkable,with high values in winter. δ18O and δ2H in atmospheric water vapor were positively correlated with absolute humidity in winter. There were some fluctuations of the δ18O and δ2H in atmospheric water vapor,especially when the precipitation events occurred. Precipitation events had a significant effect on the variations of δ18O and δ2H in atmospheric water vapor,and low values were often accompanied with precipitation events; 2 Diurnal Variations of δ18O and δ2H in atmospheric water vapor had a close correlation with the atmospheric water vapor content,whereas the absolute humidity was mainly controlled by the strength of the local evapotranspiration and atmospheric turbulence. The ＂precipitation amount effect＂was observed during the process of a single precipitation event; 3Values of δ18O and δ2H in atmospheric water vapor were always lower than those of precipitation in Changsha,but he variation trends were completely consistent,the average difference values were 8. 6 ‰ and 66. 82 ‰,respectively; 4The meteoric vapor line（ MVL） in cold months was δ2H = 7. 18 δ18O ＋ 10. 58,the slope and intercept of MVL were always lower than those of MWL,and the slope and intercept of MVL in spring were significantly higher than those of winter.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2016年第2期475-481,共7页
Environmental Science
基金
国家自然科学基金项目(41171035,41571021)
湖南省重点学科建设项目(2011001)
湖南重特大干旱机理研究项目(2015001)
关键词
大气水汽
降水
氢同位素
氧同位素
长沙地区
atmospheric water vapor
precipitation
hydrogen isotope
oxygen isotope
Changsha
