摘要:
大气降水是水文循环的重要环节，对降水氢氧稳定同位素的研究有利于揭示水循环规律、推断水汽来源，进而可深入分析流域水文过程。本文收集2013年11月~2014年5月鄱阳湖湿地降水样品，采用MAT253同位素比质谱仪连接Flash EA/HT对该地区降水氢氧稳定同位素进行测定，分析了其组成特征；并结合研究区气象观测数据，研究了降水中δ18O与氘盈余的变化规律。结果表明，鄱阳湖湿地大气降水线方程δD = 8.99δ18O + 11.52的斜率、截距均大于全球及我国大气降水线的平均水平，符合该地区湿润多雨的气候特点。δ18O与降水量呈显著负相关关系，表现为“降水量效应”，而温度效应在季风气候的影响下受到一定的抑制。氘盈余值受冬夏季风的影响，呈现出冬高夏低的季节性变化规律，与我国东部季风区的变化特征相符；影响氘盈余值的主要因素为相对湿度，两者呈显著负相关关系。
Abstract:
Precipitation is an important part of hydrologic cycle. Study on stable hydrogen and oxygen isotopes is advantageous to reveal the laws of water circulation and infer vapor source for further analysis of wa-tershed hydrological processes. We collected the samples of rainfall in Poyang Lake wetland from No-vember 2013 to May 2014, measured oxygen 18 and deuterium by using MAT253 IRMS connecting with Flash EA/HT and analyzed the characteristics of stable isotopes afterwards. In addition, factors affecting and deuterium excess with the meteorological data of Poyang lake wetland were discussed. The results show that the local meteoric water line is fitting the equation: δD = 8.99δ18O + 11.52, which the slope and intercept are above the average level of the Global and National Meteoric Water Line, is according with the characteristic of humid and rainy climate in the region. A significant negative correlation called “pre-cipitation effect” between oxygen 18 and precipitation is indicated. In contrast, temperature effect is re-strained under the influence of monsoon climate. Deuterium excess shows the obvious seasonal variation: deuterium excess is higher in winter than in summer which conforms to the laws in monsoon area in eastern China. Moreover, the main influencing factor is mean relative humidity which showed a negative correlation with deuterium excess.