| 黑河流域大气降水稳定同位素变化及模拟 |
| 摘要点击 4693 全文点击 3100 投稿时间：2010-07-15 修订日期：2010-11-19 |
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| 中文关键词 稳定同位素 大气降水 温度效应 降水量效应 模拟 内陆河流域 |
| 英文关键词 precipitation stable isotopes temperature effect precipitation effect simulation inland river basin |
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| 中文摘要 |
| 利用2002～2004年黑河流域6个采样点上的301个降水数据，对黑河流域大气降水中δD和δ18O的变化进行了分析.结果表明,流域降水δ18O和δD的变化范围分别为6.5‰～-33.4‰和59‰～ -254‰，这主要是由于降水水汽来源不同和气象条件特别是气温和降水量的较大变化使得降水形成的凝结机制发生变化引起；降水中同位素的变化和气温之间呈现出非常明显的正相关关系，即温度效应明显；在月时间尺度上，降水量效应是不存在的，但在降水事件尺度上，存在降水量效应；δ18O加权平均值随着采样点海拔高度增加而降低，呈现出较好的高度效应，效应梯度为-0.47‰ /100 m；区域大气降水线(RMWL) 为δD=7.82 δ18O+7.63，其斜率和截距与中国北方地区接近；后向轨迹法追踪黑河流域水汽来源结果表明，冷季（10～次年3月）水汽主要来源于西风带而暖季（4～9月）的水汽来源复杂；模拟显示，δ18O随时间呈现明显的正弦趋势. |
| 英文摘要 |
| To study the variations of δD and δ18O in precipitation, 301 samples were sampled during 2002-2004 in 6 sites in the Heihe River basin, Northwestern China. The δD and δ18O values ranged from 59‰ to -254‰ and 6.5‰ to -33.4‰, respectively. This wide range indicated that stable isotopes in precipitation were controlled by different condensation mechanisms as a function of air temperature and varying sources of moisture. δ18O in precipitation had a close positive relationship with the air temperature, i.e., a clear temperature effect existed in this area. At a monthly scale, no precipitation effect existed. On the other hand, a weak precipitation effect still accrued at precipitation events scale. The spatial variation of δ18O showed that the weighted average δ18O values decreased with the increasing altitude of sampling sites at a gradient of -0.47‰ /100m. A regional Meteoric Water Line, δD=7.82 δ18O+7.63, was nearly identical to the Meteoric Water Line in the Northern China. The results of backward trajectory of each precipitation day at Xishui showed that the moisture of the precipitation in cold season (October to March) mainly originated from the west while the moisture source was more complicated in warm season (April to September). The simulation of seasonal δ18O variation showed that the stable isotope composition of precipitation tended to a clear sine-wave seasonal variation. |
