| 三江平原露水水汽来源的氢氧稳定同位素辨析 |
| 摘要点击 2669 全文点击 2144 投稿时间：2010-06-08 修订日期：2010-07-08 |
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| 中文关键词 稳定同位素 湿地 水田 露水 水汽来源 |
| 英文关键词 stable isotope wetland paddy dew vapour source |
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| 中文摘要 |
| 为探讨湿地、水田露水氢氧同位素变化规律并辨析露水水汽来源，于2009年作物/植物生长季对三江平原雨水、地表积水及露水进行样品采集.通过测定样品δ18O和δD，研究了露水、地表水体、雨水间的水力联系，确定了不同生态系统露水的水汽来源.结果表明，受不同降雨水汽来源影响，6月末～8月末露水中δ18O和δD值总体变化趋势呈V型曲线，7月中旬达到最低值（湿地与水田露水中δ18O和δD值分别为-12.1‰、-87.4‰、-12.0‰和-88.0‰），9月初δ18O和δD值有下降趋势.根据同位素质量守恒规律，计算得到雨季水田露水中约30%的水分来自于水稻蒸腾和作物吐水、约70%来源于空气中水汽和田面水、雨水蒸发的水汽的再次凝结；湿地露水主要由地表积水及雨水蒸发水汽冷凝而成.露水与雨水中氢氧同位素变化规律的一致性，说明露水可反映降雨水汽来源变化信息.同时土地利用变化引起的下垫面水体δ18O和δD变化导致湿地露水δ18O和δD总体高于水田露水.本研究将稳定同位素方法应用于区分露水水汽来源，对进一步认识露水的凝结过程和影响因素有重要意义. |
| 英文摘要 |
| This study aims to discuss the change of δ18O and δD values and discriminate different vapour sources of dew in paddy and wetland. Rain, surface water of paddy and wetland as well as dew sample were collected in Sanjiang Plain during the growing season in 2009. By analysing the isotope composition of different kinds of water, the transformation among dew, surface water and rain was studied. The contribution of different vapour sources of dew in each ecosystem was identified. The results demonstrated the δ18O and δD values of dew which effected by the different vapour sources of rain showed a V-shape curve from the late June to late August. The δ18O and δD values reached the bottom in mid-July. The δ18O and δD values of dew in wetland and paddy were -12.1‰，-87.4‰，-12.0‰ and -88.0‰, respectively. The values had a downward tendency in the beginning of the September again. Based on isotopic mass conservation to partition quantitatively the contribution of different vapour sources of dew, the guttation and transpiration from the plant accounted about 30% and the evaporation of surface water mixed with vapour in air accounted the other partition of paddy dew in rainy season. As to wetland dew, the evaporation of surface water took the most partition. The δ18O and δD values of dew exhibited the similar trend to the stable isotope in rain. Therefore, the stable isotope of dew is useful as a vapour resource of rain. The difference of δ18O and δD values in surface layer water of wetland and paddy because of land use-cover change (LUCC) leaded to the δ18O and δD values in wetland dew were higher than that in paddy dew. The research used stable isotope in discriminating the different vapour sources of dew. It was significant to identify the process of dew condensation and analyse dew formation conditions. |
