Knowledge Resource Center for Ecological Environment in Arid Area
| 基于稳定同位素的塔河典型植物水分来源和蒸散发组分分割研究 | |
| 其他题名 | Study on Water Consumption Source of Typical Plants In Tarim River and Evapotranspiration Component Segmentation Based on Stable Isotopes |
| 王勇 | |
| 出版年 | 2018 |
| 学位类型 | 硕士 |
| 导师 | 赵成义 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 蒸散发是陆地生态系统水分耗散的重要途径，与陆地植被总生态系统生产量密切相关。干旱区陆地生态系统水文过程的动态变化取决于植物水分利用和植物水分利用效率。识别地表植被水分来源，明确地表生态系统中非生产性（裸地蒸发）与生产性水分损失（蒸腾）的相对量，是探明干旱地区水分耗散过程的关键。本文结合相关气象资料和实测数据，研究了塔里木河流域降水δD 和δ18O 时空变化特征，分析了大气降水同位素分馏特征和影响因素；结合当地大气水线特征，对不同林龄胡杨和柽柳的蒸腾进行了水源分割，定量确定了蒸腾耗水的来源。利用蒸腾和蒸发同位素特征不同对不同地下水埋深地表蒸散发组分进行水文分割，并结合水量平衡方法验证了同位素方法分割结果；结合植物生长指标测定以及同位素特征值定量识别不同地下水埋深地表蒸散发及其组分的耗水来源。主要研究结论如下：（1）塔里木河流域地区大气降水线方程（LMWL）为δD=6.92δ18O+5.58（n=38,R2=0.94），斜率和截距分别为6.98和5.58，均显著低于全球、全国以及新疆地区大气水线。塔里木河流域降水δ18O和δD与空气温度存在正相关关系，温度效应较为明显，相关方程分别为：δ18O=0.78T-17.88 (R2=0.35,n=38)和δD=5.46T-119.03 （R2=0.36,n=34）。大气降水的氘盈余变化范围为-15.23‰~24.24‰，均值为8.25‰，小于全球降水线方程的截距10，氘盈余变化范围较大说明大气降水水汽来源区湿度和蒸发非平衡分馏程度变化大。（2）研究区植物水和土壤水的降水偏离值分别为-8.57和-6.88，与地下水的降水偏离程度（-1.89）存在显著差异（P<0.05），表明大气降水补给各水源过程中会发生生态水文分离现象。不同林龄胡杨和柽柳水分利用来源存在差异，吸水层位随林龄增加而加深。无论在幼苗阶段或成熟阶段，柽柳水分利用层位均低于胡杨，对干旱环境的适应性更强。（3）整个试验阶段胡杨的蒸腾量随地下水埋深增加而增加，且占地表蒸散量的比重不断增加，最大值达到77.55%，蒸散量达到最大值62.62mm。当地下水埋深浅于100cm时，土壤蒸发比重较高，植物水分耗散仅来源于表层土壤，可消耗量小，使得土壤蒸发成为浅地下水埋深条件下主要的水分耗散形式，胡杨蒸腾占地表蒸散的比重低于或近似于50%，地表耗水以土壤蒸发为主；当地下水埋深低于100cm时，地表水分耗散形式以植物蒸腾为主。柽柳蒸腾量在100cm地下水埋深处达到最大值，且后期蒸腾量远高于前期。试验前期，柽柳的蒸腾蒸散比重（mt/me）均低于50%，各地下水埋深下柽柳地表蒸散发以土壤蒸发的形式为主；试验后期，当地下水埋深低于100cm时，地表耗水以植物蒸腾为主。与胡杨相比，试验前期柽柳地表蒸散发量低于胡杨，且蒸腾量较小，mt/met的值较低。 |
| 英文摘要 | Evapotranspiration is an important part of the water balance of ecosystems, and it is also an important way for water dissipation in ecosystems. The dynamic changes in the hydrological processes of the ecosystem in arid regions depend on the plant water use efficiency and the plant water use efficiency. It is necessary to clarify the water use of plants and the laws of surface water and groundwater dissipation, and to increase the utilization rate of water resources. In this paper, the transpiration of Populus euphratica and Tamarix ramosisssima water source segmentation to quantitatively identify the source of transpiration water consumption. Transpiration and evaporation isotopes are used to hydrologically segment evapotranspiration components in different groundwater depths, and the results of isotope method segmentation are verified by combining water balance methods; combined with the determination of plant growth indexes and quantitative identification of different groundwater depths for the quantification of isotope characteristics. The result is as follows: (1)The atmospheric precipitation line equation (LMWL) in the Tarim River is δD=6.92δ18O+5.58 (N=38, R2=0.94), and the slope and intercept are 6.98 and 0.43, respectively, both significantly lower than those of the whole world,country and Xinjiang.It shows that water vapor is affected by the secondary evaporation fractionation during the process of condensation and precipitation falling to the ground. There is a positive correlation between temperature and temperature effect. The correlation equations are:δ18O=0.78T-17.88 (R2 = 0.35, n=38) andδD=5.46T-119.03 (R2 = 0.36, n=34). The effect of precipitation is not significant. The mean value is 8.25‰, which is less than the intercept 10 of the global precipitation equation. The larger range of d-excess surplus shows that the humidity and the non-equilibrium fractional fraction of evaporation in the atmospheric water vapor source region vary greatly.(2) The precipitation deviations of plant water and soil water in the study area were -8.57 and -6.88, respectively, which were significantly different from the precipitation depreciation (-1.89) of groundwater (P<0.05), indicating that the atmospheric precipitation will be recharged in the course of various water sources. The phenomenon of ecological water separation occursThere were differences in water use sources of Populus euphratica and Tamarix ramosisssima at different ages, and the water-absorption depth increased with the forest age increasing. Populus euphratica seedlings and mature woods mainly use 0-60cm shallow soil water, and the utilization ratio is 53.4%. The average water absorption depth is 33.77cm. There may be water competition relationship between the mature Populus euphratica and Tamarix seedlings, and the main source of both water is 30-100cm soil. For water and groundwater, the specific utilization ratio is slightly different. The average water absorption depth is 65.71cm and 46.54cm respectively. For mature tamarisk, deep soil water and groundwater are mainly used, and the utilization ratio reaches 61.9%. No matter the seedling stage or mature stage, the water use layer of Tamarix ramosisssima was lower than that of Populus euphratica and its adaptability to arid environment was stronger.(3) The transpiration of Populus euphratica increased with the increase of groundwater depth during the whole experiment period, and the proportion of surface evapotranspiration increased continuously. The maximum value reached 77.55%, and the evapotranspiration reached a maximum of 62.62mm. When the depth of groundwater is shallower than 100cm, the surface soil strongly evaporates The transpiration of plant water comes from the topsoil only, and the consumption is small, making the soil evaporation the main water dissipation form under shallow groundwater depth conditions. The transpiration of the Populus euphratica accounts for the surface evapotranspiration. The proportion is less than or close to 50%, and the surface water consumption is mainly based on soil evaporation. When the groundwater depth is deeper than 100cm, the surface water dissipation pattern is mainly plant transpiration. The transpiration of Tamarix ramosissima reaches its maximum at the groundwater depth of 100cm, and the transpiration is much higher than the previous period. At the early stage of the experiment, the mt/met of Tamarix ramosissima are below 50%, and the evapotranspiration of Tamarix is mainly based on the form of soil evaporation at the depth of each groundwater. At the later stage of the experiment, when the groundwater depth was less than 100cm, the surface water consumption was dominated by plant transpiration. Compared with Populus euphratica, the surface evapotranspiration of Tamarix was lower than that of Populus euphratica, and the transpiration was smaller and the mt/met value was lower. |
| 中文关键词 | 稳定同位素 ; 水分来源 ; 蒸散发 ; 土壤蒸发 ; 植物蒸腾 |
| 英文关键词 | stable isotopes source of water evapotranspiration plant transpiration soil evaporation |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生态学 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/288195 |
| 推荐引用方式 GB/T 7714 | 王勇. 基于稳定同位素的塔河典型植物水分来源和蒸散发组分分割研究[D]. 中国科学院大学,2018. |
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