水库底泥碳沉积特性研究

发布时间：2018-05-02 17:27

本文选题：水库 + 底泥　；参考：《清华大学》2014年博士论文

【摘要】：拦河筑坝的水库化进程显著改变了天然河流的输运状态,水库蓄水后大量外源碳随着径流携带物的沉积储存在水库内;另一方面,新形成的水域环境有利于水生植被的生长,内源碳随着植物的死亡沉积在水库底部。在全球碳收支计算失衡的背景下,水库底泥作为重要的碳积蓄场所,可以解释大气中一部分“遗失碳”的去向。本文以我国华北地区北京市周边和东南沿海地区福州市周边的11座典型水库为研究对象,通过野外调查和实验测量,分析了各水库底泥中碳的组成、分布、来源和储量,并针对水库区别于其它淡水生态系统的碳沉积特性进行了研究。取得了如下主要成果:我国华北地区水库底泥的碳累积率为270 g/(m2?a),其中有机碳所占比例为57%,无机碳为43%;东南地区水库底泥的碳累积率为160 g/(m2?a),其中有机碳所占比例为44%,无机碳为56%,水库底泥中无机碳的储量和有机碳大体相当。同时,结合我国水库的淤积情况,初步估算我国水库底泥的储碳总量为36.6亿吨,并且该值每年还在以1.5亿吨的速率增加。通过对不同地区、不同地貌、不同功能水库底泥碳沉积特点的分析,建立了流域土壤碳与底泥外源碳、水库沉积因子与底泥沉积率、水生植被因子与底泥内源碳含量的相关关系,进而提出预测水库底泥碳储量的方法。在本研究各水库进行验证的结果表明,该预测方法可以较准确的预测水库底泥的碳储量。利用稳定同位素技术对底泥中有机质的来源进行了定性分析和定量计算,结果表明,外源对水库底泥有机质的贡献总体上大于内源,且所处区域温度高的水库,外源因素的主导作用更大。同时,水库底泥中有机质的来源组成与一般的天然湖泊和河流均有所区别。针对水库拦蓄作用和人工水位管理的特点、以及水土流失和富营养化问题的研究表明,水库的碳沉积有区别于其它淡水生态系统的特性。水库拦蓄作用对底泥碳沉积的影响表现在外源碳的拦截和内源碳的积蓄两个方面;水库水位人工管理方式的差异会对底泥中有机碳的分布和来源组成产生影响;流域水土流失导致大量外源碳汇入水库,且主要沉积在河口的三角洲区域,而水体的富营养化显著增加了水库底泥中内源碳的沉积。
[Abstract]:The reservoir process of blocking and damming has significantly changed the transport state of natural rivers. A large amount of exogenous carbon is stored in the reservoir with the sediment of runoff carriers after reservoir storage. On the other hand, the newly formed water environment is conducive to the growth of aquatic vegetation. Endogenous carbon deposits at the bottom of the reservoir with plant death. Under the background of global carbon budget imbalance, reservoir sediment, as an important place for carbon storage, can explain the fate of some "carbon loss" in the atmosphere. Taking 11 typical reservoirs around Beijing and Fuzhou in the southeast coastal area of China as the research object, the composition, distribution, source and reserves of carbon in the sediment of each reservoir are analyzed by field investigation and experimental survey. The characteristics of carbon deposition of reservoirs different from other freshwater ecosystems are also studied. The main results are as follows: the carbon accumulation rate of reservoir sediment in North China is 270 g / m ~ 2 ~ (2) A ~ (-1), of which organic carbon is 57 and inorganic carbon is 433.The carbon accumulation rate of reservoir sediment in southeast China is 160 g / m ~ (2) ~ (2) a ~ (-1), of which organic carbon is a proportion of 70 g / m ~ (2) a ~ (-1). The inorganic carbon is 56 and the storage of inorganic carbon in reservoir sediment is about the same as that of organic carbon. At the same time, combined with the accumulation of reservoirs in China, it is estimated that the total amount of carbon storage in the reservoir sediment is 3.66 billion tons, and the value is increasing at the rate of 150 million tons per year. Based on the analysis of the characteristics of sediment carbon deposition in different regions, different landforms and different function reservoirs, the soil carbon and external carbon, reservoir sedimentation factors and sediment sedimentation rate of the basin are established. The correlation between the factors of aquatic vegetation and the content of endogenous carbon in sediment is discussed, and the method of predicting the carbon storage in reservoir sediment is put forward. The results of this study show that the prediction method can accurately predict the carbon reserves of the reservoir sediment. The source of organic matter in sediment is qualitatively analyzed and quantitatively calculated by using stable isotope technique. The results show that the contribution of exogenous source to organic matter of sediment is generally greater than that of endogenous reservoir, and the source of organic matter is located in a reservoir with high regional temperature. The dominant role of exogenous factors is greater. At the same time, the source composition of organic matter in reservoir sediment is different from that of natural lakes and rivers. According to the characteristics of reservoir impoundment and artificial water level management, as well as soil erosion and eutrophication, it is shown that the carbon deposition of reservoir is different from that of other freshwater ecosystems. The influence of reservoir impoundment on sediment carbon deposition is manifested in two aspects: the interception of external carbon and the accumulation of endogenous carbon, the difference of artificial management mode of reservoir water level will affect the distribution and source composition of organic carbon in sediment. Water and soil erosion in the basin results in the accumulation of a large amount of exogenous carbon into the reservoir and is mainly deposited in the delta region of the estuary. The eutrophication of the water body significantly increases the deposition of endogenous carbon in the reservoir sediment.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：X143;TV145

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