【作者】 陈瑜鹏；

【导师】 魏世强； 冯新斌；

【作者基本信息】 西南大学 ， 环境科学， 2010， 硕士

【摘要】 “蓄水河流”生态系统正在成为典型的“汞敏感生态系统”(Mercury-sensitive ecosystems)。在世界河流正广泛地受到筑坝拦截影响的背景下,大型水库对河流汞生物地球化学循环影响的研究,已受到国际上的普遍重视。筑坝拦截形成的水库环境被证实为有利于汞活化、甲基化和生物累积的场所。水库对汞转化和(甲基)汞污染的“敏感性”,迫使我们不得不重新审视蓄水河流汞污染的生态风险。本文从2006-2009年间将乌江流域不同演化阶段的6个水库作为研究对象,对水库入出库河流中不同形态汞的浓度进行了连续四年的系统观测,为不同水库中汞的研究提供了基础数据,探讨水库建造对河流汞形态的影响,主要研究内容有以下两个方面:(1)各水库入出库河流中汞的分布特征；(2)大气降水中汞浓度,得出以下主要结论：1乌江流域河流中总汞、活性汞、颗粒态汞、溶解态汞、总甲基汞、溶解态甲基汞在2006-2009年四年间算术平均浓度分别为5.56±14.0、0.29±0.32、3.33±12.05、1.70±1.63、0.12±0.11、0.07±0.05ng／L。与本文所选国内外其他河流比较发现,总汞的浓度低于国外受到污染的河流,略高于国外未受污染的河流。活性汞、溶解态汞、甲基汞的浓度略低于受污染的河流,和未受污染河流基本相当。与国内其他河流相比如松花江、黄浦江以及偏远的雅鲁藏布江相比,发现其总汞远远低于受到污染的河流,略高于未受到污染的河流。2从2006-2009年,总汞和甲基汞的年均算术和加权浓度,可以得出总汞在08年出现了四年中的最高值,结合采样月份和采样地点对比分析,可能与08年冰冻灾害和汶川地震有关；出入库河流水体中甲基汞浓度的年均变化(除洪家渡水库外),06-09年呈现逐年降低的趋势。对比出入库河流水体中总汞加权浓度：发现水库对总汞有“清除”作用,在乌江流域上游的普定、洪家渡水库尤为明显。3水库的修建显著降低了出库河流中总汞、颗粒态汞的浓度,在库区内部发生甲基化作用,使总甲基汞和溶解态甲基汞的浓度升高,从而增加了出库河流中总甲基汞、溶解态甲基汞、活性汞占总汞的比例。梯级水库的修建改变了河流原有的汞的生物地球化学过程,使汞的形态组成、空间分布发生变化,改变了河流原有的分布情况和输送过程。随水库生态系统的不断演化,输出的甲基汞浓度有随水库库龄增加而增加的趋势。4大气降雨中总汞、甲基汞的浓度分别为47.54±29.91、0.13±0.11ng/l。在2006-2009年间,总汞和甲基汞算加权平均浓度呈现出一个逐年降低的趋势,并且有明显的季节变化趋势,冬春季高于夏秋季;方差分析总求空间分布差异性显著,甲基汞空间分布差异性不明显。与国内外其他区域的大气降雨相比,本流域雨水中总汞含量远高于北美和我过长白山地区：甲基汞浓度与美国的Long Island Sound和Superior湖基本相当。更多还原

【Abstract】 ’Storage of water river’ecosystem is a typical’Mercury-sensitive ecosystems’. Rivers in the world are widely affected by damming the background of large reservoirs on the rivers of mercury biogeochemical cycles of the study, which has been received widespread international attention. Reservoirs formed by damming are the environment which found to be conducive to the activation of mercury, methylation and bioaccumulation place. The sensitivity of mercury transformation and (methyl) mercury pollution in the reservoir, forcing us had to re-examine the ecological risk of mercury pollution of the river water.In this article we studied the 6 reservoirs in different evolution stages of the Wujiang River between the year 2006 and 2009, and we also carried out a systematic observation toward the concentration of different forms of mercury in the river inflows and outflows of the reservoir(January,2006 to June,2007, Guo Yanna; July,2007 to September,2007, Xie Wen; October,2007 to September,2008,Yang Fang; October, 2008 to December,2009, the author).Different reservoirs of mercury in the basic data were provided; we also discussed the construction of reservoirs on the river morphology of mercury. There are three main research topics in this thesis, (1) Characteristics of mercury speciation and distribution inflows and outflows of six reservoirs; (2) the concentration of mercury in precipitation. Based on the detailed researches, the main conclusions we have obtained are as follows:1.The mean annual concentration in four years of total, particulate, dissolved, reactive, total methyl and dissolved methyl mercury in Wujiang River was 5.56±14.0, 0.29±0.32,3.33±12.05,1.70±1.63,0.12±0.11、0.07±0.05ng/L, respectively. Compared to published data from foreign countries, concentrations of THg were significantly lower than values in polluted rivers, and slightly higher than values in unpolluted rivers. Concentrations of DHg, RHg, and TMeHg were slightly lower than those in Hg-impacted rivers, and similar to levels in uncontaminated rivers. Compared to Songhua River, Huangpu River and the remote Brahmaputra, mercury levels were significantly lower.2. From the year 2006 to 2009, the weighted average concentration of total mercury and methylmercury can be drawn the maximum appear in 2008 of the four years. Combined with sampling month and sampling sites comparative analysis, this phenomenon may attribute to the deep-freeze disaster and earthquake in 2008. The average annual change concentration of methylmercury inflows and outflows of the reservoir (except for Hongjiadu reservoir) showed a current decrease year by year from 2006 to 2009. Compared with the weighted average concentration of total mercury inflows and outflows of the reservoir, the total mercury found in reservoirs took on a "clear" function, especially in Puddings and Hongjiadu reservoir in the upstream of Wujiang River.3. Due to the construction of reservoir, concentrations of THg and PHg in outflow rivers decreased, while concentrations of TMeHg and DMeHg increased, and elevated ratio of DHg, RHg, TMeHg to THg also appeared in outflow rivers. Distribution of Hg along the Wujiang River showed that construction of cascade reservoirs influenced the initial biogeochemical cycling of Hg, and concentration of methyl mercury increased at several sites below reservoir. Therefore, it is possible that MeHg would increase with the evolution of reservoir.4. The concentration of THg and TMeHg are 47.54±29.91、0.13±0.11ng/l, respectively. From 2006 to 2009, the total mercury and methylmercury count showed a weighted average concentration decreased year by year, and marked seasonal trend, winter and spring higher than summer and autumn; Analysis of variance spatial distribution of total mercury was significantly higher, and there is no significant difference spatial distribution of methylmercury. The concentration of Methylmercury is roughly equal to the Long Island Sound lake and Superior lake in the United States.更多还原