富营养化水库食物链中汞和脂肪酸的积累模式

发布时间：2018-01-01 06:23

本文关键词：富营养化水库食物链中汞和脂肪酸的积累模式　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：甲基汞作为毒性最强的有机汞化合物,极易在水生食物链中传递、积累和生物放大,致使高营养级生物体中的汞含量超标,并最终对水产品消费人群的健康构成威胁。研究发现,水库营养化程度不仅影响水环境中汞的甲基化率,而且也影响食物链中汞的积累,而我国的大部分水体均呈富营养化状态,因此,探究富营养化水库中汞的积累模式及其影响因素十分重要。必需脂肪酸作为脂肪酸的重要组成部分,不仅是人类健康必需的营养物质,也是水生动物如鱼类等生命必需的营养物质。水库的富营养化导致的藻类种群结构变化会势必会极大的影响到必需脂肪酸在食物链的传输和积累。其次,由于脂肪酸在被生物吸收后具有保守性,脂肪酸也被作为重要的生物标记物示踪食物来源。本研究旨在将脂肪酸和汞在食物链中的积累模式结合、比较,探究富营养化状况对食物链中汞与能量传输的影响。同时,结合碳氮稳定同位素,探究水生食物链中脂肪酸随食物链的积累特征。本研究以贵州省乌江流域七个梯级水库为研究对象,按其富营养化程度水库分为:富营养化水库(乌江渡)、中富营养化水库(百花湖和红枫湖)、贫中营养化水库(洪家渡、引子渡、东风、索风营)。分别采集了水样、浮游生物、底栖生鱼类。通过测定其中的总汞、甲基汞及生物体中的碳氮同位素,乌江渡和红枫湖两个水库生物样品的脂肪酸含量,研究不同富营养化水库食物链中汞和脂肪酸的积累模式,主要结论如下:(1)生物体汞含量,以及生物富集放大率大小在不同营养化水库中的变化趋势不同。(2)水体汞浓度与鱼体汞浓度之间无明显正相关关系,富营养化因子叶绿素a与食物链中甲基汞含量呈明显负相关性关系,总氮、总磷含量与食物链中甲基汞含量相关性不明显。此外,各个水库的食物链长度不同,食物链中汞的生物传输率不同,造成顶端食物链中的汞含量以及甲基汞在总汞所占百分含量的差异。(3)乌江渡和红枫湖水库五种必需脂肪酸组成不同,其中红枫湖食物链及浮游生物中n-3PUFAs的百分含量高于乌江渡,原因可能是富营养化会导致水生食物链中n-3PUFAs的减少。(4)必需脂肪酸不随营养级的升高而增加;甲基汞与总脂肪及必需脂肪酸之间均无明显相关关系;根据甲基汞与不同脂肪酸之间的相关性显示:乌江渡和红枫湖食物链中的甲基汞均来自于细菌类食物源,和藻类及陆地食物源无明显关系。
[Abstract]:As the most toxic organic mercury compound, methylmercury is easy to transfer, accumulate and biomagnify in the aquatic food chain, resulting in the mercury content in high nutritious organisms exceeds the standard. The study found that the level of reservoir nutrition not only affects the methylation rate of mercury in the water environment, but also affects the accumulation of mercury in the food chain. However, most of the water bodies in China are eutrophication. Therefore, it is very important to explore the accumulation mode of mercury in eutrophication reservoirs and its influencing factors. Essential fatty acids are important components of fatty acids. It is not only a necessary nutrient for human health. Eutrophication caused by eutrophication of the reservoir will inevitably greatly affect the transport and accumulation of essential fatty acids in the food chain. Since fatty acids are conserved after bioabsorption, fatty acids are also used as important biomarkers to trace food sources. The aim of this study was to combine fatty acids with mercury accumulation patterns in the food chain. Explore the effects of eutrophication on mercury and energy transport in the food chain, and combine carbon and nitrogen stable isotopes. To explore the accumulation characteristics of fatty acids in aquatic food chain. This study took seven cascaded reservoirs in Wujiang River Basin of Guizhou Province as the research object and divided them into eutrophication reservoirs (Wujiangdu) according to their eutrophication degree. Middle eutrophication reservoirs (Baihua Lake and Hongfeng Lake) and poor and medium nutritious reservoirs (Hongjiadu, Yinzidu, Dongfeng, Suofengying). Water samples, plankton and benthic fish were collected respectively. Carbon and nitrogen isotopes in methylmercury and organisms, fatty acid contents in two reservoirs, Wujiangdu and Hongfeng Lake, were used to study the accumulation patterns of mercury and fatty acids in the food chain of different eutrophication reservoirs. The main conclusions are as follows: (1) there is no significant positive correlation between mercury concentration in water and mercury concentration in fish. There was a negative correlation between chlorophyll a and methylmercury content in food chain, but there was no significant correlation between total nitrogen and total phosphorus content and methylmercury content in food chain. In addition, the length of food chain was different in different reservoirs. The different biotransport rate of mercury in the food chain results in the difference of mercury content in the top food chain and the percentage of methylmercury in the total mercury content. 3) the composition of five essential fatty acids in Wujiangdu and Hongfeng Lake reservoirs is different. The content of n-3 PUFAs in food chain and plankton in Hongfeng Lake was higher than that in Wujiangdu. The reason may be that eutrophication leads to the decrease of n-3PUFAs in aquatic food chain. There was no significant correlation between methylmercury and total fat and essential fatty acids. According to the correlation between methylmercury and different fatty acids, methylmercury in the food chain of Wujiangdu and Hongfeng Lake were derived from bacterial food sources, but had no obvious relationship with algae and terrestrial food sources.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X524

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