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首页> 外文期刊>Journal of great lakes research >Mercury Concentrations in the Food Web of Lake Malawi, East Africa
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Mercury Concentrations in the Food Web of Lake Malawi, East Africa

机译：东非马拉维湖食物网中的汞含量

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摘要

Little is known about the concentrations of mercury (Hg) and factors affecting this contaminant in tropical freshwater biota. Lake Malawi, an East African Rift Valley lake, is internationally renowned for having the highest diversity of fish species in the world, and the lake supports subsistence fisheries for the three riparian countries. In this study the concentrations of Hg in fish and invertebrates collected from the lake in 1996 and 1997 were examined, and tissue stable carbon (δ~(13)C) and nitrogen (δ~(15)N) isotopes were used to distinguish and contrast those consumers relying upon carbon fixed by either benthic or pelagic primary producers, and their trophic positioning. Concentrations of Hg were generally low (2 to 200 ng/g wet weight) in fish from Lake Malawi. In addition, pelagic fish contained significantly higher concentrations of Hg than the benthic species. As in temperate systems, log-transformed Hg concentrations were significantly predicted by δ~(15)N and the highest concentrations of Hg were found in the largest fish within each species. The rate of Hg accumulation was not significantly different between the pelagic and benthic fishes but pelagic species had significantly higher Hg concentrations at a common weight and trophic position. The slope of the Hg-δ~(15)N relationship in Lake Malawi was comparable to what has been found in temperate and arctic lakes, suggesting that Hg accumulation in freshwater food webs is independent of climatic factors and species composition.
机译：关于汞（Hg）的浓度以及影响热带淡水生物群系中该污染物的因素知之甚少。马拉维湖是东非大裂谷湖，以世界上鱼类种类最多而闻名国际，该湖为这三个河岸国家提供自给自足的渔业。本文研究了1996年和1997年从湖泊中收集的鱼类和无脊椎动物中Hg的浓度，并使用组织稳定的碳（δ〜（13）C）和氮（δ〜（15）N）同位素进行区分和鉴定。相比之下，那些依靠底栖或浮游初级生产者固定的碳及其营养定位的消费者。马拉维湖鱼类的汞含量通常较低（2至200 ng / g湿重）。此外，远洋鱼类的汞含量明显高于底栖鱼类。与温带系统一样，δ〜（15）N可以显着预测对数转化的Hg浓度，并且每个物种中最大的鱼类中Hg的浓度最高。远洋鱼类和底栖鱼类的汞积累速率没有显着差异，但是在相同的重量和营养位置，远洋鱼类的汞含量明显更高。马拉维湖中Hg-δ〜（15）N关系的斜率与温带和北极湖中的Hg-δ〜（15）N关系的斜率相当，表明淡水食物网中Hg的积累与气候因素和物种组成无关。

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