摘要
本文中,我们综合了有关生态系统无机汞(Hg)载荷变化与鱼体内甲基汞(MeHg)浓度之间联系的现有信息。尽管人们普遍假定水生生态系统汞载荷的增加导致鱼体内甲基汞浓度的增加,验证这一假定的定量数据尚很有限。这里,我们研究了源于一系列出处的现有证据:关于被工业排放物污染的生态系统的研究;关于鱼类甲基汞对大气载荷的响应的观测资料;跨越空间和环境梯度的研究以及实验操作。本文概述了目前对从汞载荷到鱼体甲基汞的运输和转化所涉及的主要过程的了解情况。还结合影响与鱼体内甲基汞响应的时机和大小有关的汞循环和生物积累的其他因素探讨了汞载荷的作用。所得出的主要结论是,汞载荷的变化(增加或减少)将引起鱼体内甲基汞的反应,这种反应的时间和大小将根据生态系统特有的变量和所添加的汞的形态而变化。
In this paper,we synthesize available information on the links between changes in ecosystem loading of inorganic mercury (Hg) and levels of methylmercury (MeHg) in fish.Although it is widely hypothesized that increased Hg load to aquatic ecosystems leads to increases in MeHg in fish,there is limited quantitative data to test this hypothesis.Here we examine the available evidence from a range of sources:studies of ecosystems contaminated by industrial discharges,observations of fish MeHg responses to changes in atmospheric load,studies over space and environmental gradients,and experimental manipulations.A summary of the current understanding of the main processes involved in the transport and transformation from Hg load to MeHg in fish is provided.The role of Hg loading is discussed in context with other factors affecting Hg cycling and bioaccumulation in relation to timing and magnitude of response in fish MeHg.The main conclusion drawn is that changes in Hg loading (increase or decrease) will yield a response in fish MeHg but that the timing and magnitude of the response will vary depending of ecosystem-specific variables and the form of the Hg loaded.
