Ecological processes controlling methylmercury production in prairie wetlands

无机汞（HgII）的微生物甲基化是环境汞循环中最重要的转化，因为其产物是一种神经毒性的甲基化形式的汞（甲基汞；MeHg），很容易被人类和野生动物生物积累。甲基汞的产生被认为主要是由微生物介导的，水生环境中汞甲基化的量取决于控制微生物种群生长或代谢功能的环境因素。促进汞甲基化的因素在湿地沉积物中尤为重要，北美大平原草原湿地为汞甲基化的高速率提供了理想的条件。草原湿地是重要的野生动物栖息地，为数百种狩猎和非狩猎野生动物提供了掩护和筑巢地，并包含了北美现存的一些最重要的水禽繁殖栖息地。甲基汞产量的增加可能给草原野生动物带来重大的健康和环境风险。同样，如果水禽的甲基汞浓度很高，猎人和他们的家人在食用草原野生动物时可能会接触到超过汞消费指南的甲基汞水平。目前关于草原湿地中甲基汞的信息尚不明确，这一课题提出了两个重要问题：1.草原湿地中甲基汞的存在；不同类型草原湿地水体、沉积物和生物群中甲基汞的浓度有哪些？和2。控制草原湿地甲基汞产生的化学和物理机制是什么？为了描述草原湿地甲基汞的产生和生物积累，作者提出了一个新的生态系统水平的研究，旨在探讨草原湿地甲基汞产生的环境因素。这项研究将为草原食物网中甲基汞的生物生产和随后的吸收的途径和调节机制提供新的见解。研究调节草原湿地甲基汞产生的环境因素对于解决理解汞甲基化环境控制的基本空白至关重要，并将为保护居住在这些脆弱栖息地的野生动物种群提供必要的信息。

The microbial methylation of inorganic mercury (HgII) is the most important transformation in the environmental Hg cycle because the product, a neurotoxic, methylated form of Hg (methylmercury; MeHg), is easily bioaccumulated by humans and wildlife.  MeHg production is thought to be mainly mediated by microbes and the amount of Hg methylation in an aquatic environment depends on environmental factors that control microbial population growth or metabolic function.  Factors that promote Hg methylation are particularly important in wetland sediments and prairie wetlands across the Great Plains of North America offer ideal conditions for high rates of Hg methylation.  Prairie wetlands are critical wildlife habitats, providing cover and nesting sites for hundreds of game and non-game wildlife species and containing the some of the most important waterfowl breeding habitat remaining in North America.  Elevated rates of MeHg production could result in significant health and environmental risks to prairie wildlife.  As well, if waterfowl have high MeHg concentrations, hunters and their families consuming prairie wildlife could be exposed to MeHg levels that exceed Hg consumption guidelines.  There is no current information on MeHg in prairie wetlands and this topic raises two important questions: 1. What are the concentrations of MeHg in water, sediment, and biota in different types of prairie wetlands?; and 2. What are the chemical and physical mechanisms that control MeHg production in prairie wetlands?  To characterize the production and bioaccumulation of MeHg in prairie wetlands, I propose a new ecosystem-level study designed to investigate environmental factors regulating MeHg production in prairie wetlands.  This research will provide novel insights on the pathways and regulatory mechanisms involved in biological production, and the subsequent uptake, of MeHg into prairie food webs. Examining environmental factors regulating MeHg production in prairie wetlands is vital to addressing fundamental gaps in understanding of environmental controls on Hg methylation and will provide information necessary to protect wildlife populations inhabiting these vulnerable habitats.