Microbial controls of mercury geochemistry

汞地球化学的微生物控制

• 批准号: RGPIN-2019-04134
• 负责人: Poulain, Alexandre
• 金额: $ 5.46万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=714644
• 关键词: Microbial; controls; mercury; geochemistry

My research program investigates how microbes control the entry of contaminants into food webs. I study how microbes sense and transform metals and how such processes evolved. Although I am broadly interested in threats to ecosystem health that are associated with toxic metal(oid)s, this proposal focuses on mercury (Hg) biogeochemistry. Globally, Hg is a priority contaminant due to biomagnification of the potent neurotoxin methylmercury (MeHg) in food webs. Microbes are involved in most reactions controlling the relative abundance of Hg species in the environment. Some microbes catalyze the interconversion between Hg(II) and its elemental volatile form, Hg(0), while others catalyze the production and degradation of MeHg. The relative importance of such reactions varies throughout geochemical gradients, from oxic to low redox potential methanogenic or sulfidic environments. My long-term objective is to identify the microbial controls of Hg geochemistry in past and current environments. The continued importance of Hg as a chemical of concern to human health was underscored by the recent ratification of the UNEP Minamata convention (2017) that requires governments to regulate Hg emissions and their environmental impacts, and to ban the export of Hg waste to other countries. With this new international regulatory context, industries must develop solutions to deal with their domestic Hg waste. Over the next 5 years, my program will train 31 HQPs while addressing knowledge gaps identified in the UNEP Global Hg assessment and supporting implementation of the Minamata convention, namely the link between Hg deposition, methylation and uptake by organisms, the parameters that determine the rates of exchange between air, water, air and soil and a better characterization of the lag in aquatic ecosystem response to atmospheric mercury deposition. My first objective is to evaluate whether there are universal controls of Hg bioavailability across microbial taxa. My second objective is to determine anaerobic microbial reduction processes. My third objective aims to develop genomic paleo-proxies for historical Hg deposition and determine to which extent bacterial metal resistance mechanisms have evolved in response to recent changes in metal delivery to ecosystems over broad spatial scales. Indeed, the development of effective risk reduction strategies depends on a comprehensive understanding of the present and past effects of toxic pollutants on ecosystems.

我的研究项目研究微生物如何控制污染物进入食物网。我研究微生物如何感知和转化金属，以及这些过程是如何进化的。虽然我对与有毒金属（oid）有关的生态系统健康威胁广泛感兴趣，但本提案侧重于汞（Hg）的地球化学。在全球范围内，汞是一种重要的污染物，这是由于食物网中的强效神经毒素甲基汞（MeHg）具有生物放大作用。微生物参与了控制环境中汞物种相对丰度的大多数反应。一些微生物催化Hg（II）与其元素挥发形式Hg（0）之间的相互转化，而另一些微生物则催化甲基汞的产生和降解。这种反应的相对重要性在整个地球化学梯度中变化，从好氧到低氧化还原电位的产甲烷或硫化物环境。我的长期目标是确定汞地球化学在过去和现在的环境中的微生物控制。最近批准的联合国环境规划署水俣公约（2017年）强调了汞作为一种对人类健康有影响的化学品的持续重要性，该公约要求各国政府监管汞排放及其环境影响，并禁止向其他国家出口汞废物。在这一新的国际监管背景下，各行业必须制定解决方案来处理其国内汞废物。在接下来的5年里，我的项目将培训31名HQP，同时解决环境署全球汞评估中发现的知识差距，并支持水俣公约的实施，即汞沉积、甲基化和生物体吸收之间的联系，这些参数决定了空气、水、大气和土壤中的汞含量，以及水生生态系统对大气汞沉降反应滞后的更好表征。我的第一个目标是评估是否有通用的控制汞生物利用度的微生物类群。我的第二个目标是确定厌氧微生物还原过程。我的第三个目标是开发基因组古代理历史汞沉积，并确定在何种程度上细菌金属抗性机制的演变，以应对最近的变化，金属交付到生态系统在广泛的空间尺度。实际上，制定有效的减少风险战略取决于对有毒污染物目前和过去对生态系统的影响的全面了解。