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: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=745586
• 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.

我的研究项目是调查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演变的。尽管我对与有毒金属S(OID)有关的生态系统健康威胁普遍感兴趣，但这项建议侧重于汞(Hg)生物地球化学。在全球范围内，由于食物网中强有力的神经毒素甲基汞(MeHg)的生物放大，汞是一种优先污染物。微生物参与了大多数控制环境中汞物种相对丰度的反应。一些微生物催化汞(II)与其元素挥发性形式汞(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。这些反应的相对重要性在不同的地化梯度中是不同的，从氧化到低氧化还原电位，产甲烷或硫化环境。我的长期目标是确定过去和现在环境中汞地球化学的微生物控制。环境规划署最近批准了《水稻田公约》(2017)，该公约要求各国政府管制汞排放及其对环境的影响，并禁止向其他国家出口汞废物，这突显了汞作为一种令人关切的化学品对人类健康的持续重要性。在这种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，我的计划将培训31名HQP，同时解决联合国环境规划署全球汞评估中确定的知识空白，并支持水稻田公约的实施，即汞沉积、甲基化和生物吸收之间的联系，决定空气、水、空气和土壤之间交换率的参数，以及更好地表征水生生态系统对大气汞沉积反应的滞后。我的第一个目标是评估是否存在跨微生物类群的汞生物利用度的通用控制。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汞历史沉积的基因组古替代物，并确定细菌金属抗性机制在多大程度上随着金属在广泛空间尺度上向生态系统输送的最近变化而演变。事实上，制定有效的减少风险战略取决于对有毒污染物现在和过去对生态系统的影响的全面了解。