PECASE: Mercury Methylation in Sulfate-Reducing Biofilms

0348783j食物链中的汞污染是一个全球性问题，即使在原始地区也对公众健康构成威胁。在水生系统中，汞甲基化是一个关键过程，在此过程中，毒性较低的无机汞被微生物转化为甲基汞，甲基汞是一种强效神经毒素，在食物链中具有浓度放大的强烈趋势。虽然汞甲基化过程对于理解我们是否要预测或减轻汞污染的影响至关重要，但控制其速率的因素极其复杂。硫酸盐还原细菌（SRB）已被证明是广泛的水生系统中的主要汞甲基化者，汞对细菌的生物利用度以及存在的特定硫酸盐还原细菌的活性都已被证明是控制汞甲基化速率的重要因素。知识价值：这项工作解决了有关控制汞甲基化的环境因素的基本问题。本研究将阐明在还原环境中汞物种形成对甲基化的影响，硫酸盐还原菌菌株的重要性，以及硫酸盐还原生物膜形成对甲基化的影响。在服务学习方面的教育创新成果，亦会透过文献和可上网的文件，向公众公布。更广泛的影响：拟议工作的结果对于准确模拟汞在环境中的命运是必要的。获得的信息可以扩展到研究生物膜系统中的其他污染物，包括天然的和工程的。这项工作也可以直接应用于湿地恢复和湖泊管理决策。PI目前正在与加州大学洛杉矶分校体验教育和服务学习中心（CEESL）合作，开发一门创新的服务学习课程，加州大学洛杉矶分校的学生将在六年级的课堂上学习湿地的功能，然后向洛杉矶经济困难的学生讲授。该教学单元将包括四次课堂实验，并将以六年级学生（由加州大学洛杉矶分校学生陪同）到Ballona湿地的实地考察为高潮。每年夏天，PI将提供一次教师培训，以支持湿地科学课程。

0348783JayMercury (Hg) contamination of food chains is a worldwide problem, posing public health threats even in pristine areas. In aquatic systems, mercury methylation is a key process, whereby less-toxic inorganic mercury is microbially transformed to methylmercury, which is a potent neurotoxin with a strong tendency to magnify in concentration in food chains. While the process of mercury methylation is critical to understand if we are to predict or mitigate impacts due to mercury contamination, the factors controlling its rate are extremely complex. Sulfate-reducing bacteria (SRB) have been shown to be the primary mercury methylators in a wide range of aquatic systems, and bioavailability of mercury to the bacteria, as well as the activity of particular species of sulfate-reducing bacteria present, have both been shown to be important factors in controlling the rate of mercury methylation. Intellectual merit: This work addresses fundamental questions regarding the environmental factors controlling mercury methylation. This work will elucidate the effects of mercury speciation on methylation in reducing environments, the importance of the strain of sulfate-reducing bacteria, and the effects of biofilm formation on methylation in sulfate-reducing biofilms. Results from the educational innovations in service-learning will also be made available to the public via the literature and web-accessible documents. Broader impacts: Results from the proposed work are necessary for accurately modeling of the fate of mercury in the environment. Information gained can be extended to the study of other contaminants in biofilm systems, both natural and engineered. This work may also be directly applicable to wetland restoration and lake management decisions. The PI is currently working with the UCLA Center for Experiential Education and Service Learning (CEESL) to develop an innovative service-learning course in which UCLA students will learn and then teach wetland functions in grade 6 classrooms to economically disadvantaged students of Los Angeles. The teaching unit to be developed will involve four in-class laboratory sessions and will culminate in a field trip for the grade 6 students (accompanied by the UCLA students) to Ballona Wetland. A teacher training to support the wetland science curriculum will be given by the PI each summer.