Biogeochemical Cycling of Heavy Metals in Lake Coeur d'Alene Sediments: The Role of Indigenous Microbial Communities

0420374佩顿重金属在环境中具有很高的毒性，它们在爱达荷州的科达伦湖（LCdA）沉积物中的存在主要是上游山区历史采矿的结果。 本项目的目标是：1）利用现代分子生物学技术表征LCdA沉积物中微生物的多样性，2）量化微生物群落中单个成员在金属（Cu，Pb和Zn）的生态地球化学循环中的作用，3）开发沉积物系统中重金属循环的动态数值生态地球化学模型，校准到LCdA的独特环境。 这些目标将得到满足，同时测试以下的总体假设：一个复杂的和动态的社区，在历史上的金属污染的沉积物的科达伦湖的微生物是独特的，以前没有特征的微生物。 在有毒金属胁迫下，耐金属物种将主导沉积物中存在的金属敏感物种，时间和空间的微生物分布和多样性取决于金属的类型和浓度。 动态生物地球化学模型将化学迁移和反应与新的微生物压力/反应关系和群落动态结合起来，可用于：1）整合空间和时间尺度上复杂的微生物和地球化学观测; 2）更好地预测广泛的群落水平的反应和对有毒金属循环的影响。该项目将显著提高对沉积物微生物群落在严重重金属胁迫下的相互作用和响应的定量理解。 项目目标将通过对LCdA沉积物进行采样并根据16 S rDNA和rpoB基因序列鉴定微生物多样性来实现。 这些分子技术极大地促进了对自然环境中微生物的研究，并将提供一个合理的平台，以观察社区对有毒金属添加物的反应。 将使用末端限制性片段长度多态性（T-RFLP）定量金属强制降解后微生物种群的变化。 重点实验室研究将用于量化有毒金属对微生物生长和抑制的影响，以纳入预测模型。建模工作将首次整合到我们的知识，互养财团生物转化动力学，剂量依赖性抑制，氧化还原前沿形成的扩散运输制度下的空间和时间动态。 拟议活动产生的更广泛影响：虽然研究重点是历史上金属污染的LCdA沉积物中的微生物群落，但随着全球工业化的增加，环境和人类污染物的相互作用已成为美国和国际上科学和社会上更重要的问题。 该项目整合了研究指导和毕业生，博士后助理和研究人员的培训。 本科生研究经验的补充补助金将用于将本科生纳入研究。 研究结果将发表在一些高质量的同行评审期刊文章中，并将通过在当地监管和公共会议以及国家和国际会议上的演讲向公众传达。 将建立一个为科学家和非技术读者编写的因特网网址。 完成后，这项研究将大大扩展对金属关键地球化学过程的基本和定量理解。 该项目有可能建议从根本上改进金属生物修复技术，因为其结果将广泛适用于支持创新的生物战略，以减少金属污染场地对人类健康的风险和环境的破坏

0420374PeytonHeavy metals are highly toxic in the environment and their presence in sediments of Lake Coeur d'Alene (LCdA) in Idaho is mainly the result of historical mining in the mountains upstream. The objectives of this project are to 1) characterize the diversity of microorganisms in LCdA sediments using modern molecular biology techniques, 2) quantify the role of individual members of the microbial community in biogeochemical cycling of metals (Cu, Pb, and Zn), and 3) develop a dynamic numeric biogeochemical model of heavy metal cycling in sediment systems, calibrated to the unique environments of LCdA. These objectives will be met while testing the following overall hypothesis:A complex and dynamic community of phylogenetically distinct and previously uncharacterized microorganisms is present in the historically metal-contaminated sediments of Lake Coeur d'Alene. In response to a toxic metal stress, metal-tolerant species will dominate metal-sensitive species present in the sediments, with temporal and spatial microbial distribution and diversity dependant on the metal type and concentration. Dynamic biogeochemical models that incorporate chemical transport and reaction with novel microbial stress/response relationships and community dynamics can be used to 1) integrate complex microbial and geochemical observations across spatial and temporal scales, and 2) better predict broad community level response and influence on toxic metal cycling.Intellectual merit of the proposed activity: This project will significantly improve the quantitative understanding of interaction and response of a sediment microbial community subjected to severe heavy metal stress. Project objectives will be achieved by sampling LCdA sediments and identifying microbial diversity based on both 16S rDNA and rpoB gene sequences. These molecular techniques greatly facilitate the study of microbes in their natural environments and will provide a rational platform to base observations of community response to toxic metal additions. Shifts in microbial populations after being subjected to metal-stress will be quantified using terminal-restriction fragment length polymorphism (T-RFLP). Focused laboratory studies will be used to quantify the effects of toxic metals on microbial growth and inhibition for incorporation into the predictive model. The modeling effort will integrate for the first time to our knowledge, syntrophic consortium biotransformation dynamics, dose-dependent inhibition, and spatial and temporal dynamics of redox front formation under a diffusive transport regime. Broader impacts resulting from the proposed activity: While the research is focused on microbial communities in historically metal contaminated LCdA sediment, with increased industrialization worldwide, interactions of the environment and human contaminants have become more important issues, scientifically and socially, to the U.S. and internationally. The project integrates research mentoring and training of graduates, postdoctoral associate, and a research faculty. A supplemental grant for research experiences for undergraduates will be used to integrate undergraduate students into the research. The results will be published in a number of quality peer reviewed journal articles and will be conveyed to the public through presentations at local regulatory and public meetings, and at national and international conferences. An internet web site written for both scientists and non-technical readers will be developed. When complete, this research will significantly expand the fundamental and quantitative understanding of key biogeochemical processes for metals. The project has the potential to suggest fundamental improvements in metals-bioremediation technologies, since results will be broadly applicable in supporting innovative biological strategies to reduce human health risks and environmental damage from metal contaminated sites