Collaborative Research: Selenium redox reactions and isotope ratios: The role of microbial and abiotic Selenium oxidation

合作研究：硒氧化还原反应和同位素比：微生物和非生物硒氧化的作用

• 批准号: 1529830
• 负责人: Thomas Johnson
• 金额: $ 8.6万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2019-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1529830&HistoricalAwards=false
• 关键词: Collaborative; Research; Selenium; redox; reactions

Selenium (Se) is an essential micronutrient, a potential environmental contaminant, and an indicator of chemical reactions involving oxidation and reduction, in both present and past environmental systems. Chemical and biological processes control the mobility and environmental impact of Se. Although Se oxidation is an important Se-mobilizing process, our understanding of this process is limited. Additionally, although measurements of variations in Se stable isotope abundances (82Se/76Se ratios) provide a powerful new way to study key chemical reactions involving Se in modern and ancient environments, poor understanding of Se stable isotope shifts caused by Se oxidation limits interpretation of Se isotope data. Therefore, this project will investigate stable Se isotope variation caused by oxidation as a means to achieve a robust understanding of Se oxidation in the environment. Investigators will train one postdoctoral fellow, two doctoral students, and 6-8 undergraduate students per year through programs that target underrepresented students. The societal benefits of this project include communications with the concerned governmental agencies to enable better assessments of Se fate linked to human nutritional adequacy, toxic thresholds and the fundamental understanding of Se in the earth system.The scope of the project is to integrate stable isotope geochemistry and microbiology to gain an improved understanding of biotic and abiotic Se oxidation. The specific objectives are to (1) demonstrate that microbial Se oxidation supports chemoautotrophic growth, (2) determine the magnitude of Se isotopic fractionation caused by microbial and abiotic oxidation of reduced Se-species, and (3) examine oxidation of Se in natural soil/sediment matrices to determine how the laboratory-derived fractionation factors will apply in natural environments. Controlled laboratory experiments will be conducted to determine reaction rates and Se isotope fractionation during microbial and abiotic Se oxidation. Slurry experiments with soils and sediments of two different field sites will provide complementary understanding of Se oxidation in natural samples under well-defined conditions. By establishing a link between Se oxidation and Se isotope fractionation, the results will open new avenues for studies of Se cycling and the fate of Se as a micronutrient and contaminant.

硒（SE）是必不可少的微量营养素，一种潜在的环境污染物，并且是当前和过去环境系统中涉及氧化和还原的化学反应指标。化学和生物过程控制SE的活动性和环境影响。尽管SE氧化是一个重要的SE-SE-MOBILE过程，但我们对这一过程的理解是有限的。此外，尽管对SE稳定的同位素丰度（82SE/76SE比率）的变化的测量为研究涉及SE在现代和古老环境中涉及SE的关键化学反应提供了一种有力的新方法，但对SE氧化限制SE同位素数据的解释引起的SE稳定同位素转移的了解不足。因此，该项目将研究由氧化引起的稳定的SE同位素变化，以此作为实现对环境中SE氧化的强烈理解的一种手段。调查人员将通过针对代表性不足的学生进行培训一名博士后研究员，两名博士生和6-8名本科生。该项目的社会利益包括与有关政府机构的沟通，以更好地评估与人类营养充足性，有毒阈值以及对地球系统中SE的基本了解有关的SE命运。该项目的范围是整合稳定的同位素地球化学和微生物学，以提高对生物的了解，以提高对生物的了解。特定目标是（1）证明，微生物SE氧化支持化学自动营养的生长，（2）确定SE同位素分馏的大小是由微生物和非生物氧化减少的SE物种所引起的，（3）（3）检查自然土壤/沉积物中SE的氧化以确定自然层次范围内的自然层次范围差异。将进行受控实验室实验，以确定微生物和非生物SE氧化过程中的反应速率和SE同位素分馏。对两个不同田间位点的土壤和沉积物进行的泥浆实验将在定义明确的条件下对天然样品中的SE氧化提供互补的理解。通过建立SE氧化与SE同位素分馏之间的联系，结果将为SE循环研究和SE作为微量营养素和污染物的命运开辟新的途径。