Collaborative Research: Experimental calibration of the isotopic content of marine sulfate

合作研究：海洋硫酸盐同位素含量的实验校准

• 批准号: 1536574
• 负责人: David Johnston
• 金额: $ 7.4万
• 依托单位: Harvard University
• 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 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1536574&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimental; calibration; isotopic

Collaborative Research: Experimental Calibration of the Isotopic Content of Marine SulfateAlexander BradleyID: 1536559Sulfur is an essential element to life, and its biogeochemical cycle is of interest to a broad range of scientific disciplines. A requirement for understanding the sulfur cycle involves revealing and quantifying the mechanisms by which microbes oxidize and reduce sulfur species. This can be done by tracing stable sulfur and oxygen isotopes. Enzymes play a key role in the cycling of sulfur, but the degree to which individual enzymes preferentially use specific oxygen isotopes (fractionation) is not known and prevents complete understanding of observed oxygen isotopes patterns in marine sulfate. This project will investigate isotope fractionation (oxygen and sulfur) associated with two key enzymes, which are involved in the metabolism of both sulfate reducing microbes and some sulfur oxidizing microbes. Resolving the influence of these enzymes on the isotopic composition of marine sulfate is important to stable isotope biogeochemistry and chemical oceanography. The project will serve as a vehicle to educate and train a postdoctoral researcher and undergraduate students, and will provide a teacher training opportunity in the investigators' labs to aid teachers in the design of student field trips and hands-on exercises for their students.The cycling of sulfur between its oxidized and reduced forms is a major determinant of the oxidation of organic matter in the oceans and underlying sediments, and microbes play a key role in the biogeochemical cycling of sulfur. One of the key tracers of microbial sulfur cycling involves measuring the distribution of stable isotopes among sulfur phases. A number of studies have shown that the stable oxygen isotope composition of sulfate is an informative way to investigate the sulfur cycle. Despite its utility, there are few direct constraints on how biology impacts the oxygen isotopes of sulfate. The goal of this project is to place quantitative constraints on the enzymatic oxygen isotope fractionation associated with microbial sulfate reduction. This project will involve in vitro investigations of the kinetic isotope fractionations associated with ATP sulfurylase and APS reductase, and incorporate the resulting data into an existing model for understanding isotope fractionation during sulfate reduction and its resulting influence on the isotopic composition of marine sulfate. These models will provide critical insight into the behavior of the sulfur cycle and evolution of marine chemistry over key timescales.

协作研究：海洋硫酸盐硫磺的同位素含量的实验校准：1536559Sulfur是生命的重要元素，其生物地球化学周期对广泛的科学纪律范围都很有趣。理解硫周期的需求涉及揭示和量化微生物氧化和减少硫种类的机制。这可以通过追踪稳定的硫和氧同位素来完成。酶在硫的循环中起关键作用，但是尚不清楚单个酶优先使用特定的氧同位素（分级）的程度，并且无法完全了解海洋硫酸盐中观察到的氧气同位素模式。该项目将研究与两个关键酶相关的同位素分馏（氧和硫），这些酶涉及硫酸盐还原微生物和一些硫酸氧化微生物的代谢。解决这些酶对海洋硫酸盐同位素组成的影响对于稳定的同位素生物地球化学和化学海洋学很重要。该项目将作为教育和培训博士后研究人员和本科生的工具，并将在调查人员的实验室中提供教师培训机会，以帮助老师为学生设计学生实地考察和动手练习。氧化和还原形式之间的硫磺循环是氧化和减少形式的主要确定性，并在海洋中的氧化量是有机化的氧化，并在海洋中氧化了，这是有机化的氧化量。硫的生物地球化学循环。微生物硫循环的关键示踪剂之一是测量硫相之间稳定同位素的分布。许多研究表明，硫酸盐的稳定氧同位素组成是研究硫循环的一种信息。尽管有效用，但几乎没有直接限制生物学如何影响硫酸盐的氧同位素。该项目的目的是将定量约束放在与微生物硫酸盐还原相关的酶氧同位素分馏上。该项目将涉及与ATP硫酸盐酶和APS还原酶相关的动力学同位素分馏的体外研究，并将所得数据纳入现有模型中，以理解硫酸盐还原过程中同位素分馏及其对海洋硫酸盐同位素组成的影响。这些模型将为关键时标的硫周期和海洋化学演变的行为提供关键的见解。