Using novel genetic and isotopic techniques to understanding how microbial activity affects rates of dissolution of the mineral olivine.

使用新颖的遗传和同位素技术来了解微生物活动如何影响矿物橄榄石的溶解速率。

• 批准号: 1324929
• 负责人: A Joshua West
• 金额: $ 12.46万
• 依托单位: University of Southern California
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1324929&HistoricalAwards=false
• 关键词: Using; novel; genetic; isotopic; techniques

The results of this research will advance basic understanding in the Earth sciences and will have practical implications for understanding Earth's carbon cycle and the potential for carbon sequestration in mineral substrates. The chemical breakdown of minerals ("mineral dissolution") regulates the availability of carbon and other nutrient elements across a range of scales in space and time. This means that understanding mineral dissolution is fundamental to the study of the Earth system, and particularly to the study of Earth's climate and biosphere. The rate at which minerals dissolve is known to depend on a number of factors. Of these, the roles of biological activity and the approach to thermodynamic equilibrium remain particularly poorly understood. This knowledge gap stands in the way of efforts to develop models that scale laboratory observations to field conditions and makes it difficult to use the results from experimental studies to address large-scale Earth system problems. Meanwhile studies of weathering in natural systems are often confounded by multiple variables. The project proposed here will use novel experimental methods to take a major step forward in understanding how microbial activity and the approach to equilibrium affect the dissolution rate of the silicate mineral olivine. Olivine plays a key role in the carbon cycle as a primary constituent of highly weatherable rocks, and has been proposed as a substrate for carbon dioxide sequestration, making it a noteworthy mineral for focused investigation.Numerous field observations have shown that biological activity drives higher increased silicate weathering rates, but a mechanistic understanding is lacking because prior experimental efforts have been complicated by variations in the activity and phenotypic expression of organisms within and between experiments. To minimize this variability, experiments in the proposed study will be preformed using microorganisms with targeted genetic mutations. With this approach, the effects of a single microbial process can be isolated and quantified over a range of environmental conditions, allowing for a more robust determination of the effects of biological activity on olivine dissolution rates than have previously been possible. The dependence of mineral dissolution rates on the departure from thermodynamic equilibrium is a critical factor that controls dissolution rates in natural environments. Theoretical predictions vary significantly in both the functional form of the thermodynamic equilibrium dependence as well as the value of the thermodynamic equilibrium at which a significant change in rate is observed. For olivine, near-equilibrium experiments are complicated because solutions become supersaturated with respect to secondary magnesium silicate minerals that precipitate at non-negligible rates, making it impossible to quantify dissolution rates using standard methodologies. To circumvent this problem, a novel method of determining dissolution rates by isotope dilution will be used to study the near equilibrium dissolution kinetics of olivine.The project will support the training of a doctoral student, who will supervise high school students from traditionally underrepresented backgrounds. The doctoral student will also lead the development of a laboratory exercise that demonstrates the carbon dioxide sequestration potential of the mineral olivine while teaching basic science concepts. This exercise will be incorporated into a display at the University of Southern California and will be provided free of charge over the Internet for educational use at other institutions.

这项研究的结果将提高地球科学中的基本理解，并将对理解地球周期和矿物底物中碳固存的潜力具有实际意义。矿物质的化学分解（“矿物质溶解”）调节了时空中一系列尺度上碳和其他营养元素的可用性。这意味着了解矿物质溶解是对地球系统的研究，尤其是对地球气候和生物圈的研究至关重要的。已知矿物质溶解的速率取决于许多因素。其中，生物学活性的作用和热力学平衡的方法仍然特别了解。这种知识差距竭尽全力开发模型，以扩展实验室观察到现场条件，并使实验研究的结果难以解决大规模的地球系统问题。同时，自然系统中风化的研究通常被多个变量混淆。这里提出的项目将使用新型的实验方法迈出了重要的一步，以了解微生物活性和平衡方法如何影响硅酸盐矿物橄榄石的溶解速率。橄榄石是高度可口岩石的主要组成的碳循环中的关键作用，并已被提议作为二氧化碳二氧化碳隔离的底物的提议，这使其成为集中研究的值得注意的矿物质。逐渐研究的现场观察结果表明，生物学活动促进了较高的硅化速率，并且由于硅酸盐的发展而导致了硅酸盐的效果，并且在现场上缺乏硅酸盐的努力，而现有的努力则是相对的，现场的努力是对现场的反应。实验之间和之间的生物体。为了最大程度地减少这种可变性，将使用具有靶向遗传突变的微生物进行拟议研究的实验。通过这种方法，可以在一系列环境条件下分离和量化单个微生物过程的影响，从而可以比以前可能更强大地确定生物活性对橄榄石溶解速率的影响。矿物质溶解速率对脱离热力学平衡的依赖性是控制自然环境中溶解速率的关键因素。理论预测在热力学平衡依赖性的功能形式以及观察到速率显着变化的热力学平衡的值以及热力学平衡的值中都有很大差异。对于橄榄石，近平衡的实验是复杂的，因为溶液相对于以不可忽略的速率沉淀的硅酸盐矿物质过饱和，因此无法使用标准方法来量化溶解速率。为了解决这个问题，一种新的方法来确定同位素稀释的溶解率，将用于研究橄榄石的近乎平衡的溶解动力学。该项目将支持培训博士生的培训，该博士生将监督传统上代表性不足背景的高中生。博士生还将领导实验室演习的发展，该实验室演习表明矿物橄榄石在教授基础科学概念时具有二氧化碳的隔离潜力。该练习将被纳入南加州大学的展览中，并将通过互联网免费提供其他机构的教育用途。