权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Biogenic Calcium Carbonate Solubilities and Reaction Rates by Lab and Field Saturometry

通过实验室和现场饱和度测定法测定生物碳酸钙溶解度和反应速率

基本信息

批准号：
1923998
负责人：
Adam Subhas
金额：
$ 61.38万
依托单位：
Woods Hole Oceanographic Institution
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-01 至 2023-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1923998&HistoricalAwards=false
关键词：
Biogenic Calcium Carbonate Solubilities Reaction

项目摘要

The ocean actively exchanges carbon dioxide with the atmosphere and is currently absorbing about a third of the carbon dioxide humans emit through fossil fuel burning. Because carbon dioxide is acidic, ocean pH drops as it takes up carbon dioxide, a process known as "ocean acidification". Ocean acidification negatively affects the health of marine ecosystems by making it harder for organisms to grow their calcium carbonate shells. Yet, the dissolution of these calcium carbonate shells in the deep ocean helps neutralize the carbon dioxide we emit as humans. The extent to which this process takes place is a function of the solubility of marine calcium carbonate. This project will evaluate the temperature and pressure effects on the stability of biologically produced calcium carbonate minerals. The results from this study will allow us to better predict where, how much, and how fast, carbon dioxide will be neutralized and stored in the world's ocean. We will also investigate the ways in which small changes in the chemical composition of calcium carbonate shells - such as the incorporation of magnesium - influence their stability. This project will also conduct micro-computed tomography scans of microorganisms' shells to better visualize them in 3-dimensional detail. We will print these 3-dimensional scans for use as educational tools in the classroom and in the Woods Hole Visitor Center. In addition, professional development workshops for high school teacher on ocean acidification and the importance of marine calcification will be held yearly.The ocean is the ultimate repository for most of anthropogenic carbon dioxide emissions, which in turn is making ocean chemistry less favorable for biogenic carbonate precipitation through the process of ocean acidification. Ocean acidification decreases seawater pH but dissolution of primarily biogenic carbonate minerals has the capacity to buffer this acidification and over thousands of years push whole-ocean pH and atmospheric carbon dioxide to their preindustrial values. Unfortunately, the relationship between seawater chemistry, carbonate mineral solubility, and the kinetics that govern carbonate dissolution and precipitation are not fully understood. Currently, it is clear that relationships based solely on inorganic calcite are insufficient to describe the cycling of biogenic calcites in the ocean. This project will conduct a systematic determination of the solubilities and reaction kinetics of the three most common biogenic carbonates (coccoliths, foraminifera, and pteropods), both in the laboratory and in the field, using spectrophotometric pH saturometry. The saturometer incubates calcium carbonate with seawater in a closed system. During each run, the change in pH within the saturometer traces the progression of calcium carbonate dissolution/precipitation as the system approaches equilibrium. The saturometer therefore has the potential to link mechanistic interpretations of mineral dissolution/precipitation kinetics to measurements of solubility in a single experiment. The spectrophotometric pH method uses well-calibrated indicator dyes, allows solubility and data to be tied to modern pH calibrations and reference materials, and can be used in the laboratory or deployed on a hydrowire at sea. Field experiments will be conducted at multiple depths, elucidating in-situ controls on solubility and kinetics, as well as the sensitivity of biogenic calcite solubility to temperature and pressure. Experiments will be conducted from both sides of equilibrium, allowing for robust determinations of inorganic and biogenic solubilities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

海洋积极地与大气交换二氧化碳，目前正在吸收人类通过化石燃料燃烧排放的二氧化碳的约三分之一。由于二氧化碳是酸性的，海洋的pH值会随着二氧化碳的吸收而下降，这一过程被称为“海洋酸化”。海洋酸化对海洋生态系统的健康产生负面影响，使生物体更难生长碳酸钙外壳。然而，这些碳酸钙壳在深海中的溶解有助于中和我们作为人类排放的二氧化碳。这一过程发生的程度是海洋碳酸钙溶解度的函数。该项目将评估温度和压力对生物生产的碳酸钙矿物稳定性的影响。这项研究的结果将使我们能够更好地预测二氧化碳将在哪里，多少以及多快被中和并储存在世界海洋中。我们还将研究碳酸钙壳的化学组成的微小变化（如镁的掺入）如何影响其稳定性。该项目还将对微生物的外壳进行微型计算机断层扫描，以更好地显示它们的三维细节。我们将打印这些三维扫描作为教学工具在教室和伍兹霍尔游客中心使用。此外，每年还将为高中教师举办关于海洋酸化和海洋钙化重要性的专业发展讲习班。海洋是大多数人为二氧化碳排放的最终储存库，这反过来又使海洋化学通过海洋酸化过程不利于生物碳酸盐沉淀。海洋酸化降低了海水的pH值，但主要是生物成因的碳酸盐矿物的溶解有能力缓冲这种酸化，并在数千年的时间里将整个海洋的pH值和大气中的二氧化碳推到工业化前的水平。不幸的是，海水化学，碳酸盐矿物溶解度，以及碳酸盐溶解和沉淀的动力学之间的关系还没有完全理解。目前，很明显，仅基于无机方解石的关系不足以描述海洋中生物成因方解石的循环。该项目将在实验室和野外使用分光光度pH饱和度法系统测定三种最常见的生物碳酸盐（球菌、有孔虫和翼足类）的溶解度和反应动力学。饱和度计在封闭系统中用海水培养碳酸钙。在每次运行期间，饱和度计内的pH变化跟踪碳酸钙溶解/沉淀的进展，因为系统接近平衡。因此，饱和度计有可能将矿物溶解/沉淀动力学的机械解释与单个实验中的溶解度测量联系起来。分光光度法pH值方法使用校准良好的指示剂染料，允许将溶解度和数据与现代pH值校准和参考材料联系在一起，并且可以在实验室中使用或部署在海上的水文线上。将在多个深度进行现场实验，阐明对溶解度和动力学的原位控制，以及生物方解石溶解度对温度和压力的敏感性。实验将从平衡的两侧进行，以便对无机和生物溶解度进行强有力的测定。该奖项反映了NSF的法定使命，并且通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。