Experimental Determination of Temperature and Precipitation Rate Effects on Element Partitioning Between Aragonite and Seawater

温度和降水率对文石和海水元素分配影响的实验测定

• 批准号: 0527350
• 负责人: Glenn Gaetani
• 金额: --
• 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: 2005
• 资助国家: 美国
• 起止时间: 2005-08-01 至 2009-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0527350&HistoricalAwards=false
• 关键词: Experimental; Determination; Temperature; Precipitation; Rate

The elemental composition of the aragonitic skeletons of marine invertebrates contribute an increasingly significant proportion of the climate proxy data used to understand and model Earth's climate system. However, the factors that control how elements are partitioned between aragonite and seawater are not well understood. To date only three experimental studies have determined element distribution between aragonite and seawater, all focused exclusively on the behavior of Sr2+ and two were carried out at a single temperature. In this project, researchers at the Woods Hole Oceanographic Institution will address this critical gap in knowledge through an experimental determination of aragonite- seawater partition coefficients for a range of divalent cations that show promise as environmental proxies (e.g., Mg2+, Sr2+, Ba2+, Cd2+, and Mn2+) as functions of temperature and precipitation rate. The experimental data will be used to calibrate a lattice strain partitioning model that will provide a quantitative basis for interpreting the compositions of aragonitic skeletons. In addition, a comparison of experimental results with data obtained from selected, naturally occurring aragonites will permit identification of combinations of the proxies and aragonite accretions that most faithfully record environmental variables. The proposed work builds on results from an experimental pilot study to determine the partitioning of Mg2+, Ca2+, Sr2+, and Ba2+ between abiogenic aragonite and seawater at 15 to 45 C. This approach differs from previous studies in that the SIMS ion microprobe will be used to analyze the concentrations of a full range of divalent cations in individual aragonite grains, rather than focusing exclusively on Sr partitioning using the bulk precipitate. The high spatial resolution afforded by SIMS analyses allows recognition of the presence of compositional gradients across individual grains, and the presence of aragonite that may have been epitaxially converted from high-Mg-calciteThis research promises a number of broader impacts. There is reason to believe that this research will provide the paleoclimate, geochemical, biological and environmental conservation communities with a quantitative basis for interpreting the compositional record preserved in living and ancient aragonitic accretions, which is presently unavailable. It will bridge traditional disciplinary boundaries and bring together scientists with very different but complementary expertise. Moreover, this study will contribute significantly toward the PhD thesis of NSF graduate student fellow. This project will also provide for the education and training of graduate and summer student fellows. The results from this study will be made publicly available in a timely manner on the investigators' website.

海洋无脊椎动物文石骨骼的元素组成在用于了解和模拟地球气候系统的气候代用数据中所占比例越来越大。然而，控制元素如何在文石和海水之间分配的因素还不清楚。到目前为止，只有三个实验研究确定了文石和海水之间的元素分布，都集中在Sr 2+的行为和两个在一个单一的温度下进行。在这个项目中，伍兹霍尔海洋研究所的研究人员将通过实验测定一系列二价阳离子的文石-海水分配系数来解决这一关键的知识缺口，这些二价阳离子有望成为环境代理（例如，Mg 2+、Sr 2+、Ba 2+、Cd 2+和Mn 2+）作为温度和沉淀速率的函数。实验数据将被用来校准晶格应变分配模型，这将提供一个定量的基础上解释文石骨架的组成。 此外，从选定的，自然发生的文石获得的数据与实验结果的比较将允许识别的代理和文石增生，最忠实地记录环境变量的组合。 这项工作是建立在一项实验性初步研究的基础上的，该研究确定了15至45 ℃下Mg 2+、Ca 2+、Sr 2+和Ba 2+在非生物成因文石和海水之间的分配。 这种方法不同于以往的研究中，西姆斯离子微探针将被用来分析一个完整的范围内的二价阳离子在个别文石颗粒的浓度，而不是专门专注于Sr分区使用散装沉淀。 西姆斯分析提供的高空间分辨率允许识别单个颗粒之间的成分梯度的存在，以及可能从高镁方解石外延转化的文石的存在。 有理由相信，这项研究将提供古气候，地球化学，生物和环境保护社区与定量的基础上解释的组成记录保存在生活和古老的文石增生，这是目前不可用的。 它将弥合传统的学科界限，汇集具有非常不同但互补的专业知识的科学家。此外，这项研究将有助于显着的博士论文的NSF研究生研究员。 该项目还将为研究生和暑期研究生提供教育和培训。本研究的结果将及时在研究者网站上公开。