Experimental Determination of Equilibrium and Kinetic Fractionation of Boron, Carbon, and Oxygen Isotopes during Carbonate Precipitation

碳酸盐沉淀过程中硼、碳和氧同位素的平衡和动力学分馏的实验测定

• 批准号: 9730371
• 负责人: Joseph Ortiz
• 金额: $ 34.71万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-03-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9730371&HistoricalAwards=false
• 关键词: Experimental; Determination; Equilibrium; Kinetic; Fractionation

Istopic fractionation of boron, carbon and oxygen will be evaluated under controlled conditions. Accurate equilibrium fractionation factors from these inorganic calcification experiments will provide a common yardstick against which to evaluate the potential magnitude of biogenic disequilibrium calcification. Simutaneous experimental analysis of 8 11 B, 8 13 C, and 8 18 O fractionation during inorganic calcificaiton is attractive because a recent theory of biogenic calcification proposes correlated kinetic dissequilibria in 8 13 C and 8 18 O as a function of calcification rate. According to this model, isotopic disequilibrium arises from rate dependent inorganic hydration and hydroxylation reactions during calcification. Because calcification rate is controlled to some extent by solute pH at the site of calcification, 8 11 B fractionation, which is pH sensitive, should be correlated with 8 13 C, and 8 18 O kinetic disequilibrium. A pH controlled, continuously stirred tank reactor (CSTR) will be used to evaluate the effects of temperature and precipitaiton rate (solute chemistry) on the isotopic composition of seeded inorganic calcite precipitation. Carefully selected reagent grade calcite seed material with XRD confirmed mineralogy and known isotopic composition will be employed during these experiments to control for fractionation effects due to minerological differences (e.g. aragonite vs. calcite).

硼、碳和氧的同位素分馏将在受控条件下进行评估。 这些无机钙化实验的准确平衡分馏因子将为评估生物不平衡钙化的潜在程度提供一个共同的标准。 无机钙化期间 8 11 B、8 13 C 和 8 18 O 分级分离的同步实验分析很有吸引力，因为最近的生物钙化理论提出 8 13 C 和 8 18 O 中的相关动力学不平衡作为钙化速率的函数。 根据该模型，同位素不平衡是由钙化过程中速率依赖性无机水合和羟基化反应引起的。 由于钙化速率在一定程度上受钙化部位溶质pH的控制，因此对pH敏感的8 11 B分级分离应与8 13 C和8 18 O动力学不平衡相关。 pH 控制的连续搅拌釜反应器 (CSTR) 将用于评估温度和沉淀速率（溶质化学）对晶种无机方解石沉淀的同位素组成的影响。 在这些实验中，将采用经过 XRD 确认的矿物学和已知同位素组成的精心挑选的试剂级方解石种子材料，以控制由于矿物学差异（例如文石与方解石）引起的分馏效应。