Ground Truthing the Boron Isotope Paleo-pH Proxy

硼同位素古 pH 代理的地面实况调查

• 批准号: 0326952
• 负责人: N. Gary Hemming
• 金额: --
• 依托单位: CUNY Queens College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0326952&HistoricalAwards=false
• 关键词: Ground; Truthing; Boron; Isotope; Paleo

ABSTRACTOCE-0326952Boron isotopes in marine carbonates may provide information about past ocean chemistry because the inclusion of this isotope into carbonates is controlled primarily by the carbonate chemistry of the ocean. However, to date no systematic, global evaluations of this proxy have been carried out. For this reason, a PI from Queens College plans to test the utility of the boron isotope paleo-pH proxy by analyzing planktonic and benthic formaminifera obtained from surficial sediments recovered globally from regions with well-defined water chemistries. Results from this study will provide an opportunity to document potential deviations from predicted isotopic compositions in response to species effect, temperature and alkalinity. In addition, the PI will carry out laboratory calcite growth experiments to determine the influence of pH, temperature, pressure, salinity and growth rate on the boron isotope composition of calcite. Foraminifera culture experiments with Orbulina universa and Globigerina bulloides (species with and without symbionts, respectively) also will be done under controlled water composition and temperature to assess boron fractionation in response to symbiont density and other variables. Lastly, the effect of diagenesis (dissolution and recrystallization) on the boron isotope composition will be evaluated. Broader impacts. Results from this study will determine whether boron isotopes can be used as a paleo-pH proxy to obtain information on ancient climate change in lieu of direct evidence. An understanding of past natural fluctuations in the earth's climate is essential to comprehending and evaluating current pattern of, and anthropogenic impacts on, global climate change.

海相碳酸盐中的硼同位素可以提供有关过去海洋化学的信息，因为这种同位素在碳酸盐中的包裹体主要受海洋的碳酸盐化学控制。然而，到目前为止，还没有对这一代理进行系统的全球评价。出于这个原因，皇后学院的一位PI计划通过分析浮游和底栖甲虫来测试硼同位素古pH替代物的实用性，这些甲虫来自全球从水化学定义明确的地区采集的表层沉积物。这项研究的结果将提供一个机会，记录物种效应、温度和碱度对预测的同位素组成的潜在偏差。此外，PI还将在实验室进行方解石生长实验，以确定pH、温度、压力、盐度和生长速度对方解石的硼同位素组成的影响。此外，还将在控制水组成和温度的情况下，进行普通奥布利纳和球状有孔虫(分别有无共生体)的有孔虫培养实验，以评估共生体密度和其他变量对硼的分馏作用。最后，评价了成岩作用(溶解作用和重结晶作用)对硼同位素组成的影响。更广泛的影响。这项研究的结果将决定是否可以用硼同位素代替直接证据作为古pH值的替代物来获取关于古代气候变化的信息。了解过去地球气候的自然波动对于理解和评估当前的全球气候变化模式及其人为影响至关重要。