SGER: Improving the Utility of Paleoproxies from Coccolith Chemistry: Calibration and Analytical Advances

SGER：提高球石化学古代理的实用性：校准和分析进展

• 批准号: 0424474
• 负责人: Heather Stoll
• 金额: $ 4.69万
• 依托单位: Williams College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-05-01 至 2006-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0424474&HistoricalAwards=false
• 关键词: SGER; Improving; Utility; Paleoproxies; Coccolith

This SGER request funding to develop a new indicator of paleo-productivity of coccolithophorid algae, based on elemental (Sr/Ca) chemistry of coccolith calcite. Culture studies of a single species, Emiliania huxleyi, and analysis of coccoliths from sediment core tops in two transects across upwelling areas, suggest that coccolith Sr/Ca ratios vary with nutrient-stimulated changes in coccolithophorid growth rates. However, it is unclear whether these responses are widespread in the ocean, whether Sr/Ca variations in coccoliths are triggered by nutrient concentrations or the effect of nutrients on growth rate, whether a particular nutrient is responsible for this effect or if the state of nutrient limitation in general drives the response, and whether these responses are the same for different species. Calibration studies will be conducted through nutrient-limited culture of three additional species (Calcidiscus leptoporus, Coccolithus pelagicus, and Gephyrocapsa oceanica) and by analysis of time series plankton and sediment trap samples before, during, and after nutrient-stimulated bloom events. The very small amount of material collected in plankton samples and some sediment traps can be analyzed only through the development of a new ion probe (SIMS) technique capable of precise Sr/Ca measurements of individual or small groups of 10-20 picked coccoliths. In addition to improving calibration of the indicator, the SIMS ion probe technique will also benefit Sr/Ca analysis of downcore sediments for paleoproductivity determinations because it would eliminate elemental contributions from noncarbonate phases and permit determinations of Sr/Ca on pure samples of a given species or genera.

该SGER请求资助开发一种新的基于颗石方解石元素（Sr/Ca）化学的颗石藻类古生产力指标。一个单一的物种，Emiliania huxleyi，并从沉积物芯顶部在两个断面的上升流地区的球石分析的文化研究表明，球石Sr/Ca的比例变化与营养刺激的变化，球石生长速率。 然而，目前尚不清楚这些反应是否广泛存在于海洋中，是否锶/钙的变化，是否在cocoliths的营养物质浓度或营养物质对生长速度的影响，是否一个特定的营养物质是负责这种影响，或者如果营养限制的状态一般驱动的响应，以及这些响应是否是相同的不同物种。 校准研究将通过三个额外的物种（Calcidiscus leptoporus，Coccolithus pelagicus和Gephyrocapsa oceanica）的营养有限的文化，并通过分析时间序列浮游生物和沉积物陷阱样本之前，期间和之后的营养刺激的水华事件。 在浮游生物样品和一些沉积物收集器中收集到的极少量的材料只能通过开发一种新的离子探针（西姆斯）技术进行分析，该技术能够对单个或10-20个小群体采集的球石进行精确的Sr/Ca测量。 除了提高校准的指标，西姆斯离子质谱离子探针技术也将有利于Sr/Ca分析的地下沉积物古生产力的测定，因为它将消除元素的贡献，从非碳酸盐相和允许确定Sr/Ca的纯样品的一个给定的物种或属。