Accurate Calibration of Multiple Paleoceanographic Proxies in Benthic Foraminifera

根据该奖项，PI将校准几种底栖有孔虫的多个古海洋地球化学代理。这一工作将有助于对底栖有孔虫地球化学代用指标的理解和应用。由于这种测量形成了许多古气候研究的基础，改进的校准是必不可少的，并将被广泛采用。 代用指标包括温度和盐度（Mg/Ca，d18 O）、营养物含量（Cd/Ca，Zn/Ca，d13 C）、pH值（d11 B）和可能的碳酸根离子浓度（U/Ca，Li/Ca）的估算值。2002年，专门为此目的，从佛罗里达和古巴之间的38个地点收集了一系列多岩心顶部和海水样本。由于以下几个原因，这一收集代表了一个独特的校准机会：（1）丰富的底栖有孔虫，高沉积速率和大量收集的沉积物允许对近现代标本进行多次测量;（2）这些地点跨越了大范围的目标参数（例如，15 ℃，1.9 psu，0.24 pH）;（3）从安装在多芯取样器上的Niskin瓶收集的海水提供了现场水条件的准确测定，即盐度、d18 O、元素浓度和碳酸盐系统参数（精确温度可从随附的CTD铸件获得）。

Under this award the PIs will calibrate multiple paleoceanographic geochemical proxies in several species of benthic foraminifera. This work should contribute significantly to the understanding and application of benthic foraminiferal geochemical proxies. Since such measurements form the foundation of many paleoclimatic studies, improved calibrations are essential and will be widely employed. Proxies include estimators for temperature and salinity (Mg/Ca, d18O), nutrient content (Cd/Ca, Zn/Ca, d13C), pH (d11B), and possibly carbonate ion concentration (U/Ca, Li/Ca). A series of multicore tops and seawater samples were collected from 38 locations between Florida and Cuba in 2002, expressly for this purpose. This collection represents a unique calibration opportunity for several reasons: (1) abundant benthic foraminifera, high sedimentation rates, and large volumes of collected sediment allow for multiple measurements of near-modern specimens; (2) the sites span large ranges of the targeted parameters (e.g., 15 C, 1.9 psu, 0.24 pH); and (3) seawater collected from a Niskin bottle mounted on the multicorer provides accurate determinations of in-situ water conditions, namely salinity, d18O, elemental concentrations, and carbonate system parameters (accurate temperatures are available from accompanying CTD casts).