Fractionation of Cd and P by Marine Phytoplankton

在这个项目中，罗格斯大学的研究人员将继续他们正在进行的沿海海洋浮游植物对镉的吸收依赖于分类亲和力、生长速度、其他生物活性金属的相对浓度和海水中二氧化碳的环境溶解浓度的研究。有了这笔更新的资金，重点将放在实验室培养研究上，以补充过去四年进行的实地工作。预计这项研究的影响将具有普遍的适用性，研究人员设计了这项研究，以量化几种浮游植物的基本依赖关系。然而，这项工作的一个强大推动力是了解南大洋表层水中镉/磷的分馏。研究小组希望通过浮游有孔虫化石的Cd/Ca比值，为过去南大洋表层水磷利用的可靠估计制定基本规则。这个为期三年的项目将解决两个主要问题：(1)对镉的吸收是否强烈依赖于浮游植物的系统发育，还是细胞大小、生长速度和其他金属的可用性更重要？(2)在所有主要浮游植物群中，或者仅仅是硅藻中，Cd的吸收是否随着pCO2的减少而增加？它是由对pCO2的生理反应引起的，还是由水化学中ph依赖性的变化引起的？为了回答这些问题，研究小组将进行两组实验。首先，他们将从四个主要分类类群中确定浮游植物对Cd的吸收，并测试Cd吸收对其他生物活性金属的可用性和生长速度的依赖性。其次，他们将通过测量不同CO2对浮游植物物种的影响，研究环境溶解CO2浓度控制Cd吸收的机制和普遍性。作为后一项研究的一部分，他们将进行实验，以区分Cd在碳获取中的生理作用和pH对竞争金属可用性的影响。

ABSTRACTOCE-0137592In this project, researchers at Rutgers University will continue their ongoing studies of the dependence of cadmium uptake by coastal marine phytoplankton on taxonomic affinity, growth rate, relative concentrations of other bioactive metals, and the ambient dissolved concentration of carbon dioxide in seawater. With this renewal funding, the focus will be on laboratory culture studies to complement field work carried out over the last four years. Anticipating that the implications of the study will be of general applicability, the investigators have designed the study to quantify fundamental dependencies for several classes of phytoplankton. Nevertheless, a strong impetus for the work is the desire to understand cadmium/phosphorous fractionation in Southern Ocean surface waters. The team hopes to develop ground rules for the robust estimation of phosphorous utilization in past Southern Ocean surface waters from the Cd/Ca ratio of fossil planktonic foraminifera. The three-year project will address two major questions: (1) Does uptake of Cd depend strongly on phytoplankton phylogeny, or are cell size, growth rate and availability of other metals more important? (2) Is increased Cd uptake with decreased pCO2 found in all major phytoplankton groups, or just diatoms, and is it caused by a physiological response to pCO2 or by pH-dependent changes in water chemistry? To answer these questions the research team will conduct two sets of experiments. First, they will determine Cd uptake in phytoplankton species from four major taxonomic groups, and test the dependence of Cd uptake on availability of other bioactive metals and on growth rate. Secondly, they will investigate the mechanism and ubiquity of Cd uptake control by ambient dissolved CO2 concentration by measuring the effect of varying CO2 on species across a wide phylogenetic spectrum of the phytoplankton. As part of the latter studies, they will conduct experiments to distinguish a physiological role for Cd in carbon acquisition from pH effects on availability of competing metals.