Biogeochemistry & Earth Science
Funded March 2015.
Groundtruthing rare earth element behaviour in cold water corals - pilot data acquisition.
Projected atmospheric CO2 concentrations are set to approach 1000 ppm by the end of the century, greatly exceeding natural variation in ice cores over the last 800 ka and in proxy data over the last 25 Ma or longer. Such an abrupt increase will certainly impact the marine environment and especially the marine carbonate system (e.g. seawater pH), although consequences for marine calcifiers remain uncertain. One way of evaluating future change is to investigate the response to past change. However, our ability to do gauge changes in the marine carbonate system depends critically on our ability to measure these in suitable archive materials. The marine carbonate system can be reconstructed providing proxies can characterise at least two of its six independent parameters (i.e. pH, dissolved CO2, bicarbonate and carbonate ion concentrations, total alkalinity, total dissolved carbon). Boron isotopes are currently the best quantitative proxy of seawater pH. The geochemical behaviour of rare earth elements (REE) in seawater shows a strong carbonate ion dependence that can be exploited in fossil coral aragonite to reveal past variations in the marine carbonate system. Accurately interpreting this powerful archive requires knowledge of the seawater-carbonate REE partitioning, together with “vital effects” (biological factors that modify the primary signal). The proposed research aims to define seawater REE partitioning into modern coral aragonite through culturing experiments of cold water Lophelia pertusa. We propose to combine the REE measurements with boron isotope compositions to test their combined ability to quantify changes in the marine carbonate system.
Dr Crocket is a palaeoceanographer with expertise in the measurement of radiogenic isotope composition (Pb, Sr, Nd) and trace metal concentrations (rare earth elements) in marine sample materials. Her research involves the application of these techniques to a variety of current marine and palaeoceanographic research topics, e.g. carbonate biomineralisation and the response of skeletal uptake of trace metals to environmental change, how dissolved trace metal concentrations respond to changes in environment and climate.
Her webpage at SAMS: