Use of Me/Ca ratios as proxies for coastal marine conditions in ostracod shells of Sinocytheridea impressa and Neomonoceratina delicata

Abstract

<p>Paleo-reconstructions using element to calcium ratios (Me/Ca) of marine <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/ostracod" title="Learn more about ostracods from ScienceDirect's AI-generated Topic Pages">ostracods</a> were usually focused on Mg/Ca and Sr/Ca, whereas paleo-environmental applications using other ostracod Me/Ca including Na/Ca, Ba/Ca, Mn/Ca, Zn/Ca, Ni/Ca, Cd/Ca, Cu/Ca and Cr/Ca have been rather limited due to the lack of a general understanding of the control of physicochemical marine variables on trace-elements uptake. Ba/Ca and Na/Ca were linked to temperature, while Mn/Ca was suggested to be an indicator of <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/redox-condition" title="Learn more about redox conditions from ScienceDirect's AI-generated Topic Pages">redox conditions</a> and used to track oxide contamination in marine shells. The potential of other ostracod ratios as environmental proxies has rarely been investigated. Here, we study the empirical relations between seawater physicochemical variables and several Me/Ca of ostracod shells in shallow marine waters. Our results suggest that shallow sea parameters related to the control of metal concentrations in seawater and sediments such as suspended solids, <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/salinity" title="Learn more about salinity from ScienceDirect's AI-generated Topic Pages">salinity</a>, electrochemical potential and total carbon are correlated to Me/Ca such as Mn/Ca and Zn/Ca in ostracod shells of <em>Sinocytheridea impressa</em> and <em>Neomonoceratina delicata</em> from Hong Kong coastal waters. Correlations are not always significant for both species, indicating that other factors such as species-specific habitats or <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/biomineralization" title="Learn more about biomineralization from ScienceDirect's AI-generated Topic Pages">biomineralization</a> processes may also play a role in the incorporation of metals. We demonstrate that the combination of multiple linear regressions using several significant sea parameters provides useful information to reconstruct shallow marine conditions including water temperature, <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/salinity" title="Learn more about salinity from ScienceDirect's AI-generated Topic Pages">salinity</a>, suspended solid and total carbon in sediments. Thus, a detailed description of the marine environment in Hong Kong coastal waters can be achieved.<br></p>