In situ calibration of Mg/Ca ratio in planktonic foraminiferal shell using time series sediment trap: A case study of intense dissolution artifact in the South China Sea

Abstract

This study examines Mg/Ca‐temperature equations through the use of planktonic foraminifers collected from continuous time series sediment traps at four water depths in the South China Sea. This deployment provides an opportunity to refine partial dissolution artifacts and to identify responses of shell chemistry to changes in ambient seawater conditions. Paired Mg/Ca and δ18O measurements on shells are strongly correlated with seasonal variability in terms of temperature at specific habitat depths. However, partial dissolution can significantly alter Mg/Ca ratios even at depths well above the calcite lysocline or carbonate compensation depth. Of the three species studied, Neogloboquadrina dutertrei is the most sensitive species to dissolution relative to the other surface‐dwelling species (Globigerinoides ruber and Globigerinoides sacculifer). Differences between the Mg‐derived temperature equation here and those from previously established core top or sediment trap calibrations can be attributed to various degrees of dissolution and lateral advection, thus highlighting the need for in situ empirical calibration for different ocean basins.