A review of the marine calcium cycle and stable isotope tracers in geoscience studies

Abstract

Calcium is the fifth most abundant element in seawater and an essential nutrient in the marine and terrestrial biospheres. Dissolved Ca derived from rock weathering is transported to the ocean by rivers and groundwater, followed by active precipitation from seawater by organisms to form skeletal hard parts, such as Ca carbonates and phosphates. At the earth's surface, Ca has been regarded as an important element for controlling the carbon cycle over geological time. High precision isotope measurements over the last two decades provide insight into the role of Ca isotope ratios as a tool for elucidating biological, chemical and geological processes. This review notes the potential of Ca isotopes as a recorder of marine Ca-cycling in the present and the past.