화학공학소재연구정보센터
Science, Vol.371, No.6536, 1346-+, 2021
A 35-million-year record of seawater stable Sr isotopes reveals a fluctuating global carbon cycle
Changes in the concentration and isotopic composition of the major constituents in seawater reflect changes in their sources and sinks. Because many of the processes controlling these sources and sinks are tied to the cycling of carbon, such records can provide insights into what drives past changes in atmospheric carbon dioxide and climate. Here, we present a stable strontium (Sr) isotope record derived from pelagic marine barite. Our delta Sr-88/86 record exhibits a complex pattern, first declining between 35 and 15 million years ago (Ma), then increasing from 15 to 5 Ma, before declining again from similar to 5 Ma to the present. Numerical modeling reveals that the associated fluctuations in seawater Sr concentrations are about +/- 25% relative to present-day seawater. We interpret the delta Sr-88/86 data as reflecting changes in the mineralogy and burial location of biogenic carbonates.