Abstract
Ocean acidification causes biocalcification stress. The calcium isotope composition of carbonate producers can archive such stress because calcium isotope fractionation is sensitive to precipitation rate. Here, we synthesize morphometric observations of planktic foraminifera with multi-archive calcium isotope records from Gubbio, Italy and the Western Interior Seaway spanning Cretaceous Ocean Anoxic Event 2 (~94 million years ago). Calcium isotope ratios increase ~60 thousand years prior to the event. The increase coincides with foraminiferal abnormalities and correlates with existing proxy records for carbon dioxide release during large igneous province volcanism. The results highlight Ocean Anoxic Event 2 as a geologic ocean acidification analog. Moreover, decreasing calcium isotope ratios during the event provide evidence for ocean alkalinization, which could have shifted air-sea carbon dioxide partitioning. These data offer an explanation for the Plenus Cold Event and further have implications for refining ocean alkalinity enhancement, a leading anthropogenic carbon dioxide removal strategy.
| Original language | English (US) |
|---|---|
| Article number | 315 |
| Journal | Communications Earth and Environment |
| Volume | 3 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2022 |
Funding
We thank NU IRMS Laboratory Manager Andrew Masterson who assisted with stable isotope data collection. We also thank Tirzah Abbot for assisting with SEM training and imaging. Members of the Jacobson Laboratory Group provided many useful discussions. In addition, we thank Encana Inc. for donating the Aristocrat Angus core to Northwestern University and the USGS Core Research Center in Denver, CO for facilitating transfer of core material. We also thank two anonymous reviewers for their contributions in improving the manuscript. This work was supported by a NSF-GRFP (Grant No. DGE-1842165) awarded to GDK, as well as a David and Lucile Packard Foundation Fellowship (2007-31757) and a NSF grant (NSF-EAR 0723151) awarded to ADJ. The National Oceanic and Atmospheric Administration Ocean Acidification Program and the Illinois Indiana Sea Grant supported GDK during revision of this manuscript.
ASJC Scopus subject areas
- General Environmental Science
- General Earth and Planetary Sciences
