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Severity of ocean acidification following the end Cretaceous asteroid impact

Severity of ocean acidification following the end Cretaceous asteroid impact
Severity of ocean acidification following the end Cretaceous asteroid impact
Most paleo-episodes of ocean acidification (OA) were either too slow or too small to be instructive in predicting near-future impacts. The end-Cretaceous event (66 Mya) is intriguing in this regard, both because of its rapid onset and also because many pelagic calcifying species (including 100% of ammonites and more than 90% of calcareous nannoplankton and foraminifera) went extinct at this time. Here we evaluate whether extinction-level OA could feasibly have been produced by the asteroid impact. Carbon cycle box models were used to estimate OA consequences of (i) vaporization of up to 60 × 1015 mol of sulfur from gypsum rocks at the point of impact; (ii) generation of up to 5 × 1015 mol of NOx by the impact pressure wave and other sources; (iii) release of up to 6,500 Pg C as CO2 from vaporization of carbonate rocks, wildfires, and soil carbon decay; and (iv) ocean overturn bringing high-CO2 water to the surface. We find that the acidification produced by most processes is too weak to explain calcifier extinctions. Sulfuric acid additions could have made the surface ocean extremely undersaturated (?calcite <0.5), but only if they reached the ocean very rapidly (over a few days) and if the quantity added was at the top end of literature estimates. We therefore conclude that severe ocean acidification might have been, but most likely was not, responsible for the great extinctions of planktonic calcifiers and ammonites at the end of the Cretaceous.
ocean acidification, asteroid impact, K/Pg boundary, mass extinction
0027-8424
6556- 6561
Tyrrell, Toby
6808411d-c9cf-47a3-88b6-c7c294f2d114
Merico, Agostino
9ebd799e-73e5-4337-ae8c-5e2f3b6eb783
Armstrong Mckay, David I.
9e7fc75d-311e-4980-9911-288d965a9e56
Tyrrell, Toby
6808411d-c9cf-47a3-88b6-c7c294f2d114
Merico, Agostino
9ebd799e-73e5-4337-ae8c-5e2f3b6eb783
Armstrong Mckay, David I.
9e7fc75d-311e-4980-9911-288d965a9e56

Tyrrell, Toby, Merico, Agostino and Armstrong Mckay, David I. (2015) Severity of ocean acidification following the end Cretaceous asteroid impact. Proceedings of the National Academy of Sciences, 112 (21), 6556- 6561. (doi:10.1073/pnas.1418604112).

Record type: Article

Abstract

Most paleo-episodes of ocean acidification (OA) were either too slow or too small to be instructive in predicting near-future impacts. The end-Cretaceous event (66 Mya) is intriguing in this regard, both because of its rapid onset and also because many pelagic calcifying species (including 100% of ammonites and more than 90% of calcareous nannoplankton and foraminifera) went extinct at this time. Here we evaluate whether extinction-level OA could feasibly have been produced by the asteroid impact. Carbon cycle box models were used to estimate OA consequences of (i) vaporization of up to 60 × 1015 mol of sulfur from gypsum rocks at the point of impact; (ii) generation of up to 5 × 1015 mol of NOx by the impact pressure wave and other sources; (iii) release of up to 6,500 Pg C as CO2 from vaporization of carbonate rocks, wildfires, and soil carbon decay; and (iv) ocean overturn bringing high-CO2 water to the surface. We find that the acidification produced by most processes is too weak to explain calcifier extinctions. Sulfuric acid additions could have made the surface ocean extremely undersaturated (?calcite <0.5), but only if they reached the ocean very rapidly (over a few days) and if the quantity added was at the top end of literature estimates. We therefore conclude that severe ocean acidification might have been, but most likely was not, responsible for the great extinctions of planktonic calcifiers and ammonites at the end of the Cretaceous.

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KPG_OA preprint.pdf - Accepted Manuscript
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Submitted date: March 2015
e-pub ahead of print date: 10 May 2015
Published date: 2015
Keywords: ocean acidification, asteroid impact, K/Pg boundary, mass extinction
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 375265
URI: https://eprints.soton.ac.uk/id/eprint/375265
ISSN: 0027-8424
PURE UUID: a6bea8c9-26af-4e46-84e9-eea07bdaf643
ORCID for Toby Tyrrell: ORCID iD orcid.org/0000-0002-1002-1716
ORCID for David I. Armstrong Mckay: ORCID iD orcid.org/0000-0002-0020-7461

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Date deposited: 18 Mar 2015 13:09
Last modified: 06 Jun 2018 13:03

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Author: Toby Tyrrell ORCID iD
Author: Agostino Merico
Author: David I. Armstrong Mckay ORCID iD

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