Dying in the sun : direct evidence for elevated UV-B radiation at the end-Permian mass extinction

Liu Feng; Peng Huiping; Marshall, John E.A.; Lomax, Barry H.; Bomfleur, Benjamin; Kent, Matthew S.; Fraser, Wesley T.; Jardine, Phillip E.

Journal Article

Dying in the sun : direct evidence for elevated UV-B radiation at the end-Permian mass extinction

Abstract

Land plants can adjust the concentration of protective UV-B-absorbing compounds (UACs) in the outer wall of their reproductive propagules in response to ambient UV-B flux. To infer changes in UV-B-radiation flux at the Earth’s surface during the end-Permian mass extinction, we analyze UAC abundances in ca. 800 pollen grains from an independently-dated Permian-Triassic boundary section in Tibet. Our data reveal an excursion in UACs that coincide with a spike in mercury concentration and a negative carbon-isotope excursion in the latest Permian deposits, suggesting a close temporal link between large-scale volcanic eruptions, global carbon- and mercury-cycle perturbations, and ozone-layer disruption. Because enhanced UV-B radiation can exacerbate the environmental deterioration induced by massive magmatism, ozone depletion is considered a compelling ecological driver for the terrestrial mass extinction.