Ozone depletion A collapse of the atmospheric ozone shield has been invoked as an explanation for the mass extinction, particularly that of terrestrial plants. Ozone production may have been reduced by 60-70%, increasing the flux of ultraviolet radiation by 400% at equatorial latitudes and 5,000% at polar latitudes. The hypothesis has the advantage of explaining the mass extinction of plants, which would have added to the methane levels and should otherwise have thrived in an atmosphere with a high level of carbon dioxide. Fossil spores from the end-Permian further support the theory; many spores show deformities that could have been caused by ultraviolet radiation, which would have been more intense after hydrogen sulfide emissions weakened the ozone layer. Malformed plant spores from the time of the extinction event show an increase in ultraviolet B absorbing compounds, confirming that increased ultraviolet radiation played a role in the environmental catastrophe and excluding other possible causes of mutagenesis, such as heavy metal toxicity, in these mutated spores. Extremely positive Δ33S anomalies provide evidence of photolysis of volcanic SO2, indicating increased ultraviolet radiation flux. Sulphur isotope data from North China are inconsistent with a total collapse of the ozone layer, however, suggesting it may have not been as major a kill mechanism as others.
Ozone depletion A collapse of the atmospheric ozone shield has been invoked as an explanation for the mass extinction, particularly that of terrestrial plants. Ozone production may have been reduced by 60-70%, increasing the flux of ultraviolet radiation by 400% at equatorial latitudes and 5000% at polar latitudes. The hypothesis has the advantage of explaining the mass extinction of plants, which would have added to the methane levels and should otherwise have thrived in an atmosphere with a high level of carbon dioxide. Fossil spores from the end-Permian further support the theory; many spores show deformities that could have been caused by ultraviolet radiation, which would have been more intense after hydrogen sulfide emissions weakened the ozone layer. Malformed plant spores from the time of the extinction event show an increase in ultraviolet B absorbing compounds, confirming that increased ultraviolet radiation played a role in the environmental catastrophe and excluding other possible causes of mutagenesis, such as heavy metal toxicity, in these mutated spores Extremely positive Δ33S anomalies provide evidence of photolysis of volcanic SO2, indicating increased ultraviolet radiation flux. Sulphur isotope data from North China are inconsistent with a total collapse of the ozone layer, however, suggesting it may have not been as major a kill mechanism as others