Gaseous Mercury Emissions from Volcanoes Contributed to End-Triassic Mass Extinction

The end-Triassic mass extinction occurred 201.51 million years ago and resulted in the demise of some 76% of all marine and land species. Up until now, most scientists believed that the catastrophe was caused by the release of volcanic carbon dioxide with global warming as a consequence. According to new research, the increased concentrations of mercury — the most genotoxic element on Earth — contributed to the end-Triassic crisis.

Normal and mutated fern spores from the end-Triassic mass extinction. Scale bar - 20 μm. Image credit: Sofie Lindström, Geological Survey of Denmark and Greenland.

Normal and mutated fern spores from the end-Triassic mass extinction. Scale bar – 20 μm. Image credit: Sofie Lindström, Geological Survey of Denmark and Greenland.

“Prior to industrialism, volcanic activity was the major release mechanism of large amounts of mercury from the Earth’s crust,” said Aarhus University researcher Hamed Sanei, co-author of the study.

“That makes it possible to use mercury in sediments to trace major volcanic activity in the Earth’s past and in extent tie the extinctions of fossil organisms to large igneous province (LIP) volcanism.”

“Previous studies found elevated mercury concentrations in Triassic-Jurassic boundary sediments over a very large area stretching from Argentina to Greenland and from Nevada to Austria and that made us curious about the impact on the end-Triassic event.”

“We decided to examine whether mercury could have played a role.”

The scientists analyzed fossil fern spores from core samples dating to the end-Triassic mass extinction and found a link between the increased mercury levels and mutations in the spores.

This rise in mutations happened during a period of increased volcanic activity in a LIP called the Central Atlantic Magmatic Province leading to rising mercury levels.

“By looking at fern spores in sediments from the mass extinction, it was evident that these ferns were negatively affected by the mercury levels,” said lead author Dr. Sofie Lindström, from the Geological Survey of Denmark and Greenland.

“Since mercury is accumulated in the food chain, it seems likely that other species have suffered as well.”

“These results suggest that the end-Triassic mass extinction was not just caused by greenhouse gases from volcanoes causing global climate change, but that they also emitted toxins such as mercury wreaking havoc.”

The findings were published in the journal Science Advances.

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Sofie Lindström et al. 2019. Volcanic mercury and mutagenesis in land plants during the end-Triassic mass extinction. Science Advances 5 (10): eaaw4018; doi: 10.1126/sciadv.aaw4018

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