The deadliest time in earth’s history was also the stinkiest – After the world

UC Riverside Earth system modeler Dominik Hülse reacts to the toxic smell of hydrogen sulfide. Photo credit: Dominik Hülse / UCR

A new study suggests that tiny microbes emitting toxic gas caused and prolonged the largest mass extinction in Earth’s history.

In general, scientists believe that Siberian volcanoes spit Greenhouse gases mainly drove the mass extinction about 250 million years ago, at the end of the Permian. The gases caused extreme warming, which in turn caused 80% of all sea ​​animals, as well as many land species, are dying out.

So far, scientists have not been able to explain exactly how the heat caused these deaths. A new UC Riverside-led study in Natural geosciences shows that the heat speeds up the metabolism of the microbes and creates deadly conditions.

“After the oxygen in the ocean was used up to decompose organic material, Microbes began to “breathe” sulfate and produce hydrogen sulfide, a gas that smells like rotten eggs and is toxic to animals, ”said Dominik Hülse, systems modeler at UC Riverside Earth.

As ocean photosynthesis – the microbes and plants that make up the basis of the food chain – rotted away, other microbes quickly depleted the oxygen, leaving little of it for larger organisms. In the absence of oxygen, microbes consumed sulfate and then excreted toxic, smelly hydrogen sulfide, or H2S, resulting in an even more extreme condition called euxinia. These conditions were maintained by the release of nutrients during the decomposition, which encouraged the production of more organic matter, which helped keep this smelly, toxic cycle going.

“Our research shows that the entire ocean was not Euxinian. These conditions started in the deeper parts of the Water columnsaid Sleeve sea ​​animals lived and poisoned them. ”

The expanding euxinic zones can be detected by chemical signatures in sediment samples.

Oxygen starvation is a problem that continues today and will be made worse by future climate change. Euxinian water can be found in places like Los Angeles County’s 16-mile-long Dominguez Canal, where a campfire released ethanol in September 2021. The ethanol killed the vegetation in the canal, which was decaying and being consumed by microbes. They then produced Hydrogen sulfide at the toxic values. Thousands in the breathing zone of the stinking river reported vomiting, diarrhea, dizziness, insomnia, headache, sneezing and other symptoms.

Insights from ancient times can be important in understanding the processes that challenge our modern oceans and waterways.

“It would be speculative to superimpose the age-old mass extinction on today’s planet,” said Hülse. “However, the study shows us that the ocean’s response to higher levels of carbon dioxide in the atmosphere may be underestimated.”

Animals died in “poisonous soup” during the worst mass extinction on earth: a warning for today

More information:

Dominik Hülse et al., Marine extinction in the terminal perm due to temperature-related nutrient recycling and euxinia, Natural geosciences (2021). DOI: 10.1038 / s41561-021-00829-7

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