Deadliest period in Earth's history was also the stinkiest
Toxic microbe burps caused mass extinction

Date:
December 20, 2021
Source:
University of California - Riverside
Summary:
Tiny microbes belching toxic gas helped cause -- and prolong -- the
biggest mass extinction in Earth's history, a new study suggests.



FULL STORY ==========================================================================
Tiny microbes belching toxic gas helped cause -- and prolong -- the
biggest mass extinction in Earth's history, a new study suggests.


========================================================================== Generally, scientists believe Siberian volcanos spitting greenhouse
gases primarily drove the mass extinction event about 250 million years
ago, at the end of the Permian period. The gases caused extreme warming,
which in turn led 80% of all marine species, as well as many land species,
to go extinct.

Until now, scientists could not explain exactly how the heat caused those deaths. A new UC Riverside-led study in Nature Geoscience shows that
the heat accelerated microbes' metabolisms, creating deadly conditions.

"After oxygen in the ocean was used up to decompose organic material,
microbes started to 'breathe' sulfate and produced hydrogen sulfide,
a gas that smells like rotten eggs and is poisonous to animals," said
UC Riverside Earth system modeler Dominik Hu"lse.

As ocean photosynthesizers -- the microbes and plants that form the
base of the food chain -- rotted, other microbes quickly consumed the
oxygen and left little of it for larger organisms. In the absence
of oxygen, microbes consumed sulfate then expelled toxic, reeking
hydrogen sulfide, or H2S, creating an even more extreme condition called euxinia. These conditions were sustained by the release of nutrients
during decomposition, promoting the production of more organic material
which helped to maintain this stinky, toxic cycle.

"Our research shows the entire ocean wasn't euxinic. These conditions
began in the deeper parts of the water column," Hu"lse said. "As
temperatures increased, the euxinic zones got larger, more toxic, and
moved up the water column into the shelf environment where most marine
animals lived, poisoning them." The expanding euxinic zones can be
detected through chemical signatures in sediment samples.

Oxygen depletion is a problem that persists today and is bound to
get worse under future climate change. Euxinic waters can be found in
places like Los Angeles County's 16-mile-long Dominguez Channel, into
which a September 2021 warehouse fire released ethanol. The ethanol
killed vegetation in the channel, which decayed and got consumed by
microbes. They then produced hydrogen sulfide at toxic levels. Thousands
in breathing range of the reeking river reported vomiting, diarrhea,
dizziness, insomnia, headaches, sneezing, and other symptoms.

Lessons from the ancient world may be important for understanding the
processes that are challenging our modern oceans and waterways.

"It would be speculative to superimpose the ancient mass
extinction event on today's planet," Hu"lse said. "However, the
study does show us that the ocean's response to higher carbon
dioxide concentrations in the atmosphere may be underestimated." ========================================================================== Story Source: Materials provided by
University_of_California_-_Riverside. Original written by Jules
Bernstein. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Dominik Hu"lse, Kimberly V. Lau, Sebastiaan J. van de Velde, Sandra
Arndt, Katja M. Meyer, Andy Ridgwell. End-Permian marine extinction
due to temperature-driven nutrient recycling and euxinia. Nature
Geoscience, 2021; 14 (11): 862 DOI: 10.1038/s41561-021-00829-7 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/12/211220083059.htm

--- up 2 weeks, 2 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)