Chinese scientists have developed a hypothesis that poisonous gas from the deep ocean may have driven one of the severest mass extinctions on the planet.
Sulfureted hydrogen in the depths of the sea may have contributed to the end-Permian extinction that wiped out more than 80 percent of marine life about 250 million years ago, according to the University of Science and Technology of China.
Scientists have posited many hypotheses explaining the mass extinction, including a possible celestial impact and volcano activity.
Through the study of samples of deep-sea sediment, the Chinese team believe they have found evidence indicating the presence of rich sulfureted hydrogen, a poisonous gas, said Shen Yan'an, head of the research.
The interaction between the gas in the deep water with oxygen-rich water on the surface is a deadly mixture, Shen said.
"Today, sulfureted hydrogen exists in some waters in Gulf of Mexico, California and India", said Shen, adding that the findings could also give insight into climate and environmental changes and inform policies.
The findings have been published in the Proceedings of the National Academy of Sciences of the United States of America.