Did volatile halogenated gases from giant salt lakes at the end of the Permian Age lead to a mass extinction of species?The team of researchers found that microbial processes in present-day salt lakes in the south of Russia and South Africa naturally produce and emit highly volatile halocarbons such as chloroform, trichloroethene, and tetrachloroethene. They applied these findings to the Zechstein Sea, which about 250 million years ago in the Permian Age, was situated about where present day Central Europe is. With a total surface area of around 600.000 km2 the Zechstein Sea was almost as large as France is today.
The scientists calculated that from the Zechstein Sea alone an annual VHC emissions rate of at least 1.3 million tonnes of trichloroethene, 1.3 million tonnes of tetrachloroethene, 1.1 million tonnes of chloroform as well as 0.050 million tonnes of methyl chloroform can be assumed. By comparison, the annual global industrial emissions of these compounds amount to only about 20 percent of that respectively.
"Using steppe plant species we were able to prove that halogenated gases contribute to speeding up desertification: The combination of stress induced by dryness and the simultaneous chemical stressor `halogenated hydrocarbons´ disproportionately damages and destabilize the plants and speeds up the process of erosion," Dr. Karsten Kotte.
Based on both of these findings the researchers were able to form their new hypothesis: At the end of the Permian Age the emissions of halogenated gases from the Zechstein Sea and other salt seas were responsible in a complex chain of events for the world’s largest mass extinction in the history of the earth, in which about 90 percent of the animal and plant species of that time became extinct. link