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New Theory On Largest Known Mass Extinction In Earth's History

 
 
Reply Mon 30 Mar, 2009 11:47 am
Quote:
ScienceDaily (Mar. 30, 2009) " The largest mass extinction in the history of the earth could have been triggered off by giant salt lakes, whose emissions of halogenated gases changed the atmospheric composition so dramatically that vegetation was irretrievably damaged.

At least that is what an international team of scientists have reported in the most recent edition of the Proceedings of the Russian Academy of Sciences (Dokladi Earth Sciences). At the Permian/Triassic boundary, 250 million years ago about 90 percent of the animal and plant species ashore became extinct. Previously it was thought that volcanic eruptions, the impacts of asteroids, or methane hydrate were instigating causes.

The new theory is based on a comparison with today's biochemical and atmospheric chemical processes. "Our calculations show that airborne pollutants from giant salt lakes like the Zechstein Sea must have had catastrophic effects at that time", states co-author Dr. Ludwig Weißflog from the Helmholtz-Center for Environmental Research (UFZ). Forecasts predict an increase in the surface areas of deserts and salt lakes due to climate change. That is why the researchers expect that the effects of these halogenated gases will equally increase.

The team of researchers from Russia, Austria, South Africa and Germany investigated whether a process that has been taking place since primordial times on earth could have led to global mass extinctions, particularly at the end of the Permian. The starting point for this theory was their discovery in the south of Russia and South Africa that microbial processes in present-day salt lakes naturally produce and emit highly volatile halocarbons such as chloroform, trichloroethene, and tetrachloroethene.

They transcribed 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. The Zechstein Sea with a total surface area of around 600.000 km2 was almost as large as France is today. The hyper saline flat sea at that time was exposed to a predominantly dry continental desert climate and intensive solar radiation " like today’s salt seas. "Consequently, we assume that the climatic, geo-chemical and microbial conditions in the area of the Zechstein Sea were comparable with those of the present day salt seas that we investigated," Weißflog said.

In their current publication the authors explain the similarities between the complex processes of the CO2-cycle in the Permian Age as well as between global warming from that time and at present. Based on comparable calculations from halogenated gas emissions in the atmosphere from present-day salt seas in the south of Russia, 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 trichloroethene and tetrachloroethene amount to only about 20 percent of that respectively, and only about 5 percent of the chloroform from the emissions calculated for the Zechstein Sea by the scientists. Incidentally, the industrial production of methyl chloroform, which depletes the ozone layer, has been banned since 1987 by regulation of the Montreal Protocol.

"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 from the University of Heidelberg explained.

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.

According to the forecast from the International Panel on Climate Change (IPCC), increasing temperatures and aridity due to climate change will also speed up desertification, increasing with it the number and surface area of salt seas, salt lagoons and salt marshlands. Moreover, this will then lead to an increase in naturally formed halogenated gases. The phytotoxic effects of these substances become intensified in conjunction with other atmospheric pollutants and at the same time increasing dryness and exponentiate the eco-toxicological consequences of climate change.
The new theory could be like a jigsaw piece that contributes to solving the puzzle of the largest mass extinction in the history of the earth. "The question as to whether the halogenated gases from the giant salt lakes alone were responsible for it or whether it was a combination of various factors with volcanic eruptions, the impact of asteroids, or methane hydrate equally playing their role still remains unanswered," Ludwig Weißflog said. What is fact however is that the effects of salt seas were previously underestimated.

In their publication the researchers working with Dr. Ludwig Weißflog from the UFZ and Dr. Karsten Kotte from the University of Heidelberg want to showed that recent salt lakes and salt deserts of south-east Europe, Middle Asia, Australia, Africa, America can not only influence the regional but also the global climate. The new findings on the effects of these halogenated gases are important for revising climate models, which form the basis for climate forecasts.

Journal reference:
Weissflog et al. Late permian changes in conditions of the atmosphere and environments caused by halogenated gases. Doklady Earth Sciences, 2009; 425 (2): 291 DOI: 10.1134/S1028334X09020263

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Type: Discussion • Score: 3 • Views: 1,867 • Replies: 12
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Lightwizard
 
  1  
Reply Mon 30 Mar, 2009 01:37 pm
@Walter Hinteler,
Fascinating.
0 Replies
 
farmerman
 
  1  
Reply Mon 30 Mar, 2009 02:04 pm
@Walter Hinteler,
I have to be the one to ask, IS this an April Fools joke?
Lightwizard
 
  1  
Reply Mon 30 Mar, 2009 02:12 pm
@farmerman,
Nope -- click on the link.
Walter Hinteler
 
  1  
Reply Mon 30 Mar, 2009 02:26 pm
@farmerman,
No, it's published in quite a few other serious scientific reviews here (plus on all major papers).
0 Replies
 
farmerman
 
  1  
Reply Mon 30 Mar, 2009 02:32 pm
@Lightwizard,
More fundamental. The formation of TCE is tied to the formation of ethylene (ethene) gas, which is a product of combustion. SO, is their proposed mechanism not a mere result of ongoing fires?
The geologic record DOES show the "fossil evidence" of large burn areas in the basal Cenozoic (The Tartarian/Induan sequences). By recognizing that this was a time of great cataclysm planet wide, they are proposing a mechanism that I find semi-dubious.

The natural world produces about 20+million tons of ethylene per year (most all from gas vents and bio ) To be toxic to 90% of life, there would have to be a hewmongous increase in the production of ethene (and then there would be the problem of making TCE and PCE to actually snuff the critters)

THE toxicity of both PCE and TCE are a function of dosage and duration, The natural solubilities of these chemicals is below its toxicity to marine life)

farmerman
 
  1  
Reply Mon 30 Mar, 2009 03:05 pm
@farmerman,
Im gonna have to do a "six degrees of Kevin BAcon" to see whether I cant learn more about the evidence and the model they propose. THey dont seem to recognize that , at the termi9nal Permian were still , large "forests" of fungi. These were mushrooms that helped break down the dead wood from the earlier cataclysmic actions (yet the full effects of the P die off had not been felt). The fungi pass right ovr the P/T border seemeingly unaffected. To me, a TOXIC level of either PCE/TCE and other chlorocarbons would mean the end to all plant life as well as animals. (We have evidence from tree ring analyses beneath TCE spill areas, With concentrations of TCE in the 10-50 ppm levels , the trees are decimated, at highre concentrations, they are all wiped out.)


I need better evidence before I jump on board of this. Itt sounds like it could be reasonable but at the "extreme" edge of reasonableness.



0 Replies
 
Walter Hinteler
 
  1  
Reply Mon 30 Mar, 2009 03:11 pm
Press release by the Helmholtz Centre for Environmental Research (UFZ).


And if your Russian is good enough ...
http://www.maikonline.com/maik/showArticle.do?auid=VAFR1OI7XN
farmerman
 
  1  
Reply Mon 30 Mar, 2009 03:22 pm
@Walter Hinteler,
Getting published does not automatically mean that youre right. It means that, in the present case,"we have an idea and were gonna throw it up on the wall and see if it sticks". What usually happens is that other researchers in this area will present corroborating evidence(or data that refutes it).
I only presented the info from the Treatise on Plant Paleontology re" large fungus deposits from all over the world at the termnal Permian . That is actual evidence, not a model based proposal.

0 Replies
 
farmerman
 
  1  
Reply Mon 30 Mar, 2009 03:23 pm
@Walter Hinteler,
Actually, this is a HYPOTHESIS, not a theory.
spendius
 
  1  
Reply Mon 30 Mar, 2009 05:11 pm
It takes "natural selection" transformation mechanisms into one more area than those few I suggested in another place. It could be, according to scientists, exposure to salt and not lingerie as I had previously thought.
0 Replies
 
Lightwizard
 
  1  
Reply Mon 30 Mar, 2009 07:13 pm
@farmerman,
I think you're right.
farmerman
 
  1  
Reply Tue 31 Mar, 2009 05:37 am
@Lightwizard,
The recent announcements about the huge meteorite in the late Pleistocene that killed the megafauna had a short lifespan. It was evidenced that several of the species survived well beyond the start of the Holocene. These oncluded several species of mammoth that lived to at least 6k bce. A small mastodon was found in a pet bog in SE NY state and this one was about 7k bce.
A short faced bear skeleton in a cave in Arizona was about 9k bce.

Also, the "fires" that were associated with the supposed meteor strike were not found to be very widespread.

I imagine that this hypothesis will be given attention and be the subject of debate as more evidence (plus or minus) shows up and is added to the mix.
0 Replies
 
 

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