[LINK] Smoking Gun for Pollution - The Great Dying - or How burning Coal killed all life on earth (250m yrs.)

[Tom Koltai]

It is rare for me to quote an article in it's entirety. Occasionally the
content mandates full revelation.

Quote from the Authors on the paper:


"We saw layers with abundant organic matter and Hamed immediately
determined that they were layers of coal-ash, exactly like that produced
by modern coal burning power plants," says Beauchamp. 


>From the annals of ArsT
http://arstechnica.com/science/news/2011/01/massive-volcanic-eruptions-c
oal-fires-the-great-dying.ars

Quote/
The late Permian extinction, which kicked off roughly 250 million years
ago, has a rather gruesome nickname: the Great Dying. Over 90 percent of
the species in the oceans went extinct in the geological blink of an
eye, and similar devastation took place on land. It's about as close as
we've come to having multicellular life wiped out. The timing of the
event coincides with a volcanic outburst that covered an area the size
of Western Europe in volcanic rock. That might be enough to trigger a
major catastrophe on its own, but new research indicates that the hot
magma ignited coal deposits, sending toxic coal ash into the oceans. 

The remains of these eruptions, called the Siberian Traps, now cover
about 2 million square kilometers of Russia. The rock formation is
what's called a flood basalt, thought to be caused by a plume of hot
mantle breaking through to the surface. The Siberian Traps may be the
largest event of this sort we know about, and the dimensions are
staggering: over 1,000 Gt (Gigatonnes) of magma were released during the
eruptions that created them, and they are thought to have put material
into a plume that rose over 40 kilometers into the atmosphere. 

The effects on life were devastating. Massive ash falls, huge changes in
the carbon cycle, ocean acidification, and climate change all
accompanied the eruptions, and all of those are capable of pushing
species to extinction. But is that really enough to account for wiping
out over 90 percent of the life in the oceans? 

Some researchers don't think so, and have focused on a secondary effect
of the eruptions: burning coal. There is evidence that the hot magma
intruded into large deposits of coal found in Siberia and set it alight.
Some estimates suggest that over 3 trillion tons of carbon could have
been placed into the atmosphere through the burning of coal alone
(that's in addition to the carbon dioxide released by the volcanism
proper). That release would come in the form of methane, a potent
greenhouse gas. Methane is rapidly oxidized into carbon dioxide, which
could then contribute to ocean acidification. 

As if all of that weren't enough, the new paper, published in Nature
Geoescience, indicates that the Siberian Traps eruptions might have
added another insult to the oceans: toxic coal ash. The authors examined
deep ocean sediments from a site that was off the west coast of the
supercontinent at the time. To get there with the prevailing winds,
material from the eruption would have to travel around the globe, a
distance the authors estimate as more than 20,000 kilometers. And yet
the sediments contain organic material that, under the microscope, looks
remarkably similar to coal ash obtained from a modern power plant. 

The authors were able to detect three pulses of this material derived
from coal burning in the half-million years before the onset of the
Great Dying, with the third and most significant ending just as marine
life collapsed. Each of them were associated with changes in the carbon
cycle, either resulting from the large release of the eruptions
themselves, or the burning of organic materials that continued in their
wake. 

This combustion material is known to stress aquatic ecosystems in two
ways. To begin with, the coal ash will block enough sunlight to inhibit
photosynthesis, a major source of the ocean's dissolved oxygen. That
creates anoxic conditions, and isotope ratios confirm that the oceans
probably experienced an anoxia event that coincided with the last major
eruption. In addition, coal ash carries toxic metals with it; levels of
chromium increased with each of the eruptions, and peaked with the third
and final one. Thus, the coal ash itself probably contributed directly
to the conditions that were so harmful to life in the oceans. 

It's clear from this data that the formation of the Siberian Traps
created conditions that would severely stress life in the oceans through
a variety of mechanisms. Although problems would obviously have started
before the Great Dying itself, the final, critical event seems to have
been the most severe. The preponderance of evidence clearly links the
extinction to the eruptions that made Traps themselves. 

The biggest open question is whether all the factors were global in
nature. Diffusion of gasses is rapid, so issues like ocean acidification
would clearly have a global impact. But the spread of fly ash is very
dependent on the prevailing winds, and the site examined by the authors
is at roughly the same latitude as the eruptions themselves. Sampling of
sites further removed from the Siberian Traps may indicate whether what
the authors see there (which they refer to as "Catastrophic dispersion
of coal fly ash" in the title) was a truly global catastrophe. 
/Quote