|Lime Quarry, Springfield, MO- thelibrary.org|
In 1973 it caught fire and the carbon monoxide produced killed a night watchman. The heavy noxious smoke affected local businesses for several weeks. Plumes of smoke reached 200 degrees, nearby businesses closed and Barbara Lucks, then a new college graduate, was nearly driven out of her apartment. Heavy equipment, large cranes and relocated water mains finally snuffed it out until it recurred briefly in 1976. The quarry contained green water until 2001 when it was drained and subsequently filled in. Parts of the landfill are still settling to this day.*
|Quarry 2007- News-Leader|
While the trees weren't burned which would have released large amounts of carbon dioxide, they also didn't undergo the normal slow surface decomposition by fungi and bacteria. This slow recycling normally allows nature to incorporate carbon into soil, then plants and eventually animals, our beloved carbon cycle.
Unfortunately, when wood is buried and damp, decomposition occurs from anaerobic bacteria in an oxygen-free mileu. Anaerobic bacteria produce methane just like they do in a cow's gut. Methane is produced directly from the carbon that is no longer sequestered in the soil. The same process occurs in dense piles of un-aereated wood chips used for power plants. "Forest debris left in the woods will produce very minor amounts of methane, if any, unless it is squashed into a swamp or buried in a stump dump."** Sound like the quarry? Again describing large pulpwood piles:
"This is why the piles often spontaneously catch fire, the piles get very hot while they are generating flammable breakdown products like methane, alcohols, and other gasses or volatile compounds that have a low flash point. These are produced under anaerobic conditions and high temperature, something that does not typically occur in upland forests." **There has been a lot of debate over the last decade about whether trees can produce methane or merely transmit it from the soil. Studies in 2006 concluded that living plants produced methane, a dramatic finding at the time. More research in 2009 described in Science magazine suggested that they are merely transporting it. "Instead, plants appear to merely be passing gas, so to speak, originally made by soil microbes."
Now a study from Yale.edu has shown that living trees do produce methane. This occurs when trees which appear healthy on the outside are hollowed out inside by common fungal infections. This supports the growth of anaerobic methane-producing microorganisms called methanogens. A tree in this condition can produce methane concentrations 80,000 times higher than the ambient ground level atmospheric levels.
Does this mean that cows gets a pass on their gas as the source of atmospheric methane? It is a significant greenhouse gas, 23 times as potent as carbon dioxide. Actually ruminants such as cows and goats produce much more methane than trees, contributing two-thirds of the atmospheric levels through their belching and to a lesser extent flatus. It is hard to picture a way to burn off their methane but ongoing studies on how to reduce their methane will be fuel for another blog.
* The fascinating history of the industry and fighting the fire is summarized in this 2007 News-Leader story.
** The Myths of Dangerous Methane Emissions from Forests, and Cutting Trees to Curb Greenhouse Gas Emissions (PDF)