Wildfires release 15 times more toxic mercury - Canada ramifications

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Wildfires release 15 times more toxic mercury

Mnr, the Canadian Press

The Hamilton Spectator

(Sep 19, 2006)

http://www.hamiltonspectator.com/NASApp/cs/ContentServer?pagename=

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Vastly increased emissions of highly toxic mercury are an unexpected

result of climate change in Canada's northern woods.

New data suggest wildfires release 15 times more of the poisonous element

into the air than previously thought, more than every U.S. coal-fired

power plant combined. And those emissions could double again as the boreal

forest grows hotter and drier.

" This could be quite significant, " said Mike Flannigan of the Canadian

Forest Service, who co-authored the recently published scientific paper.

Scientists have long known that forest fires release mercury into the

atmosphere. But researchers assumed peatlands -- widespread in the vast

boreal forest stretching across nearly every Canadian province -- released

the potent neurotoxin at the same rate as trees and other so-called " first

fuels. "

But Flannigan and his American colleagues at the United States Geological

Service found that mercury tends to concentrate in boggy peatlands.

For thousands of years, that mercury has been accumulating in peatlands,

where it is buried and away from plants, animals and humans. But when

peatlands burn, mercury is released into the atmosphere, eventually

falling to earth where it combines with sulphur to form mercury's most

toxic form: methylmercury.

And as climate change creates drier boreal forests with longer droughts,

especially in the global warming hotspot of northern Canada, fires are

likely to burn both larger areas and deeper into peatlands once protected

by groundwater.

source: The Canadian Press

An Ontario Ministry of Natural Resources helicopter conducts an aerial

back burn operation on a forest fire 150 kilometres north of Thunder Bay

attempting to bring the fire to a natural water boundary. Satellite images

show the fire grew to 16,800 hectares, quadrupling in size since last

Thursday.

Of 294 active fires in Northern Ontario, 202 were not under control.

Thirty-seven were held or under control, and the rest were being observed.

Fire watchers were also seeing fires burn right over wet areas like

marshes, which would normally stop flames.

Mercury is a versatile material known for thousands of years. It is the

only metal that is liquid at room temperature. It is a good electrical

conductor, has a very high density and high surface tension, expands and

contracts uniformly when pressure and temperature change, and it can kill

micro-organisms, including pathogenic organisms and other pests.

Elemental mercury has been used

* To extract gold and silver from ore (for centuries).

* In the manufacture of chlor-alkali chemicals.

* In manometers, which measure pressure.

* In thermometers.

* In electrical and electronic switches.

* In fluorescent lamps.

* In dental amalgam fillings.

Mercury compounds have been used

* In batteries

* As biocides, to control or destroy micro-organisms, e.g. in the paper

industry, in paints and on seed grain

* As antiseptics in pharmaceuticals

* For chemical analysis

* As catalysts, to make the manufacture of other chemicals more efficient.

Mercury pollution can threaten the health of people, fish, and wildlife

everywhere, from industrial sites to remote corners of the planet, but

reducing mercury use and emissions would lessen those threats.

Scientists attending the eighth International Conference on Mercury as a

Global Pollutant in August also declared that a significant portion of the

mercury deposited near industrial sources comes from those sources and

that evidence of mercury's health risks is strong enough that people,

especially children and women of child-bearing age, should be careful

about how much and which fish they eat.

The conference found:

* On average, three times more mercury now falls out of the sky than

before the Industrial Revolution 200 years ago.

* For the last 30 years, emissions from developing countries have increased.

* More mercury is falling to earth's surface.

* Understanding of the global mercury cycle is being confounded by climate

change.

* There is solid scientific evidence that methylmercury has toxic effects,

particularly to the developing fetus. New evidence indicates that

methylmercury may increase the risk of cardiovascular disease,

particularly in adult men.

* Consumers should choose fish with high levels of omega-3 fatty acids

with lower levels of methylmercury.

* There is no evidence that selenium in the diet protects people from the

neurological and developmental effects of methylmercury.

* Methylmercury exposure may lead to population declines in birds and

possibly in fish and mammals as well.

* The concentration of methylmercury in fish is expected to decline with

reduced mercury inputs.

* The use of mercury in small-scale gold mining is polluting thousands of

sites around the world, posing long-term health risks to up to 50 million

inhabitants of mining regions and contributing more than 10 per cent of

the mercury in Earth's atmosphere resulting from human activities.

Source: University of Wisconsin-Madison

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