Clean Air Act was boon to Appalachian forests

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Rand
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Clean Air Act was boon to Appalachian forests

Post by Rand » Thu Sep 12, 2013 9:42 am

Researchers from West Virginia University and Kansas State University collected tree ring cores from a stand of old eastern red cedars near the south branch of the Potomac River. The rings showed that although the trees were from one to five centuries old, they are now in the midst of a youthful growth spurt that began around 1980. By measuring the isotopes of carbon in the wood, the researchers were able to track changes in the trees’ physiology over the last 100 years.

Trees, of course, combine carbon dioxide and water (using sunlight) to produce carbohydrates for energy and growth. They take in CO2 through stomata—open pores in the leaves—through which they also lose water. An increase in the amount of CO2 will typically allow most plants to constrict their stomata, losing less water while obtaining the same amount of CO2.

But carbon dioxide isn't the only thing that influences stomata. Exposure to the sulfuric acid in acid rain constricts stomata without the corresponding boost in the availability of CO2. Through this and other mechanisms, acid rain limits the growth of plants.

The carbon isotopes show that the trees’ stomata increasingly constricted through the early to mid-1900s before reversing course around 1980. The 1930s bucked the trend, however, with stomata opening back up a bit. If the only thing affecting the stomata was rising atmospheric CO2, you wouldn’t expect this sort of pattern.

One factor can explain this behavior nicely: sulfur pollution. The region is downwind of the coal-fired power plants in the Ohio River Valley and has received its share of sulfuric acid over the years. Emissions rose in the early 1900s, fell temporarily during the Great Depression, and declined from their peak starting around 1980—and all this is reflected in the carbon isotopes of those trees. The researchers even measured isotopes of sulfur in the wood and found clear differences before, during, and after the period of high sulfur emissions.
GibraltarRock_cedar-640x963.jpg
http://arstechnica.com/science/2013/09/ ... n-forests/

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Rand
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Joined: Tue Mar 16, 2010 9:25 pm

Re: Clean Air Act was boon to Appalachian forests

Post by Rand » Sun Sep 15, 2013 4:56 pm

I found a web site with maps showing the actual changes in acid concentration and deposition over the last 2 decades:
(I picked the worst extremes to start with)

S-legend.jpg
S-con-1.jpg
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You can find the complete animations as well as maps for ammonia and nitrous oxides here:
http://nadp.sws.uiuc.edu/data/animaps.aspx

And that persistent wart in SE Ohio? It appears to be from just 2 coal fired power plants:
S-ohio.jpg
S-ohio.jpg (45.25 KiB) Viewed 1787 times
Which with a little googling are mercifully in the process of being decommissioned because gas is currently cheaper than installing modern pollution controls on the things.

http://www.bizjournals.com/columbus/new ... rning.html

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