Eco-Friendly Way of Decomposing BPA-Containing Plastic

Just as cooking helps people digest food, pretreating polycarbonate plastic -- source of a huge environmental headache because of its bisphenol A (BPA) content -- may be the key to disposing of the waste in an eco-friendly way, scientists have found. Their new study is in ACS' Biomacromolecules.

Mukesh Doble and Trishul Artham note that manufacturers produce about 2.7 million tons of plastic containing BPA each year. Polycarbonate is an extremely recalcitrant plastic, used in everything from screwdriver handles to eyeglass lenses, DVDs, and CDs. Some studies have suggested that the BPA may have a range of adverse health effects, sparking the search for an environmentally safe way of disposing of waste plastic to avoid release of BPA.
The scientists pretreated polycarbonate with ultraviolet light and heat and exposed it to three kinds of fungi -- including the fabled white-rot fungus, used commercially for environmental remediation of the toughest pollutants. The scientists found that fungi grew better on pretreated plastic, using its BPA and other ingredients as a source of energy and breaking down the plastic. After 12 months, there was almost no decomposition of the untreated plastic, compared to substantial decomposition of the pretreated plastic, with no release of BPA.

Source: http://www.sciencedaily.com/releases/2010/01/100127113753.htm

Greenhouse Gas Carbon Dioxide Ramps Up Aspen Growth

That is the finding of a new study of natural stands of quaking aspen, one of North America's most important and widespread deciduous trees. The study, by scientists from the University of Wisconsin-Madison and the University of Minnesota at Morris (UMM) and published December 4 in the journal Global Change Biology, shows that elevated levels of atmospheric carbon dioxide during the past 50 years have boosted aspen growth rates by an astonishing 50 percent.
"Trees are already responding to a relatively nominal increase in atmospheric carbon dioxide over the past 50 years," says Rick Lindroth, a UW-Madison professor of ecology and an expert on plant responses to climate change. Lindroth, UW-Madison colleague Don Waller, and professors Christopher Cole and Jon Anderson of UMM conducted the new study.
The study's findings are important as the world's forests, which cover about 30 percent of the Earth's land surface, play an important role in regulating climate and sequestering greenhouses gases. The forests of the Northern Hemisphere, in particular, act as sinks for carbon dioxide, helping to offset the increase in levels of the greenhouse gas, widely viewed as a threat to global climate stability.
What's more, according to the study's authors, the accelerated growth rates of aspen could have widespread unknown ecological consequences. Aspen is a dominant tree in mountainous and northern forested regions of North America, including 42 million acres of Canadian forest and up to 6.5 million acres in Wisconsin and Minnesota. Aspen and their poplar cousins are considered "foundation species," meaning they exert a strong influence on the plant and animal communities and dynamics of the forest ecosystems where they reside.
"We can't forecast ecological change. It's a complicated business," explains Waller, a UW-Madison professor of botany. "For all we know, this could have very serious effects on slower growing plants and their ability to persist."
Carbon dioxide, scientists know, is food for plants, which extract it from the air and through the process of photosynthesis convert it to sugar, plant food.
Previously, scientists have shown that plants and trees in growth chambers respond to levels of carbon dioxide well above levels in the atmosphere. The new study is the first to show that aspen in their native forest environments are already growing at accelerated rates due to rising ambient levels of carbon dioxide in the atmosphere.
"It's a change hiding right in front of us," says Cole, a biologist at UMM. "Aspens respond to all sorts of things we had to account for -- water, genetics and other factors -- but the strong response to carbon dioxide surprised all of us."
The study measured the growth rates of 919 trees from Wisconsin forests dominated by aspen and birch. Trees ranging in age from 5 to 76 years old were sampled and subjected to tree-ring analysis. Comparing the tree-ring data, a measure of annual tree growth, with records of atmospheric carbon dioxide, the researchers were able to correlate increased rates of growth with changes in the chemistry of the air.
The surprising increase in growth rates for the trees sampled in the study is coupled, the authors note, with moist conditions. By contrast, aspen in the western United States do not seem to grow as fast as those in the American Midwest, most likely due to recent extended periods of drought. Also, while the researchers found that aspen grow much faster in response to elevated carbon dioxide, similar effects have not been observed in other trees species, notably oak and pine.
Findings from the new study, the authors note, could augur revisions of the estimates of how much carbon northern temperate northern forests can sequester.
"Forests will continue to be important to soak up anthropogenic carbon dioxide," says Waller. "But we can't conclude that aspen forests are going to soak up excess carbon dioxide. This is going to plateau."
"Aspens are already doing their best to mitigate our inputs," agrees Cole. "The existing trees are going to max out in a couple of decades."
The new study was funded by the National Science Foundation and UMM.

Source: http://www.sciencedaily.com/releases/2009/12/091204092445.htm

Marine Lab Hunts Subtle Clues to Environmental Threats to Blue Crabs

Science Daily: The Atlantic blue crab, Callinectes sapidus, long prized as a savory meal at a summer party or seafood restaurant, is a multi-million dollar source of income for those who harvest, process and market the crustacean along the U.S. Atlantic and Gulf coasts.

 

Unfortunately, the blue crab population has been declining in recent years under the assault of viruses, bacteria and man-made contaminants. The signs of the attack often are subtle, so researchers from the National Institute of Standards and Technology (NIST) and the College of Charleston (CofC) are at work trying to identify the clues that will finger specific, yet elusive, culprits.
Pathogens and pollutants impair the blue crab’s metabolic processes, the chemical reactions that produce energy for cells. These stresses should cause tell-tale changes in the levels of metabolites, small chemical compounds created during metabolism. Working at the Hollings Marine Laboratory (HML) in Charleston, S.C., the NIST/CofC research team is using a technology similar to magnetic resonance imaging (MRI) to identify and quantify the metabolites that increase in quantity under common environmental stresses to blue crabs — metabolites that could be used as biomarkers to identify the specific sources.

In a recent paper in Metabolomics, the HML research team describes how it used nuclear magnetic resonance (NMR) spectroscopy to study challenges to one specific metabolic process in blue crabs: oxygen uptake. First, the researchers simulated an environmentally acquired bacterial infection by injecting crabs with the bacterium Vibrio campbellii. This pathogen impairs the crab's ability to incorporate oxygen during metabolism. Using NMR spectroscopy to observe the impact on metabolite levels, the researchers found that the yield of glucose, considered a reliable indicator of mild oxygen starvation in crustaceans, was raised.
In a second experiment, the HML team mimicked a chemical pollutant challenge by injecting blue crabs with a chemical (2,4-dinitrophenol (DNP)) known to inhibit oxidative phosphorylation, a metabolic process that manufactures energy. This time, the metabolite showing up in response to stress was lactate, the same compound seen when our muscles need energy and must take in oxygen to get more produced. A rise in the amount of lactate proved that the crabs were increasing their oxygen uptake in response to the chemical exposure.
"Having the glucose and lactate biomarkers -- and the NMR spectroscopy technique to accurately detect them -- is important because the blue crab's responses to mild, non-lethal metabolic stresses are often so subtle that they can be missed by traditional analyses," says Dan Bearden, corresponding author on the HML paper.
The research was supported in part by the National Science Foundation.
The HML is a partnership of governmental and academic agencies including NIST, NOAA's National Ocean Service, the South Carolina Department of Natural Resources, the College of Charleston and the Medical University of South Carolina.


Source: http://www.earthportal.org/news/?p=3104