NEWS OF THE WEEK
BURDEN OF POLLUTION SUPERFUND: EPA explores tougher
financial requirements to ensure that companies pay for cleanups
FAN TAIL MEDIA
EPA wants to ensure that companies don’t leave taxpayers to pay for costly toxic cleanups.
T
HE ENVIRONMENTAL Protection Agency is
considering new regulations that will require chemical companies to have adequate resources to clean up environmental damage that may result from their operations. In a late-December announcement, EPA said it is taking the first step to ensure that plant owners—not taxpayers—foot the bill for cleaning up pollution under the Superfund law. In explaining its concern, the agency cited the case of Vertac Chemical, in Jacksonville, Ark. When the firm went bankrupt in 1986, it left behind 29,000 drums of chemical waste and a $127 million cleanup bill to be paid by the federal government. EPA also singled out a Delaware chlorinated-benzene manufacturer that folded in 2002, sticking federal taxpayers with a cleanup tab that is expected to reach $100 million. EPA has spent some $2.7 billion of taxpayer dollars
GILDED GRAPHENE MATERIALS: Gold coat and microscopy
methods offer new way to see and analyze atoms-thick carbon sheets
G
LIANFENG SUN/NCNT
RAPHENE FILMS between one and four atomic
layers thick can be distinguished by coating them with a layer of gold. According to a new study, the gold layer adopts a unique appearance based on the number of graphene layers (J. Am. Chem. Soc., DOI: 10.1021/ja909228n). Graphene’s exceptional electronic, optical, and mechanical properties have recently focused attention on the sheet of carbon as little as one atom thick. Yet advances in this area have been hampered by the small number of microscopy and spectroscopy techniques capable of “seeing” graphene and distinguishing between samples of various thicknesses. COLOR CODED In this SEM The study, by Lianfeng Sun of the image, a thin gold coat helps National Center for Nanoscience & distinguish a four-layer-thick Technology, in Beijing, and coworkregion of graphene (left) from ers, adds to a short list of recently bare silica (middle) and a bilayer developed techniques for enhancing region (right). contrast between graphene films of WWW.CEN-ONLINE.ORG
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through 2009 to clean up pollution from bankrupt chemical company plants. In the past, a Superfund tax on chemicals paid for the cost of cleanups when companies could not, but that tax ended in 1995. By law, EPA must require facility owners to show “evidence of financial responsibility consistent with the degree and duration of risk” from plant operations, the agency noted. But chemical plants, which often handle large quantities of toxic chemicals, can sidestep these requirements by a change of ownership, EPA explained. The agency’s view is supported by a 2005 Government Accountability Office report warning that chemical companies are at risk of incurring huge environmental liabilities but can avoid this liability through bankruptcy. At this time, EPA said it is seeking comments only on the need for new financial assurance requirements and the form they might take. EPA’s announcement affects not only chemical companies but also petroleum refineries, gas and coal-related industries, and electric power generation companies. Future requirements are yet to be determined, an EPA official stressed, but options could include insurance or establishment of a dedicated cleanup fund. The American Chemistry Council, an industry trade association, is monitoring the issue and meeting with member companies to gauge the impact the requirements could have, an ACC official said.—JEFF JOHNSON
various thicknesses and between the carbon films and the solid surfaces that typically support them. Sun and coworkers used Raman microspectroscopy to benchmark the number of atomic layers in graphene samples and mapped out regions of differing thickness within a single sample. Then they evaporated gold onto the samples. They found that they could use scanning electron microscopy to recognize differences in the morphology, grain size, and general appearance of the gold films and that those differences depend directly on the number of underlying graphene layers. The SEM analysis can be done faster and with higher spatial resolution than the Raman analysis, they say. “This work reveals an intriguing layer-dependent surface property of graphene,” says Jiaxing Huang, a materials science professor at Northwestern University. That property may play a diagnostic role in future hybrid materials and electronic devices built from metal-graphene composites, he adds. Huang’s group just developed an alternative method for graphene imaging that exploits graphene’s knack for quenching fluorescence in nearby dye molecules. Treating a solid that supports numerous graphene samples with fluorescein (which can be removed after analysis) causes the carbon films to appear dark, in strong contrast to bare regions of the support, which fluoresce brightly. The technique can distinguish between films of various thicknesses and works on films suspended in solution, they report (J. Am. Chem. Soc. 2010, 132, 260).—MITCH JACOBY
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