July 2011, Vol. 23, No.7


More types of algae mean better nutrient uptake

Preserving biodiversity helps improve water quality by removing excess nutrients, such as nitrate, from streams, according to a new study by Bradley J. Cardinale of the University of Michigan (Ann Arbor).

“[The study] provides solid evidence of a cause-and-effect relationship between biodiversity and water quality that was previously missing,” said Cardinale in a National Science Foundation (NSF; Arlington, Va.) news release.

Algae proved to be the key to water filtration. Each species of algae has adapted to a different set of conditions and occupies a unique portion of habitat in a waterbody. The study shows that as the number of algae species in a stream increases, the distribution of algae expands, and the more water the organisms are able to clean, the news release says.  

Cardinale began growing one to eight species of algae common in North America, each in 150 miniature model streams, and measured the ability of each algal community to soak up nitrate. In the study, nitrate uptake increased linearly with algae species diversity. On average, the combined eight species removed nitrate 4.5 times faster than a single species alone, the news release says.

Cardinale’s study, funded by NSF, appears in the April 7 issue of Nature.


Ionic liquids make recovering oil and tar more reliable and environmentally friendly

The problem of separating and recovering oil or tar from sand or soil following environmental disasters is being tackled by Paul Painter, a Penn State University (University Park, Pa.) professor of polymer science and engineering.

Work completed within the past 18 months at the university has yielded evidence that certain ionic liquids can be used to separate bitumen — a black, oily, viscous material — from tar and oil sands to free contaminated beach sand of spilled oil, according to a Penn State news release. The separation usually is conducted in conjunction with a nonpolar solvent at room temperature to lower the viscosity of the tar or bitumen to facilitate separation.

Painter’s method yields no wastewater. And while other methods of oil separation, such as incineration or washing with detergents, can be costly, unreliable, and cause further environmental harm, this method recovers essentially all of the bitumen in clean form with no detectable mineral fines and no contamination from the ionic liquids, the news release says.


Filter uses paper coated with silver nanoparticles to clean drinking water

McGill University (Montreal) researchers are discovering that silver has a more practical application than jewelry: It can clean drinking water in emergency situations.

Disease often spreads following floods, tsunamis, and earthquakes because of the lack of quality drinking water, but inexpensive, portable, paper-based filters coated with silver nanoparticles could help prevent this problem, according to a McGill news release. The filters have proven efficient in eliminating harmful bacteria and cleaning affected drinking water.

Derek Gray, a professor from McGill’s Department of Chemistry, coated thick (0.5-mm), hand-sized sheets of an absorbent, porous paper with silver nanoparticles and then poured live bacteria through them, the news release says. Gray found that when the paper contained a small amount of silver, the filter was able to kill nearly all of the bacteria and produce water that met standards set by the U.S. Environmental Protection Agency.

Gray is looking to develop and implement the filter as a way of providing rapid small-scale assistance in emergency settings.


U.S. EPA and Coast Guard work together to combat imported pollutants and invasive species

U.S. waters will be rid of some pollutants in the coming years as the U.S. Environmental Protection Agency (EPA) and the U.S. Coast Guard (USCG) work to fulfill the terms of a memorandum of understanding (MOU) they signed. The MOU outlines steps to prevent illegal discharges of pollutants from nearly 70,000 commercial and foreign ships based and operating in the United States.

The MOU creates a framework for better cooperation on data tracking, monitoring, training, verifying compliance, and achieving industry outreach, according to a USCG news release.

Also under the agreement, USCG will incorporate components of EPA’s vessel general permit (VGP) program into its existing inspection protocol and procedures. This move will enable the United States to better monitor and address vessel pollution in domestic waters.

Cruise ships, or oil and cargo tankers operating in U.S. waters fall under the VGP, which applies to owners and operators of nonrecreational vessels at least 24 m (79 ft) long. The permit covers 26 types of discharges, such as deck runoff from rain; ballast water used to stabilize ships; and wastewater from showers, sinks, and laundry machines, the release says. These discharges are detrimental to growing ecosystems.


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