May 2011, Vol. 23, No.5
Web surfing for eutrophication and hypoxia
Keeping track of the health of waterways proves a daunting and important task — but it is one that the World Resources Institute (WRI; Washington, D.C.) and Virginia Institute of Marine Science (VIMS; Gloucester Point) are working on. Research by these two organizations has identified more than 530 low-oxygen “dead zones” and an additional 228 sites worldwide exhibiting signs of marine eutrophication, according to a WRI news release.
Eutrophication and hypoxia often accompany each other as excessive nutrients fuel algae blooms, which die and sink to the floor of a waterbody to provide a food source for bacteria. Bacteria then consume the algae, as well as the dissolved oxygen in the water, leading to dead zones where aquatic life cannot survive.
VIMS professor Bob Diaz began monitoring the extent of eutrophication and dead zones in the mid-1990s and has published an ongoing list of hypoxic areas. He worked with WRI to expand the list and include areas where symptoms of eutrophication have been observed but lack monitoring data, the news release says.
Together, VIMS and WRI have compiled the collected information on the Web site Eutrophication and Hypoxia: Nutrient Pollution in Coastal Waters, which is accessible at www.wri.org/eutrophication. The global database includes an interactive map of affected areas, as well as links to articles, photos, and other resources on hypoxia and eutrophication. The site also includes a comments section to solicit feedback and to encourage updates to information by those familiar with local conditions, the news release says.
Buoying energy production from ocean waves
The next time you see a buoy bobbing in the ocean, it might be helping to power your home. The PB150 Power Buoy wave-power device boasts a peak-rated power output of 150 KW, which is equivalent to the energy consumption of approximately 150 homes, according to an Ocean Power Technologies Inc. (Pennington, N.J.) news release.
The buoy is designed for use in arrays for grid-connected power-generation projects. With a majority of the structure submerged, the system is designed to have a low visual profile and minimal environmental effects, the news release says.
Ocean Power Technologies signed an agreement with 11 U.S. federal and state agencies and three nongovernmental stakeholders for the phased development of a 1.5-MW wave-power project at Reedsport, Ore. A second buoy is under construction in the United States for this proposed utility-scale project.
Snails and crayfish monitor St. Petersburg’s water
In St. Petersburg, Russia, Vodokanal, the local water and wastewater provider, is putting its own twist on an early warning system for hazardous water with crayfish and its newest addition, snails.
In 2005, the company began introducing biomonitoring quality control systems to all of its water treatment plants in the form of an indigenous narrow-clawed crayfish. The company places the environmentally sensitive crayfish in aquariums fed with intake water and monitors their heartbeats and stress index. When the crayfish show substantial stress, water samples are taken for detailed laboratory analysis, according to the company’s Web site.
In 2011, the company expanded the system to include snails. It implemented a new bioelectronic monitoring system at the South-West Wastewater Treatment Plant, where giant African snails, Achatina gastropods, are being used to monitor air conditions near the plant’s solids incinerators. The snails have heartbeat and behavior sensors attached to their shells, and software monitors the animals’ health and “well-being,” the Web site says.
Even with updated smoke-cleaning systems and thorough emission monitors in place, harmful compounds can be present in slight doses. Instead of installing many costly special sensors that might be unable to register trace emissions, scientists from the Russian Academy of Sciences Research Center for Ecological Safety (St. Petersburg) proposed the use of shellfish.
The snails were chosen because they have lungs similar to humans that breathe air, are relatively active, and have a shell that sensors can be attached to without affecting their lives.
The snails will be monitored to test their ability as a toxic-air warning system, the Web site says. The snails should show any negative effects from long-term exposure to chronic toxic pollutants. During the testing phase, snails sit on a ball that floats on water, enabling them to crawl. Water drips on them from above to keep them moist, and they are fed about once a week.
During the first year of operation, three snails will breathe normal air, and three others will breathe incinerator exhaust diluted 1000 to 10,000 times with clean air. The diluted exhaust approximates concentrations at the border of the sanitary protection zone of the plant, the Web site says.
©2011 Water Environment Federation. All rights reserved.