September 2009, Vol. 21, No.9
Waterline - The Risky Tamarisk
Pretty pink shrubs are presenting an unsightly threat to western U.S. river ecosystems. The tamarisk (Tamarix ramosissima), also known as saltcedar, is causing headaches as it invades riparian forests and harms native species.
Introduced to the United States from central Asia about 200 years ago, the once ornamental tamarisk quickly spread throughout the West. Its extensive root system makes it well suited for the hot, dry climate, according to the Tamarisk Coalition (Grand Junction, Colo.) Web site.
The Tamarisk Coalition, formed in 2002, aims to restore riparian lands, which tamarisk populations can alter significantly from their natural state. According to Stacy Kolegas, executive director of the coalition, the tamarisk has invaded riparian zones — areas along river banks — throughout all 17 western states below elevations of 1981 m (6500 ft).
Riparian zones are unique river ecosystems populated by both terrestrial and aquatic flora and fauna. These plants and animals depend on the water source for survival, according to Kolegas. Not only does the tamarisk displace native plants, it also “has a reputation for using more water than the native vegetation it displaces,” leading to decreased water supplies, Kolegas said.
With its extensive root system, the tamarisk can tap deeper groundwater, using up the limited water supply in the West. The tamarisk also creates an increased risk of flooding, as it can clog river channels.
In addition to water issues, the tamarisk also competes with native species for natural resources and can increase soil salinity, making the ground uninhabitable for native species. Furthermore, it can make a poor habitat for wildlife and increase the risk of dangerous wildfires, Kolegas said.
Various methods for tamarisk control exist, including hand and mechanical control, herbicide spraying, and biological control. The tamarisk leaf beetle, which feeds on tamarisk leaves and kills the plant, underwent rigorous testing by the U.S. Department of Agriculture and was determined to be a safe control measure. According to Kolegas, the best approach depends on specific circumstances.
The cost of tamarisk removal varies based on the methods used. Herbicide and mulching can cost from $865 to $2965/ha ($350 to $1200/ac), while hand removal can cost as much as $12,355/ha ($5000/ac), depending on the density of tamarisk cover, according to the Riparian Restoration report prepared by the Tamarisk Coalition.
Beyond the impacts and costs of tamarisk populations, there is also a sentimental factor driving tamarisk control. “Many people feel that it is important to restore native plants because they are part of our natural heritage,” Kolegas explained.
Study Finds Wastewater Treatment Creates ‘Superbugs’
Scientists at the University of Michigan (Ann Arbor) are pointing to wastewater treatment facilities as potential sources of “superbugs,” bacteria that are resistant to multiple antibiotics. Superbugs are easily selected in wastewater treatment plants, according to the results of a new study, and can be transferred in effluent to local lakes and streams.
A recent report on the study, “Wastewater Treatment Contributes to Selective Increase of Antibiotic Resistance Among Acinetobacter spp.,” says researchers found a significant increase in multidrug-resistant forms of Acinetobacter in effluent water compared to raw influent, suggesting that wastewater treatment caused the increase. The report, authored by researchers Yongli Zhang, Carl F. Marrs, Carl Simon, and Chuanwu Xi, appeared in the June issue of the journal Science of the Total Environment.
The collection of antibiotics in wastewater treatment facilities, coupled with antibiotic-resistant genes, high microbial density, and antimicrobial agents, may create a favorable setting for selection of antibiotic-resistant bacteria, the report says.
Though more research is needed, the risks of creating superbugs may be a cause for concern. According to Xi, Acinetobacter poses a low threat to healthy adults, but the threat “may be high to sick or immunocompromised populations.”
Xi said more research is necessary to better understand the risk of these superbugs, as well as the long-term effects of pharmaceuticals in the water. It is still unknown what levels of antibiotics are required to foster the creation of superbugs in wastewater. There are advanced treatment technologies that can rid water of antibiotics, but, as Xi notes, their costs may be prohibitive for many facilities.
The study demonstrates that wastewater treatment practices can select multidrug-resistant bacteria, and they can be transported to receiving waters. Though consumers can help by disposing of pharmaceuticals properly, Xi said the responsibility to rid water of the antibiotics that help create superbugs should lie in the hands of wastewater treatment facilities.
Ultraviolet Disinfection Manufacturer Wins Stockholm Industry Water Award
Trojan Technologies (London, Ontario) was presented with the 2009 Stockholm Industry Water Award during World Water Week in Stockholm, Sweden, in August.
The Stockholm International Water Institute (SIWI) nomination committee noted Trojan’s technological innovation and drive for commercial, engineering, and regulatory acceptance of ultraviolet (UV) disinfection systems for water treatment, according to a SIWI news release.
“Trojan’s success has contributed to a viable competitive industry in the area of ultraviolet technologies, leading to the development of a full range of industrial technologies in both specialized and general applications,” the committee said in the news release.
Trojan provides open-channel and pressurized UV disinfection systems for industrial, municipal, agricultural, and residential water treatment. The company has installed more than 5800 systems in 80 countries. Trojan UV technology is applied to both wastewater and drinking water treatment worldwide.
Curbing Watershed Pollution, One Viral Video at a Time
Protecting America’s watersheds begins with a camcorder and a computer. That is the premise of U.S. Environmental Protection Agency (EPA) Water Quality Video Contest. This spring, EPA invited participants to create and submit original short videos “that inspire people to help protect our streams, lakes, wetlands, and coasts,” according to the Web site for EPA’s Office of Wetlands, Oceans, and Watersheds (OWOW).
Videos were submitted in two categories: a 30- or 60-second video that can be used as a TV public service announcement, or a 1- to 3-minute instructional video. According to the OWOW Web site, EPA wanted the videos to convey “easy, low cost steps that can be taken to protect water quality.”
To sweeten the deal, EPA offered a $2500 prize to the winner of each category.
The winner of the shorter public service announcement video was Lucas Ridley of Trenton, Ga. His video, “Protect Our Water — Check Cars for Oil Leaks” highlighted motor oil as one source of watershed pollution, noting that one quart of oil can pollute up to 946,250 L (250,000 gal) of water.
Nora Kelley Parren of Hinesburg, Vt., won the instructional video category for her video “Dastardly Deeds and the Water Pollution Monster.” The stop-motion animation video, made entirely of discarded paper, emphasizes how runoff carries pollution to local watersheds and offers several tips for limiting runoff.
View the winning videos and honorable mentions at www.epa.gov/owow/videocontest.html.