Environmental▼News most of the concern has centered around nonylphenol and its parent compounds because they are more abundant in the environment. It is unclear whether airport runoff is likely to be a major source of alkylphenols. In a stream near General Mitchell International Airport in Milwaukee, Wis., the researchers found nonylphenol at a concentration of 3.89 micrograms per liter (µg/L) after an intense aircraft deicing event on January 31, 2002. For comparison, in a recent USGS study, Dana Kolpin and colleagues found nonylphenols in 43 out of 85 U.S. rivers, with a median concentration of 0.8 µg/L and a maximum concentration of 40 µg/L (Environ. Sci. Technol. 2002, 36, 1202–1211). In laboratory studies, nonylphenols have been shown to cause endocrine-disrupting effects in rainbow trout exposed to levels as low as 8.3 µg/L (Environ. Sci. Technol. 2001, 35, 2909–2916). Wastewater treatment plants (WWTPs) are likely to be a much bigger source of alkylphenols, believes Alba Torrents, an associate professor of civil and environmental engineering at the University of Maryland, College Park, who has been investigating nonylphenols in WWTP discharge near Washington, D.C., and Baltimore, Md. “As a
source, WWTPs probably contribute higher loads to the receiving streams, because they operate constantly and discharge large volumes. At airports, deicing occurs only a few times a year, and the amount of runoff, even if concentrated, will not match that of a WWTP effluent,” she says. Nonetheless, biota living in streams near airports are exposed to concentrations of nonylphenols that could be toxic, even if it is for a short period of time, she adds. The U.S. EPA estimates that 21 million gallons of aircraft deicing fluid (50% concentration) are discharged annually into U.S. surface waters, according to a 2000 report. Alkylphenol ethoxylates and their breakdown products add to a growing list of toxic compounds hidden in aircraft deicers. Proprietary additives make up about 1–5% of deicer fluids, according to coauthor Devon Cancilla of Western Washington University, who previously reported finding tolyltriazoles in aircraft deicers (Environ. Sci. Technol. 1998, 32, 3834–3835). Tolyltriazoles are anticorrosion chemicals used extensively in paints, cooling towers, car radiator fluids, and anywhere metal and water are together, Cancilla says. The chemicals are much more toxic to fish
Global climate change is altering the thermal structure and productivity of lakes recovering from acid rain, according to researchers studying lakes in the southern boreal forest of Ontario, Canada. Impacted by climate change and additional stressors, such as calcium depletion and invasive species, the lakes may not all return to their original biological condition, says Bill Keller, a limnologist with the Ontario Ministry of the Environment. Loss of dissolved organic carbon (DOC) is making the lakes clearer, driving photosynthetic production to the lake bottom and warming the water above tolerance thresholds for once-native trout, says John Gunn, a fisheries researcher with the Ontario
ED SNUCINS
Climate change undermines recovering lakes
Some Canadian lakes are too clear for their own good.
Ministry of Natural Resources. Because the lakes exhibit strong thermal responses to small differences in DOC, they have become sensitive indicators of climate change and may also be used to predict future changes in Arctic lakes under a warming climate, he
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and other organisms than glycols. Cancilla and colleagues have detected tolyltriazoles in groundwater near airports and in fish. They are currently investigating their cellular effects in fish. “We know triazoles are in aircraft deicers, but there are a lot of other compounds as well. We still don’t know what they are,” Cancilla adds. “The triazoles can’t account for all of the toxicity that we observe. One of these days, we’d like to come up with more funding to do some more fractionation of the material itself,” he says. “There is the potential for these things to have long-term low-level effects that nobody knows about.” Meanwhile, airports such as General Mitchell International are taking a proactive approach to improve the quality of their discharge, according to the airport’s environmental manager, Greg Failey. Unlike many other airports that use high volumes of aircraft deicers, General Mitchell International is one of the few that is aggressively trying to understand what is causing toxicity in the receiving waters, he says. “We are taking an extra step that a lot of other airports would not in order to understand the actual chemistry of the problem,” he says. —BRITT E. ERICKSON
said at the International Mining and the Environment conference in May. “As lakes recover from acid rain, you would expect them to become more opaque because the DOC that colors the water should increase in concentration as levels of acid and metals, which precipitate DOC, decline,” Gunn explains. Instead, lakes in Killarney Park, south of Sudbury, are becoming some of the clearest in North America, he says. Nellie and O.S.A. Lakes have less than 0.2 milligrams per liter of DOC, and their clarity has increased by 10 meters (m) over the last 30 years to a secchi depth (a clarity measure) of 32 m. Prior to acidification, the lakes probably had a secchi depth of 11–12 m, says Gunn. Two traits of global climate change, declining rainfall and in-
and their distributions could change if calcium drops below critical thresholds, he says. Some of the Sudbury area lakes are close to the threshold, but researchers cannot say when or whether the lakes will cross the threshold, he notes. Invasive species are another stressor that will change the kinds and abundance of native algae and fish, Dillon says. “There are a rapidly growing number of lakes with Bythotrephes cederstroemi, the spiny water flea, which is hard for fish to eat and is a heavy predator on zooplankton,” he says. “The clear lakes in Killarney provide the best long-term signal of climate change,” Gunn says. There are thousands of shallow, clear trout lakes in the Arctic that now stay cold because they are exposed to bright light for only brief periods. But if global warming increases the time during which these lakes are ice-free, they could become sunburned and, like the Killarney lakes, lose the thermal stratification so vital to trout, he says. The change in thermal regime is not limited to the Sudbury area. It controls habitat availability for certain species of algae, zooplankton, and fish, Dillon says. —JANET PELLEY
EPA perchlorate decision takes many by surprise The U.S. EPA announced in July that it would not move forward with developing regulations for any unregulated drinking water contaminants at this time. This decision surprised many in the drinking water arena, particularly because perchlorate, which is the primary ingredient used in manufacturing solid propellant for rockets, missiles, and fireworks, is a high-priority contaminant of concern on EPA’s Contaminant Candidate List (CCL). The list includes 50 chemical and 10 microbial contaminants, and EPA is required under the Safe Drinking Water Act to select at least 5 contaminants from this list every 5 years and determine whether a regulation would likely result in a reduction of health risks.
EPA recommended a preliminary drinking water limit of 1 part per billion (ppb) for perchlorate in 2002 (Environ. Sci. Technol. 2002, 36, 125A), but there are still many unknowns, says John Millett, an EPA spokesperson. He points to ongoing activities such as data collection on occurrence, work to improve low-level detection methods, and reviews of perchlorate removal technologies, all of which will need to be finalized before a standard can be developed. Additionally, the National Academy of Sciences is currently reviewing the risk assessment on which the draft 1-ppb limit is based (Environ. Sci. Technol. 2003, 37, 166A–167A). Environmentalists are concerned, however, that “the effect of EPA’s lat-
News Briefs Good news for GM crops The risks to human health from commercial genetically modified (GM) crop varieties or foods made from them are very low, according to a report commissioned by the U.K. government. Investigators found no evidence to show crops are toxic, allergenic, or nutritionally deleterious. The report, which reviewed all relevant scientific literature, also noted that the three main commercial GM crops—maize, canola, and cotton—are unlikely to be toxic to wildlife, invade the countryside, or become problematic plants. However, the report stressed that the findings were not a blanket approval for GM crops and recommended a case-by-case approach to making environmental impact assessments. An open review of the science is available at www.gmsciencedebate.org.uk/ report/default.htm.
Businesses slacking on climate change Most of America’s biggest greenhouse gas-emitting companies are still pursuing business strategies that fail to respond adequately to the potential impacts of global warming, finds a report by the Coalition for Environmentally Responsible Economies (CERES), composed of environmental, investor, and public interest groups. In contrast, non-U.S. companies are more likely to report on the financial risks of climate change and undertake mitigation strategies. The report profiles 20 companies and finds that most of their securities filings do not disclose the financial risks associated with emissions. The electric power industry scored lowest. Those that scored highest include oil companies BP and Royal Dutch/Shell. Corporate Governance and Climate Change: Making the Connection is at www.ceres.org.
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creasing evaporation, mean that fewer organics are washed into lakes and water doesn’t spill as quickly out of the lakes, leaving DOC exposed to sunlight for longer periods, Gunn says. The ultraviolet portion of sunlight breaks down the DOC, eventually oxidizing it to carbon dioxide and making the lakes a net source of greenhouse gases, says Peter Dillon, a biogeochemist at Trent University in Canada. Whereas photosynthesis was once carried out mainly by suspended algae in the upper water layers, light now penetrates to the bottom of the “sunburned” lakes in Killarney, stimulating lush aquatic moss growth as deep as 50 m below the surface, Gunn says. In the 1940s, the cool dark lake depths sheltered cold-loving trout. Killed off by acid rain, trout would find today’s lakes too warm to live in, as dark bottom sediments not covered by moss soak up the sun’s rays and elevate temperatures of the deep waters to 13–15 °C. Acid rain has depleted the calcium pool in watershed soils, and this continues to be a problem even as lakes become less acidic, Keller adds. Crayfish, other crustaceans, and daphnia (a group of water fleas) all depend on calcium,
