Environmental▼News just limit ourselves to talk about water scarcity but actively seek ways and opportunities to further lower the water resources threshold.” Among the potential improvements, say the researchers, are greater emphasis on wastewater treatment, reuse, recycling, and artificial recharge to groundwater. Finding ways to limit pollution and environmental degradation will also be important. Malin Falkenmark, a hydrologist with the Stockholm International Water Institute, who was among the first to concentrate on water scarcity issues, is not surprised by the EAWAG results. In 1992, Falkenmark estimated the water stress threshold at 1700 m3/(capita year) solely on the basis of empirical data. Comparison of water needs, or consumption values, shows that “there are huge differences among various regions in the world,” says Falkenmark. Several regions cluster around 1000 m3/(capita year). The highest water consumers are the United States and countries in Cen-
tral Asia, which use 2500 m3/(capita year), whereas China reports water withdrawals of only 500 m3/(capita year). Until recently, most countries below the water threshold were oilrich and thus could afford cereal imports. However, the new analysis predicts that many poor and populous countries, such as Afghanistan, India, Iran, Nigeria, Pakistan, and Uganda, will fall below the water resources threshold before 2030.
California to develop selenium standard for wildlife The California offices of the U.S. EPA, the U.S. Fish and Wildlife Service (USFW), and several other agencies have agreed to develop an aquatic standard for selenium to protect wildlife in California. This would be the first water quality regulation intended to protect birds and other wildlife in addition to fish. The move comes at a time when draft federal EPA guidelines, which used selenium tissue concentrations in fish as the basis for revising water quality recommendations, have been blocked for almost a year by objections from USFW. Selenium is an essential micronutrient, but at high concentrations it leads to reproductive abnormalities in fish and birds. Its toxic effects have been the topic of furious debate among aquatic toxicologists for
Image Not Available for Use on the Web
more than 10 years. Government scientists charged with protecting wildlife say existing standards must be tightened because selenium contamination is widespread, but industry scientists say that it is an environmental oddity and that EPA’s draft addresses the issue. Like mercury, selenium’s aquatic cycle is complex and diet is the
274 A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / AUGUST 1, 2003
The looming threat of insufficient food production will have to be met by bigger efforts “to enhance water use efficiency,” asserts Falkenmark. Yang agrees, adding that these efforts “should be devoted to innovation and application of environmentally sustainable agricultural technologies,” as well as improving international food trade. —ORI SCHIPPER
main exposure route. Consequently, EPA’s current chronic criterion for selenium, 5 parts per billion (ppb) in water, is often not closely related to the amounts found in fish. EPA’s draft selenium chronic criterion, completed in March 2002, used tissue concentrations with the intent of safeguarding fish reproduction. Toxicologists agree that tissue concentrations “offer an opportunity to let the fish tell us whether the environment is safe,” says William Adams, senior science adviser for Rio Tinto, a mining company. “I think the selenium chronic criterion is a unique step forward in environmental protection.” However, USFW claimed that the draft standard could lead to adverse reproductive effects in many of California’s threatened and endangered species and delayed it by appealing to the Endangered Species Act.
EPA’s draft is overly simplistic because it doesn’t account for food webs, counters U.S. Geological Survey (USGS) scientist Theresa Presser, in Menlo Park, Calif. As an example, Presser cites the San Francisco Bay, where bass that feed on algae have low selenium levels, but sturgeon that feed on bivalves, which concentrate selenium, get a high dose. To know which wildlife are at risk, it’s necessary to understand the ecosystem, she says. In addition, EPA’s draft guidelines say little about implementation—the details of what, when, and how to analyze fish, or how to set water discharge permits so that fish tissue concentrations stay low. Implementation oversights in EPA’s mercury tissue guidance, which is intended to protect humans who eat fish, have caused chaos in states and agencies, according to USGS scientist Steve Schwarzbach in Sacramento, Calif. But EPA would
have produced implementation guidance for selenium if the new standard hadn’t been sidelined, counters EPA selenium project manager Charles Delos, in Washington, D.C. The draft’s analysis of fish data yields a good standard that addresses dietary exposure, according to Delos, who defends the draft. The proposal to develop a wildlife standard for California uses a method with ample uncertainty factors, he says. “USFW knows what criteria they want in the end. With this methodology, they’ll get it,” he said. California’s site-specific selenium guidelines to protect wildlife could become a model for national standards, say many aquatic toxicologists. In the meantime, discharging industries are pushing EPA to get its tissue concentration draft out of limbo. —REBECCA RENNER
Invasive species drives selenium poisoning
USGS
Invasive zebra mussels, which are bioconcentrating toxic selenium in the Great Lakes, may be poisoning ducks that eat the bivalves, according to new research from the Long Point Water and Wetlands Research Fund, a Canadian nonprofit organization located on Lake Erie. If further studies confirm that the high selenium burdens in waterfowl are causing reproductive or health problems, the findings could put pressure on governments to regulate selenium sources around the Great Lakes, researchers say. Selenium burdens in lesser and greater scaup, two species of diving ducks, averaged 18 and 28 parts per million (ppm), dry weight, and ex-
Because zebra mussels are bioconcentrating selenium, they may be poisoning wild ducks.
ceeded safe thresholds, according to preliminary analyses by Scott Petrie and colleagues. These levels are alarming because tissue concentrations of 4–9 ppm selenium, dry weight, begin to disrupt physiological functioning in mallards, and at 9 ppm the trace element impairs reproduction, leading to fewer eggs and deformed hatchlings, Petrie says. However, these types of effects have not yet been studied in scaup, and more research is needed to determine whether the diving birds can tolerate the high selenium levels, he says. Zebra mussels taken from the guts of birds contained 8.1 ppm selenium, dry weight, well over the toxic threshold of 3 ppm selenium that other researchers consider safe for aquatic foodchain organisms eaten by fish and birds, he adds (see “California to develop selenium standard for wildlife,” p 274A). Tissue from ducks sampled in the mid-1980s, just prior to the accidental 1986 introduction of zebra mussels to Lake St. Claire, contained 6–9 ppm selenium, roughly
News Briefs ES&T Associate Editors cited Three ES&T Associate Editors, Walter Giger, Ron Hites, and Jim Pankow, have been named to the list of highly cited journal authors in all fields of science maintained by Thomson ISI, also known as the Institute for Scientific Information. The ISI’s “highly cited” index is widely recognized as the definitive source of journal citation information. According to an ISI spokesperson, Hites, Giger, and Pankow are among the 248 most highly cited researchers in ISI’s ecology/ environment category, based on articles published between 1981 and 1999. Their influential publications rank them with the top 0.5% of all publishing researchers worldwide, according to Thomson ISI. For more information, go to http://isihighlycited. com/formBrowse.cgi.
Maximizing EPA and industry partnerships To promote collaboration in the development of environmental technologies between industry and the U.S. EPA, the National Technology Transfer Center (NTTC) launched a new website in May. The site highlights projects and facilities currently funded through EPA’s $500 million technology R&D budget. EPA cannot commercialize any technologies it develops, but technology transfers and partnerships with industry help the agency justify federal spending. Based at Wheeling Jesuit University in Wheeling, W.V., NTTC is a technology management group that identifies opportunities and facilitates communication to build partnerships, such as EPA’s Environmental Technologies Partnership. The site lists EPA research opportunities for industrial scientists and provides an organized primer on technology transfers between the federal government and the private sector. For more information, go to www.nttc. edu/etprogram.
AUGUST 1, 2003 / ENVIRONMENTAL SCIENCE & TECHNOLOGY ■ 275 A
