lytical procedure to estimate exposure in the aquatic environment. They account for bioconcentration in the environment by measuring the concentration of each chemical onto a hydrophobic substrate, which serves as a surrogate for bioconcentration in the environment (Environ. Set Technol. 1995,29, 726, 734). By analyzing the chemicals on the substrate and not the mixture itself, they account for some of the changes in the effluent composition that occur in the environment. Because narcotic chemicals dominate the toxicity of the mixtures being analyzed, the toxicologists need only measure the total molar concentration extracted during this concentration process to determine the total mixture toxicity The results of such analyses must be treated with some caution, according to Hermens. The procedure measures only the nonspecific toxicity of mixtures; chemicals with more specific modes of actions (for example, mixtures of polychlorinated biphenyls [PCBs] and dioxins) must be treated in another way. But despite these limitations, this approach is a breakthrough, according to Bradbury. "The Utrecht group is using the modeof-action idea to sort out this one toxicological group. It's a pattern for handling other groups." Most aquatic toxicologists agree that the QSAR-based approach for determining the toxicity of mixtures requires further development before it can be put to practical application. Mixture effects are, to a limited extent, already incorporated into regulations, and there are indications that such approaches will be increasingly used. In the Netherlands, the government applies an extra "application factor" of 100 to individual standards to deal with combined exposure. Although this is a first step, Hermens says, the factor does not have a sound scientific basis and is still controversial. Instead, he believes that because regulation of chemicals usually is based on standard bioassays, the theoretical work on mode-of-action groups forms the basis for including mixture effects in regulations. —REBECCA RENNER
NEWS
TECHNOLOGY
NOAA project attempts to rebuild coral reefs Widespread deterioration of coral reefs and a recent project to rebuild damaged ones was addressed at a symposium of the American Association for the Advancement of Science at its annual meeting Feb. 11. Marine biologists estimate that up to 10% of the world's coral reefs have been altered beyond recovery and another 30% will reach that status within 10 to 20 years. A new research project that attempts to reconstruct damaged reefs, although not a cure-all, may offer a tool to help preserve these elaborate ecosystems. Siltation and eutrophication from erosion and sewage, overharvesting of aquatic species, and physical destruction from shipwrecks and dynamiting by fishermen are the chief forces destroying the world's coral reefs and the species that inhabit them, said marine biologists at the meeting. In turn, the damage makes corals and other reef organisms more susceptible to infectious pathogens, noted Esther Peters, a biologist with the consulting firm TetraTech, and an expert in histopathological changes in coral. Coral reefs are also hit by long-term, global factors, such as increased ultraviolet light caused by depletion of the stratospheric ozone layer, speakers emphasized, which results in coral bleaching through expulsion of symbiotic algae. The decline of coral reefs may
increase, according to recent data presented by James Thomas of the Smithsonian Institution. Thomas said reef species have a much higher level of endemism than previously thought. Because they are restricted, endemic species are particularly susceptible to extinction by catastrophic local events, noted Marjorie ReakaKudla of the University of Maryland, who added that only 10% of reef species may be known. A pioneering project by the National Oceanic and Atmospheric Administration (NOAA) in the Florida Keys addresses one of the more severe impacts on reefs: gross destruction by shipwrecks. The project was conducted on a larger scale and with greater technological support than previous efforts, and it appears to have been successful, according to project director Charles M. Wahle. At two sites of 1989 ship groundings off Key Largo, 4000 square meters of reef had been destroyed by the groundings and subsequent salvage operations. The reconstruction used barges as floating work stations, tethered over the reefs to prevent additional damage. Unstable coral rubble piles were removed and craters in the reefs filled in. At one site, both the shallow, six-foot depth and large crater size presented major challenges, Wahle said. There, 10-ton custom-made concrete blocks with embedded fossil coral from upland quarries
A construction barge works at reef restoration site in the Florida Keys.
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were maneuvered into place and mortared with sand and underwater cement. Surveys done just weeks after the reconstruction, which was completed in September, showed algal recolonization and egg-laying by fish within reef crevices. The next phase in the project will be "ecological restoration," in which adult corals and sponges will be transplanted to the restored reef in an effort to accelerate the slow process of recolonization. Several marine biologists, however, said protection is the best course to save reefs. Reconstruction projects are sometimes useful, said Jack Sobel of the Center for Marine Conservation in Washington, D.C., but they are economically and biologically less efficient than preventing damage in the first place. Wahle conceded that the rebuilding process is not a panacea for the gradual degradation of reef habitats by humans. NOAA plans to try the engineering approach at other sites, but Wahle added that globally coral reefs are "going to hell in a hand basket." He reflected the prevailing mood among reef biologists at the symposium that a fundamental protective program is needed. —ROBIN EISMAN
California electric vehicle delay may boost introduction of cleaner cars nationwide A proposal before the California Air Resources Board (CARB) may slow down the market for electric cars there but speed introduction of cleaner cars to the rest of the country. On March 28, board members are expected to sign off on a staff-negotiated plan that gives automakers more time to meet a state electric vehicle mandate in return for their agreement to a quicker introduction of lowemission vehicles throughout the United States. The deal has been initialed by CARB's chair and the seven major automakers in the California market, and the board is expected to support it or a similar version. "There is pretty widespread agreement on the need to modify the ZEV [zero-emission vehicle] mandate," said a source close to CARB. In exchange for relaxing the California 1998 ZEV mandate from 2% to less than 1% of all cars sold in the state, automakers promised to market Californiastyle low-emission vehicles (LEVs) throughout the country by 2001, three years earlier than required by the 1990 Clean Air Act Amendments. According to CARB, these
BUSINESS Growth projected for global environmental markets The demand for environmental goods and services worldwide is expected to grow 5% over the next five years to more than $570 billion, according to a new study commissioned by EPA. Developing countries are the fastest growing environmental markets for firms seeking foreign business, the researchers say, especially in Asia and Latin America, where growth rates are projected at 17% and 12%, respectively. The projected major market sectors worldwide are water delivery, water treatment, and solid waste management, which combined constitute 60% of the demand in developing countries, according to Environmental Business International, Inc. (EBI), the San Diego, Calif., environmental market research firm that conducted the study. Having privatized their water utilities, France and the United Kingdom now dominate the water services market, EBI reports. French and British companies have won all the major water project contracts in developing countries. U.S. firms are the most competitive internationally in solid waste management, according to EBI. They also are superior in the hazardous waste management, analytical services, instrumentation, and remediation markets, although there is less demand outside the United States for these. U.S. environmental firms, however, have been largely complacent internationally, EBI said. Instead, they have focused on the $165.5 billion domestic market, the world's largest, and captured 97% of it. —DANIEL SHANNON
LEVs emit 70% less pollution than current models. In justifying the plan, CARB officials said some 20% of cars registered in California were purchased out of state and the introduction of LEVs nationwide would more than offset any emissions increase from the lower number of electric cars. CARB officials also noted that the rest of the state's far-reaching ' vehicle requirements will stay in place, including the mandate that 10% of all vehicles sold in California in 2001 be electric. The delay in the early years is intended to give automakers and battery manufacturers some temporary breathing room to firm up designs. CARB and the auto industry noted last year that although the companies will not make the 2% mandate in 1998, they will introduce a few electric vehicles this year and in 1997 (ES&T, Jan. 1996, 18A). However, CARB's decision may upset other states that have planned pollution reductions based on the California mandate. According to EPA and Northeastern state officials as well as spokespersons for the American Automobile Manufacturers Association (AAMA), after the California vote is taken attention will turn to the 12 Northeast states and the District of Columbia, which make up the Ozone Transportation Commission (OTC). These states have put together their own plan to require emissions reductions based on the California model. Automakers and OTC states were close to an agreement to require a phase-in of LEVs in Northeastern states beginning in 1997 and full implementation by 1999. But negotiations between automakers and OTC states have stalled over a demand by the states that "advanced technology vehicles" powered by natural gas and clean fuels be included in any agreement. Additionally, two states—Massachusetts and New York—adopted California's requirement for electric cars, and officials in those states want to retain that requirement despite California's decision to restructure
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