Research Watch Air Quality Pollution history. The lead isotope composition of tree rings can be used as a proxy of the atmospheric lead isotope composition of urban areas. (Tommasini, S., et al. "Lead Isotope Composition of Tree Rings as Biogeochemical Tracers of Heavy Metal Pollution: A Reconnaissance Study From Firenze, Italy", Appl. Geochem. 2000,15 (7)) 891-900)
Climate Change Carbon storage. The effect of increasing C0 2 and climate on net carbon storage in terrestrial ecosystems of the conterminous United States from 1895 to 1993 was modeled with new, detailed historical climate information. (Schimel, D., et al. "Contribution of Increasing C0 2 and Climate to Carbon Storage by Ecosystems in the United States", Science 2000, 287 (5460), 2004-2006)
Contaminants
Assessing chemical persistence. The authors include case studies to demonstrate the advantages of a using a tiered classification scheme and a multimedia model for classifying a chemical as "persistent" or "nonpersistent" when only a few properties are known and can be used to direct further data collection. (Bennett, D. H., et al. "Evaluating Multimedia Chemical Persistence: Classification and Regression Tree Analysis", Environ. Toxicol. Chem. 2000 J 9 (4), 810-819)
Energy Oxidation fuels. The direct electrochemical oxidation of dry hydrocar-
Chinese scientists evaluate mercury emissions Until now, no comprehensive assessment of mercury emissions from coal combustion in China has been performed, although the country is the world's largest coal consumer—1380 Mt of coal were consumed in 1995. To establish this information, Q. Wang and co-workers performed an extensive study of emissions. They found that the average mercury concentration of coals is 0.22 mg/kg and that mercury emission factors of coal-fired boilers range from 64.0 to 78.2%. They also estimated that the total amount of mercury emissions from coal combustion was 302.87t in 1995, including 213.8 t into the atmosphere and 89.07 t into ash and cinder. For comparison, annual global emissions of mercury to the atmosphere range from about 2000 to 40001. The study also indicates that 2493.8 t of mercury were emitted into the atmosphere during the coal combustion process from 1978 to 1995. {Environ. Sci. Techno!..,his issue, pp. 2771-2713)
bon fuels to generate electric power has the potential to substantially accelerate the use of fuel cells in transportation and distributed-power applications. (Park, S., et al. "Direct Oxidation of Hydrocarbons in a Solid-Oxide Fuel Cell", Nature 2000,404 (6775), 265-267)
harmful effects of mercury compounds. (Boening, D. W. "Ecological Effects, Transport, and Fate of Mercury: A General Review", Chemosphere 2000, 40 (12), 1335-1351)
Modeling Health Cancer promotion. The symmetry of the way both arsenic and dioxin act at the promotional step of cancer development in a select but broad array of tissues—arsenic to promote initiated cancer cells and dioxin to promote blocking them—is explored. (Kayajanian, G. M. "Arsenic, Dioxin, and the Promotional Step in Cancer Creation", Ecotoxicol. Environ. Saf. 2000, 45 (3), 195-197)
Ozone concentrations. Modeling the effects of increased urban tree cover on ozone concentrations from Washington, DC, to central Massachusetts reveals that urban trees generally reduce ozone concentrations in cities but tend to increase average ozone concentrations in the overall modeling domain. (Nowak, D. J., et al. "A Modeling Study of the Impact of Urban Trees on Ozone", Atmos. Environ. 2000 34 (10), 1601-1613)
Recycling Mercury Microorganism impacts. The authors examine the impact of mercury on various organisms, including microorganisms, aquatic and woody plants, aquatic invertebrates, and birds and conclude that the form of retained mercury in birds is more variable and that with few exceptions, terrestrial plants are generally insensitive to the
3 1 4 A • JULY 1, 2000 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
Computer recycling. The disposal of the estimated 300,000 scrap personal computers generated each year in Taiwan presents a difficult task for the island due to the scarcity of landfills and incineration facilities available locally. (Lee, C.-H., et al. "Management of Scrap Computer Recycling in Taiwan", /. Hazard. Mater. 2000. 73 (3), 209-220)
