RESEARCH WATCH
AIR QUALITY Aerosol concentrations. A comparison of 24-hour mean PM 2 5 aerosol loadings determined by a TEOM and by two manual gravimetric samplers revealed systematically lower results from the TEOM, consistent with other reports suggesting that semivolatile aerosol material is lost from the TEOM's heated sample filter. (Ayers, G. P.; Keywood, M. D.; Gras, J. L. "TEOM vs. Manual Gravimetric Methods for Determination of PM Aerosol Mass Concentrations " Atmos.Environ. 1999 33 (22) 3717-3721) Analytical methods. Methods for analyzing gaseous and particulate air pollutants are reviewed. (Fox, D. L. "Air Pollution," Anal. Chem. 1999, 71 (12), 109R-119R) Mercury vapor analyzer. The Tekran 2537 A mercury vapor analyzer, which is designed to measure mercury in air by cold-vapor atmospheric ffuorescence spectrometry, has been modified to determine mercury in solution. (Hall, G. E. M.; Pelchat, P. "Development of a Mercury Vapor Air Analyzer for Measurement of Hg in Solution," Water, Air, Soil Pollut. 1999, 111 (1-4), 287-295) Secondary organic aerosols. In a study conducted to examine the formation of secondary organic aerosols, it was found that the presence of an organic in the aerosol did not significantly affect the aerosol's hygroscopic properties. (Kleindienst, T. E.; Smith, D. E; Li, W.; Edney, E. O; Driscoll, D. J.; Speer, R. E.; Weathers, W. S. "Secondary Organic Aerosol Formation From the Oxidation of Aromatic Hydrocarbons in the Presence of Dry Submicron Ammonium Sulfate Aerosol" Atmos. Environ. 1999 33 (22) 3669-3681)
Ozone disinfection byproducts The number of drinking water plants in the United States that use ozone as a disinfectant is increasing—in 1997,150 plants used ozone; in 1998 the number increased to more than 260 plants. However, numerous halogenated disinfection byproducts (DBPs) can form if ozone is used to treat water in which high natural levels of bromide are present. Many of these ozone DBPs have yet to be identified, because most studies performed did not use methods to extract and identify highly polar byproducts. S. Richardson and coworkers used a combination of analytical techniques to isolate and identify many of these previously unidentified products. (Environ. Sci. Techno!..,his issue, pp. 3368-3377 and 3377-3383)
ASSESSMENT Equilibrium composition. The influence of thermodynamic data errors on the results of the calculated equilibrium composition of complex chemical reacting systems is examined. (Belov, G. V; Trusov, B. G. "Influence of Thermodynamic and Thermochemical Data Errors on Calculated Equilibrium Composition," Ber. Bunsen-Ge.. Phys. Chem. 1998 102 (12), 1874-1879)
CLIMATE CHANGE Avian breeding. Warmer monthly minimum temperatures were associated with earlier breeding habits for the Mexican jay in southeastern Arizona, indicating that more attention should be given to the possible ecological importance of global change in minimum temperatures. (Brown, J. L.; Li, S.-H.; Bhagabati, N. "Long-Term Trend Toward Earlier Breeding in an American Bird: A Response to Global Warming?" Proc. Natl. Acad. Sci. U.S.A. 1999 96 (10) 5565-5569) Climate model. Using a global climate model with sufficient resolution in the tropics to adequately represent the narrow equatorial upwelling and low-frequency waves,
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the authors found that more frequent El Nino-like conditions and stronger cold events in the tropical Pacific Ocean could result. (Timmermann, A.; Oberhuber, J.; Bacher, A.; Esch, M.; Latif, M.; Roeckner, E. "Frequency in a Climate Model Forced by Future Greenhouse Warming," Nature 1999, 398 (6729), 694-697) Oceanic CO2 disposal. Field experiments were conducted to test ideas for oceanic disposal of fossil fuel carbon dioxide as a solid hydrate at depths ranging from 349 m to 3627 m and from 8 °C to 1.6 °C. (Brewer, P. G.; Friederich, G.; Peltzer, E. T; Orr, F. M., Jr. "Direct Experiments on the Ocean Disposal of Fossil Fuel C0 2 ," Science 1999, 284 (5416), 943-945) Peat bog archive. From a peat core taken in northwestern Spain, it was found that cold climates promoted an enhanced accumulation and preservation of mercury with low thermal stability, whereas warm climates were characterized by a lower accumulation and predominance of mercury with moderate to high stability. (Martinez-Cortizas, A.; Pontevedra-Pombal, X.; Garcia-Rodeja, E.; Novoa-Munoz, J. C ; Shotyk, W. "Peat Bog: Archive of Climate Change and Atmospheric Metal Deposition" Science 1999 284 (5416) 939-942)
