RESEARCH WATCH
AIR
Radionuclides in the environment Gas/Particle partitioning. To establish baseline environmental contamination prior to the startup of a new municipal incinerator, air samples were collected continuously over a one-year period at eight locations in southern Bavaria and analyzed at six-week intervals for particle-bound and gaseous concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans, biphenyls, and naphthalenes, as well as polycyclic aromatic hydrocarbons. (Kaupp, H.; McLachlan, M. S. "Gas/Particle Partitioning of PCDD/Fs, PCBs, PCNs, and PAHs," Chemosphere 1999,38 (14), 3411-3421) PM source apportionment. Aerosol samples for PM2 5 and PM10 were collected from 1993 to 1995 at five sites in Brisbane, Australia, to determine the contribution of various emission sources. (Chan, Y. C; Simpson, R. W.; Mctainsh, G. H.; Vowles, P. D.; Cohen, D. D.; Bailey, G. M. "Source Apportionment of PM 25 and PMl0 Aerosols in Brisbane (Australia) by Receptor Modeling," Atmos. Environ. 1999,33 (19), 3251-3268)
ASSESSMENT Solid wastes. Using municipal solid waste incinerator bottom ash as a test matrix for comparing the responses of different variables through toxicity tests and resulting endpoints, the authors demonstrated that increasing oxidant stress enzyme activities are a good indicator of solid- or leachatephase toxicity. (Ferrari, B.; Radetski, C. M; Veber, A.-M; Ferard, J.-F. "Ecotoxicological Assessment of Solid Wastes: A Combined Liquid- and Solid-Phase Testing Approach Using a Battery of Bioassays and Biomarkers," Environ. Toxicol. Chem. 1999,18 (6), 1195-1202)
Radionuclides are frequently discharged into the marine environment from nuclear facilities. A. Cundy and coworkers evaluated the rate at which 60Co and 65Zn declined in the marine environment along the southern U.K. coast over the period 1988-1998 following closure of a steam-generating heavy water reactor. They observed a general exponential decline in radionuclide activity in intertidal mudflat sediments, seaweed, and marine fauna. The slow rate of decline in seaweed and in marine fauna even after the virtual cessation of discharge from nuclear facilities suggests that contamination of these organisms may persist for a number of years. This persistence was attributed to absorption of radionuclides from sediment and release and recycling of radionuclides via breakdown of contaminated organic material. {Environ. Sci. Technol., this issue, pp. 2841-2849)
CHEMISTRY
Carbon dioxide. The relaxation time for chemical equilibrium in the carbon dioxide system in seawater is 15.9 s for the 12C isotope and 17.5 s for isotopic equilibrium. (Zeebe, R. E.; Wolf-Gladrow, D. A; Jansen, H. "On the Time Required To Establish Chemical and Isotopic Equilibrium in the Carbon Dioxide System in Seawater," Mar. Chem. 1999, 65 (3-4), 135-153)
Chromium VI reduction. After the reduction of hexavalent chromium, the kinetic constants of tannic acid and gallic acid are 2 to 3 orders of magnitude larger than those of humic substances. (Nakayasu, K.; Fukushima, M; Sasaki, K.; Tanaka, S.; Nakamura, H. "Comparative Studies of the Reduction Behavior of Chromium (VI) by Humic Substances and Their PrecurOzone-Depleting halogens. sors," Environ. Toxicol. Chem. 1999,18 Although emissions of most gases (6), 1085-1090) regulated by the Montreal Protocol have decreased substantially over the past 10 years, halon-1211 emissions have remained fairly constant despite stringent production limits CLIMATE CHANGE in developed countries. (Montzka, S. A.; Butler, J. H.; Elkins, J. W.; Atmospheric circulation regimes. Thompson, T. M.; Clarke, A. D.; Atmospheric circulation data from Lock, L. T. "Present and Future the Northern Hemisphere are used Trends in the Atmospheric Burden to show that recent climate change of Ozone-Depleting Halogens," can be interpreted in terms of Nature (London) 1999, 398 (6729), changes in die frequency of occur690-694) rence of natural atmospheric circulation regimes, with the result that recent warming may be more directly related to the thermal structure of these regimes than to any anthropoCONTAMINANTS genic forcing pattern. (Corti, S.; Molteni, E; Palmer, T. N. "Signature of Childhood lead levels. Average Recent Climate Change in Frequenobserved blood lead levels declined cies of Natural Atmospheric Circulaby about 21% after in-home edution Regimes," Nature (London) cational visits, indicating that such 1999, 398 (6730), 799-802) visits may be an effective compo-
3 8 0 A • SEPTEMBER 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
