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-
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nent of programs designed to reduce blood lead levels. (Schultz, B.; Pawel D.; Murphy, A. "A Retrospective Examination of In-Home Educational Visits To Reduce Lead Levels," Environ. Res. 1999, 80 (4), 364-368)
MEASUREMENTS Oceanic particle characterization. Applying flow cytometric sorting and direct temperature-resolved mass spectrometry to oceanic particulate organic matter samples can bridge the gap between information available from bulk measurements, such as elemental analyses, and information derived from detailed, but laboriously compiled, class-specific analyses. (Minor, E. C; Eglinton, T. I.; Boon, J. J.; Olson, R. "Protocol for the Characterization of Oceanic Particles via Flow Cytometric Sorting and Direct TemperatureResolved Mass Spectrometry," Anal. Chem. 1999, 71 (10), 2003-2013)
MODELING Ambient sulfur concentrations. The adaptation of a regional Lagrangian approach for making longterm simulations of S0 2 and sulfate ambient concentrations at the resolution needed for health effects risk assessment in Asian megacities and their surroundings is explored. (Calori, G.; Carmichael, G. R. "An Urban Trajectory Model for Sulfur in Asian Megacities: Model Concepts and Preliminary Application," Atmos. Environ. 1999, 33 (19), 3109-3117)
PESTICIDES Exposure assessment. Four different mixing-loading and application practices in potato fields were measured individually to assess their relative contribution to the total exposure of pesticide users. (Vercruysse, E; Drieghe, S.; Steurbaut, W.; Dejonckheere, W. "Exposure Assessment of Professional Pesticide Users During Treatment of Potato Fields," Pestic. Sci. 1999, 55 (4), 467-473)
Polybrominated diphenyl ethers synthesized Polybrominated diphenyl ethers (PBDEs) are produced industrially and are used widely as flame retardant additives—the estimated global consumption of PBDEs in 1992 was 40,000 metric tons. Recent data suggest that this substance class may be more harmful than previously believed—for example, 2,2',4,4',5-pentabromo diphenyl ether has been reported to induce learning disabilities in mice. Increased knowledge of the physical chemical parameters of PBDEs can aid in their identification and quantification in environmental samples and support assessments of their toxicity. In support of this objective, G. Marsh and colleagues synthesized and characterized 32 PBDEs, and report melting points as well as UV, 1H NMR, and mass spectra. {Environ. Sci. Technol., this issue, pp. 3033-3037)
SOILS
PAHs. The genotoxicity of two polycyclic aromatic hydrocarbons was experimentally shown to decline after aging in soil for 7 to 15 days, with little or no loss of the compounds. (Alexander, R. R.; Alexander, M. "Genotoxicity of Two Polycyclic Aromatic Hydrocarbons Declines as They Age in Soil," Environ. Toxicol. Chem. 1999,18 (6), 1140-1143)
TOXICOLOGY Neural network-based modeling. A model based on probabilistic neural networks without using the octanol-water partition coefficient is applied to the estimation of toxicological effects of chemicals on the fathead minnow. (Kaiser, K. L. E.; Niculescu, S. P. "Using Probabilistic Neural Networks To Model the Toxicity of Chemicals to the Fathead Minnow {Pimephales promelas): A Study Based on 865 Compounds," Chemosphere 1999, 38 (14), 3237-3245)
WASTEWATER
PCDD/F levels. Soil samples collected near an old municipal solid waste incinerator in Spain were analyzed to determine the temporal variation in polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran levels. (Domingo, J. L; Schuhmacher, M.; Granero, S.; Iiobet, J. M.; De Kok, H. A. M. "PCDD/F Levels in the Vicinity of an Old Municipal Solid Waste Incinerator: Temporal Variation in Soils," Arch. Environ. Contam. Toxicol. 1999, 36 (4), 377-383)
TOXICITY Aquatic biomarker. The p53 gene was sequenced from five fish species with a view to the possible use of mutations in the highly conserved domains of p53 to identify genotoxins in the aquatic environment. (Bhaskaran, A.; May, D.; RandWeaver, M.; Tyler, C. R. "Fish p53 as a Possible Biomarker for Genotoxins in the Aquatic Environment," Environ. Mol. Mutagen. 1999,33 (3), 177-184)
Industrial effluents. Technologies and tests that enable water utilities to monitor sewage treatment and water treatment works intakes to identify and apply consent limits on pollution sources or to automatically switch to enhanced processes or diversion mechanisms are discussed. (Fearnside, D; Caffoor, I. "The Detection of Pollution: Some Novel Approaches,"£>iwron. Toxicol. Water Qual. 1998,13 (4), 347-357)
WETLANDS Early pollution indicators. A review of rapid assessment techniques for determining wetland degradation describes the ideal attributes of early warning indicators and evaluates the potential of existing assessment methods. (Van Dam, R. A.; Camilleri, C; Finlayson, C. M. "The Potential of Rapid Assessment Techniques as Early Warning Indicators of Wetland Degradation: A Review," Environ. Toxicol. Water Qual. 1998,13 (4), 297-312)
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