RESEARCH WATCH Assessment PCDD/F formation. Experiments in which plastics were co-combusted indicated that PCDD/F formation did not depend on the distance between co-combusted materials and that PCDD/F formation took place exclusively in a gas phase reaction. (Wirts, M.; Lorenz, W.; Bahadir, M. "Does Co-Combustion of PVC and Other Plastics Lead to Enhanced Formation of PCDD/F?" Chemosphere 1998, 37(8), 1489-1500)
Biodegradation Methane cycling. Molecular methods were developed to analyze methane producing and methaneoxidizing microbial communities. (Edwards, C ; Hales, B. A.; Hall, G. H.; Mcdonald, I. R.; Murrell, J. C ; Pickup, R.; Ritchie, D. A.; Saunders, J. R.; Simon, B. M.; Upton, M. "Microbiological Processes in the Terrestrial Carbon Cycle: Methane Cycling in Peat" Atmos. Environ. 1998, 32(19) 3247-3255)
Contaminants Acid rain effects. The miluence of sulfate concentrations on me production and emission of methane in two contrasting peat sites was determined. (Watson, A.; Nedwell, D. B. Methane Production and Emission From Peat: The Influence of Anions (Sulfate, Nitrate) From Acid Rain," Atmos. Environ. 1998, 32(19), 32393245) Dioxinlike compounds. High fish consumers seem to be subject to elevated TEQ exposure from dioxinlike PCBs, and this has implications for exposure assessment studies that previously only considered PCDDs and PCDFs. (Alcock, R. E.; Behnisch, P. A.; Jones, K. C; Hagenmaier, H. "Dioxin-Like PCBs in the Environment: Human Exposure and the Significance of Sources," Chemospere 1998, 37(8), 1457-1472)
MTBE in lakes Discovery of methyl tert-butyl ether (MTBE) in drinking water supplies is of concern to public health officials, water suppliers, and the public. Few published studies exist on the concentrations, sources, and fate of MTBE in surface waters. At Donner Lake, Calif., J. E. Reuter and co-workers determined the relative contribution of motorized watercraft as a source of MTBE, seasonal distribution, loss from the water column, extent of vertical transport, and persistence between years. Results indicated that recreational boating was the most important source of MTBE. Statistically, 86% of the change in MTBE was explained by variation in motorized watercraft use, and neither highway runoff nor precipitation contributed significantly. (Environ. Sci. Techno!..,his issue, pp. 3666-3672)
History of lead deposition. A continuous record of atmospheric lead 12,370 carbon-14 years before the present (14C yr BP) is preserved in a Swiss peat bog. (Shotyk, W; Weiss, D.; Appleby, R G.; Cheburkin, A. K.; Frei, R.; Gloor, M.; Kramers, J. D.; Reese, S.; Van Der Knaap, W O. "History of Atmospheric Lead Deposition Since 12,370 14C yr BP From a Peat Bog," Science 1998, 281 (5383), 1635-1640) Methane release. Temperature and water table profiles in a peatland were investigated to understand how these factors influence methane emissions. (Daulat, W E.; Clymo, R. S. "Effects of Temperature and Watertable on the Efflux of Methane From Peatland Surface Cores," Atmos. Environ. 1998, 32(19), 3207-3218) Pollutant transport. Miscible displacement and batch sorption experiments were conducted using a wide range of solute concentrations to investigate the impact of concentration-dependent behavior on 2,4dichlorophenoxyacetic acid transport in soil. (Hu, M. Q.; Brusseau, M. L. "Coupled Effects of Nonlinear, Rate-Limited Sorption and Biodegradation on Transport of 2,4-Dichlorophenoxyacetic Acid in Soil," Environ. Toxicol. Chem. 1998 17(9), 1673-1680)
Control Catalytic NOx reduction. The authors review what is known about
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chemical and mechanistic aspects of the selective catalytic reduction of NO by ammonia (SCR process) on metal oxide catalysts. (Busca, G.; Lietti, L.; Ramis, G.; Berti, F. "Chemical and Mechanistic Aspects of the Selective Catalytic Reduction of NO x by Ammonia Over Oxide Catalysts: A Review," Appl. Catal, B 1998, 18 (1-2), 1-36) Methyl bromide control. Results from a study on a methylotrophic bacterium suggest that soil treatment strategies can be devised whereby bacteria can effectively consume methyl bromide during field fumigations, diminishing or reducing the outward flux of the pesticide to the atmosphere. (Connell Hancock, T L; Costello, A. M.; Lidstrom, M. E.; Oremland, R. S. "Strain IMB-1, a Novel Bacterium for the Removal of Methyl Bromide in Fumigated Agricultural Soils " Appl. Environ. Microbiol 1998 64(8) 2899-2905)
Green Chemistry Adipic acid production. Cyclohexene can be oxidized directly to colorless crystalline adipic acid with aqueous 30% hydrogen peroxide under organic solvent- and halide-free conditions. (Sato, K.; Aoki, M.; Noyori, R. "A 'Green' Route to Adipic Acid: Direct Oxidation of Cyclohexenes With 30% Hydrogen Peroxide," Science 1998, 281 (5383), 1646-1647)
0013-936X/98/0932-550A$15.00/0 © 1998 American Chemical Society
