Cass, G. R. "Source Contributions to Atmospheric Fine Carbon Particle Concentrations," Atmos. Environ. 1998, 32(22), 3805-3825) Biodegradation. Modeling experiments identified the key trends of adsorption, biodegradation from dissolved and adsorbed phases, bubble volatilization, and surface volatilization for compounds having a range of molecular properties. (Lee, K-C; Rittmann, B. E.; Shi, J.; McAvoy, D. "Advanced Steady-State Model for the Fate of Hydrophobic and Volatile Compounds in Activated Sludge," Water Environ. Res. 1998, 70(6), 1118-1131) Biological nutrient removal. A new biological phosphorus and nitrogen removal process with a step-feed configuration allows an increased bioreactor suspended solids inventory to be maintained while, at the same time, reducing the solids loading rate to the secondary clarifiers. (Nolasco, D. A.; Daigger, G. X; Stafford, D. R.; Kaupp, D. M.; Stephenson, J. P. "The Use of Mathematical Modeling and Pilot Plant Testing To Develop a New Biological Phosphorus and Nitrogen Removal Process " Water Environ. Res. 1998 70(6) 1205-1215) Contaminant generation rate. Concentration gradients distort the measured contaminant generation rate function in a poorly mixed environment. (Nicas, M. "The Effect of Concentration Gradients on Deducing a Contaminant Generation Rate Function," Am. lnd. Hyg. Assoc. J. 1998, 59, 680-688) Environmental persistence. A twotiered procedure is suggested for determining the environmental persistence of chemical contaminants—the first tier considers media half-lives, and the second tier considers the overall half-life as deduced by massbalance models. (Webster, E.; Mackay, D.; Wania, F. "Evaluating Environmental Persistence," Environ. Toxicol. Chem. 1998, 77(11), 2148-2158)
Risk Perceived risk. Senior managers of a major U.K. chemical company were found to judge risks to be quite small for most chemicals; their risk perceptions were low compared with those of British Toxicological Society
Nitrite in rainwater Processes involving nitrite in rainwater have an impact on acid rain. Using a recently developed sensitive detection technique, R. Kieber and coworkers (University of North Carolina) monitored nitrite levels in rainwater over 18 months and found no seasonal variation or correlation with pollution indicators (pH, nitrate, sulfate). This suggests that nitrite has a complex behavior with no single source. Levels were higher in rains that contained a continental component, indicating a terrestrial source of nitrite or its precursor Laboratory experiments demonstrated that nitrite can be oxidized by H 0 under environmentally relevant conditions This process is p^nprially likely to occur in urban environmprrts because of the lower pH of continental rain The results ha\/P implicatinn*; for understanriing the dynamics anrl n p t t o r n s of spin 1
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Soils Metal bioavailability. The concept of critical loads, previously applied to acidifying substances, is being extended, within the Convention on Long-Range Transboundary Air Pollution, to several metals—cadmium, copper, mercury, lead, and zinc. (Rieuwerts, J. S.; Thornton, I.; Farago, M. E.; Ashmoret, M. R. "Factors Influencing Metal Bioavailability in Soils: Preliminary Investigations for the Development of a Critical Loads Approach for Metals," Chem. Spec. Bioavai.. 1998 70(2) 61-75)
Waste Recycling. The Thermoselect hightemperature recycling process provides an industrial-scale technique for productively using the material and the energy content of waste. (Calaminus, B.; Stahlberg, R. "Thermal Waste Treatment: A Better Approach," CHEMTECH, October 1998, 40-46)
Wastewater
members and very low compared with risk perceptions of a Canadian citizen group. (Mertz, C. K.; Slovic, P.; Purchase, I.F.H. "Judgments of Chemical Risks: Comparisons Among Senior Managers, Toxicologists, and die Public," Risk Analysis 1998, 18(4), 391-404)
Sediments Ammonia toxicity. Techniques for reducing ammonia toxicity in freshwater sediments were investigated as part of a project to develop toxicity identification and evaluation procedures for whole sediments. (Besser, J. M.; Ingersoll, C. G.; Leonard, E. N.; Mount, D. R. "Effect of Zeolite on Toxicity of Ammonia in Freshwater Sediments: Implications for Toxicity Identification Evaluation Procedures," Environ. Toxicol. Chem. 1998, 17(ll), 2310-2317) Heavy metals. Benthic oxygen demand influences early diagenetic recycling of metals at the sediment-water interface. (Shine, J. R; Ika, R.; Ford, T. E. "Relationship Between Oxygen Consumption and Sediment-Water Fluxes of Heavy Metals in Coastal Marine Sediments," Environ. Toxicol. Chem. 1998, 17(11), 2325-2337)
Heavy metals. Improved site-specific water quality criteria can be developed on the basis of metal speciation characteristics. (Erten-Unal, M.; Wixson, B. G.; Gale, N.; Pitt, J. L. "Evaluation of Toxicity, Bioavailability, and Speciation of Lead, Zinc, and Cadmium in Mine/Mill Wastewaters," Chem. Spec. Bioavai.. 1998, 70(2), 37-46) Removal efficiency. A reverse osmosis unit reduced virus concentrations below the detection threshold at a Los Angeles wastewater treatment plant; microfiltration membranes consistently reduced virus concentrations by about an order of magnitude. (Iranpour, R. "Virus Removal by Advanced Membrane Filtration for Wastewater Reclamation," Water Environ. Res. 1998, 70(6), 1198-1204)
Contributors: Michael Brauer, University of British Columbia, Vancouver, Canada; Brian Eitzer, Connecticut Agricultural Experiment Station, New Haven, Conn.; Stephen Geiger, ThermoRetec, Fairfax, Va.; Vincent Hand, Miami University, Institute of Environmental Sciences, Oxford, Ohio; Louis Kovach, Ecolife Associates, Wiimington, Del.; and Raewyn Town, Queen's University of Belfast, Northern Ireland.
FEB. 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 8 9 A
