Research Watch: Soil-climate change dynamics - Environmental

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Soils

Reductive dechlorination Reductive dechlorination is the most common reaction in the remediation of groundwater and soils that are contaminated with chlorinated compounds. The dechlorination reaction occurs in anaerobic bacteria and can also be catalyzed by vitamin B12 (cyanocobalamin) and titanium citrate. In order to elucidate a possible mechanism of reaction in this substitute system for anaerobic bacteria, S. Lesage and coworkers studied the vitamin B12-catalyzed reductive dechlorination of chlorinated ethenes. On the basis of the kinetic and spectroscopic evidence that was developed, they proposed a reaction pathway that involves reductive dechlorination without the release of chlorinated ethene intermediates from chloroalkylcobalamin complexes. The distribution of dechlorination products was found to be dependent on the availability of titanium from different chelating agents. The authors suggest that reaction control may be possible by adjusting the amount and type of titanium chelate used. (Environ. Sci. Technol,, ,his issue, pp. 2264-22772

"Development of a Highly Sensitive Enzyme-Linked Immunosorbent Assay Based on Polyclonal Antibodies for the Detection of Polychlorinated Dibenzo-p-dioxins," Anal. Chetn. 1998 70(6), 1092-1099) Lipids in fish tissue. Results show that a standard test method for total lipids is needed to reliably establish pollutant concentrations. (Randall, R. C ; Young, D. R.; Lee II, H.; Echols, S. E. "Lipid Methodology and Pollutant Normalization Relationships for Neutral Nonpolar Organic Pollutants," Environ. Toxicol. Chem. 1998, 17(5) 788-791) Supercritical fluid extraction. By mixing nitrogen with carbon dioxide, trace levels of analytes can be selectively extracted from lipid-rich samples with little lipid coextraction. (King, J. W.; Zhang, Z. "Selective Extraction of Pesticides from LipidContaining Matrixes Using Supercritical Binary Gas Mixtures," Anal. Chem. 1998, 70, 1431-1436)

Metals Leaching of metals from soil. A mathematical model was developed and used to analyze metal leaching from contaminated soils subjected to acid extraction in a batch reactor. (Ganguly, C ; Matsumoto, M. R.; Rabideau, A. J.; Van Benschoten, J. E. "Metal Ion Leaching From Contaminated Soils: Model Development," /. Environ. Eng. (Reston, Va.) 1998, 124(3), 278-287) Metal-contaminated sludge. Microbial community tolerance measurements can be used to monitor the effects of heavy metals in sludge

amendments. (Baath, E.; Diaz-Ravina, M.; Frostegard, A.; Campbell, C. D. "Effect of Metal-Rich Sludge Amendments on the Soil Microbial Community," Appl. Environ. Microbiol. 1998, 64(1), 238-245)

Modeling Acid rain. An integrated acid rain model was evaluated with recent data and model consistency was cross-checked with optimized and scenario testing results for Eastern Canada. (Lam, D.C.L.; et al. "An Integrated Acid Rain Assessment Model for Canada: From Source Emission to Ecological Impact," Water Qual. Res. J. Can. 1998, 33(1), 1-17)

Sediments Metals in Boston Harbor. Based on an analysis of surface sediments, metal concentration profiles in sediment cores, and historical data from a contaminated-sediment database, the concentrations of metals in Boston Harbor surface sediments have decreased during the period 19771993. (Bothner, M. H.; Ten Brink, M.; Buchholtz, M.; Manheim, E T. "Metal Concentrations in Surface Sediments of Boston Harbor Changes with Time," Mar. Environ. Res. 1998, 45(2), 127-155) Toxicity of marine sediments. Sediment quality guidelines provide estimates of chemical concentrations that are toxic or nontoxic in laboratory assays but should be used with caution. (Long, E. R.; Field, L. J.; MacDonald, D. D. "Predicting Toxicity in Marine Sediments With Numerical Sediment Quality Guidelines," Environ. Toxicol. Chem. 1998, 17(4), 714-727)

3 7 6 A • AUG. 1, 1998 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS

Nitrogen mineralization. Soil, moisture, and temperature were the most important factors influencing the gross rate of nitrogen mineralization. (Puri, G; Ashman, M. R. "Relationship Between Soil Microbial Biomass and Gross Nitrogen Mineralization," Soil Biol. Biochem. 1998, 30(2), 2 5 1 256) Soil-climate change dynamics. The distribution of soil organic carbon, total nitrogen, and total sulfur in particle-size fractions were measured to assess the response of soil organic matter dynamics to climate change: (Amelung, W.; Zech, W.; Zhang, X.; Follett, R. E; Tiessen, H.; Knox, E.; Flach, K-W. "Carbon, Nitrogen, and Sulfur Pools in Particle-Size Fractions as Influenced by Climate," Soil Sci. Soc. Am. J. 1998, 62(1), 172181)

Toxicity Algal bound metals. Metal contaminants, such as Cd 2+ can adsorb to algal cells and reduce the feeding rate of water-borne organisms. (Taylor, G.; Baird, D. J.; Soares, A.M.V.M. "Surface Binding of Contaminants by Algae: Consequences for Lethal Toxicity and Feeding to Daphnia magna Straus," Environ. Toxicol. Chem. 1998, 77(3), 412-419)

Treatment Municipal effluents toxicity. Results indicate that whole-effluent toxicity testing plays a key role in controlling toxic substance discharges to surface waters from point sources. (Fisher, D. J.; et al. "Acute and Chronic Toxicity of Industrial and Municipal Effluents in Maryland, U. S.," Water Environ. Res. 1998, 70(1), 101-107)

Contributors: Michael Brauer, University of British Columbia, Vancouver, Canada; Brian Eitzer, Connecticut Agricultural Experiment Station, New Haven, Conn.; Stephen Geiger, Remediation Technologies, Inc., King of Prussia, Pa.; Vincent Hand, Miami University, Institute of Environmental Sciences, Oxford, Ohio; Louis Kovach, Ecolife Associates, Wilmington, Del; Geoffrey Nobes, McGill University, Montreal, Canada; and Raewyn Town, Queen's University of Belfast, Northern Ireland.