RESEARCH WATCH
BIOREMEDIATION Bioenhanced cleanup Biological remediation of contaminated soils can effectively reduce ecological and human health risks. S. D. Siciliano and J. J. Germida studied the ability of bacteria, plants, and plant-bacteria associations to bioremediate soil contaminated with 2-chlorobenzoic acid. Forage grasses were inoculated with different rhizobacteria. Results indicate that different forage grasses enhance the disappearance of soil contaminants, and plant-bacteria associations increase 2-chlorobenzoic acid degradation more than plants or bacteria alone. Increased degradation was not related to increased plant growth resulting from the use of inoculants. (Environ. Toxicol. Chem. 1997,16, 1098-1104)
Land farming with molasses Land farming for bioremediation of soil contaminants is inexpensive and reclaims soil, but remediation is slow and requires a proper balance of nutrients, water, and organic carbon substrate. D. L. Widrig and co-workers did a laboratory study to evaluate the degradation of 2,4,6-trinitrotoluene (TNT) in soils treated with a dilute molasses solution. A low-cost additive, molasses serves as a primary carbon source and enhances the growth of microbial organisms, which then produce enzymes that degrade TNT Adding molasses resulted in a 92% degradation of TNT in eight months compared with a 19.5% degradation when only water was added. The authors conclude that, when used in combination with moisture control and aeration, molasses can enhance the degradation of TNT by land farming. {Environ. Toxicol. Chem. 1997, 16, 1141-48)
Mercury cleanup Sites contaminated with mercury, one of the most toxic heavy-metal contaminants in water and soil envi-
Dioxin transport and the Great Lakes Chlorinated dioxins and furans (PCDD/F) are potent toxicants capable of producing adverse health effects in biota and humans. The Great Lakes are particularly sensitive to contamination by these compounds. R. Pearson and colleagues studied PCDD/F concentrations, accumulations, and inventories in sediments taken from the Great Lakes and control lakes. Their analysis identifies historic accumulation rates and establishes the importance of localized atmospheric and nonatmospheric sources compared with long-range regional atmospheric PCDD/F source inputs. Present accumulation rates are 30-70% of maximum rates that occurred around 1970. Localized sources account for a variable portion of total load, ranging from —0% in Lake Superior to >90% (mostly from nonatmospheric sources) in Lake Ontario. These findings support the development of management strategies for effectively controlling PCDD/F inputs to the Great Lakes. (Environ. Sci. Technol., this issue, pp. 2903-09)
ronments, are difficult to clean up. Conventional remediation methods for Hg2+ removal, based on the use of ion-exchange resins or biosorbents, are sensitive to ambient conditions, can fail to remove or recover soilbound or complexed ions, and lack specificity when binding metal ions. S. Chen and D. B. Wilson report that strains of Escherichia coli, genetically engineered for intracellular bioaccumulation of Hg2+, have excellent properties for bioremediation of contaminated sites. The strains show good resistance to extremes of pH and ionic strength. Moreover, the high specificity of the Hg2* bioaccumulation process may enable recovery and recycling of accumulated mercury. {Appl. Environ. Microbiol. 1997, 63, 2442-45)
evaluated the use of Clostridium perfringens spores as a surrogate indicator of disinfectant effectiveness. Results indicate that the mixed-oxidant disinfection system is more effective than chlorine disinfection in controlling both organisms and that C. perfringens spores may be used as a surrogate indicator of disinfectant effectiveness. Preliminary estimates suggest that the cost of using the mixed-oxidant system is comparable to that of chlorine disinfection and more affordable than using calcium hypochlorite. (Appl. Environ. Microbiol. 1997, 63, 1598-1601)
GREEN CHEMISTRY Biodegradable polypeptides
DRINKING WATER Disinfection alternative Conventional disinfection methods are sometimes ineffective in controlling Cryptosporidium parvum in drinking water supplies and thus pose a significant risk to public health. L. V. Venczel and colleagues compared the effectiveness of a mixed-oxidant disinfection system with conventional use of chlorine in controlling C. parvum. They also
0013-936X/97/0931-445A$14.00/0© 1997 American Chemical Society
The development of biodegradable polymers has focused mainly on polyesters. Polypeptides, another interesting class of biodegradable polymers, are difficult to study because of their insolubility in organic solvents and poor thermal stability. M. Miyamoto and colleagues have replaced the hydrogen on the amide nitrogen with a protecting group to improve the solubility, immunogenicity, and processibility of the polypeptide. They studied polyfjVethoxycarbonyl-L-valine), which was prepared by the cationic ring-open-
VOL. 31, NO. 10, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 4 4 5 A
