BIOREMEDIATION
Dissolved metals in groundwater
PCB-degrading strains
Concerns exist over the potential of ethylenediaminetetraacetic acid (EDTA) and other industrially important organic ligands to increase the concentration of dissolved metals in groundwater. E0TA is not degraded in sewage treatment plants and is present in significant concentrations in effluents. 8. Nowack and colleagues investigated the behavior of dissolved metals, EDTA, and natural ligands during infiltration of river water into an aquifer in Switzerland. They inferred that the presence of natural ligands and slow exchange kinetics of some complexes did have a significant impact. The critical factor was pH, with remobilization of adsorbed metals in the infiltration zone by EDTA occurring at pH values above 7. The authors propose a combination of experimental measurements and equilibrium calculations to assess potential speciation changes in infiltration paths. {Environ. Sci. Technoll this issue pp. 866-72)
Biodegradation of PCBs and other persistent environmental contaminants often requires more than one microorganism. Typically, PCBs are co-metabolized to chlorobenzoates, which are mineralized by other microorganisms. A common bioremediation strategy is to combine genes encoded for both metabolic capabilities into one strain in the laboratory and then introduce that strain into the environment. D. D. Focht and colleagues conducted in situ studies of single strains with both degradative capabilities. Their results demonstrated the transference of scries from indigenous PCB-degrading strains to inoculated strains capable of chlorobenzoate degradation in soil (ADDI Environ Microbiol 1199 62 3910-13)
HEALTH Ozone and lung function Humans experience an acute inflammatory response when exposed to ozone under controlled conditions, but it is uncertain whether naturally occurring ozone levels can also cause lung inflammation. R L. Kinney and co-workers checked for biological markers of inflammation in joggers exposed, to ozone. Inflammatory cells and mediators were measured during the summer and the following winter. The mean (daily 1-h maximum) ozone concentration was 58 ppb in the summer and 32 ppb in the winter; there was little difference in ]^0 or PIvI concen— trations between the seasons Although the results provided little evidence for an acute summer inflammatory response other measures suggested an ongoing inflammatorv resnonse during the summer (Am
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Cryptosporidium disinfectants The ability to disinfect agricultural buildings and equipment contaminated with Cryptosporidium parvum from livestock feces is important in preventing human infections. Only a few of 59 common chemical disinfection agents have been reported as effective. R. Fayer and colleagues
investigated the effectiveness of gaseous compounds as disinfectants for C. parvum. Gases studied were ammonia, carbon monoxide, ethylene oxide, formaldehyde, and methyl bromide. Oocysts exposed to these gases were inoculated into test animals to determine whether infection would occur. The results indicated that low molecular weight gases such as ammonia, ethylene oxide, and methyl bromide were effective disinfectants against C. parvum. Unlike other disinfectants these aeents 11J>.V* 1/1111*1 U101111V*V~I.CllllO, U l t O t
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can penetrate C. parvum's nearly impervious oocyte wall and reduce infectivity or viability (Appl Environ Microbiol 1996 62 3908-09)
MEASUREMENTS Solvent-free extractions Several new techniques for extracting pollutant samples reduce or eliminate the use of organic solvents, minimizing the amount of waste generated by laboratories. S. B. Hawthorne and colleagues report development of an extraction and analysis procedure that couples subcritical water extraction of solid samples with solid phase microextraction (SPME) and uses no organic solvents. Solid samples are extracted in a stainless steel cell heated to 250 °C for 1 h. The cell is then cooled and the supernatant water transferred to a vial for automated SPME GC/MS analysis The procedure was tested with both polar and nonpolar (PAH) analytes in soil samples and urban particulate matter There was a good overall agreement with conventional extraction procedures with relative standard deviations randne from 2 to 339" (Anal Chem. 1996, 68, 3892-98)
POLICY Climate change effects Global climate change could seriously affect regional rainfall and future surface and groundwater supplies. R. B. Wardlaw and coworkers assessed the impact of climate change on water resources and investment programs by utility companies in southeastern Britain. Regional climatic change scenarios were estimated from global climate models that predicted global warming and a concomitant increase in global mean precipitation Difficulties arose in trying to interpret the results of such models on a local scale. Predictions for summer precipitation in southeastern Britain in the year 2050 ranged from a decrease of 14% to an increase of 25% The authors conclude that more data will be needed to aDDly models on such small scales (Water Environ Manag.996 7flf5) 355-64)
Adaptive management Resource managers must make decisions despite incomplete information about how ecosystems work. Successful ecosystem management depends on learning about the system while managing it. A. Haney and R. L. Power review the process of "adaptive management" and describe its application at the Necedah National Wildlife Refuge, Wis. Adaptive management is an iterative process that includes collecting data, setting goals, modeling the effects of management options on ecological and social attributes, monitoring outcomes and revising the management plan (Environ Manae 1199 20(6), 879-86)
VOL. 31, NO. 3, 1997/ENVIRONMENTAL SCIENCE S TECHNOLOGY / NEWS * 1 1 7 A
