RESEARCH WATCH
AIR Fingerprinting particulates Developing effective control strategies for fine airborne particulates requires knowledge of the relative importance of each contributing source. Recent advances in source testing allow quantification and "fingerprinting" of hundreds of specific compounds. J. J. Schauer and co-workers applied a chemical mass balance receptor model to Los Angeles air samples and identified major sources of ambient fine particulate matter. On an annual averbasis, the largest primarysource contributors were diesel soot paved-road dust gasolinepowered vehicle exhaust foodcooking operations and wood smoke Sulfate nitrate and ammonium ions from secondary aerosol formation were also major contributors to particle mass With this approach virtually all of the annual fi„ „„l*;^a ™ooo „„ ,uruan Q particle l r u„„ „,.„,, line mass ;~ in an area can De traceo uacK 10 us source. I At F ' .QQfi Wf??l
Fiberglass fungus Many studies have documented biocontamination of fiberglass duct materials commonly used in residential and commercial heating, cooling, and ventilation systems. K. K. Foarde and co-workers report on a series of 6-week experiments that assess the conditions affecting fiberglass' ability to support mold. The authors found that moisture and soiling of three different fiberglass duct liners were critical factors in supporting fungal growth. Even on fiberglass containing a biocide, fungal growth resulted after only moderate soiling The authors recommend improved filtration of dust entering the ventilation systems and frequent inspection of interior duct surfaces exposed to high humidity or moisture (Indoor Air 1996 6(2) 83-92)
Solvents decrease contaminant solubility Contaminated sites often contain mixtures of organic compounds with varying water solubilities. G. T. Coyle and co-workers examined the solubility of extremely low solubility compounds in water containing dissolved volatile organic chemicals. They showed that partially miscible organic solvents (PMOS) depressed the aqueous solubility of hydrophobic organic compounds (HOC) in mixtures. Solubility of PCBs was reduced by as much as 85% in water saturated with methylene chloride and methanol. The authors attribute the effect to "solventing-out," analogous to salting-out. The depression of solubility increases with increasing hydrophobicity of PMOS and HOC. The presence of saturated solutions of PMOS will reduce the solubility and mobility of HOC and may reduce the risk of dangerous HOCs such as PCBs being transported to drinking water supplies. (Environ. Sci. Technol,.,his issue pp. 384-89)
BIODEGRADATION Biomass carbon Better methods are needed to determine the carbon content of biomass formed during composting of biodegradable polymers. These determinations permit estimates on how completely different polymers biodegrade. B. Spitzer and co-workers report a new method based on the Lowry protein assay method. The researchers evaluated various polymers placed in an aerobic aqueous system consisting of nutrients and a compost inoculum. The ratio between the protein and carbon present in the biomass was not constant Rather it depended on the microbial population the phase of growth of the microbes and the substrate supply The researchers believe the technique could be used for degradation tests in which the polymer is the sole carbon source and no significant mass transDort occurs (T Fnviron
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CBA pathways Chlorobenzoic acids (CBAs) are released into the environment from the microbial breakdown of polychlorinated biphenyls (PCBs) and benzoate herbicides. Because CBAs are toxic and relatively persistent, researchers want to know how these
0013-936X/97/0931-67A$14.00/0 © 1997 American Chemical Society
compounds are biodegraded. F. Fava and co-workers describe a biodegradation pathway of certain CBAs in Alcaligenes sp. strain CPE3. They studied metabolic activity of Alcaligenes in the presence of 3- and 4-chlorobenzoic acid and 3,4dichlorobenzoic acid. CPE3 was able to use all of the CBAs as carbon sources. Metabolic activity was not linear with respect to protein concentration, thus suggesting that a multicomponent enzyme system m a v be involved in CBA metabolism. The research detected a larger spectrum of CBA metabolic activities than had anv previous studv [Biotechnol Lett 1996 18 1007-12)
Degrading vinyls Most biodegradable polymers prepared so far are polyester derivatives; most mass-produced polymers in municipal waste, however, are vinyl-polymerized plastics. These include poly(ethylene), poly(propylene), and (poly) styrene, which generally are not biodegradable. Y. Nagasaki and colleagues describe the results of end functionalization experiments to encourage degradation of such plastics. They studied poly(oc-methylstyrene) (PMS) and its derivatives under various temperature and pH conditions. The most effective end modifier used 2-phenylallyl halide which had a very high modification efficiency
VOL. 31, NO. 2, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 6 7 A
