RESEARCH WATCH
GREEN CHEMISTRY Renewable carbon sources Natural, renewable carbon sources are expected to become increasingly important as replacements for petroleum derivatives. Lignin, which comprises 15% to 30% by weight of wood, is being investigated as a potential carbon source for materials. M-J. Chen and colleagues investigated the properties of graft copolymer of lignin and 1-ethenylbenzene. They found that the thermoplastic graft products formed stable emulsions, bonded adhesively to wood surfaces 3.11(1 were surface active. Bioconversion and degradation of the copolymers vvere confirmed with several analytical methods. Results supppst that copolymerization of
synthetic side chains onto naturally occurring polymer backbones could be a means to produce environmentally degradable materials (Macromolecules 1996 29(5) 1389-98)
Biodegradable polymers Biodegradable polymers are important for making the life cycles of products environmentally sound. Polyhydroxyalkanoates, a class of polymers being considered for biodegradable applications, are produced by a variety of bacteria as energy reserve materials. S. Y. Lee studied several aspects of bacterial polyhydroxyalkanoates, including biosynthesis, production, recovery, biodegradation, and applications. Lee found that development of this thermoplastic material in transgenic plants presents an economically feasible source of biodegradable plastic production. {Biotechnoll Bioens. 1996 49(1) 1-14)
Blending polymers The degradability of commercial polymers can be increased by blending them with degradable materials. A. M. Gajria and co-workers formed immiscible melt blends of poly(lactic
acid) and poly (vinyl acetate). Some blends showed greater tensile strength and elasticity than the original products. The authors attribute the improvements to interactions between the polymers in the blend. They found that surface tension effects of the blends in turn substantially affected the enzymatic degradability. Results suggest that the surface tension of the polymer film affects enzyme adhesion, thus 3.C" counting for the variability in enzymatic degradability. {Polymer 1996, 37(3) 437-44)
based on capillary electrophoresis (CE) that has a detection limit of 0.2 ppb and can separate enantiomeric components. In their procedure, phenoxy acid herbicides are derivatized with 7-aminoapthalene1,3-disulfonic acid prior to CE. The derivatization was quantitative and produced stable fluorescent derivatives without side products. The derivatives were detected after CE using laser-induced fluorescence. The addition of a cyclodextrin, particularly 2,3,6-tri-O-methyl-p-cyclodextrin, to the running electrolyte facilitated the enantiomeric separation. (Anal Chem 1996 68(10) 1771-77)
MEASUREMENTS
GC/MS analysis
POLICY
Unknown compounds in environmental samples are often identified through gas chromatography/mass spectrometry (GC/MS) analysis. However, complex samples can have many overlapping and coeluting gas chromatographic peaks, which cause problems for mass spectral search programs or with the interpretation of the mass spectra. N. R. Herron and colleagues developed software that reprocesses GC/MS data to enhance the quality of the spectra used to identify unknown compounds. The program converts raw GC/MS data to ASCII text which is incorporated into a spreadsheet. A spreadsheet macro selects only those ions that maximize within a selected number of scans and discards all other ions The resultant chromatogram shows much narrower and better resolved peaks each with enhanced sDectral qualitv (f Am Maw Spertmm 1996 7(61 598-604)
Does environmental protection cost jobs? E. Goodstein reviewed economic research on this question and found that very few jobs are lost because of the costs of environmental regulation. Even studies by labor unions suggest that only 1000-3000 layoffs per year, which account for 0.1% of all layoffs, are attributable to environmental regulation. Similarly, Goodstein found that relocation of jobs to other countries is driven far more by lower offshore labor costs than by decreased environmental costs. A review of environmental improvement as a mechanism for job creation determined that in economically depressed regions environmental improvement may accelerate job creation However this is not true for the U S economy as a whole Goodstein found (Environ Management 1996 20(3) 313-21)
Regulation versus jobs
Capillary electrophoresis Current methods for analyzing phenoxy acid herbicides are not highly sensitive and selective. New methods with improved sensitivity and selectivity need to be developed. Y. Mechref and Z. El Rassi and colleagues developed a new method
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RISK Weight of evidence C. Menzie and colleagues developed a weight-of-evidence evaluation procedure that integrates the results of
0013-936X/96/0930-374AS12.00/0 © 1996 American Chemical Society
Aromatic amines in aquatic ecosystems Aniline is involved in many industrial chemical processes, and its release into the environment is of concern. The kinetics and reactions of the covalent binding of aniline with humic substances have been studied in two papers by Eric J. Weber et al. and Kevin A. Thorn et al. The results corresponded to a second-order rate expression, and the reaction pathway was proposed to involve nucleophilic addition to carbonyl humic moieties. Only 10% of the humic binding sites were highly reactive and quickly saturated. The rate of binding decreased with decreasing pH. The low concentration of reactive sites found for typical dissolved organic matter led the authors to conclude that the sink for most aromatic amines in aquatic ecosystems will be the natural organic matter associated with bottom sediments. (Environ. Sci. Technol., ,his issue, 2755-63,2764-75)
multiple measurements in ecological risk assessments. The evaluation can be used to determine whether a stressor has caused or could cause harm to the environment. Their procedure evaluates three characteristics including the weight assigned to each measurement endpoint, the magnitude of responses observed in the measurement endpoint, and the concurrence among outcomes of multiple measurement endpoints. [Human and Ecological Risk Assessment 1996, 2(2), 277-304)
SOIL Landfill soil liners Compacted soil liners are an essential element of landfill leachate containment systems. However, some soils crack as they dry, leading to poorer containment in the field than laboratory studies predict. G. H. Omidi and co-workers attempted to quantitate the effect of desiccation cracking on compacted soil liners and find methods for increasing resistance to cracking. They found that compacted clay soils normally used for liner systems shrink by as much as 16% and increase hydraulic conductivity of soils by as much as two orders of magnitude as a. result of drying They found that amending the soils with 30% sand could significantly minimize both volume and conductivity changes (Water Air Soil Pollut 1996 89 91-103)
evaluate sorption kinetics of multiple metals on humic materials. The model incorporates functions which use the rate constants of individual metal species. Results of a study involving seven metals showed that the most reactive metals followed a first-order reaction during the initial reaction period, followed by a second-order reaction in longer periods with less reactive metal species. The authors state that the lumped model can be used to predict the total toxicity of complex systems such as waste dumps, landfills, or Superfund sites. (J. Environ. Qual. 1996, 25, 552-61)
Controlled test facility Controlled environment facilities are often used to study plant, soil, and environmental interactions. D. T. Tingey and colleagues developed a facility that uses solar radiation, tracking of temperature and vapor pressure deficit, control of atmospheric carbon dioxide (C0 2 ), and a large lysimeter to allow reconstruction of field soils. They designed the facility to operate continuously for several years to permit long-term studies. Initial tests comparing the facility with an adjacent weather station showed that it effectively simulated seasonal and diurnal variations in CO
laboratory and the field. E. R. Kline and colleagues compared the effects of a non-ionic surfactant on the survival, growth, and reproduction of bluegill sunfish and fathead minnows in laboratory studies and outdoor stream mesocosms. No-observed and lowest-observed effect concentrations were similar between the two testing systems. Results indicate that a safety factor in extrapolating the laboratory results to field situations may not be necessary [Environ. Toxicol. Chem. 1996 15(6) 997-1002)
WASTEWATER Household metal sources Domestic activities are a significant uncontrolled diffuse source of heavy metals, particularly zinc and copper, to sewage treatment works. S.D.W. Comber and A. M. Gunn conducted an analysis of houses in England and found a link between the concentration of copper being discharged and the age of plumbing or the quality of construction materials. They determined that domestic sources contribute 64% of the total copper load to sewage treatment systems, 93% of which came from plumbing. Zinc discharges were highest in older houses with galvanized header tanks Domestic sources contributed about 50% of the total zinc load to sewage systems Household products had low h e a w metal contents except
medicated shampoos (Zn) and washint? powders (Cd) Washine machines were also major sources Dochromium and cadmium was IPSS than 269/ of t h e total load t o t r p a r m p n t p l a n r s t h p v fnnnrl (Writer Fnvirnn Mnnnce tnpnt l
