CHEMISTRY PAC partitioning The transport, fate, and bioavailability of polycyclic aromatic compounds (PACs) in the aquatic and terrestrial environment depend on partitioning PACs in water, dissolved organic matter, and soil or sediment organic matter. T. Nielsen and colleagues used HPLC to determine partitioning of 45 PACs to humic acid {K ) Humic acid was chemically immobilized to an HPLC column sil3.n0! surface, sucl the measured capacity coefficients were correlated with experimentally determined K values. Sorption of PACs to humic acid was affected by Hand ionic bonding in addition to hydrophobic bonding Log K increased with the size of the PAC molecule and was influenced by the ring heteroatoms humic acid composition and PAH substituents Most of the variation in log K among compounds was due to "variations in water solubilitv {Environ Sci Technnl 1447 31 1102-08)
GREEN CHEMISTRY Biodegradable plastics Commercial biodegradable plastics must have a wider range of chemical and physical properties than those available with existing polymers. In an effort to extend the range of biodegradable polymers from renewable biomass, M. Okada and colleagues synthesized a series of polyesters by the bulk polycondensation of 1,4 : 3,6-dianhydrohexitols with aliphatic dicarboxylic acids. Biodegradability of the resulting series of polyesters was determined in activated sludge, soil, and by enzymatic degradation. Biodegradability varied significantly with molecular structure Crystalline polvesters underwent little degradation whereas those with sufficient amorphous content were biodegradable (/ Awl Polym Sci 1996 62 2257-65)
HEALTH Air quality and lung function Exposure to air pollutants is known to cause short-term decreases in
lung function. Less is known about how chronic exposure to air pollution affects lung function. U. Ackermann-Liebrich and colleagues studied lung function in more than 9000 adults living in eight areas of Switzerland, each with varying levels of air pollution. Consistent and significant associations were found between the level of lung function and levels of NO , SO,, and PM10. These results suggest that air pollution from fossil fuel combustion is associated with long-term decreases in lung function {Am J Respir. Crit Care Med 1997 155 122-29)
Ozone and mortality Many epidemiological studies suggest a relationship between particulate air pollution and human mortality and other health effects. The association is stronger for particulates than it is for ozone. V BorjaAburto and colleagues conducted an epidemiological study to evaluate the association between ozone and other air pollutants and mortality in Mexico City. The study took advantage of ozone levels that are aniong the world's highest. The authors found a significant association between air pollution especially ticulate pollutants—and mortality but they could not specifically attribute increased mortality to ozone {Am I Epidemiol 1997 145 258-68)
MEASUREMENTS PAH differentiation Overlapping chromatographic peaks for compounds with the same molecular weight and electron impact mass spectra can complicate mass spectrometric analysis of PAHs. S. M. Pyle and colleagues report that collision-induced dissociation (CID) for tandem MS within an ion-trap mass spectrometer can differentiate between PAHs of the same molecular weight. The technique improves identification of individual PAHs. Unlike resonant excitation nonresonant excitation of the molecular ionenhanced fragmentation produced significantly different CID spectra for five PAH isomers of molecular weight 252 Method detection limits were similar to those for electron impact mass spectra based on standards {1 Am Soc Mass Spectrom 1997 8(2) 183-90)
MONITORING Radial diffusive sampler Low cost, small size, and ease of use make passive samplers popular for remote-site ambient monitoring and for personal monitoring of air pollution exposure. But current devices are unsuitable for many applications because of low sample collection rates and specific desorption requirements before analysis. V Cocheo and colleagues describe a new radial diffusive sampler for thermal and solvent desorption. It has a sufficiently high sample collection rate to be used for 1- to 24-h monitoring The sampler can also be used for active sampling and is suitable for a variety of collection sorbents Tests with activated charcoal indicate that the sampler collection rates for 32 organic vapors were reproducible and unaffected bv wind speed or pollutant mixtures (Am Ind Hve Assoc 1 1996 57 897-904)
PESTICIDES Herbicide half-lives Herbicide dissipation in a cultivated environment depends on herbicide characteristics and site characteristics. Tillage practices can have a significant effect on herbicide halflives, yet have received relatively little attention. S. Otto and colleagues modeled the half-lives of several herbicides (metolachlor, terbuthylazine, and isoproturon) and herbacide metabolites (desethylterbuthylazine, and monomethylisoproturon) in three tillage systems (conventional tillage, ridge tillage, and no tillage). They found that dissipation followed first-order kinetics and that the field data agreed with a fugacity-based mathematical model Tillage practice affected only metolachlor the most volatile herbicide Its dissipation was enhanced in the notillage system The enhancement was attributed to interceDtion of herbicide bv croD residue (Chemotohere 1997 34fl) 163-78)
Bioaccumulation of POPs Scientists and laypersons suspect that migratory birds accumulate persistent organic pesticides (POPs) mainly in their wintering grounds in Mexico and Latin America. Many
VOL. 31, NO. 5, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 2 1 1 A
