A 2-phenylallyl substituent at the end of a PMS chain induced the most effective degradation. Degradation occurs through several mechanisms, including radical, anionic, and cationic depolymerization. {Polymer 1996, 37, 4321-26)
Surfactants and bioavailability Degradation of environmental contaminants such as hexachlorobenzene (HCB) is dependent on the bioavailability of the contaminant in the matrix. Addition of surfactants to the matrix can enhance bioavailability and thus enhance degradation. R L. Van Hoof and C. H. Jafvert studied the reductive dechlorination of HCB in sediment slurries amended by two classes of nonionic surfactants: polyoxehylene (POE) sorbitan fatty acids esters (Tweens) and POE alcohols (Brijs). They found that Tween 80 reduced dechlorination at concentrations well above the critical micelle concentration (CMC) but it enhanced dechlorination at concentrations rinse to the CMC The Brijs s h o w e d r e d u r p d or inhibited dechlorination at all r n n r p n t r a t i o n s tested R p r a u s e t h e Twppns a n d t h e Rrijs i m n r o v e d HCB soluhilitv the pnhanrpd dprhlorination nrohahly rpsultpd from snprific i n t p r a r t i n n s hptwppn thp surfactants a n d thp mi rrnhial mpHia (Fnviran Tnrirnl
chem. 1996, / 5 ( l l ) , 19i4-?4i.
BIOREMEDIATION Selenium in drainage water Irrigation of agricultural land may result in leaching naturally occurring selenium into subsurface drainage water. Disposal of drainage water containing toxic concentrations of selenium has led to serious environmental problems. A. W. Cantaflo and co-workers describe a method for bioremediation of selenium from agricultural drainage water. They used a selenate-respiring bacterium, Thaurea selanatis, to remediate agricultural drainage water in the San Joaquin Valley in California Results indicate that selenium oxyanion concentrations selenate and selenit6 were reduced by 98%' and 9 1 96% of the total selenium recovered was elemental selenium They estimate that widespread use of the
Composting and chlorophenol remediation Chlorophenols (CPs) were widely used at sawmills in Finland to preserve wood, and about 800 sites there must be remediated. Composting in "biopiles" will be the predominant technology. M. M. Laine and K. S. Jorgensen studied degradation of CP-contaminated soil during composting. They constructed four 13-m3 compost piles from mixes of contaminated soil with a combination of bark chips, remediated soil, straw compost, or contaminated wood chips. Each of the four compost mixes showed more than 90% removal of CPs over 12 weeks. The authors observed an initial production of chloroanisoles, with levels declining overtime. Bench scale experiments with the same mixtures showed an average of 60% mineralization of a radio-labeled pentachlorophenol. (Environ. Sci. Techno!., ,his iisue, pp. 377-78)
method in a properly engineered bioremediation system could reduce the amount of selenium deposited in the San Joaquin River from 3000 to 60 kg/year. (Appl. Environ. Microbiol. 1996, 62, 3298-303)
Engineered microbes Improved methods are needed for monitoring the survival and fate of genetically engineered microorganisms (GEMs) in the environment. L. G. Leff and A. A. Leff report the development of a method for detecting GEMs by using a green fluorescent protein (GFP) gene. Survival of Escherichia coll bearing a GFP gene was evaluated in an aqueous environment. GEMs could be enumerated by plating and microscopy using this approach. The GFP had no adverse effects on the host strain. Results demonstrated that E. coli persisted in stream water at higher densities than indicated by conventional culture techniques The GFP has advantages over traditional detection techniques such as culturintr a n d provides a n e w a n d m o r e
accurate tool for trarlcino' r F M s in thp> e m / i r o n m e n t (AnrtI Pmrimn Microbiol 1996 62 3486-88)
HEALTH Traffic-induced asthma Studies have suggested an association between motor vehicle emissions and illness from asthma and other respiratory diseases. H. Duhme and colleagues have reported such an association in a study of adolescents in Bochum, Germany. The group has now found a similar association between traffic density and respiratory illness in Miinster, a city of about 270,000 people. Using a standardized written and video
6 8 A • VOL. 31, NO. 2, 1997 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
questionnaire administered to 3700 students, they found an association between self-reported symptoms of wheezing and allergic rhinitis and self-reported levels of truck traffic. The researchers suggest that abraded tire fragments containing potentially allergenic latex particles may be partially responsible for the symptoms. Truck tires contain larger amounts of latex than do automobile tires. (Epidemiology 1996 7 578-82)
MEASUREMENTS Enhanced SFE Supercritical fluid extraction (SFE) is finding numerous applications in the extraction of environmental samples. But extraction of polar analytes remains difficult. T S. Reighard and S. V. Olesik report a modification to SFE, termed enhanced fluidity liquid extraction (EFLE), that can enhance such extractions. An enhanced fluidity liquid is prepared by combining an organic solvent such as methanol with a low-viscosity liquid such as CO- The resultant single-phase liquid is then used in an SFE apparatus to perform the extraction at elevated (but subcritical) temnprature and pressurp The authors evaluated EFLE by extracting 11 phenolic and nitroaromatic pollutants from household dust Rproveries Ynr SPP a n d EPT E wrpre as crnnd as or b e t t e r t h a n Soxhlet extractions for thp s a m p analvtes (Anal Cbpm lQQfi fifl 3fi12-?l1
VOCs in air Rapid methods for monitoring volatile organic compounds (VOCs) are needed to understand a wide range of atmospheric processes and air quality problems. G. L. Kok and colleagues report development of a
