Collection of vapors of selected chlorocarbons and benzene on Tenax GC

Breakthrough and retention volume studies have been done for a series of chlorocarbon compounds on Tenax GC adsorbent with results compared to data of other workers. Initial data indicates that carrier velocity (Time to establish equilibrium) may significantly effect retention of these chemicals.     

The importance of investigating for uniparental disomy in prenatally identified balanced acrocentric rearrangements

We report the finding of paternal isodisomy for chromosome 14 in a fetus found to have a der(14;14)(q10;q10) by amniocentesis. The pregnancy was complicated by severe polyhydramnios and elevated amniotic fluid alpha-fetoprotein (AFP). The infant showed features consistent with paternal uniparental disomy (UPD) including postnatal growth retardation, poor respiratory function, feeding difficulties, and evidence of hypertrophic cardiomyopathy. The present case, in addition to other reported cases of UPD involving balanced acrocentric rearrangements, supports testing for UPD in prenatally detected Robertsonian translocations and isochromosomes. Copyright © 2002 John Wiley & Sons, Ltd.     

Influential factors in freeway crash response and clearance times by emergency management services in peak periods

OBJECTIVE: Various factors influence the time performance of emergency management personnel when a freeway traffic crash occurs. The proper identification and prioritization of factors that contribute to emergency management services' response times and clearance times result in better usage of taxpayer resources. METHOD: Use of a proportional hazard-based Cox-regression model analyzed statewide, peak-period, traffic crash data from 1999 Ohio logs. These data included time performance measures of emergency management services. RESULTS: Traffic crash severity had the most effect on response times. Those crashes involving injuries or fatalities had up to 20% less emergency management service response times than "property damage only" crashes. Environmental factors such as weather or roadway conditions had minimal effect on response times to traffic crashes. Day of week, urban or rural area, off or opposing-lane crash location, number of vehicles involved, heavy vehicle involvement, and response time significantly affected clearance time and the resulting total time during peak periods. CONCLUSIONS: By assessing resources currently dedicated to insignificant factors, emergency management services can further improve response times to those casualties that crucially need emergency services. By accurately identifying and deciphering traffic crash severity from initial field reports, services can further improve. Moreover, improvements in crash severity prediction reduce "false alarms" for emergency services. The improvements reduce the probability of a very short response time for a property damage only crash in which initial reports implied a very severe injury. By focusing on factors that significantly reduce traffic crash clearance times on freeways in peak periods, more reductions in average delay experienced by freeway users, in fuel consumption, and in motor vehicle emissions can occur.     

Laboratory studies of the remediation of polycyclic aromatic hydrocarbon contaminated soil by in-vessel composting

The biodegradation of 16 polycyclic aromatic hydrocarbons (PAHs), listed as priority pollutants by the USEPA, present in a coal-tar-contaminated soil from a former manufactured gas plant site was investigated using laboratory-scale in-vessel composting reactors to determine the suitability of this approach as a bioremediation technology. Preliminary investigations were conducted over 16 weeks to determine the optimum soil composting temperature (38, 55 and 70 degrees C). Three tests were performed; firstly, soil was composted with green-waste, with a moisture content of 60%. Secondly, microbial activity was HgCl2-inhibited in the soil green-waste mixture with a moisture content of 60%, to evaluate abiotic losses, while in the third experiment only soil was incubated at the three different temperatures. PAHs and microbial populations were monitored. PAHs were lost from all treatments with 38 degrees C being the optimum temperature for both PAH removal and microbial activity. Calculated activation energy values (E(a)) for total PAHs suggested that the main loss mechanism in the soil-green waste reactors was biological, whereas in the soil reactors it was chemical. Total PAH losses in the soil-green waste composting mixtures were by pseudo-first order kinetics at 38 degrees C (k = 0.013 day(-1), R2 = 0.95), 55 degrees C (k = 0.010 day(-1), R2 = 0.76) and at 70 degrees C (k = 0.009 day(-1), R2 = 0.73).     

A STUDY OF THE SURFACE SYNOPTIC CIRCULATION PATTERNS IN ASSOCIATION WITH THE DROUGHT OF THE 1960's IN THE NORTHEASTERN UNITED STATES1

A comparative evaluation is made of the frequency of air mass and frontal types during a 4-year representative portion of the drought as opposed to an equivalent non-drought period. Selection of the non-drought period is based on the Palmer Drought Index. Results indicate a statistically significant increase in the occurrence of continental polar air during the drought. Other conclusions concerning conditions during the drought, not statistically significant but worth further study, are: lower frequency of maritime tropical air in the summer months, more occurrences of cold and occluded fronts, and fewer occurrences of stationary fronts.     

Measurement of unregulated emissions: Some heavy duty diesel engine results

Development of analytical capabilities to evaluate unregulated emissions are discussed. The sampling and analysis methods along with some problem areas are included. Results obtained on three heavy-duty diesel engines are reported. Emphasis was placed on analysis of the particulate fraction including the solvent extractable material. Preliminary experiments suggest appreciable quantities of organic extract and BaP pass through the primary filter. Other species analyzed to obtain a baseline for emission reduction research included aldehydes, sulfates, sulfur dioxide, ammonia, hydrogen sulfide, and hydrogen cyanide. Of primary concern is the proper assessment of the results.     

Bio-reduction of arsenate using a hydrogen-based membrane biofilm reactor

Arsenate (As(V)) is a carcinogen and a significant problem in groundwater in many parts of the world. Since As(III) is generally more mobile and more toxic than As(V), the reduction of As(V) to As(III) is not a conventional treatment goal. However, reducing As(V) to As(III) may still be a means for decontamination, because As(III) can be removed from solution by precipitation or complexation with sulfide or by adsorption to Fe(II)-based solids. A promising approach for reducing oxidized contaminants is the H2-based membrane biofilm reactor (MBfR). In the case of arsenate, the MBfR allows bio-reduction of As(V) to As(III) and sulfate to sulfide, thereby giving the potential for As removal, such as by precipitation of As2S3(s) or formation of Fe(II)-based solids. When As(V) was added to a denitrifying MBfR, As(V) was reduced immediately to As(III). Decreasing the influent sulfate loading increased As(V) reduction for a fixed H2 pressure. A series of short-term experiments elaborated on how As(V) loading, nitrate and sulfate loadings, and H2 pressure controlled As(V) reduction. Lower nitrate loading and increased As(V) loading increased the extent of As(V) reduction, but increased H2 pressure did not increase As(V) reduction. As(V) reduction was sensitive to sulfate loading, with a maximum As(V)-removal percentage and flux with no addition of sulfate. As(III) could be precipitated with sulfide or adsorbed to Fe(II) solids, which was verified by scanning electron microscopy and energy dispersive X-ray analysis.     

Interaction effects of metals and salinity on biodegradation of a complex hydrocarbon waste

The presence of high levels of salts because of produced brine water disposal at flare pits and the presence of metals at sufficient concentrations to impact microbial activity are of concern to bioremediation of flare pit waste in the upstream oil and gas industry. Two slurry-phase biotreatment experiments based on three-level factorial statistical experimental design were conducted with a flare pit waste. The experiments separately studied the primary effect of cadmium [Cd(II)] and interaction effect between Cd(II) and salinity and the primary effect of zinc [Zn(II)] and interaction effect between Zn(II) and salinity on hydrocarbon biodegradation. The results showed 42-52.5% hydrocarbon removal in slurries spiked with Cd and 47-62.5% in the slurries spiked with Zn. The analysis of variance showed that the primary effects of Cd and Cd-salinity interaction were statistically significant on hydrocarbon degradation. The primary effects of Zn and the Zn-salinity interaction were statistically insignificant, whereas the quadratic effect of Zn was highly significant on hydrocarbon degradation. The study on effects of metallic chloro-complexes showed that the total aqueous concentration of Cd or Zn does not give a reliable indication of overall toxicity to the microbial activity in the presence of high salinity levels.