Impacts of biodiesel on pollutant emissions of a JP-8-fueled turbine engine

The impacts of biodiesel on gaseous and particulate matter (PM) emissions of a JP-8-fueled T63 engine were investigated. Jet fuel was blended with the soybean oil-derived methyl ester biofuel at various concentrations and combusted in the turbine engine. The engine was operated at three power settings, namely ground idle, cruise, and takeoff power, to study the impact of the biodiesel at significantly different pressure and temperature conditions. Particulate emissions were characterized by measuring the particle number density (PND; particulate concentration), the particle size distribution, and the total particulate mass. PM samples were collected for offline analysis to obtain information about the effect of the biodiesel on the polycyclic aromatic hydrocarbon (PAH) content. In addition, temperature-programmed oxidation was performed on the collected soot samples to obtain information about the carbonaceous content (elemental or organic). Major and minor gaseous emissions were quantified using a total hydrocarbon analyzer, an oxygen analyzer, and a Fourier Transform IR analyzer. Test results showed the potential of biodiesel to reduce soot emissions in the jet-fueled turbine engine without negatively impacting the engine performance. These reductions, however, were observed only at the higher power settings with relatively high concentrations of biodiesel. Specifically, reductions of approximately 15% in the PND were observed at cruise and takeoff conditions with 20% biodiesel in the jet fuel. At the idle condition, slight increases in PND were observed; however, evidence shows this increase to be the result of condensed uncombusted biodiesel. Most of the gaseous emissions were unaffected under all of the conditions. The biodiesel was observed to have minimal effect on the formation of polycyclic aromatic hydrocarbons during this study. In addition to the combustion results, discussion of the physical and chemical characteristics of the blended fuels obtained using standard American Society for Testing and Materials (ASTM) fuel specifications methods are presented.     

Road rage experience and behavior: vehicle, exposure, and driver factors

Road rage has generated increasing public concern. Research has shown that victimization and perpetration of road rage is more common among males and younger drivers. We aimed to extend the understanding of determinants of road rage to driving exposure and vehicle factors, based on a 20022003 population survey of 1,631 regular drivers in Ontario, Canada. Regression analyses revealed that number of times drivers reported experiencing road rage in the previous 12 months was significantly greater for males, younger respondents, and those residing in Toronto. Also, victimization was significantly greater for drivers who did all their driving on busy roads and increased with number of kilometers driven on a typical week; however, type of vehicle driven was not significant. Number of times road rage perpetration was reported in the past 12 months was significantly greater for males, younger respondents, and those residing in Toronto, and lower for those in the Eastern and Northern region. Road rage perpetration increased significantly with number of weekly kilometers driven and was significantly greater for drivers who are always on busy roads and lower for those who never drive on busy roads, and higher for high-performance vehicle drivers. Even after controlling for driving exposure, road rage victimization and perpetration were highest for drivers in Toronto, where the pace of life may be more demanding. As expected, high-performance vehicle drivers reported more road rage perpetration. These individuals may experience more frustration when they are prevented from using the full performance capacities of their vehicles by crowded urban roadways.     

Driving while impaired (DWI) by alcohol convictions among alcohol, cocaine, and cannabis clients in treatment

OBJECTIVE: Although studies have demonstrated that clients in treatment for alcohol abuse are more at risk of driving while impaired (DWI) by alcohol than normal licensed drivers from the general population, no research was found on DWI convictions among those in treatment for abusing cannabis or cocaine. The purpose of this article is to compare DWI convictions among clients in treatment for alcohol, cannabis, cocaine, or various combinations of these substances, compared to a matched population control group. METHOD: A stratified random sample of driver records was drawn from seven client groups who sought treatment in 1994 for alcohol, cannabis, cocaine, or any combination of these substances (n = 445). A random sample of drivers, frequency matched by age and sex (n = 566), served as control subjects. RESULTS: Logistic regression analysis, controlling for sex and age, was conducted to assess whether DWI convictions were elevated for each of the client groups, compared to controls. Two sets of analyses were conducted, before treatment (from 1985 to 1993) and after treatment (from 1995 to 2000). In the time period before treatment, every drug group except the "cannabis only" group had significantly more DWI convictions than controls (p < .05). In the period after treatment, the "alcohol only," "cocaine only," "alcohol and cocaine," and the "cocaine and cannabis" groups still had significantly more DWI convictions than controls (p < .05). CONCLUSION: The results show that DWI convictions are elevated among those who abused cocaine but not among those who abused cannabis. The results suggest that cross-addiction of alcohol and cocaine is common, and problematic drinking among cocaine clients can go undetected when clients are being diagnosed for treatment.     

Scaling DNAPL migration from the laboratory to the field

A particular problem with the release of dense nonaqueous phase liquids (DNAPLs) into the environment is identifying where the DNAPL is and if it is still moving. This question is particularly important at sites where thousands of cubic meters of DNAPLs were disposed of. To date, results from laboratory models have not been scaled to predict analogous migration at the larger length and time scales appropriate for sites where large volumes of DNAPLs were released. Modified inspectional analysis is a technique for developing scaling relationships through nondimensionalizing the governing equations. It was applied in this study to scale observations of DNAPL migration in a laboratory model to four hypothetical scenarios in the field where large volumes of DNAPL were released. One scenario was compared to a large DNAPL spill site. The length and time scales of DNAPL movement predicted from our analysis are consistent with those predicted from a numerical model of this site. To our knowledge, this is the first application of modified inspectional analysis for release of DNAPLs in a laboratory model. This methodology may prove useful for scaling results from other laboratory investigations of DNAPL migration to field-scale systems.     

基于指示菌的温榆河微生物健康风险评估

城市河流是城市重要的生态景观组分,发挥着一定的景观娱乐功能,但污水处理厂出水和流域分散性污水等非常规水源补给逐渐成为越来越多城市河流补给的常态.本研究在典型的非常规水源补给河流—北京市温榆河布设采样点,系统评估了2015年间河流的粪大肠菌、大肠埃希氏菌、肠球菌3种指示微生物的污染状况,运用定量微生物风险评价方法考查了非常规水源补给对河流微生物污染状况和微生物的人体健康风险的影响.研究结果显示,温榆河作为景观娱乐水体时,以不同表征方式表征的单次暴露微生物健康风险值为0.1~0.5,从风险角度考虑其作为景观娱乐水体是不可接受的;受非常规水源补给影响严重的下游河段单次暴露的健康风险可能比上游高出50%.从温榆河不同微生物表征的单次暴露健康风险来看,上下游暴露途径皆以游泳引起的风险为最高;从微生物年暴露健康风险来看,对河道保洁人员、游船驾驶人员这两类常年频繁接触温榆河水体的人群风险值最高.