In-situ bioremediation of amine- and glycol-contaminated soils using low-intervention methods

Biological plugs are an innovative, low-intervention, in-situ bioremediation methodology for both saturated and unsaturated contaminated soils. They are modular in-ground immobilized microbe bioreactors designed to rapidly increase the oxidation of organic contaminants by placing an adapted consortia of microorganisms in close proximity to the contaminants of concern. The approach is versatile, in that contaminants can be remediated in-situ without the removal of existing structures as well as being able to efficiently and economically treat contaminants over a large area. Amine- and glycol-contaminated soils at gas sweetening plants, represent a significant problem in magnitude, prevalence, and risk along pipelines stretching through Canada's western provinces. A field pilot study was conducted at an isolated former gas sweetening plant in northwestern Alberta. Monoethyamine (MEA) and several glycols were successfully remediated in situ in a 138-day time frame. Soil toxicity was significantly reduced. The engineering challenges and associated economics of remediating such isolated sites are also presented.     

Diuron occurrence and distribution in soil and surface and ground water associated with grass seed production

Little is known about the occurrence and distribution of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl urea] in soil, ground water, and surface water in areas affected by grass-seed production. A field study was designed to investigate the occurrence and distribution of diuron and its transformation products at a poorly drained field site located along an intermittent tributary of Lake Creek in the southern Willamette Valley of Oregon. The experimental sites consisted of a field under commercial grass seed production with a cultivated riparian zone and a second site that was part of the same grass seed field but with a noncultivated riparian zone. Diuron and its transformation product DCPMU [3-(3,4-dichlorophenyl)-1-methylurea] were the only significant residues detected in this study. Concentrations of diuron in surface water declined from a maximum of 28 microg/L immediately following application to low levels that persisted as long as flow was present. Diuron and DCPMU concentrations in shallow ground water (15-36 cm below ground surface) were highest (2-13 microg/L) in the zone immediately adjacent (0.5 m) to Lake Creek and indicated the influence of stream water on shallow ground water near the stream. Diuron and DCPMU detected in soil prior to the second season's application indicated the persistence of diuron and DCPMU from the previous year's application. Surface runoff during the rainy season removes only a very small percentage (<1%) of the applied herbicide. In addition, no evidence was obtained for the downward transport of diuron or its transformation products to deep ground water.     

Surrogate measures of alcohol involvement in fatal crashes: Are conventional indicators adequate?

The problem of alcohol-related highway fatalities has led a majority of states to enact new legislative countermeasures. Because few states consistently collect information on alcohol involvement in fatal crashes, the evaluation of the effectiveness of these countermeasures has relied on surrogate measures of alcohol involvement. Using data from the U.S. Department of Transportation's Fatal Accident Reporting System (FARS), this study addresses the following questions: (a) Which of the several surrogate measures used are most likely to reflect alcohol involvement in fatal crashes? and (b) Do the trends in these surrogate measures provide an accurate appraisal of the true trends in alcohol-involved fatal crashes? The authors conclude that nighttime fatal crashes are the best surrogate measure of alcohol-involved crashes, but that surrogate measures may not accurately mirror trends in alcohol-involved fatal crashes over time, particularly in small states or over short durations. All drivers in fatal crashes should be given blood alcohol level (BAL) tests to most accurately assess the effects of drunk driving countermeasures.     

Structural Dependence of Diurnal Fluctuations of Radon Progeny in Residential Buildings

Movement of radon progeny inside houses is a complex process that depends both on atmospheric conditions and on building structure. The indoor working level (WL) monitored in four houses of differing structures shows regular diurnal fluctuations related to solar warming of the atmosphere. In the two houses with full basements, radon is removed by indoor/outdoor pressure-driven airflow, and basement WL varies inversely with outdoor temperature. In the two houses with half basements open to crawl spaces, radon is drawn into the basement faster than it is removed, so that basement WL varies directly with outside temperature. Average WL's in basements are about twice as high as first floor WL's and as much as 18 times as high as outdoor WL's. Each house shows an individual pattern of radon progeny movement throughout the building.