Traffic-generated noise pollution: exposure of road users and populations in Metropolitan Kuwait

This study was carried out in metropolitan Kuwait with a sound level meter to assess peak hour and off-peak hour noise level. In local/collector streets, noise ranged between 56.0 to 79.2 dBA and 55.3 to 76.4 dBA; in arterial streets, 62.3 to 89.2 dBA and 59.6 to 78.9 dBA; and in freeways, 66.7 to 94.8 dBA and 64.9 to 89.1 dBA during peak and off-peak hour respectively. Values were higher than their prescribed standards which may pose a significant impact on quality of life. Findings of this research have shown that the level of traffic-generated noise pollution in Kuwait urban area is high enough to adversely affect the human health and well-being of its residents. Over 1,400 subjects responded to a randomly administered survey that assessed the physical health, personal well-being, and mental health. People residing in neighborhoods exposed to higher noise levels have significantly higher stress and noise annoyance levels and also adversely affected their sense of well-being. In the responder analysis, those people living in quiet neighborhoods had significantly higher mean scores in general health (35 points higher, p < 0.05), sense of vitality (30 points higher, p < 0.05), and mental health (20 points higher, p < 0.05) when compared to the other group. In addition, the component scores of stress and noise sensitivity for the participants living in quiet neighborhoods had significantly lower values (30 points lower and 59 points lower, respectively) than that of the participants living in noisy neighborhood. With the rapid expansion of the infrastructures in metropolitan Kuwait, it is virtually definite that traffic noise will shortly assume a dangerous dimension, and will be a ground of escalating fear for both the public and liable policy-makers. The quality of life in metropolitan Kuwait will certainly be negatively affected.     

Ecorisk evaluation and treatability potential of soils contaminated with petroleum hydrocarbon-based fuels

We used a series of toxicity tests to monitor oil degradation in the Kuwaiti oil lakes. Three soils from different locations with a history of hydrocarbon contamination were treated in bench-scale microcosms with controlled nutrient amendments, moisture content, and temperature that had promoted mineralization of total hydrocarbon and oil and grease in a preliminary study. Two hundred days of bioremediation treatment lowered hydrocarbon concentration to below 2 and 5 mg g(-1) for soils A and B, respectively, while in soil C hydrocarbon concentration remained at 12 mg g(-1). Although 85% of the total petroleum hydrocarbons (TPHs) in soil A were reduced 50d after treatment, results of the seed germination and Microtox tests suggested an initial increase in toxicity, indicating that toxic intermediary metabolites may have formed during biodegradation. Also, the significant decrease of TPHs and corresponding high toxicity levels were noted in soil B 200d after bioremediation. Clearly, toxicity values, and not just hydrocarbon concentration, are a key factor in assessing the effectiveness of bioremediation techniques. Field chemistry data showed a significant reduction in hydrocarbon levels after the biological treatment. We concluded that the toxicity assessment of the contaminated soil with a battery of toxicity bioassays could provide meaningful information regarding a characterization procedure in ecological risk assessment.     

Effect of microsilica addition on compressive strength of rubberized concrete at elevated temperatures

An experimental investigation was carried out to study the effects of various percentages of fine/coarse tire waste and microsilica at various temperatures on the compressive strength of concrete. The compressive strength of concrete mixtures made with tire rubber was assessed statistically with those of concrete containing microsilica and conventional concretes in order to evaluate the usefulness of recycling rubber waste as a component of concrete. Results confirmed that the recipe and processing temperature of concrete cubes influence the compressive strength values. Generally, the use of microsilica or fine rubber mixed with microsilica as aggregate replacement of 5% by volume improved the compressive strength of concrete processed at a temperature of 150°C. The addition of coarse rubber did not achieve any increase in strength when used as an aggregate replacement at any percentage. Moreover, the reductions in the compressive strength of concrete mixes at higher temperatures were much smaller for the fine rubber with 5 vol% microsilica than those for control and coarse rubber mixes. The specimens made with fine rubber and 5 vol% microsilica at elevated temperatures above 400°C appeared to show very similar compressive strength values. The use of fine rubber in building construction could help save energy and reduce costs and solve the solid waste disposal problem posed by this type of waste.