Hematological study of petrol station workers exposed to unleaded petrol

This study was undertaken to assess the level of exposure of petrol station workers to toxic components of unleaded petrol and to investigate whether this exposure, under normal working conditions, is associated with any significant changes in hematological parameters. In this cross-sectional study, 400 subjects (200 exposed and 200 reference subjects) were included. Atmospheric concentrations of benzene (B), toluene (T), and xylene (X) (BTX) were measured and all subjects underwent complete blood counts and white blood cell differential tests. The geometric means of airborne concentrations of BTX were lower than their recommended exposure limits. The results of blood tests showed that the means of red blood cell distribution width and hematocrit parameters, while within the normal range, were significantly different in the two groups. In conclusions, the average exposure level of petrol station workers to BTX did not exceed the current threshold limit values for these chemicals. Additionally, overt hematotoxicity is unlikely to be the outcome of exposure to unleaded petrol under the conditions described in our study. Possible long-term consequences of subtle, clinically insignificant changes in the hematological parameters of exposed employees observed in this study deserve further investigation.     

Natural dyes and antimicrobials for green treatment of textiles

Increasing studies on extraction, purification and modification processes of natural dyes and antimicrobials, and their subsequent application on textiles demonstrate the revival of natural dyeing and finishing. Natural dyes have been widely used in textile coloration since ancient times. But, with advent of man-made synthetic dyes in the mid-nineteenth century, the dye market has been captured due to a variety of competitive properties of synthetic dyes against natural ones such as lower cost, higher fastness, color variety, ability to dye synthetic fibers and availability in large industrial scale. However, most of the synthetic dyes raise some serious problems in human health and cause environmental risks. Due to these drawbacks along with the growing awareness about cleaner surroundings and healthy lifestyle, there has been recently a worldwide interest in the production and application of dyes from two natural sources, plants and microorganisms. Most of these natural dyes have also inherently antimicrobial properties and could consequently possess high medicinal activity. They are extracted from different types of microorganisms as well as various parts of the plants that contain coloring materials such as tannin, flavonoids and quinonoids. Here we review the latest scientific researches on extraction and application of natural dyes/antimicrobials on textiles as effective coloring and antibacterial agents. First, different methods of extraction of natural dyes/antimicrobials will be discussed, and then, current methods of textile treatments and examples of early applications of these dyes on textile processing, properties achieved and the results obtained will be presented.     

A stochastic stormwater quality volume-sizing method with first flush emphasis

A Monte Carlo simulation technique was applied to assess the effect of stormwater quality volume captured by best management practices (BMPs) on the frequency of discharging concentrations of constituents above certain designated threshold limits. The method used an assumption of a power law relationship between the cumulative load and flow to incorporate the first flush effect. The exponent of this relationship was considered a random variable and its frequency distribution was obtained from 78 measured pollutographs from three urban highway sites in West Los Angeles, California. Although the effect of rain depth captured by BMPs is site-specific, the method offered here provides a systematic approach to evaluate the effect of selecting various regulatory guidelines for controlling urban stormwater pollution on the overall discharge of pollutants into waterways. This allows selecting the requirements for capturing runoff volume by BMPs based on the tradeoff between the probability of concentration criteria violation and economic factors.     

Carbon and energy taxation for CO<Subscript>2</Subscript> mitigation: a CGE model of the Malaysia

Malaysia has made a pledge to reduce voluntarily her carbon dioxide-equivalent (CO₂-e) gas emission’s intensity of gross domestic product by up to 40 % based on 2005 levels by 2020. The country is considering implementing economic instruments, among others, to assist the achievement of emission reduction targets while contributing towards the nation’s energy security and sustainable development goals. This paper develops a computable general equilibrium model with explicit energy-emission linkages to appraise the economy-wide and welfare impacts of carbon and energy tax policies to reduce CO₂ emissions in Malaysia. Results indicate that the negative macroeconomic impacts of carbon and energy taxes are small relative to the quantum of emission reduction. A Hicksian welfare criterion is utilized to determine the impact of revenue natural shifts in carbon and energy taxes. Revenue neutrality assumptions show that carbon taxation is the best choice when it can provide a double dividend if the generated revenue is used for the purpose of consumption subsidy on household purchases. The notion of the double dividend is confirmed when the change in the consumption structure will result in a welfare improvement, while CO₂ emission is decreased effectively. The study also found that carbon tax policy results in greater emission reductions relative to energy taxes, while the use of renewable energy will increase more substantially.     

Integrating flood hazard into site selection of detention basins using spatial multi-criteria decision-making

This study presents an innovative approach for the integration of flood hazard into the site selection of detention basins. The site selection process is conducted by taking into account multiple criteria and disciplines. Hydraulic modeling results derived from stormwater management model are employed by Technique for the Order of Prioritization by Similarity to Ideal Solution (TOPSIS) to determine flood hazard score. The score generated by TOPSIS is used in a spatial multi-criteria decision-making site selection framework. Applying the framework, a suitability map is generated in which primary locations for detention basin placement are determined. The method is demonstrated through the case study of Darakeh River Catchment, which is located in northern Tehran, Iran. The presented framework can be easily utilized for site selection of other stormwater management techniques, such as low impact development and best management practices, due to its versatility.     

Permeability measurement and scan imaging to assess clogging of pervious concrete pavements in parking lots

This paper describes a study that used permeability measurement along with physical and hydrological characteristics of 20 pervious concrete pavements in parking lots throughout California. The permeability was measured at five locations: the main entrance, an area with no traffic, and three separate measurements within a parking space at each parking lot. Hydrological and physical site characteristics such as traffic flow, erosion, vegetation cover, sediments accumulation, maintenance practice, presence of cracking, rainfall, and temperature data were also collected for each parking lot. These data were used to perform detailed statistical analysis to determine factors influencing changes in permeability and hence assessing possible cause of clogging. In addition, seven representative core samples were obtained from four different parking lots with permeability ranging from very low to very high. Porosity profiles produced from CT scanning were used to assess the possible nature and extent of clogging. Results showed that there is a large variation in permeability within each parking lot and between different parking lots. In general, the age of the parking lot is the predominant factor influencing the permeability. Statistical analysis revealed that fine sediment (particles less than 38 μm) mass is also an important influencing factor. Other influencing factors with lower significance included number of days with a temperature greater than 30°C and the amount of vegetation next to the parking lot. The combined scanned image analysis and porosity profile of the cores showed that most clogging occurs near the surface of the pavement. While lower porosity generally appeared to be limited to the upper 25 mm, in some core samples evidence of lower porosity was found up to 100mm below the surface.     

Leachability of dissolved chromium in asphalt and concrete surfacing materials

Leachate metal pollutant concentrations produced from different asphalt and concrete pavement surfacing materials were measured under controlled laboratory conditions. The results showed that, in general, the concentrations of most metal pollutants were below the reporting limits. However, dissolved chromium was detected in leachate from concrete (but not asphalt) specimens and more strongly in the early-time leachate samples. As the leaching continued, the concentration of Cr decreased to below or close to the reporting limit. The source of the chromium in concrete pavement was found to be cement. The concentration of total Cr produced from leachate of different cement coming from different sources that was purchased from retail distributors ranged from 124 to 641 μg/L. This result indicates that the potential leachability of dissolved Cr from concrete pavement materials can be reduced through source control. The results also showed that the leachability of dissolved Cr in hardened pavement materials was substantially reduced. For example, the concentration of dissolved Cr measured in actual highway runoff was found to be much lower than the Cr concentration produced from leachate of both open and dense graded concrete pavement specimens under controlled laboratory study. It was concluded that pavement materials are not the source of pollutants of concern in roadway runoff; rather most pollutants in roadway surface runoff are generated from other road-use or land-use sources, or from (wet or dry) atmospheric deposition.     

Spatial Analysis of Volatile Organic Compounds from a Community-Based Air Toxics Monitoring Network in Deer Park,Texas, USA

In the summer of 2003, ambient air concentrations of volatile organic compounds (VOCs) were measured at 12 sites within a 3-km radius in Deer Park, Texas near Houston. The purpose of the study was to assess local spatial influence of traffic and other urban sources and was part of a larger investigation of VOC spatial and temporal heterogeneity influences in selected areas of Houston. Seventy 2-h samples were collected using passive organic vapor monitors. Most measurements of 13 VOC species were greater than the method detection limits. Samplers were located at 10 residential sites, a regulatory air monitoring station, and a site located at the centroid of the census tract in which the regulatory station was located. For residential sites, sampler placement locations (e. g., covered porch vs. house eaves) had no effect on concentration with the exception of methyl tertiary-butyl ether (MTBE). Relatively high correlations (Pearson r > 0.8) were found between toluene, ethylbenzene, and o,m,p-xylenes suggesting petroleum-related influence. Chloroform was not correlated with these species or benzene (Pearson r < 0.35) suggesting a different source influence, possibly from process-related activities. As shown in other spatial studies, wind direction relative to source location had an effect on VOC concentrations.     

A novel pollution index based on the bioavailability of elements: a study on Anzali wetland bed sediments

In this research, we study on the distribution of several elements in bed sediments of Anzali wetland. Anzali, one of the most important international wetlands, is located on the southern coast of the Caspian Sea in Iran. This wetland receives discharges of domestic, agricultural, and industrial wastewater, which affect the distribution of elements. Our contribution in this study is threefold. First, we measured the total concentration of metals as well as their chemical partitioning and bioavailability in the sediments. Second, we calculated anthropogenic portions of metals in the sediment of this area. The results reveal anthropogenic portion of metals as Mo > Mn > Cd > As > Zn > Hg > Co > Sn > Cu > V > Ag > Ni > Pb > Fe > Cr > Al, respectively. We evaluated the intensity of pollution by using an enrichment factor, the geo-accumulation index and the pollution index. All these indices do not take into consideration the bioavailability of the elements. As our third and most important contribution, we introduced a new formula that takes into account the bioavailability of different elements. In comparison with aforementioned pollution indices, our newly introduced pollution index has a higher Pearson correlation with anthropogenic portion of metals. This high-correlation coefficient shows that our proposed pollution index is an effective indicator for determining the level of pollution, while other indices preserve their own merits.