Seasonal variations of polycyclic aromatic hydrocarbons in coastal sediments of a marine resource hot spot: the case of pars special economic energy zone,Iran

Environmental Geochemistry and Health - Polycyclic aromatic hydrocarbons (PAHs) are an important group of compounds of major environmental concern, which are in the class of persistent organic...     

Establishing conversation spaces in hastily formed networks: the worst fire in modern Swedish history

In presenting examples from the most extensive and demanding fire in modern Swedish history, this paper describes challenges facing hastily formed networks in exceptional situations. Two concepts that have been used in the analysis of the socio‐technical systems that make up a response are conversation space and sensemaking. This paper argues that a framework designed to promote understanding of the sensemaking process must take into consideration the time and the location at which an individual is engaged in an event. In hastily formed networks, location is partly mediated through physical systems that form conversation spaces of players and their interaction practices. This paper identifies and discusses four challenges to the formation of shared conversation spaces. It is based on the case study of the 2006 Bodträskfors forest fire in Sweden and draws on the experiences of organised volunteers and firefighters who participated in a hastily formed network created to combat the fire.     

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.     

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.     

In situ sensing of subsurface contamination—part I: near-infrared spectral characterization of alkanes,aromatics, and chlorinated hydrocarbons

There is an imperative need for a chemical sensor capable of remote, in situ, long-term monitoring of chemical species at sites containing toxic chemical spills, specifically at chemical waste dumps, landfills, and locations with underground storage tanks. In the current research, a series of experiments were conducted measuring the near-infrared optical absorption of alkanes, aromatics, and chlorinated hydrocarbons. A spectral library was then developed to characterize the optical spectra of liquid hydrocarbons. Near-infrared analysis was chosen due to compatibility with optical fibers. The goal was to differentiate between classes of hydrocarbons and to also discriminate between compounds within a class of similar molecular structures. It was observed that unique absorption spectra can be obtained for each hydrocarbon, and this uniqueness can be used to discriminate between hydrocarbons from different families. Statistical analyses, namely, principal component analysis (PCA) and correlation coefficient (Spearman and Pearson methods), were attempted to match absorption spectra from an unknown hydrocarbon with the database with limited success. An algorithm was subsequently written to identify the characteristic peaks of each hydrocarbon that could be used to match data from an unknown chemical species with the database.     

Transformation of hydroxylated derivatives of 2,5-dichlorobiphenyl and 2,4,6-trichlorobiphenyl by Burkholderia xenovorans LB400

The polychlorinated biphenyl (PCB)-degrading bacterium, Burkholderia xenovorans LB400, was capable of transforming three hydroxylated derivatives of 2,5-dichlorobiphenyl (2,5-DCB) (2′-hydroxy- (2′-OH-), 3′-OH-, and 4′-OH-2,5-DCB) when biphenyl was used as the carbon source (i.e., biphenyl pathway-inducing condition), although only 2′-OH-2,5-DCB was transformed when the bacterium was growing on succinate (i.e., condition non-inductive of the biphenyl pathway). On the contrary, hydroyxlated derivatives of 2,4,6-trichlorobiphenyl (2,4,6-TCB) (2′-OH-, 3′-OH-, and 4′-OH-2,4,6-TCB) were not significantly transformed by B. xenovorans LB400, regardless of the carbon source used. Gene expression analyses showed a clear correlation between the transformation of OH-2,5-DCBs and expression of genes of the biphenyl pathway. The PCB metabolite, 2,5-dichlorobenzoic acid (2,5-DCBA), was produced following the transformation of OH-2,5-DCBs. 2,5-DCBA was not further transformed by B. xenovorans LB400. The present study is significant because it provides evidence that PCB-degrading bacteria are capable of transforming hydroxylated derivatives of PCBs, which are increasingly considered as a new class of environmental contaminants.     

Trend and concentrations of legacy lead (Pb) in highway runoff

This study presents the results of lead (Pb) concentrations from both highway runoff and contaminated soil along 32 and 23 highway sites, respectively. In general, the Pb concentration on topsoil (0-15 cm) along highways was much higher than the Pb concentration in subsurface soil (15-60 cm). The Pb deposited on soil appears to be anthropogenic and a strong correlation was found between the Pb concentration in surface soil and highway runoff in urban areas. The concentration of Pb measured during 1980s from highways runoff throughout the world was up to 11 times higher than the measured values in mid 1990 s and 2000s. The current Pb deposited on soil near highways appears to be a mixture of paint, tire weight balance and old leaded gasoline combustion. Overall, the Pb phase-out regulation reduced the Pb deposits in the environment and consequently lowered Pb loading into receiving waters.