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Oil droplet interaction with suspended sediment in the seawater column: Influence of physical parameters and chemical dispersants Full text
2014
Sørensen, Lisbet | Melbye, Alf Glein | Booth, Andy
The interaction of dispersed oil droplets with large diameter suspended particulate materials (SPM) has been little studied. In the current study, particle size, oil characteristics and chemical dispersant significantly influence the adsorption of oil droplets to SPM in seawater. Sediments with a smaller particulate size (clay) approaching that of the oil droplets (2–20 lm) adsorbed more oil per gram than sediments with large particle size (sand). Heavier, more polar oils with a high asphaltene content adsorbed more efficiently to SPM than lighter, less polar oils. A decrease in the smaller, more water soluble oil components in the sediment adsorbed oil was observed for all oil types. Addition of chemical dispersant decreased the adsorption of oil droplets to suspended carbonate sand in an exponential-like manner. No change in the relative distribution of compounds adsorbed to the sediment was observed, indicating dispersants do not alter the dissolution of compounds from oil droplets. | acceptedVersion
Show more [+] Less [-]Sorption of phenanthrene and benzene on differently structural kerogen: Important role of micropore-filling Full text
2014
Zhang, Yulong | Ma, Xiaoxuan | Ran, Yong
Shale was thermally treated to obtain a series of kerogen with varied maturation. Their chemical, structural and porous properties were related to the sorption and/or desorption behaviors of phenanthrene and benzene. As the treatment temperature increases, aliphatic and carbonyl carbon of the kerogen samples decrease, while their aromaticity and maturation increase. Meanwhile, the isothermal nonlinearity of phenanthrene and benzene increases whereas the sorption capacity and micropore adsorption volumes (Vo,d) initially increase and then decrease. The Vo,d of benzene is significantly correlated with, but higher than that of phenanthrene, suggesting similar micropore filling mechanism and molecular sieve effect. The benzene desorption exhibits hysteresis, which is related to the pore deformation of the kerogen and the entrapment of solute in the kerogen matrix. The Vo,d of phenanthrene and benzene on the kerogen samples accounts for 23–46% and 36–65% of the maximum sorption volumes, respectively, displaying the importance of the micropore filling.
Show more [+] Less [-]Homologue specific analysis of a polyether trisiloxane surfactant in German surface waters and study on its hydrolysis Full text
2014
The occurrence of a polyether trisiloxane surfactant in the ng L−1 range in German surface waters is reported for the first time. The studied surfactant does not ubiquitously occur in the aquatic environment but can reach surface waters on a local scale. As a first step towards the understanding of the environmental fate, the hydrolysis was studied according to the OECD guideline 111. It confirmed that the trisiloxane surfactant is sensitive to hydrolysis and that the hydrolysis rate strongly depends on the pH and the temperature. If one takes only into account the hydrolysis, the trisiloxane surfactant could persist several weeks in river water (the half-life in water is approximately 50 days at pH 7, 25 °C, and an initial concentration of 2 mg L−1). A degradation product, more polar than the initial trisiloxane surfactant, was identified by high resolution mass spectrometry.
Show more [+] Less [-]Potential for reducing air-pollutants while achieving 2 °C global temperature change limit target Full text
2014
Hanaoka, Tatsuya | Akashi, Osamu | Fujiwara, Kazuya | Motoki, Yuko | Hibino, Go
This study analyzes the potential to reduce air pollutants while achieving the 2 °C global temperature change limit target above pre-industrial levels, by using the bottom-up optimization model, AIM/Enduse[Global]. This study focuses on; 1) estimating mitigation potentials and costs for achieving 2 °C, 2.5 °C, and 3 °C target scenarios, 2) assessing co-benefits of reducing air pollutants such as NOx, SO2, BC, PM, and 3) analyzing features of sectoral attributions in Annex I and Non-Annex I groups of countries. The carbon tax scenario at 50 US$/tCO2-eq in 2050 can reduce GHG emissions more than the 3 °C target scenario, but a higher carbon price around 400 US$/tCO2-eq in 2050 is required to achieve the 2 °C target scenario. However, there is also a co-benefit of large reduction potential of air pollutants, in the range of 60–80% reductions in 2050 from the reference scenario while achieving the 2 °C target.
Show more [+] Less [-]Formation of brominated pollutants during the pyrolysis and combustion of tetrabromobisphenol A at different temperatures Full text
2014
Ortuño, Nuria | Moltó, Julia | Conesa, Juan A. | Font, Rafael
Formation of brominated pollutants during the pyrolysis and combustion of tetrabromobisphenol A at different temperatures Full text
2014
Ortuño, Nuria | Moltó, Julia | Conesa, Juan A. | Font, Rafael
Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant worldwide. A detailed examination of the degradation products emitted during thermal decomposition of TBBPA is presented in the study. Runs were performed in a laboratory furnace at different temperatures (650 and 800 °C) and in different atmospheres (nitrogen and air). More than one hundred semivolatile compounds have been identified by GC/MS, with special interest in brominated ones. Presence of HBr and brominated light hydrocarbons increased with temperature and in the presence of oxygen. Maximum formation of PAHs is observed at pyrolytic condition at the higher temperature. High levels of 2,4-, 2,6- and 2,4,6- bromophenols were found. The levels of polybrominated dibenzo-p-dioxins and furans have been detected in the ppm range. The most abundant isomers are 2,4,6,8-TeBDF in pyrolysis and 1,2,3,7,8-PeBDF in combustion. These results should be considered in the assessment of thermal treatment of materials containing brominated flame retardants.
Show more [+] Less [-]Formation of brominated pollutants during the pyrolysis and combustion of tetrabromobisphenol A at different temperatures Full text
2014
Ortuño García, Nuria | Moltó Berenguer, Julia | Conesa, Juan A. | Font, Rafael | Universidad de Alicante. Departamento de Ingeniería Química | Residuos, Pirólisis y Combustión
Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant worldwide. A detailed examination of the degradation products emitted during thermal decomposition of TBBPA is presented in the study. Runs were performed in a laboratory furnace at different temperatures (650 and 800 °C) and in different atmospheres (nitrogen and air). More than one hundred semivolatile compounds have been identified by GC/MS, with special interest in brominated ones. Presence of HBr and brominated light hydrocarbons increased with temperature and in the presence of oxygen. Maximum formation of PAHs is observed at pyrolytic condition at the higher temperature. High levels of 2,4-, 2,6- and 2,4,6- bromophenols were found. The levels of polybrominated dibenzo-p-dioxins and furans have been detected in the ppm range. The most abundant isomers are 2,4,6,8-TeBDF in pyrolysis and 1,2,3,7,8-PeBDF in combustion. These results should be considered in the assessment of thermal treatment of materials containing brominated flame retardants. | Support for this work was provided by the Generalitat Valenciana (Spain), research project Prometeo/2009/043/FEDER, and by the Spanish Ministry of Education and Science, research project CTQ2008-05520.
Show more [+] Less [-]Modeling of stomatal conductance to estimate stomatal ozone uptake by Fagus crenata, Quercus serrata, Quercus mongolica var. crispula and Betula platyphylla Full text
2014
Kinose, Yoshiyuki | Azuchi, Fumika | Uehara, Yui | Kanomata, Tomoaki | Kobayashi, Ayumi | Yamaguchi, Masahiro | Izuta, Takeshi
To construct stomatal conductance models and estimate stomatal O3 uptake for Fagus crenata, Quercus serrata, Quercus mongolica var. crispula and Betula platyphylla, stomatal conductance (gs) was measured in seedlings of the four tree species. Better estimates of gs were made by incorporating the acute effects of O3 on gs into the models and the models could explain 34–52% of the variability in gs. Although the O3 concentration was relatively high in spring from April to May, COU of F. crenata, Q. serrata and Q. mongolica var. crispula were relatively low and the ratios of COU in spring to total COU in one year were 16.8% in all tree species because of low gs limited mainly by leaf pre-maturation and/or low temperature. The COU of B. platyphylla were relatively high mainly because of rapid leaf maturation and lower optimal temperature for stomatal opening.
Show more [+] Less [-]Chemical characteristics of PM2.5 at a source region of biomass burning emissions: Evidence for secondary aerosol formation Full text
2014
Rastogi, N. | Singh, A. | Singh, D. | Sarin, M.M.
A systematic study on the chemical characteristics of ambient PM2.5, collected during October-2011 to March-2012 from a source region (Patiala: 30.2°N, 76.3°E; 250 m amsl) of biomass burning emissions in the Indo-Gangetic Plain (IGP), exhibit pronounced diurnal variability in mass concentrations of PM2.5, NO3−, NH4+, K+, OC, and EC with ∼30–300% higher concentrations in the nighttime samples. The average WSOC/OC and SO42−/PM2.5 ratios for the daytime (∼0.65, and 0.18, respectively) and nighttime (0.45, and 0.12, respectively) samples provide evidence for secondary organic and SO42− aerosol formation during the daytime. Formation of secondary NO3− is also evident from higher NH4NO3 concentrations associated with lower temperature and higher relative humidity conditions. The scattering species (SO42− + NO3− + OC) contribute ∼50% to PM2.5 mass during October–March whereas absorbing species (EC) contribute only ∼4% in October–February and subsequently increases to ∼10% in March, indicating significance of these species in regional radiative forcing.
Show more [+] Less [-]Partitioning of magnetic particles in PM10, PM2.5 and PM1 aerosols in the urban atmosphere of Barcelona (Spain) Full text
2014
Revuelta, María Aránzazu | McIntosh, Gregg | Pey, Jorge | Pérez, Noemi | Querol, X. (Xavier) | Alastuey, A. (Andrés)
A combined magnetic-chemical study of 15 daily, simultaneous PM10–PM2.5–PM1 urban background aerosol samples has been carried out. The magnetic properties are dominated by non-stoichiometric magnetite, with highest concentrations seen in PM10. Low temperature magnetic analyses showed that the superparamagnetic fraction is more abundant when coarse, multidomain particles are present, confirming that they may occur as an oxidized outer shell around coarser grains. A strong association of the magnetic parameters with a vehicular PM10 source has been identified. Strong correlations found with Cu and Sb suggests that this association is related to brake abrasion emissions rather than exhaust emissions. For PM1 the magnetic remanence parameters are more strongly associated with crustal sources. Two crustal sources are identified in PM1, one of which is of North African origin. The magnetic particles are related to this source and so may be used to distinguish North African dust from other sources in PM1.
Show more [+] Less [-]Possible causes of the recent rapid increase in the radial increment of silver fir in the Western Carpathians Full text
2014
Bošeľa, Michal | Petráš, Rudolf | Sitková, Zuzana | Priwitzer, Tibor | Pajtík, Jozef | Hlavatá, Helena | Sedmák, Róbert | Tobin, Brian
Silver fir is one of the most productive and ecologically valuable native European tree species, however, it has been experiencing decline which has periodically occurred over its natural range. This paper aims to investigate the recent climate–growth relationships of silver fir (Abies alba Mill.) and its temporal change along the course of its life. Long-term tree-ring databases, as well as records on climate, atmospheric SO2, NO3 and acid concentrations from four different regions in the Western Carpathians were used. The results provide clear evidence of significant increase of silver fir's radial increment over the entire Western Carpathian area since 1970–1980. The results indicated that the most probable factors behind the rapid recovery of tree radial increment were reductions in emissions of NO3 and SO2, alongside a significant increase in mean June, July and April temperatures.
Show more [+] Less [-]Urban vegetation for reducing heat related mortality Full text
2014
Chen, Dong | Wang, Xiaoming | Thatcher, Marcus | Barnett, Guy | Kachenko, Anthony | Prince, Robert
The potential benefit of urban vegetation in reducing heat related mortality in the city of Melbourne, Australia is investigated using a two-scale modelling approach. A meso-scale urban climate model was used to quantify the effects of ten urban vegetation schemes on the current climate in 2009 and future climates in 2030 and 2050. The indoor thermal performance of five residential buildings was then simulated using a building simulation tool with the local meso-climates associated with various urban vegetation schemes. Simulation results suggest that average seasonal summer temperatures can be reduced in the range of around 0.5 and 2 °C if the city were replaced by vegetated suburbs and parklands, respectively. With the limited buildings and local meso-climates investigated in this study, around 5–28% and 37–99% reduction in heat related mortality rate have been estimated by doubling the city's vegetation coverage and transforming the city into parklands respectively.
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