Arsenic species in electronic cigarettes: Determination and potential health risk

Human exposure to contaminants from electronic cigarettes(e-cigarettes) and the associated health effects are poorly understood.There has been no report on the speciation of arsenic in e-liquid(solution used for e-cigarettes) and aerosols.We report here determination of arsenic species in e-liquids and aerosols generated from vaping the e-liquid.Seventeen e-liquid samples of major brands,purchased from local and online stores in Canada and China,were analyzed for arsenic species using high-performance liquid chromatography and inductively coupled plasma mass spectrometry.Aerosols condensed from vaping the eliquids were also analyzed and compared for arsenic species.Six arsenic species were detected,including inorganic arsenate(iAs~Ⅴ),arsenite(iAs~Ⅲ),monomethylarsonic acid(MMA),and three new arsenic species not reported previously.In e-liquids,iAs~Ⅲ was detected in 59%,iAs~Ⅴ in 94%,and MMA in 47% of the samples.In the condensate of aerosols from vaping the e-liquids,iAs~Ⅲ was detected in 100%,iAsv in 88%,and MMA in 13% of the samples.Inorganic arsenic species were predominant in e-liquids and aerosols of e-cigarettes.The concentration of iAs~Ⅲ in the condensate of aerosols(median 3.27 μg/kg) was significantly higher than that in the e-liquid(median 1.08 μg/kg) samples.The concentration of inorganic arsenic in the vaping air was approximately 3.4 μg/m~3,which approaches to the permissible exposure limit(10 μg/m~3) set by the United States Occupational Safety and Health Administration(OSHA).According to the Environmental Protection Agency's unit risk factor(4.3 × 10~(-3) per μg/m~3) for inhalation exposure to inorganic arsenic in the air,the estimated excess lung cancer risk from lifetime exposure to inorganic arsenic in the ecigarette vaping air(3.4 μg/m~3),assuming e-cigarette vaping at 1% of the time,is as high as1.5 × 10~(-4).These results raise health concerns over the exposure to arsenic from electronic cigarettes.     

Emergy evaluation and economic analysis of three wetland fish farming systems in Nansi Lake area,China

Emergy and economic methods were used to evaluate and compare three fish production models, i.e., cage fish farming system, pond intensive fish rearing system and semi-natural extensive pond fish rearing system, in Nansi Lake area in China in the year 2007. The goal of this study was to understand the benefits and driving forces of selected fish production models from ecological and economic points of view. The study considered input structure, production efficiency, environmental impacts, economic viability and sustainability. Results show that the main difference among the three production systems was the emergy cost for fish feed associated with their feeding system, i.e., feeding on natural biomass such as plankton and grass or on commercial feedstock. As indicated by EYR, ELR and ESI, it can be clearly shown that the intensive production model with commercial feed is not a sustainable pattern. However, the point is that more environmentally sound patterns do not seem able to provide a competitive net profit in the short run. The intensive pond fish farming system had a net profit of 2.57E+03 $/ha, much higher than 1.27E+03 $/ha for cage fish farming system and slightly higher than 2.37E+03 $/ha for semi-natural fish farming system. With regard to the drivers of local farmer’s decisions, the accessibility of land for the required use and investment ability determine the farmer’s choice of the production model and the scale of operation, while other factors seem to have little effect. Theoretically, the development of environmentally sustainable production patterns, namely water and land conservation measures, greener feed as well as low waste systems is urgently needed, to keep production activities within the carrying capacity of ecosystems. Coupled emergy and economic analyses can provide better insight into the environmental and economic benefits of fish production systems and help solve the problems encountered during policy making.     

Treatment of municipal wastewater using a contact oxidation filtration separation integrated bioreactor

A new contact oxidation filtration separation integrated bioreactor (CFBR) was used to treat municipal wastewater. The CFBR was made up of a biofilm reactor (the upper part of the CFBR) and a gravitational filtration bed (the lower part of the CFBR). Polyacrylonitrile balls (50 mm diameter, 237 m²/m³ specific surface, 90% porosity, and 50.2% packing rate) were filled into the biofilm reactor as biofilm attaching materials and anthracite coal (particle size 1–2 mm, packing density 0.947 g/cm³, non-uniform coefficient (K₈₀ = d₈₀/d₁₀) < 2.0) was placed into the gravitational filtration bed as filter media. At an organic volumetric loading rate of 2.4 kg COD/(m³ d) and an initial filtration velocity of 5 m/h in the CFBR, the average removal efficiencies of COD, ammonia nitrogen, total nitrogen and turbidity were 90.6%, 81.4%, 64.6% and 96.7% respectively, but the treatment process seemed not to be effective in phosphorus removal. The average removal efficiency of total phosphorus was 60.1%. Additionally, the power consumption of the CFBR was less than 0.15 kWh/m³ of wastewater treated, and less than 1.5 kWh/kg BOD₅ removal.     

Strain-based design criteria of pipelines

Traditional pipeline design analysis methods presented in various codes are usually based on limit stress criteria. However, these methods may be inapposite to modern steels, especially for displacement controlled loads such as ground displacement load. Strain limits, including ovalization limit, tensile strain limit and compression strain limit, are compared in this paper based upon various codes and recommendations. In addition, most factors of strain limits are also reviewed respectively.     

Synthesis of tributyl citrate using acid ionic liquid as catalyst

Synthesis of tributyl citrate (TBC) has been studied by using acid functionalized ionic liquid as catalyst. The results indicated that acidic ionic liquids show good catalytic and reusable performance. Under the optimum conditions, using 1-methyl-3-(3-sulfopropyl)-imidazolium hydrogen sulfate as catalyst, the conversion of citric acid was 97%. After easily separated from the products the ionic liquid could be reused 13 times without any disposal, and the conversion of citric acid was not less than 93%. Therefore, an environmental friendly approach for the synthesis of tributyl citrate is provided.     

The drivers for contractors’ green innovation: an industry perspective

In the construction industry, contractors have been facing the challenge to meet the emerging needs related to the reduction of environmental impacts during the construction process. Generally, the commitment of efforts and resources from contractors to meet these needs is motivated by the influence exerted from environmental regulations and stakeholder demands. However, managerial environmental concerns and size of firms also account as key factors affecting the adoption of green construction practices. Therefore, the aim of this research is to identify those factors influencing contractors to adopt green construction practices by using data gathered from a survey. From the results, it has been found that managerial concern is the most important driver for the adoption of green practices. Significant relationships have also been found between government regulations and business size with the adoption of green construction practices. However, there is no significant evidence on the relationship among the adoption of green construction practices with perceived stakeholders’ pressures. The findings from this study are significant in the understanding on the factors of green construction management. This knowledge may contribute to better decision-making towards implementing green construction practices.