Street dusts collected from 20 locations in the Chang-Zhu-Tan (Changsha, Zhuzhou, and Xiangtan) region, Hunan, China, in May to July 2006, were investigated for sources of polycylic aromatic hydrocarbons (PAHs). The individual PAH concentrations were in the range of 10–4316 ng g?1, and ∑PAHs16 levels were in the range of 3,515–24,488 ng g?1, with a mean of 8,760 ng g?1. The high-molecular-weight PAHs (four to six rings), ranging from 47.51 to 82.11 %, with a mean of 74.79 %, were the dominant PAH compounds in almost all of the dusts. The isomer ratios suggested a rather uniform mixture of coal combustion and petroleum PAH sources. Factor analysis and multiple linear regression analysis indicate that the main sources of the 16 PAHs were coal combustion/vehicle exhaust, coking/petroleum, and plant combustion, with contribution rates of 50.9, 35.01, and 14.08, respectively. The spatial distributions of PAH concentrations were significantly related to the distribution of industries, traffic circulation, and farmland in this region. 相似文献
Environmental Science and Pollution Research - Nostoc flagelliforme is a remarkable drought-resistant terrestrial cyanobacterium whose exopolysaccharides (EPS) have been found to exert important... 相似文献
A novel Fe3O4/cellulose–polyvinyl alcohol (PVA) aerogel was successfully synthesized by an eco-friendly and facile method in this work. Cellulose/PVA matrix was prepared through an environmental friendly physical cross-linking process and further in-situ decorated with Fe3O4. Series of Fe3O4 decorated aerogels were prepared and the effects of Fe3O4 nanoparticles (NPs) on the aerogels were systematic investigated. As-prepared aerogels exhibited desirable properties including nanostructure, relatively high porosity, improved mechanical and superparamagnetism. The TEM results showed that Fe3O4 NPs were integrated in the three-dimensional matrix of cellulose/PVA with a diameter of 9–12 nm. Furthermore, the mechanical strength of the aerogels was significantly enhanced after the introduction of Fe3O4 NPs. Meanwhile, the obtained Fe3O4/cellulose/PVA aerogel exhibited excellent adsorption performance toward methyl blue dye, and can be reused through fenton-like catalysts oxidative degradation of organic dye in H2O2 solution. Therefore, they will have a great potential application as eco-friendly and economical adsorbents. 相似文献
Transport sector contributed numerous carbon emissions in China. It is important to promote low-carbon bicycle-sharing using in China. This paper aims to analyze the influencing factors of the satisfaction and engagement of bicycle-sharing in China. An extended model of customer satisfaction is established, which considers both customer satisfaction theory and customer engagement theory. We explore the different effect of convenience, health, safety, and facility on satisfaction of bicycle-sharing using. We also explore the role of satisfaction on three different dimensions of engagement: enthusiasm, participation, and social interaction. Multi-group structure equation model is employed to explore the different roles of gender on the determinants of satisfaction and engagement of bicycle-sharing using. The findings reveal that facilities had the larger effect on satisfaction of bicycle-sharing using than safety and health for male. Safety had the largest influence on satisfaction of bicycle-sharing using for female, followed by facility, convenience, and health.
• Nano zero-valent manganese (nZVMn, Mn0) is synthesized via borohydrides reduction.• Mn0 combined with persulfate/hypochlorite is effective for Tl removal at pH 6-12.• Mn0 can activate persulfate to form hydroxyl and sulfate radicals.• Oxidation-induced precipitation and surface complexation contribute to Tl removal.• Combined Mn0-oxidants process is promising in the environmental field. Nano zero-valent manganese (nZVMn, Mn0) was prepared through a borohydride reduction method and coupled with different oxidants (persulfate (S2O82−), hypochlorite (ClO−), or hydrogen peroxide (H2O2)) to remove thallium (Tl) from wastewater. The surface of Mn0 was readily oxidized to form a core-shell composite (MnOx@Mn0), which consists of Mn0 as the inner core and MnOx (MnO, Mn2O3, and Mn3O4) as the outer layer. When Mn0 was added alone, effective Tl(I) removal was achieved at high pH levels (>12). The Mn0-H2O2 system was only effective in Tl(I) removal at high pH (>12), while the Mn0-S2O82− or Mn0-ClO− system had excellent Tl(I) removal (>96%) over a broad pH range (4–12). The Mn0-S2O82− oxidation system provided the best resistance to interference from an external organic matrix. The isotherm of Tl(I) removal through the Mn0-S2O82− system followed the Freundlich model. The Mn0 nanomaterials can activate persulfate to produce sulfate radicals and hydroxyl radicals. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that oxidation-induced precipitation, surface adsorption, and electrostatic attraction are the main mechanisms for Tl(I) removal resulting from the combination of Mn0 and oxidants. Mn0 coupled with S2O82−/ClO− is a novel and effective technique for Tl(I) removal, and its application in other fields is worthy of further investigation. 相似文献
Over the past 10 years, there has been an increased recognition that matrix diffusion processes are a significant factor controlling the success of groundwater remediation. New field techniques and modeling tools have, consequently, been developed to understand how contaminants diffuse into and then out of low‐permeability (“low‐k”) zones and assess the resulting impact on groundwater quality. Matrix diffusion, in turn, is driven by one key factor: geologic heterogeneity. The importance of heterogeneity is being emphasized in the groundwater field by general rules of thumb such as “90% of the mass flux occurs in 10%‐20% of the cross‐sectional area” and conceptual models that show most of the groundwater flow occurs through the aquifer's “mobile porosity” which just a small fraction of commonly used effective porosity values (between 0.02 and 0.10 for mobile porosity vs. 0.25 for effective porosity). For this study, 141 boring logs from 43 groundwater remediation sites were evaluated to develop an empirically based estimate of the groundwater flow versus aquifer cross‐sectional area to confirm or reject the general flow versus area rules of thumb. This study indicated that at these 43 sites, an average of 30% of the cross‐sectional area carried 90% of the groundwater flow. Our flow‐only analysis does provide moderate (but not confirmatory) support for the “mobile porosity” concept with an estimated representative mobile porosity value of about 0.11 at the 43 sites. 相似文献