Ambient air monitoring of PCDD/Fs and co-PCBs in Gyeonggi-do, Korea

We started the monitoring for PCDD/Fs in ambient air and soil in August 2001, and co-PCBs in January 2002. Decreasing of PCDD/Fs and co-PCBs levels in ambient air were observed. The higher PCDD/Fs levels were found in winter and lower in autumn. We found that the industrial incinerators influenced the PCDD/Fs levels in ambient air. In the 2,3,7,8-substituted PCDD/Fs concentration profiles, the three major congeners occupied 67% of the total mass. In case of co-PCBs, PCB#118, #105 and #77 were observed as the main congeners. Five cluster groups discriminated by ratio of four components, O(8)CDD, 1,2,3,4,6,7,8-H(7)CDD, 1,2,3,4,6,7,8-H(7)CDF and O(8)CDF, were obtained from HCA (hierarchical cluster analysis).     

Ultrasound pretreatment of filamentous algal biomass for enhanced biogas production

The filamentous alga Hydrodictyon reticulatum harvested from a bench-scale wastewater treatment pond was used to evaluate biogas production after ultrasound pretreatment. The effects of ultrasound pretreatment at a range of 10–5000 J/mL were tested with harvested H. reticulatum. Cell disruption by ultrasound was successful and showed a higher degree of disintegration at a higher applied energy. The range of 10–5000 J/mL ultrasound was able to disintegrated H. reticulatum and the soluble COD was increased from 250 mg/L to 1000 mg/L at 2500 J/mL. The disintegrated algal biomass was digested for biogas production in batch experiments. Both cumulative gas generation and volatile solids reduction data were obtained during the digestion. Cell disintegration due to ultrasound pretreatment increased the specific biogas production and degradation rates. Using the ultrasound approach, the specific methane production at a dose of 40 J/mL increased up to 384 mL/g-VS fed that was 2.3 times higher than the untreated sample. For disintegrated samples, the volatile solids reduction was greater with increased energy input, and the degradation increased slightly to 67% at a dose of 50 J/mL. The results also indicate that disintegration of the algal cells is the essential step for efficient anaerobic digestion of algal biomass.     

Carbonyl emissions from vehicular exhausts sources in Hong Kong

Vehicular emission (VE) is one of the important anthropogenic sources for airborne carbonyls in urban area. Six types of VE-dominated samples were collected at representative locations in Hong Kong where polluted by a particular fueled type of vehicles, including (i) a gas refilling taxis station (liquefied petroleum gas [LPG] emission); (ii) a light-duty passenger car park (gasoline emission); (iii) a minibus station (diesel emission); (iv) a single-deck-bus depot (diesel emission); (v) a double-deck-bus depot (diesel emission); and (vi) a whole-food market entrance for light- and heavy-duty vehicles (diesel emission). A total of 15 carbonyls in the samples were quantified. Formaldehyde was the most abundant carbonyl among the VE-dominated samples, and its contribution to the total quantified amount on a molar basis ranged from 54.8% to 60.8%. Acetaldehyde and acetone were the next two abundant carbonyls. The carbonyls were quantified at three roadside locations in Hong Kong. The highest concentrations of formaldehyde and acetaldehyde, 22.7 +/- 8.4 and 6.0 +/- 2.8 microg/m3, respectively, were determined in the samples collected at a main transportation gate for goods between Hong Kong and Mainland China. The total quantified carbonyl concentration, 37.9 +/- 9.3 microg/m3, was the highest at an entrance of a cross-harbor tunnel in downtown area. The theoretical carbonyls compositions of the three roadside locations were estimated according to the VE-dominated sample profiles and the statistics on vehicle numbers and types during the sampling period. The measured compositions of formaldehyde were much higher than the theoretical compositions in summer, demonstrating that photochemical reactions significantly contributed to the formaldehyde production in the roadsides.     

Assessing the mechanism of barriers towards green finance and public spending in small and medium enterprises from developed countries

Environmental Science and Pollution Research - Due to their different abilities to improve financial growth and improve social development, small and medium enterprises (SMEs) have been referred to...     

纳氏试剂分光光度法测定水质氨氮不确定度的评估

本文对采用纳氏试剂分光光度法（HJ535-2009）测定水中氨氮的实验过程可能引入的各不确定分量的来源进行了详细的分析,然后对各分量进行评定,对测定不确定度做出评估。得出影响测定结果的几种重要因素。     

Impact of injection system design on ISCO performance with permanganate--mathematical modeling results

In situ chemical oxidation (ISCO) using permanganate (MnO(4)(-)) can be a very effective technique for remediation of soil and groundwater contaminated with chlorinated solvents. However, many ISCO projects are less effective than desired because of poor delivery of the chemical reagents to the treatment zone. In this work, the numerical model RT3D was modified and applied to evaluate the effect of aquifer characteristics and injection system design on contact and treatment efficiency. MnO(4)(-) consumption was simulated assuming the natural oxidant demand (NOD) is composed of a fraction that reacts instantaneously and a fraction that slowly reacts following a 2nd order relationship where NOD consumption rate increases with increasing MnO(4)(-) concentration. MnO(4)(-) consumption by the contaminant was simulated as an instantaneous reaction. Simulation results indicate that the mass of permanganate and volume of water injected has the greatest impact on aquifer contact efficiency and contaminant treatment efficiency. Several small injection events are not expected to increase contact efficiency compared to a single large injection event, and can increase the amount of un-reacted MnO(4)(-) released down-gradient. High groundwater flow velocities can increase the fraction of aquifer contacted. Initial contaminant concentration and contaminant retardation factor have only a minor impact on volume contact efficiency. Aquifer heterogeneity can have both positive and negative impacts on remediation system performance, depending on the injection system design.     

The in vitro effect of selected essential oils on the growth and mycotoxin production of Aspergillus species

The aim of the present study was to assess the antifungal and anti-toxinogenic activity of 15 essential oils (EOs) against three fungi of the genus Aspergillus (A. parasiticus KMi-227-LR, A. parasiticus KMi-220-LR and A. flavus KMi-202-LR). The minimum inhibitory doses (MIDs) of the tested essential oils and their antifungal activity were determined using the micro-atmosphere method. The original commercial essential oil samples of Jasminum officinale L., Thymus vulgaris L., Syzygium aromaticum (L.) Merrill &; Perry, Rosmarinus officinalis L., Ocimum basilicum L., Eucalyptus globulus Labill., Salvia officinalis L., Citrus limon (L.) Burm, Origanum vulgare L., Lavandula angustifolia Mill., Carum carvi L., Citrus sinensis (L.) Osbeck., Zingiber officinalis Rosc., Mentha piperita L. and Cinnamomum zeylanicum Nees. (C. verum J.S.Presl.) were produced in Slovakia (Calendula a.s., Nová ?ubovňa, Slovakia). All essential oils exhibited activity against all tested strains of fungi. After 14 days of incubation, A. flavus (KMi-202-LR) showed the highest susceptibility with a growth inhibition percentage (GIP) of 18.70% to C. limon and 5.92% to C. sinensis, while A. parasiticus (KMi-220-LR) exhibited a GIP of 20.56% to J. officinale. The minimum inhibitory doses (MIDs) of EOs with the most significant activity were recorded. The best antifungal activity, using the micro-atmosphere method was found in S. aromaticum with an MID of 62.5 μL L^?1 air, T. vulgaris (MID of 62.5 μL L^?1 air) and O. vulgare (MID of 31.5 μL L^?1 air) against all tested strains. Mycotoxin production of the tested strains was evaluated by the thin layer chromatography (TLC) method. Mycotoxin production of AFB₁ and AFG₁ was inhibited following all treatments with C. carvi, R. officinale and S. officinale, Eucalyptus globulus L. and O. basilicum L. Essential oils exhibited a potential inhibition activity against toxic fungi, although, these affected only the production of AFB₁.     

Mental health outcomes of job stress among Chinese teachers: role of stress resource factors and burnout

This study examined the mental health outcomes of job stress among Chinese teachers in Hong Kong. A total of 269 Chinese teachers participated in Study 1 which provided cross‐sectional data regarding the associations among stress resource factors, burnout, and negative mental health. Study 2 was a six‐month longitudinal study which aimed to establish the direction of the associations among the hypothesized variables across two time points with a separate sample of 61 Chinese secondary school teachers. Results of the structural equation modelling analyses on the cross‐sectional data at T1 showed that stress resource factors of self‐efficacy and proactive attitude were negatively related to burnout, which in turn had a direct effect on negative mental health. Stress resource factors were also directly linked to mental health status of teachers. Results of similar analyses on the longitudinal data at T2 further indicated that burnout at T1 had a direct impact on burnout at T2, which in turn had a direct effect on negative mental health at T2. Findings and limitations of the study were discussed. Copyright © 2001 John Wiley & Sons, Ltd.