Measurement of sulphur gases in ambient air

A gas chromatograph with a flame photometric detector is set up for the direct analysis of COS, H₂S, CS₂, SO₂, CH₃SH, C₂H₅SH in ambient air.Logarithmic transformation is used to counterbalance the non-linear nature of the detector response for the individual sulphur gases. A quality assurance procedure is described to compensate any variation of response during field measurement. The use of Tedlar bags for sampling COS, CS₂, CH₃SH, C₂H₅SH is acceptable despite the general conception that sulphur gases are unstable in Tedlar bags.     

Assessment of personal integrated exposure to fine particulate matter of urban residents in Hong Kong

Metropolitan residents are concerned about their exposure to airborne pollutants. But establishing these exposures is challenging. A compact personal exposure kit (PEK) was developed to evaluate personal integrated exposure (PIE) from time-resolved data to particulate matter with aerodynamic diameter less than 2.5 μm (PM_2.5) in five microenvironments, including office, home, commuting, other indoor activities (other than home and office), and outdoor activities experienced both on weekdays and weekends. The study was conducted in Hong Kong. The PEK measured PM_2.5, reported location and several other factors, stored collected data, as well as reported the data back to the investigators using global system for mobile communication (GSM) telemetry. Generally, PM_2.5 concentrations in office microenvironment were found to be the smallest (13.0 μg/m³), whereas the largest PM_2.5 concentration microenvironments were experienced during outdoor activities (54.4 μg/m³). Participants spent more than 85% of their time indoors, including in offices, homes, and other public indoor venues. On average, 42% and 81% of the time were spent in homes, which contributed 52% and 79% of PIE (during weekdays and weekends, respectively), suggesting that improvement of air quality in homes may reduce overall exposures and indicating the need for actions to mitigate possible public health burdens in Hong Kong. This study also found that various indoor/outdoor microenvironments experienced by urban office workers cannot be accurately represented by general urban air quality data reported from the regulatory monitoring. Such personalized air quality information, especially while in transit or in offices and homes, may provide improved information on population exposures to air pollution.

Implications: A newly developed personal exposure kit (PEK) was used to monitor PM_2.5 exposure of metropolitan citizens in their daily life. Different microenvironments and time durations caused various personal integrated exposure (PIE). The stationary monitoring method for PIE was also compared and evaluated with PEK. Positive protection actions can be taken after understanding the major contribution to PM_2.5 exposure.     

False non-paternity in a family for prenatal diagnosis of β-thalassaemia

Initial screening for the common β-thalassaemia mutations with allele-specific oligonucleo-tide probes in an at-risk family suggested non-paternity. Subsequent DNA fingerprinting of the members proved otherwise. The mother had a codon 41/42 frameshift mutation and the father's defect, determined by direct sequencing of PCR-amplified β gene, was a codon 43 nonsense mutation. In the affected children, the close proximity of these two defects resulted in the absence of a hybridization signal to the normal probe in that region and a wrong assumption of homozygosity for the codon 41/42 mutation. The non-reactivity of the father's amplified DNA to the codon 41/42 thalassaemic probe accounted for the initial wrong conclusion of non-paternity. Since prior screening for β-thalassaemia mutations is done in all prenatal diagnosis programmes and concomitant inheritance of these two defects is relatively common in the Chinese, this ‘artefact’ of false non-paternity is worth noting.     

The effects of male–male contests and female eavesdropping on female mate choice and male mating success in the jumping spider, <Emphasis Type="Italic">Thiania bhamoensis</Emphasis> (Araneae: Salticidae)

In experiments that comprised of three phases (fight, choice, and mating) under “seen” and “unseen” conditions, we examined the effects of the outcomes of male–male contests and female eavesdropping on female mate choice and male mating success in the fighting spider, Thiania bhamoensis (Salticidae). The results revealed female eavesdropping on agonistic interactions. Females that had watched an aggressive interaction showed no distinctive preference for the winner over the loser, but they preferred the loser when they had not observed a fight. Winners, however, achieved a greater mating success than did losers during the mating phase. Gaining access to females was based on the insistence of the winners in courtship in terms of the number of quivers, rather than on the fighting behavior of the males. Hence, the outcome of male–male contests may not be an important determinant of a male’s mating success in T. bhamoensis. Instead, courtship display plays an important role in determining the success of male mating in this species. This study also suggests that female mate preference may not be a good indicator of eventual female mate choice and male mating success. Thus, a causal relationship between female mate preference and male mating success cannot be inferred. Joanna P. Y. Chan, Pei Rong Lau, and Ai Jie Tham contributed equally.     

电化学氧化与厌氧技术联用处理垃圾渗沥水

采用电化学氧化与上流式厌氧污泥床(UASB)结合技术,提出了处理香港垃圾渗沥水的二步法工艺.对含COD和NH₃-N分别为4750mg/L和1310mg/L的垃圾渗沥水,首先进行UASB预处理(消化温度37℃,COD负荷0.78g/(L·d),HRT为6.1d),获得了66%的COD去除率;UASB的出水被引入电化学氧化反应器进行深度处理.在外加Cl 2000mg/L,电流密度为32.3mA/cm²的条件下,经6h的电解间接氧化,COD和NH₃-N的去除率分别达到87%和100%,出水的COD为209mg/L,并且不含NH3-N,此过程的COD电能消耗＜55kW·h/kg.本文讨论了电化学氧化过程中电极反应原理,各实验参数对COD和NH₃-N去除率的影响,以及电能消耗与运行成本评估等.     

Degradation of greenhouse twines derived from natural fibers and biodegradable polymer during composting

Commercial composting operations generally do not accept organic wastes with plastic twines from the greenhouse vegetable industry and the bulk of the waste materials ends up in landfills. The objectives of this paper are to identify environmentally compatible substitutes that could replace the current use of petrochemically derived plastic twines in greenhouse vegetable production, thus diverting them from landfills, and to assess the extent of their degradation via composting. Physical properties of the twines, including linear density, percent weight loss and tensile strength were monitored for the biodegradation tests. A pilot-scale composting trial was conducted in an in-vessel composting system. Results showed that the three biodegradable twine materials (cotton, jute and EcoPLA) could degrade readily in a composting environment within a reasonable time frame. Specifically, at the end of 105 days of composting, 85.3%, 84.8% and 81.1% of weight loss was observed for cotton, jute and EcoPLA, respectively. Furthermore, EcoPLA exhibited a slower decline in tensile strength with time, when compared to jute and cotton.     

Ultrafiltration tests for the reutilization of greenhouse wastewater

Abstract

A lab‐scale experiment was performed using two different pore‐size ultrafiltration membranes to investigate the removal efficiency of Tomato Mosaic Virus (ToMV), retainability of pollutant and nutrients, and flow characteristics. From the experiment, it may be concluded that ultrafiltration can be used effectively to eliminate ToMV. Tests with a 30K pore‐size ultrafiltration membrane achieved 99% virus removal efficiency and a 5K membrane practically removed 100% of the virus in greenhouse wastewater. Nutrient analysis indicated that all the essential nutrients could be retained and re‐utilized.     

Examining the effects of feeling trusted by supervisors in the workplace: A self‐evaluative perspective

Trusting and feeling trusted are related but unique components of a trusting relationship. However, we understand relatively little about the effects of felt trust on work performance and organizational citizenship behavior. From a self‐evaluative perspective, this study argued that when employees perceive that their supervisors trust them, their organization‐based self‐esteem is enhanced, leading them to perform better in the workplace. We tested our hypotheses on a sample of 497 teachers using two trust measures, that is, reliance and disclosure, and found support for them on the basis of the reliance (but not the disclosure) measure. The effect of felt trust especially reliance on the employees' work performances were mediated by their organization‐based self‐esteem. Copyright © 2013 John Wiley & Sons, Ltd.     

Profiles and removal efficiency of polycyclic aromatic hydrocarbons by two different types of sewage treatment plants in Hong Kong

Sewage discharge could be a major source of polycyclic aromatic hydrocarbons(PAHs) in the coastal waters. Stonecutters Island and Shatin Sewage Treatment Works(SCISTW and STSTW)in Hong Kong, adopted chemically enhanced primary treatment and biological treatment,respectively. This study aimed at(1) determining the removal efficiencies of PAHs,(2) comparing the capabilities in removing PAHs, and(3) characterizing the profile of each individual PAHs, in the two sewage treatment plants(STPs). Quantification of 16 PAHs was conducted by a Gas Chromatography. The concentrations of total PAHs decreased gradually along the treatment processes(from 301 ± 255 and 307 ± 217 ng/L to 14.9 ± 12.1 and 63.3 ± 54.1 ng/L in STSTW and SCISTW, respectively). It was noted that STSTW was more capable in removing total PAHs than SCISTW with average total removal efficiency 94.4% ± 4.12% vs. 79.2% ± 7.48%(p 0.05). The removal of PAHs was probably due to sorption in particular matter, confirmed by the higher distribution coefficient of individual and total PAHs in solid samples(dewatered sludge contained92.5% and 74.7% of total PAHs in SCISTW and STSTW, respectively) than liquid samples(final effluent-total contained 7.53% and 25.3% of total PAHs in STSTW and SCISTW, respectively).Despite the impressive capability of STSTW and SCISTW in removing PAHs, there was still a considerable amount of total PAHs(1.85 and 39.3 kg/year, respectively for the two STPs) being discharged into Hong Kong coastal waters, which would be an environmental concern.     

The potential inhalation hazard posed by dioxin contaminated soil.

Mathematical models and field data were used to estimate the airborne concentrations of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) vapor and particulates which could originate from soil containing 100 ppb TCDD. The model of Jury et al. (1983) and the box approach were used to predict the concentration of TCDD vapor from soil. The daily soil temperature was assumed to vary between 20 degrees C and 40 degrees C for six months of the year to account for diurnal warming and cooling of the soil. The depth of contamination was 50 mm. The model predicted average vapor flux rate for TCDD from soil for this temperature profile was 1.5 x 10(-14) mg/sec-cm2. The upper-bound estimates of the TCDD vapor concentration on-site at 40 degrees C and 20 degrees C were 2.5 pg/m3 and 1.8 pg/m3, respectively. Using a recently proposed unit risk value (URV) of 2.9 x 10(-6) (pg/m3)-1 [slope factor = 1.0 x 10(-14) (mg/kg-day)-1], the maximum plausible cancer risk is about 1 x 10(-5). If one accepts the EPA URV of 3.3 x 10(-5) (pg/m3)-1 (slope factor = 1.2 x 10(-13) (mg/kg-day)-1), then the risk is no greater than 1 x 10(4). A maximum TCDD vapor concentration of 0.21 pg/m3 was predicted 100 meters downwind (for summer days). The on-site concentration of TCDD in suspended particulate was estimated to be 1.4 pg/m3 (based on a TSP level of 0.07 mg/m3 from site soil). For persons exposed to vapors and particulates about 100 meters off-site, the exposure was about 10-fold less.(ABSTRACT TRUNCATED AT 250 WORDS)