Reductive dechlorination for remediation of polychlorinated biphenyls

Technologies such as thermal, oxidative, reductive, and microbial methods for the remediation of polychlorinated biphenyls (PCBs) have previously been reviewed. Based on energy consumption, formation of PCDD/F, and remediation efficiency, reductive methods have emerged as being advantageous for remediation of PCBs. However, many new developments in this field have not been systematically reviewed. Therefore, reductive technologies published in the last decade related to remediation of PCBs will be reviewed here. Three categories, including catalytic hydrodechlorination with H₂, Fe-based reductive dechlorination, and other reductive dechlorination methods (e.g., hydrogen-transfer dechlorination, base-catalyzed dechlorination, and sodium dispersion) are specifically reviewed. In addition, the advantages of each remediation technology are discussed. In this review, 108 articles are referenced.     

Removing perfluorooctane sulfonate and perfluorooctanoic acid from solid matrices, paper, fabrics, and sand by mineral acid suppression and supercritical carbon dioxide extraction

The removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from solid matrices has received considerable attention because of the environmental persistence, bioaccumulation, and potential toxicity of these compounds. This study presents a simple method using concentrated HNO₃ as a suppression agent, and methanol-modified supercritical carbon dioxide (Sc-CO₂) extraction for removing PFOS and PFOA from solid matrices. The optimal conditions were 16 M HNO₃ and 20% (v/v) methanol containing Sc-CO₂, under a pressure of 20.3 MPa and a temperature of 50 °C. Extraction time was set at 70 min (40 min for static and 30 min for dynamic extraction). PFOA and PFOS were identified and quantitated by liquid chromatography/mass spectrometry. The extraction efficiencies (with double extractions) were close to 100% for PFOA and 80% for PFOS for both paper and fabric matrices. The extraction efficiencies for sand were approximately 77% for PFOA and 59% for PFOS. The results show that this method is accurate, and effective, and that it provides a promising and convenient approach to remediate the environment of hazardous PFOA and PFOS contamination.     

Decoupling analysis of water consumption and economic development of arid and semiarid regions in Northwest China

The contradiction between China's economic development, its need for resources and the protection of the environment is ctitical. Scarce water resources have resulted in a considerable bottleneck restricting the economic development of water-deficient areas. An objective evaluation of the decoupling state of water consumption and economic development has become an important indicator of regional economic sustainable development. Based on panel data from 2000 to 2017 for six provinces in the arid and semiarid regions of Northwest China, the Logarithmic Mean Divisia Index method is employed to decompose the factors of the decoupling index and establish a decoupling relationship model between water consumption and economic development. The reasons that affect the decoupling state of water resource utilization and economic development are herein discussed, and the stability of the decoupling trend is analysed. Based on the overall regional trend, the decoupling state of the arid and semiarid regions in Northwest China improved from weak to strong, but the high decoupling stability index varied among the provinces. The intensity and structure were promotional factors for decoupling water consumption and economic development, and the contribution rate of the intensity factor was higher than that of the structure factor. Income and population were inhibiting factors for decoupling water consumption and economic development, and the contribution rate of the income factor was higher than that of the population factor. Based on these results, corresponding policy recommendations are provided.     

Distributive and procedural justice as predictors of employee outcomes in Hong Kong

This study examines the extent to which employee judgments about distributive and procedural justice predict job satisfaction, intent to stay and evaluation of supervision in Hong Kong. Distributive and procedural justice each plays a role in determining work outcomes of Hong Kong employees. However, some effects of these justice variables differ from results of previous studies in the United States (U.S.). First, in previous U.S. studies, procedural justice moderates the relationship of distributive justice with evaluation of supervision, but not with job satisfaction or intent to stay. For Hong Kong employees, procedural justice moderates the effects of distributive justice on job satisfaction and intent to stay, but not on evaluation of supervision. Second, previous U.S. studies have shown that procedural justice has a larger effect on work outcomes for women, while distributive justice has larger effects on outcomes for men. For Hong Kong employees, the effects of procedural and distributive justice are about the same for men and women. Differences in the effects of distributive and procedural justice between Hong Kong and the U.S. may reflect cultural dimensions, such as collectivism/individualism and power distance, as well as the relative availability of rewards for women in the work force. Practical implications and future research directions are discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Effect of metal chlorides on thermal degradation of (waste) polycarbonate

In this study, we investigated how to treat (waste) polycarbonate efficiently to reduce its degraded residue. The study was carried out in an isothermal reactor under continuous nitrogen flow at atmospheric pressure to pyrolyze polycarbonate (PC) alone and in the presence of metal chloride. Some metal chlorides were shown to be catalytic active for the degradation of PC at 400 degrees C, which increased degradation conversion from 8.5% to more than 58.3%. Among those active metal chlorides, ZnCl2 and SnCl2 can produce higher liquid product yields. Effects such as particle size of PC, temperature, the weight ratio of metal chloride/PC, and degradation time on the degradation conversion of PC without and with these two most active metal chlorides were studied. Results of the liquid product analysis by GC/MS demonstrated the product composition of PC degradation over the metal chlorides is much simpler than that of degradation alone. The main liquid product is phenol, p-isopropylphenol, diphenyl carbonate, and bisphenol A for all cases.     

Sludge-grown algae for culturing aquatic organisms: Part I. Algal growth in sludge extracts

This project is aimed at studying the feasibility of using sewage sludge to prepare culture media for microalgae (Chlorella-HKBU) and the use of the sludge-grown algae as a feed for some aquatic organisms. Part I of the project included results on preparing sludge extracts and their use on algal culture. By comparing two culturing techniques, aeration and shaking, it was noted that both lag and log phases were shortened in the aeration system. A subsequent experiment noted that algal growth subject to aeration rates of 1.0 and 1.5 liters/min had similar lag and log phases. In addition, both aeration rates had a significantly higher (P < 0.05) final cell density than that of 0.5 liters/min. A detailed study on the variation of growth conditions on the algal growth was done. The results indicated that pH values of all the cultures declined below 5 at day 12. The removal rates of ammonia N ranged from 62% to 70%. The sludge-grown algae contained a rather substantial amount of heavy metals (µg/g): Zn 289–581, Cu 443–682, Ni 310–963, Mn 96–126, Cr 25–118, and Fe 438–653. This implied that the rather high levels of heavy metals may impose adverse effects on higher trophic organisms.     

Sedimentary Pigments and Organic Matter in Relation to Benthic Fauna in the Tan-Shui Estuary,Taiwan

The benthic ecological structure of the Tan-Shui estuary, Taiwan is changed due to long term effects of dumping of urban wastewater and of engineering actions. to monitor these changes, we sampled and analyzed benthos and sediment from 12 stations on the estuary.

The composition of the dominant species of benthos varied seasonally, with molluscan and crustacean species having greater numbers and higher frequencies of occurrence than other species. the dominant taxa during winter were Nassarius sp. and Maldanidae at two stations. Analysis using Simpson's index and Shannon's index showed the benthic community varied more in coastal areas than in offshore areas.

Physicochemical analysis showed that most of the Tan-Shui estuary consisted of sandy sediment. the variations in concentrations of organic carbon and total nitrogen at each station were small. Although the concentrations of chlorophyll-a and carotenoid at all stations were generally low, the two stations had the highest concentrations, and we concluded that the concentration of pigments in these sediments was related to the abundance of benthos. the community structure of the benthos reflected the characteristics of the sediments, and benthic species exhibited selection of and adaptation to specific sedimentary environments.     

The role of black carbon as a catalyst for environmental redox transformation

Black carbon (BC) is an important class of geosorbents that control the fate and transport of organic pollutants in soil and sediment. We previously demonstrated a new role of BC as an electron transfer mediator in the abiotic reduction of nitroaromatic and nitramine compounds by Oh and Chiu (Environ Sci Technol 43:6983-6988, 2009). We proposed that BC can catalyze the reduction of nitro compounds because it contains microscopic graphitic (graphene) domains, which facilitate both sorption and electron transfer. In this study, we assessed the ability of different types of BC--graphite, activated carbon, and diesel soot--to mediate the reduction of 2,4-dinitrotoluene (DNT) and 2,4-dibromophenol (DBP) by H(2)S. All three types of BC enhanced DNT and DBP reduction. H(2)S supported BC-mediated reduction, as was observed previously with a thiol reductant. The results suggest that BC may influence the fate of organic pollutants in reducing subsurface environments through redox transformation in addition to sorption.     

Differential timing of larval starvation effects on filtration rate and growth in juvenile Crepidula onyx

This study demonstrates that the timing of larval starvation did not only determine the larval quality (shell length, lipid content, and RNA:DNA ratio) and the juvenile performance (growth and filtration rates), but also determine how the latent effects of larval starvation were mediated in Crepidula onyx. The juveniles developed from larvae that had experienced starvation in the first two days of larval life had reduced growth and lower filtration rates than those developed from larvae that had not been starved. Lower filtration rates explained the observed latent effects of early larval starvation on reduced juvenile growth. Starvation late in larval life caused a reduction in shell length, lipid content, and RNA:DNA ratio of larvae at metamorphosis; juveniles developed from these larvae performed poorly in terms of growth in shell length and total organic carbon content because of “depletion of energy reserves” at metamorphosis. Results of this study indicate that even exposure to the same kind of larval stress (starvation) for the same period of time (2 days) can cause different juvenile responses through different mechanisms if larvae are exposed to the stress at different stages of the larval life.     

A survey of international urban search-and-rescue teams following the Ji Ji earthquake

On 21 September 1999, the Ji Ji earthquake killed 2,347 people. In the immediate aftermath the international community, mobilised rapidly and sent urban search-and-rescue (US&R) teams to the scene. This paper will present an annotated survey of the expertise and standard of equipment of international US&R teams following that earthquake which could serve as a blueprint for the establishment of US&R teams elsewhere at risk from earthquakes.