The partitioning and modelling of pesticide parathion in a surfactant-assisted soil-washing system

Soil sorption of organic pollutants has long been a problematic in the soil washing process because of its durability and low water solubility. This paper discussed the soil washing phenomena over a wide range of parathion concentrations and several soil samples at various fractions of organic content (foc) levels. When parathion dosage is set below the water solubility, washing performance is stable for surfactant concentrations above critical micelle concentration (cmc) and it is observed that more than 90% of parathion can be washed out when dosage is five times lower than the solubility limit. However, such trends change when non-aqueous phase liquids (NAPL) is present in the system. Parathion extraction depends very much on the surfactant dosage but is not affected by the levels of foc in the system. In between the extreme parathion dosage, a two-stage pattern is observed in these boundary regions. Washing performance is first increased with additional surfactant, but the increase slows down gradually since the sorption sites are believed to be saturated by the huge amount of surfactant in the system. A mathematical model has included foc to demonstrate such behavior and this can be used as a prediction for extraction.     

The development of low cost adsorbents from clay and waste materials: a review

Increased energy consumption due to industrial growth has increased the levels of carbon dioxide (CO₂) emission being released into the atmosphere. CO₂ emission is a type of greenhouse gas which is a major cause of global warming. Since the issue of CO₂ emissions has drawn much attention in recent years, the development of CO₂ capture technology has become a necessity. Although CO₂ adsorbents are still at the early development stage, it has been suggested that CO₂ adsorbents are the most effective technology in controlling CO₂ emissions. Solid adsorbents have great potential as an alternative method to conventional adsorbents in adsorbing CO₂. In this paper, low cost adsorbents including activated carbon, zeolites, mesoporous silica and clays are discussed in terms of adsorbent preparation methods and CO₂ adsorption capacity. The low cost adsorbents are mainly derived from waste materials such as fly ash, steel slag, red mud, bagasses wastes and wood wastes. Besides that, natural resources such as clays have also been applied as low cost CO₂ adsorbents. Surface modifications have also been applied to the low cost adsorbents, including metal ion exchange and amine impregnation to enhance CO₂ adsorption capacity. In the last section, the current status of CO₂ adsorbents is summarized and future trends are discussed briefly to predict the potential materials which can be applied as CO₂ adsorbents.     

Environmental attitudes and behaviour of secondary school students in Hong Kong

Summary A postal survey of 992 secondary students in Hong Kong using the Weigel and Weigel environmental concern scale was conducted to investigate their environmental attitudes which were reflected in a readiness to engage in various pro-environmental behaviours including paper recycling at school and at home and the use of less tissues and plastic bags. The results indicated that students' expressed great concern about the environment and exhibited a strong willingness to participate in pro-environmental behaviour. However, students' overoptimism towards technological development and the perceived importance of the benefits of modern consumer goods were two major factors that contradicted their concern for environment. The Pearson correlation coefficient between environmental concern and comprehensive behavioural intention was strong and positive (0.52). Television and school were cited as major sources of environmental information. Mass media were more important than personal media in the dissemination of environmental information. Female students, older students and students living in private housing held more positive environmental attitudes and were more willing to engage in pro-environmental behaviour. Factor analysis indicated that the environmental concern scale was composed of two factors, personal sacrifice and optimism/issue.Ms Kara K.W. Chan is currently an assistant professor in the Department of Communication Studies, School of Communication, Hong Kong Baptist University. She has previously worked in the advertising and public relations profession and as a statistician for the Hong Kong Government. She is actively involved in research on Hong Kong and China's mass communication and advertising industry, consumer behaviour and the promotion of pro-environmental behaviour.     

Codisposal of municipal refuse, sewage sludge and marine dredgings for methane production

As marine disposal of sewage sludge and dredged sediments may impose serious adverse effects to marine ecosystems, landfilling seems to be the most feasible method for the final disposal of these wastes. A batch experiment was conducted to study waste degradation and gas production after sewage sludge and marine dredgings were mixed with municipal refuse at 13 different ratios for 36 days. The addition of sludge and dredgings to municipal refuse enhanced gas production, compared with the degradation of refuse or sludge alone. A proper mixing ratio of wastes can also shorten the time to reach the final phase of anaerobiosis. The highest gas production was obtained from the ratio of 75-20-5 (refuse-sludge-dredgings) (wet weight basis). Its average daily gas production rate was 1.42 l kg(-1) waste mixture; methane content was 68.3%. The results indicated that codisposal of the three wastes would be beneficial for energy recovery from landfill gas.     

A systems approach for the development of a sustainable community--the application of the sensitivity model (SM)

Corresponding to the concept of 'Think globally, act locally and plan regionally' of sustainable development, this paper discusses the approach of planning a sustainable community in terms of systems thinking. We apply a systems tool, the sensitivity model (SM), to build a model of the development of the community of Ping-Ding, located adjacent to the Yang-Ming-Shan National Park, Taiwan. The major issue in the development of Ping-Ding is the conflict between environmental conservation and the development of a local tourism industry. With the involvement of local residents, planners, and interest groups, a system model of 26 variables was defined to identify characteristics of Ping-Ding through pattern recognition. Two scenarios concerning the sustainable development of Ping-Ding are simulated with interlinked feedbacks from variables. The results of the analysis indicate that the development of Ping-Ding would be better served by the planning of agriculture and the tourism industry. The advantages and shortfalls of applying SM in the current planning environment of Taiwan are also discussed to conclude this paper.     

Institutional Arrangements for Flood Hazards in Malaysia: An Evaluation Using the Criteria Approach

Institutional aspects of flood hazards significantly affect their outcomes in Malaysia. Institutional arrangements to deal with floods include: legislative activity, organisational structures, attitudes and sub-culture, and policies and instruments. When assessed in terms of four specific criteria, institutional aspects of flood hazards are found to be largely inadequate. Disaster reduction programmes are over-dependent on a reactive approach based largely on technology and not even aimed at floods specifically. Structual flood reduction measures are the predominant management tool and, although the importance of non-structural measures is recognised, thus far they have been under-employed. Current laws and regulations with regard to flood management are also insufficient and both the financial and human resources of flood hazard organisations are generally found to be wanting. Finally, economic efficiency, equity and public accountability issues are not adequately addressed by institutional arrangements for flood hazards.     

Heavy Metal Contents and Magnetic Properties of Playground Dust in Hong Kong

This study examined the levels of seven heavy metals (namelyzinc, copper, cadmium, chromium, lead, manganese and iron) andtheir associations with magnetic properties in playground dustof Hong Kong. Results showed that the playground dust containedhigh concentrations of Zn (mean = 1883 g g^-1), Cu(mean = 143 g g^-1) and Cr (mean = 263 g g^-1).Qualitative examination of dust samples under microscope indicated local traffic as one of the important pollutant sources. Magnetic measurements indicated that these anthropogenicpollutants mainly consisted of coarse-grained multidomain (MD) ferrimagnetic minerals. Superparamagnetic (SP), stable single domain (SSD) ferrimagnetic grains and non-ferrimagnetic mineralswere present in relatively small amounts. Significant correlations between heavy metals and various magnetic parametersindicated a strong affinity of heavy metals to magnetic minerals hence pointed out the potential of magnetic properties for simpleand rapid proxy indications of heavy metal pollution in playground dust.     

A Multi-Channel Continuous Water Toxicity Monitoring System: Its Evaluation and Application to Water Discharged from a Power Plant

A multi-channel continuous water toxicity monitoring system was, after confirming the systems' performance, implemented to samples of water discharged from power plants to detect and classify their toxicity using several recombinant bioluminescent bacteria. Each channel of the system is composed of a series of two mini-bioreactors to enable a continuous operation, i.e., without system interruption due to highly toxic samples. A different recombinant bacterial strain was present in each channel: DPD2540 (fabA::lux CDABE), DPD2794 (recA::luxCDABE), and TV1061 (grpE::luxCDABE), which are induced by cell membrane-, DNA-, and protein-damaging agents, respectively. GC2 (lac::luxCDABE) is a constitutive strain, whose bioluminescence is reduced by an increase in cellular toxicity. Phenol and mitomycin C (MMC) were used for evaluating the system's performance to detect toxic chemicals. These samples were injected into the second mini-bioreactor according to a step or bell-curve manner. The field samples used in this study were obtained from the water discharged from two different power plants in Korea – from a nuclear power plant and a thermo-electronic power plant, and were injected into the second mini-bioreactor to initiate the toxicity test. Each channel showed specific bioluminescent (BL) response profiles due to the toxic compounds present in the water samples. Comparing the BL signals between the standard toxic chemical samples and discharged water samples, the equivalent toxicity of the field water could be estimated. Finally, it was proved that this novel continuous toxicity monitoring system can be used as an alternative tool for the quick monitoring and control of water quality, as well as aid in the setting up of a new monitoring strategy to protect the source of tap water and in the prevention of polluted water discharge.