Mapping, monitoring, and modelling of hazardous waste sites

Management of the industrial nations' hazardous waste is a current and exponentially increasing, global threatening situation. Improved environmental information must be obtained and managed concerning the current status, temporal dynamics and potential future status of these critical sites. To test the application of spatial environmental techniques to the problem of hazardous waste sites, as Superfund (CERCLA) test site was chosen in an industrial/urban valley experiencing severe TCE, PCE, and CTC ground water contamination. A paradigm is presented for investigating spatial/environmental tools available for the mapping, monitoring and modelling of the environment and its toxic contaminated plumes. This model incorporates a range of technical issues concerning the collection of data as augmented by remotely sensed tools, the format and storage of data utilizing geographic information systems, and the analysis and modelling of environment through the use of advance GIS analysis algorithms and geophysic models of hydrologic transport including statistical surface generation. This spatial based approach is evaluated against the current government/industry standards of operations. Advantages and lessons learned of the spatial approach are discussed.

What was behind the bark? : An assessment of decay among urban Tilia, Betula and Acer trees felled as hazardous in the Helsinki City area

Old trees growing in urban environments are often felled due to symptoms of mechanical defects that could be hazardous to people and property. The decisions concerning these removals are justified by risk assessments carried out by tree care professionals. The major motivation for this study was to determine the most common profiles of potential hazard characteristics for the three most common urban tree genera in Helsinki City: Tilia, Betula and Acer, and in this way improve management practices and protection of old amenity trees. For this research, material from approximately 250 urban trees was collected in cooperation with the City of Helsinki Public Works Department during 2001 - 2004. From the total number of trees sampled, approximately 70% were defined as hazardous. The tree species had characteristic features as potential hazard profiles. For Tilia trees, hollowed heartwood with low fungal activity and advanced decay caused by Ganoderma lipsiense were the two most common profiles. In Betula spp., the primary reason for tree removal was usually lowered amenity value in terms of decline of the crown. Internal cracks, most often due to weak fork formation, were common causes of potential failure in Acer spp. Decay caused by Rigidoporus populinus often increased the risk of stem breakage in these Acer trees. Of the decay fungi observed, G. lipsiense was most often the reason for the increased risk of stem collapse. Other fungi that also caused extensive decay were R. populinus, Inonotus obliquus, Kretzschmaria deusta and Phellinus igniarius. The most common decay fungi in terms of incidence were Pholiota spp., but decay caused by these species did not have a high potential for causing stem breakage, because it rarely extended to the cambium. The various evaluations used in the study suggested contradictions in felling decisions based on trees displaying different stages of decay. For protection of old urban trees, it is crucial to develop monitoring methods so that tree care professionals could better analyse the rate of decay progression towards the sapwood and separate those trees with decreasing amounts of sound wood from those with decay that is restricted to the heartwood area.

Caution, helping may be hazardous: Client abuse, threats and assaults

The shooting of a social worker by a client on the Gold Coast in 1991 graphically illustrated the issue of physical assaults and violence by service users against social workers. In this article we look at the incidence of physical assault, threats of violence, abuse of agency property and verbal abuse to social and other welfare workers by clients, using data from a survey in Melbourne. We then look at probable causes of menacing behaviour, such as issues involved in work with involuntary clients' and we discuss options for preventing and coping with violence and abuse in the welfare work place.

THE FORMATION MECHANISM OF THE VITRIFIED SLAG IN A PLASMA ARC REACTOR FOR HAZARDOUS WASTE TREATMENT

Various hazardous wastes with additives have been vitrified to investigate the formation mechanism of the glassy slag by a 30 kW DC plasma-arc reactor developed by the Institute of Mechanics, Chinese Academy of Sciences. The average temperature in the reaction area is controlled at 1500°C. The chemical compositions of three sorts of fly ashes are analyzed by XRF (X-Ray Fluorescence). Fly ashes with vitrifying additives can be vitrified to form glassy slag, which show that the ratio of the whole oxygen ions to the whole network former ions in glass (R) is appropriate in the range of 2~3 to form durable vitrified slag. In this experiment, the arc power is controlled below 5 kW to inhibit waste evaporation. To enhance the effects of heat transfer to wastes, ferrous powder has been added into the graphite crucible, which aggregates as ingot below the molten silicate after vitrification. The slag fails to form glass if the quenching rate is less than 1 K/min. Therefore, the slag will break into small chips due to the sharp quenching rate, which is more than 100 K/sec.