Management of incinerator residues in Flanders (Belgium) and in neighbouring countries. A comparison

This paper covers the Flemish legislative tools concerning the management of bottom ash, fly ash and APC residue from municipal waste incinerators, with respect to their contamination with heavy metals. The situation in Flanders is compared to the one in the Walloon region, The Netherlands, Germany and France. Waste management in the countries considered differs on the level of available management options, of leaching tests and of limit values. To make an indicative comparison of leaching tests and limit values in the different countries, leaching tests were carried out on bottom ash and fly ash, and the results are compared to the relevant limit values for recycling and landfilling of the different countries. The comparison of legislations as well as the leaching results show that discrepancies in waste management between the different regions and countries exist. Recently, European limit values for landfilling became available. European legislation on recycling, however, has not been developed and urgently needs to be considered and drafted as the market for recycling can be expanding rapidly.     

Monitoring Long-term Trends in Sulfate and Ammonium in US Precipitation: Results from the National Atmospheric Deposition Program/National Trends Network

Data from the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) indicate significant changes have occurred in precipitation chemistry and the chemical climate in the United States (US). A Seasonal Kendall Trend (SKT) analysis shows statistically significant increases in precipitation ammonium concentrations at 64% of 159 continental US NADP/NTN sites evaluated from Winter 1985 to Fall 2004 (Dec. 1984 – Nov. 2004). Sulfate decreases were widespread, with an SKT analysis indicating statistically significant decreases at 89% of sites evaluated. Ratios of chemical equivalent concentrations of ammonium to sulfate in precipitation have risen to the extent that ammonium now exceeds sulfate over more than half of the continental U.S. on a precipitation-weighted-mean annual basis. These trends in the concentrations of ammonium, sulfate, and other species have been accompanied by significant decreases in the frequency of acidic precipitation (pH < 5.0) in the last decade.     

Public attitudes to nuclear energy: Salience and anxiety

During the last decade there has been a significant increase in public concern about nuclear energy. This paper presents a brief overview of trends and developments in public opinion since the late 1970s. One possible reason for this increased concern is the public's perception of risks. Research has shown a considerable divergence in public and expert assessment of the risks associated with nuclear energy. It will be argued that qualitative aspects of these risks play a crucial role in the public's perception of nuclear energy, and that reactions such as fear and anxiety are the major determinants of attitudes to the building of new nuclear power stations in one's neighbourhood. It is also clear, however, that differences in the perception of these risks do not embrace all the relevant aspects of public acceptance of nuclear energy. Public reaction is also related to more general values and beliefs, and the issue of nuclear energy is firmly embedded in a much wider moral and political domain.     

Ecological planning proposal for Kruger National Park

This article discusses an application of the ecological planning model proposed by Van Riet and Cooks. The various steps outlined in this model have been applied to Kruger National Park in South Africa. The natural features of Kruger National Park, which form the basis of such an ecological planning exercise and from which the various land use categories, values, and zoning classes can be determined, are discussed in detail. The suitability of each of the various features is analyzed and a final zoning proposal for Kruger National Park is suggested. Furthermore a method for selecting a site for a new camp is illustrated by referring to the site for the new Mopane rest camp which is now under construction in the Kruger National Park. The conclusion is reached that the proposed ecological planning model can be used successfully in planning conservation areas such as Kruger National Park and for the selection of the most desirable sites for the establishment of new rest camps. Its suitability as a practical model in such planning exercises is proven by the fact that the siting proposals of two new camps based on this model have been accepted by the National Parks Board, the controlling body of Kruger National Park.     

Controlling substance flows: The case of chlorine

The contribution of chlorinated hydrocarbons (CHCs) to environmental problems in the Netherlands is discussed in an economic context. The economic interactions within the chlorine market, including the link to caustic soda production, are described, and PVC is taken as a case study. Key policy options are evaluated in terms of their potential for environmental improvement. It appears that 95% of CHC emissions causing environmental problems are due to dissipative applications. With respect to the specific problems of ozone depletion and global warming, only a small group of compounds is responsible for most of the impact. Moreover, economic interactions within the group of CHCs can strongly influence the net effect of environmental policy measures. Policies aimed at a reducing volume output of certain specific groups of CHCs will inevitably lead to trade-offs between environmental problems. The environmental impact of a hypothetical ban on CHCs is discussed in relation to the use of PVC as a sink for chlorine. Both these options appear to have drawbacks. Moreover, no absolute conclusion can be drawn until the environmental impact of CHC substitutes is known.     

Ecological design criteria for a sustainable Canadian society

Summary The purpose of this paper is to develop specific ecological design criteria for a sustainable Canadian society. Ecological design criteria complement socio-political ones which have also been developed by the Sustainable Society Project at the University of Waterloo. The criteria derive from an evaluation of the major areas of human activity and interaction with the natural environment in light of our knowledge of ecological systems and resource management. The criteria, like the Sustainable Society Project as a whole, are an attempt to suggest needed, feasible, medium to long-term changes in human activities to comply with the ecological and socio-political limits and constraints that must be recognized in order to achieve societal sustainability. The specific design criteria identified here are not the only ones possible, desirable, or necessary — a complete and certain list is inherently impossible. But the design criteria developed here are illustrative of the kinds of changes that are necessary to achieve sustainability.Dr D. Scott Slocombe is Assistant Professor in the Department of Geography, and Co-Director of the Cold Regions Research Centre, Wilfrid Laurier University. His principal research interests include ecosystem and regional planning, and management for sustainability.Caroline Van Bers was Project Manager for the Sustainable Society Project at the University of Waterloo and she received her MA from the School of Urban and Regional Planning at that University. She currently works in the State of the Environment Reporting Branch of Environment Canada.     

DESIGN FOR A STABLE CHANNEL IN COARSE ALLUVIUM FOR RIPARIAN ZONE RESTORATION1

Geomorphic, hydraulic and hydrologic principles are applied in the design of a stable stream channel for a badly disturbed portion of Badger Creek, Colorado, and its associated riparian and meadow complexes. The objective is to shorten the period of time required for a channel in coarse alluvium to recover from an impacted morphologic state to a regime condition representative of current watershed conditions. Channel geometry measurements describe the stream channel and the normal bankfull stage in relatively stable reaches. Critical shear stress equations were used to design a stable channel in noncohesive materials with dimensions which approximate those of less disturbed reaches. Gabion controls, spaced at approximately 300 m intervals, are recommended to help reduce the chance of lateral migration of the newly constructed channel. Controls are designed to allow for some vertical adjustment of the channel bed following increased bank stability due to revegetation. The flood plain is designed to dissipate flood flow energy and discourage multiple flood channels. The channel has approximately a 90 percent chance of remaining stable the first two years following construction, the time estimated for increased stability to occur due to revegetation.     

The citrus pyslla, Trioza erytreae (Del Guercio) (hemiptera: Triozidae): A review

The literature on the citrus psylla, Trioza erytreae, published since 1897, is reviewed. The citrus psylla is an important vector of the greening disease of citrus. The stages of development and life history are discussed. Of the factors that influence population size, flushing of the host plants and high saturation deficits are the most important. Methods of population monitoring and control are summarised. The main means of reducing vector numbers and therefore the spread of greening disease, are resistance of citrus trees to greening disease, restricting citrus growing to hot, low-lying regions of the country, and strict vector control in nurseries. Requirements for further research, are discussed.     

Inactivation effect of pressurized carbon dioxide on bacteriophage Qβ and ΦX174 as a novel disinfectant for water treatment

The inactivation effects of pressurized CO2 against bacteriophage Qβ and ΦX174 were investigated under the pressure of 0.3–0.9 MPa, initial concentration of 107–109PFU/mL, and temperature of17.8°C–27.2°C. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 3.3-log reduction in bacteriophage Qβ was achieved by CO2, while a nearly 3.0 log reduction was observed for phage ΦX174. The viricidal effects of N2O(an inactivation gas with similar characteristics to CO2), normal acid(HCl), and CO2 treatment with phosphate buffered saline affirmed the chemical nature of CO2 treatment. The pumping cycle, depressurization rate, and release of intracellular substances caused by CO2 were its viricidal mechanisms. The results indicate that CO2 has the potential for use as a disinfectant without forming disinfection by-products.     

Development of zinc bioavailability and toxicity for the springtail Folsomia candida in an experimentally contaminated field plot

The influence of outdoor exposure conditions and ageing of contamination on the toxicity of zinc was investigated for the springtail Folsomia candida to evaluate the validity of a standardised soil toxicity test. In three successive years, animals were incubated in an experimentally contaminated field plot. During the first months after construction of the test field, total zine concentrations of the soil decreased rapidly due to leaching of excess zinc with rainwater, while increased sorption of the remaining residues resulted in a reduced bioavailability of the metal. Although variation between replicates was substantial, the EC50s for the effect of zinc on reproduction of F. candida determined in the field experiments differed by less than a factor of two from effect concentrations obtained in laboratory tests in which the same soil was used. Expression of the EC50s on the basis of water soluble zinc allowed for a comparison with effect concentrations estimated for other soil types. EC50s were comparable with literature data, which indicates that bioavailability of zinc is the main factor determining toxicity for F. candida. It is concluded that laboratory based toxicity data are suitable to predict effects of zinc for F. candida under outdoor conditions, provided that the bioavailability of zinc is determined accurately using water soluble concentrations.