Scope insensitivity in contingent valuation of complex environmental amenities

It has been argued that respondents in contingent valuation (CV) surveys, asked to value complex environmental amenities, will state willingness to pay (WTP) independently of the scope of the project. Such insensitivity to scope would be at odds with rational choice, and could therefore imply that CV is not a theoretically valid method for biodiversity valuation. The scope test in the present CV study was applied to endangered species preservation. Respondents were split in four sub-samples facing different scopes of endangered species preservation. The design allowed for both external and internal scope tests. Furthermore, the tests were split according to elicitation format. Of four external tests of insensitivity to scope, one was rejected, two gave mixed results, depending on either the type of test or elicitation format, and for the last one the null hypothesis could not be rejected. Of five internal tests, insensitivity to scope was rejected in three cases, one test gave mixed results, and one could not be rejected. Survey design features of the CV study, especially an unfamiliar sub-group of endangered species, could explain the apparent insensitivity to scope observed.     

Trace Element Patterns and Seasonal Variability of Dust Precipitation in a Low Polluted City – The Example of Karlsruhe/Germany

Urban areas of different land uses can be distinguished by their specific patterns of atmospheric dust and trace element precipitation. Dusts emitted from industrial areas with fossil fuel processing, for instance, are enriched in V, Ni and Co. Cluster analysis groups sampling sites based on their specific element patterns. The resulting groups correspond to the surrounding land use: Urban sampling sites were identified showing similar patterns of dust and trace element precipitation as a reference site; dusts of other urban sites were influenced by diffuse pollution (caused by non-point and dispersed pollution sources), or by specific industrial emissions. Cluster analysis was also used to characterize the chemical dust composition. Three clusters of typical element associations were distinguished. These clusters represent the dust matrix, diffuse urban pollution and pollution due to fossil fuel processing. Dust precipitation and chemical dust composition show seasonal variations. Dust precipitation and concentrations of trace elements in the precipitated dust are negatively correlated during the annual courses. The highest concentrations of trace elements occur during winter, whereas the highest precipitations of dust were found during summer. This finding stresses that both, precipitation and concentration have to be addressed for the environmental assessment of urban dusts.     

A new generic sub-model for radionuclide fixation in large catchments from continuous and single-pulse fallouts, as used in a river model

This paper presents a new general sub-model for fixation in catchment areas to be used within the framework of a river model for substances such as radionuclides and metals from continuous and single-pulse fallouts. The model has been critically tested using data from 27 European river sites covering a very wide geographical area and contaminated by radiocesium and radiostrontium from the Chernobyl accident and from the nuclear weapons tests (NWT fallout). This modelling approach gives radionuclide concentrations in water (total, dissolved and particulate phases) at defined sites on a monthly basis. The overall river model is based on processes in the upstream river stretch and in the catchment area. The catchment area is differentiated into inflow (approximately dry land) areas and outflow (approximately wetland) areas. The model has a general structure, which can be used for all radionuclides or substances. It is simple to apply in practice since all driving variables may be readily accessed from maps and standard monitoring programs. The driving variables are: latitude, altitude, catchment area, mean annual precipitation and fallout. Note that for large catchments, this model does not require data on the characteristic soil type or the percentage of outflow areas (wet lands) in the catchment, as in most previous models, since in practice it is very difficult to obtain reliable data on characteristic soil type or percentage of outflow areas, especially in large and topographically complex catchments. Modelled values have been compared to empirical data from rivers sites covering a wide domain (catchment areas from 3000 to 3,000,000 km2, precipitation from 400 to 1700 mm/year; fallouts from 1600 to 280,000 Bq/m2; altitudes from 0 to 1000 m.a.s.l. and latitudes from 41 degrees to 72 degrees N). The river model with its sub-model for fixation predicts close to the uncertainty factors given by the empirical data, which have been shown to be about a factor of 1.6 for 137Cs and a factor of 2.2 for 90Sr in river water. The obtained characteristic uncertainty factors for 137Cs from the Chernobyl fallout is 2.4, for 137Cs from the NWT fallout it is 1.3 and for the 90Sr results from the NWT fallout it is 3 using the new model.     

Automatic sorting of ichthyoplankton; Factors controlling plankton density in gradients of silica

Following isopycnic sedimentation in density gradients of colloidal silica (Ludox AM), zooplankton segregated into 3 broad bands of increasing density which included, respectively, fish eggs, invertebrates, and fish larvae. The zone of fish eggs was contaminated with Sagitta spp. and the zone of fish larvae was overlapped partially by mysids and euphausids. We have sought to minimize contamination through modifications of the silica gradients which might shift banding densities of the ichthyoplankton or of the contaminating invertebrates. Density shifts in fact occurred in different commercial formulations of silica sols and in gradients modified by small amounts of polymers, osmotica or charged small molecules. Sagitta were specifically shifted out of the zone of fish eggs by the addition, of 1% w/v dextran sulfate or in a silica sol composed of very small particles of silica (Nalcoag 1115). Fish larvae were shifted to higher densities by the addition of 1% w/v trimetaphosphate or 1% w/v dextran sulfate. Additions of 1% w/v polyvinyl alcohol, and of 10 mM glycine, and potassium phosphate had intermediate effects. The same banding densities of plankton in silica gradients were reached in less than 10 h at one gravity, independent of the immediate pretreatment of the sample.     

Fire-LCA study of TV sets with V0 and HB enclosure material

A novel Life-Cycle Assessment model (Fire-LCA) has been defined for the determination of the environmental impact of measures taken to attain a high level of fire safety. This study, which represents the first application of this LCA model, concentrates on a comparison between a TV with an enclosure manufactured with a flame retardant (FR) plastic (V0-rated high impact polystyrene, HIPS, typical for the US market) and one manufactured with a non-flame retardant (HB-rated HIPS, typical for the European market). A fire model has been defined based on international statistics, which indicate that use of V0 rated enclosure material essentially removes the risk of TV fires while approximately 165 TV fires occur per million TVs in Europe each year where the enclosure material is breached. The application of the model indicates that emissions of some key species (such as dibenzodioxins and PAH) are actually lower for the TV with the FR enclosure than for the TV with the NFR enclosure. This has direct reprercussions for the assessment of the environmental impact of the FR TV relative to that of the NFR TV. Finally, when considering the risk associated with the use of flame retardants, it is also important to consider the risk associated with fires. Based on the in-depth analysis of available fire statistics, conducted as a part of this study, it has been estimated that as many as 160 people may die each year in Europe as a direct result of TV fires and as many as 2000 may be injured in the same period.     

Transport and degradation of toluene and o-xylene in an unsaturated soil with dipping sedimentary layers

A lysimeter trench was established at the Gardermoen delta (50 km north of Oslo, Norway) to study the flow of water and transport and degradation of aromatic jet fuel components (toluene and o-xylene) in the undisturbed unsaturated zone. Site investigations with ground-penetrating radar revealed the presence of dipping sedimentary layers within the foreset unit. This study has shown that the foreset bed of the Gardermoen delta structure provided a preferential flow path for the transport of the solute plumes, but did not have dramatic effects on the degradation potential under the current conditions. The degradation potential for toluene and o-xylene in the unsaturated zone at Gardermoen was very high and almost all of the injected hydrocarbons were biodegraded before reaching the saturated zone. However, the horizontal displacement of the plume showed that knowledge about sedimentary structures in the unsaturated zone is important for a sufficient monitoring of contaminant transport and for remediation purposes. Carbon dioxide and O2 were measured in situ simultaneously with extraction of water samples, and indicated aerobic biodegradation of toluene and o-xylene. Overall, first-order degradation coefficients were calculated to be in the range of 0.19 to 0.21 d(-1) and 0.10 to 0.11 d(-1) for toluene and o-xylene, respectively.     

Review and assessment of models used to predict the fate of radionuclides in lakes

A variety of models for predicting the behaviour of radionuclides in fresh water ecosystems have been developed and tested during recent decades within the framework of many international research projects. These models have been implemented in Computerised Decision Support Systems (CDSS) for assisting the appropriate management of fresh water bodies contaminated by radionuclides. The assessment of the state-of-the-art and the consolidation of these CDSSs has been envisaged, by the scientific community, as a primary necessity for the rationalisation of the sector. The classification of the approaches of the various models, the determination of their essential features, the identification of similarities and differences among them and the definition of their application domains are all essential for the harmonisation of the existing CDSSs and for the possible development and improvement of reference models that can be widely applied in different environmental conditions. The present paper summarises the results of the assessment and evaluation of models for predicting the behaviour of radionuclides in lacustrine ecosystems. Such models were developed and tested within major projects financed by the European Commission during its 4th Framework Programme (1994-1998). The work done during the recent decades by many modellers at an international level has produced some consolidated results that are widely accepted by most experts. Nevertheless, some new results have arisen from recent studies and certain model improvements are still necessary.     

Plant uptake of cadmium-109 and zinc-65 at different temperature and organic matter levels

The uptake of 109Cd and 65Zn and their stable isotopes by ryegrass (Lolium multiflorum Lam.), grown on two different soil types, was investigated in climatically controlled growth chambers at 9 and 21 degrees C. The soils were treated with 0 and 4% organic matter (pig [Sus scrofa] manure) and spiked with 109Cd and 65Zn before sowing. The organic matter addition resulted in increased uptake of the 109Cd, Cd, and Zn by ryegrass, but the uptake of 65Zn was decreased. The latter effect was ascribed to isotopic dilution of 65Zn as the amount of stable Zn in the plant tissues increased with the organic matter addition. The effect of temperature was more pronounced than that of organic matter addition, and the uptake of both 109Cd and 65Zn and their stable isotopes was higher in ryegrass grown at 21 degrees C than that grown at 9 degrees C. Results from fractionation and speciation analysis of soil cadmium and zinc were correlated with plant uptake, and there was a good consistency between observed plant uptake and the physico-chemical forms of cadmium and zinc in soil and soil solution presumed to be plant available.     

A mechanistic sub-model predicting the influence of potassium on radiocesium uptake in aquatic biota

It is often argued that the quality of science is related to the possibilities of making accurate predictions. It has also long been argued that due to the complex nature of ecosystems, it will never be possible to predict important target variables, especially with more comprehensive dynamic models. New results in radioecology have, however, demonstrated that those arguments are no longer valid. The key to the predictive success lies in the structuring of the model. The accident at Chernobyl has, in fact, provided science with an intriguing opportunity to study how the pulse of 137Cs is transported through ecosystem pathways, thus revealing the basic structure of these ecosystems, i.e. which are the key and the less-important pathways. It is paradoxical to conclude that the Chernobyl accident is, perhaps, the most important factor behind the revolution in predictive ecosystem modelling which lies behind the decrease in the uncertainty factor from 10 to 0.25-0.5. The sub-model for the potassium moderator presented in this paper is an example of a mechanistically based sub-model used within the framework of a more comprehensive lake model for 137Cs. The K-moderator presented is derived from the existing knowledge on ion transport in biological membranes and takes into account ion equilibria modelled by the Nernst equation and the uptake kinetics quantified by the Michaelis-Menten model. It provides the type of structure to this overall lake model that helps to explain the excellent predictive power of this model.     

Lead exposure of small herbivorous vertebrates from atmospheric pollution

Concentrations of Pb in livers of willow grouse (Lagopus lagopus), black grouse (Tetrao tetrix), and hare (Lepus timidus) were determined in samples collected during the period 1990-92 from 77 locations distributed across Norway. Our objective was to elucidate the impact of long-range atmospheric transport on the Pb exposure of the animals. The moss Hylocomium splendens was measured for atmospheric Pb deposition and Pb in soil at 60-cm depth was determined to reflect the natural geochemical background at the study locations. Strong positive relationships were found between Pb in liver and atmospheric deposition of Pb for all species and age groups studied. Results indicate that long-range atmospheric transport was the main source of Pb in the animals studied. This conclusion was supported by Pb analysis of typical food plants for the animals. Correlation between Pb in liver and Pb in soil mineral matter was observed only when considering sites with very low impact of atmospheric deposition. Even though the observed liver Pb concentrations may seem low (< or =12 microg g(-1) dw) they approach levels where sub-lethal effects cannot be ignored.