Effect of pH on the sorption of uranium in soils

This work was undertaken to study the influence of soil type and chemical composition on uranium sorption ratios (SR in 1 kg-1) in order to reduce the uncertainty associated with this parameter in risk assessment models. Thirteen soil samples were collected from three different locations in France under different geological conditions. Clay content varied from 7.0 to 50.0%, pH ranged from 5.5 to 8.8 and organic matter content from 1.0 to 4.6%. Soils were incubated at room temperature in polyethylene packets for 28 days in the presence of 1 mg U kg-1 soil. Sorption ratio values varied from 0.9 to 3198 for all soils with no significant effect of soil texture or of organic matter. However, soil pH was highly linearly correlated with (log SR) as a probable consequence of the existence of different uranium complexes as a function of soil pH. The sorption behaviour differences between UO2(2+) and UO2(2+)-carbonate complexes are so great that any other effect of soil properties on U sorption is hidden. Thus, soil pH should be the focus variable for reduction of the uncertainty associated with the soil Kd value used in environmental risk assessments, even for reducing the uncertainty in site-specific Kd values.     

Trace elements determination in lichens and in the airborne particular matter for the evaluation of the atmospheric pollution in a region of northern Italy

Lichens as biomonitors and neutron activation analysis as analytical technique have been employed to study the distribution of trace elements (TE) in a mountain region of north Italy (Biella) characterized by settlements of wool industry. Samples of airborne particulate matter collected onto filters, different species of lichens and samples of soils have been analyzed for the calculation of the enrichment factors (EFs) of more than 25 TE. By comparison of the corresponding EFs, the most suitable lichen species (Parmelia caperata) was selected as specific TE biomonitor of the area investigated. Samples of this lichen were collected and analyzed for the evaluation of the TE distribution in four different locations. The results obtained from the analysis of the lichens gave information about the predominant direction of pollutants transportation, while those related to the concentrations found in the air particulate allowed the evaluation of the degree of the local TE atmospheric pollution.     

Simulation of Live and Dead Phytomass Formation and Transformation in Optimized Agrocenoses

The formation and transformation of live and dead phytomass in agrocenoses with a complex horizontal structure are described. These processes are demonstrated to be specific and to be determined by differences in the horizontal structure. Only agrocenoses of a mosaic structure (with square parcels) have optimal conditions for these processes.     

Rendering the world unsafe: 'vulnerability' as western discourse

Disasters seem destined to be major issues of academic enquiry in the new century if for no other reason than that they are inseparably linked to questions of environmental conservation, resource depletion and migration patterns in an increasingly globalised world. Unfortunately, inadequate attention has been directed at considering the historical roots of the discursive framework within which hazard is generally presented, and how that might reflect particular cultural values to do with the way in which certain regions or zones of the world are usually imagined. This paper argues that tropicality, development and vulnerability form part of one and the same essentialising and generalising cultural discourse that denigrates large regions of world as disease-ridden, poverty-stricken and disaster-prone.     

The Information Cycle as a Framework for Defining Information Goals for Water-Quality Monitoring

/ The necessity to tailor information becomes increasingly urgent as the information revolution continues to generate ever-increasing flows of data and so-called information. From European experiences, a new approach for monitoring system design is suggested in this paper. In this approach, careful and detailed specification of information needs is a major contributing factor to the effectiveness of information products. To develop better specifications for information products, the process of collecting and transforming data into useful information requires careful thought and guidance. A dialogue between information users on one hand and information producers on the other is essential. This dialogue can be based on the information cycle, describing the continuous process from specifying information needs for water management and a strategy to collect information through data collection and data analysis up to utilization of information by water management. By following the respective steps in the information cycle, the process of information gathering can be completed. The cyclic character provides a quantitative means of connecting monitoring system design and operations with the information expectations and/or products required by management.     

The effect of EDTA and fulvic acid on Cd, Zn, and Cu toxicity to a bioluminescent construct (pUCD607) of Escherichia coli

The hypothesis, that metal toxicity is dominated by free ion activity, was tested by comparing calculated metal activities with measured toxic responses to a genetically modified, luminescent bacterium, Escherichia coli. The toxicity of Cd, Cu, and Zn sulphate salts in the presence of EDTA and fulvic acid in well-defined solutions was measured. Good agreement between free metal activity and toxicity was found for Cu but not for Zn and Cd. The toxicity relationships were altered by glucose addition to the organism. Stable chloride complexes may have contributed to the toxicity of Cd under the test conditions. The results suggest that there is not always a simple relationship between toxicity and free-ion metal concentration and that further account should be taken of competitive interactions between living cells and ligands and the physiological status of the organism.     

Levels of toxaphene congeners in fish from Danish waters

The levels of toxaphene congeners, in addition to PCB congeners and organochlorine pesticides, were determined in various fish samples from different Danish waters. While PCB-153 and p,p'-DDE show different levels depending on the fishing area, with highest levels in fish from the Western Baltic Sea, toxaphene was detected in all the samples investigated at a more constant level. The distribution of the three toxaphene congeners Parlar #26, #50 and #62 depends on the fishing area, with the Western Baltic Sea being different from the other waters by having almost equal levels of toxaphene congeners #26 and #50.     

Testicular cancer and occupational exposures with a focus on xenoestrogens in polyvinyl chloride plastics

In a case-control study of 148 cases of testicular cancer and 314 healthy controls information was collected on lifetime working histories and specific exposures. The main finding was a six-fold increase in the risk for seminoma, one type of testicular cancer, among plastic workers exposed to polyvinyl chloride (PVC). No overrisks were observed for other plastics than PVC. There may be an aetiological link to xenoestrogens, i.e. chemicals in the environment with oestrogenic properties. Phthalates are used in PVC as plasticizer and have oestrogenic properties that could promote the growth of endocrine sensitive tumour cells. However, this "endocrine disruptors" hypothesis must be further evaluated in experimental models with regard to the causative mechanisms of the oestrogenic tumour promotion.     

Soil organic matter mobilization by root exudates

In order to study the different soil organic matter mobilisation by agrarian (Zea mais: cultivars Paolo and Sandek) and forest (Picea abies Karst. and Pinus sylvestris L.) root exudates, three different soils (Dystric Spodic Cambisol--S1, Haplic Luvisol--S2 and Calcaric Cambisol--S3) have been considered. Treating the soils with water (control) or plant root exudates, soil organic matter extracts were obtained. The extracts were characterised by hormone-like activities and gas chromatographic/mass spectrometric (GC/MS) measurements. Water extract and plant root exudates exhibited no hormone-like activity, while the other soil-extracts were endowed with a different hormone-like behaviour. GC/MS data indicated that in the acid soils (S1) Sandek and Picea abies exudates showed a greater ability in extracting organic acid isomers (Cl4COOH, Cl5COOH and Cl7COOH), while in neutral soils (S3) all the exudates were active in separating organic acids. In intermediate conditions (S2), Picea abies and Pinus sylvestris exudates liberated C15COOH isomers, Paolo C11COOH isomers, while Sandek was not effective. The different role of plant root exudates in mobilising bio-molecules from the bulk of the soil is proposed.