Radioecological characterization of a uranium mining site located in a semi-arid region in Brazil

The work presents the radioecological characterization of the new Brazilian uranium mining and milling site located in a semi-arid region of the country. The process characterization demonstrated that in heap leach plants most of the 226Ra remains in the leached ore. Despite the potential higher availability of radium isotopes in the soils of the studied region the lack of precipitation in that area reduces the leaching/mobilization of the radionuclides. High 226Ra and 228Ra concentrations were found in manioc while 210Pb was significant in pasture. It was suggested that a range from 10(-3) to 10(-1) may conveniently encompass most of the transfer factors (TF) values for soil/plant systems (i.e. involving different cultures, different soils and natural radionuclides). Impacts due to aerial transportation of aerosols and radon generated in the mining were proved to be minimal and restricted to an area not greater than 15 km2. Finally, uranium complexation by carbonates was shown to be the main mechanism responding for the elevated radionuclide concentration in groundwater.     

226Ra bioavailability to plants at the Urgeiriça uranium mill tailings site

Large amounts of solid wastes (tailings) resulting from the exploitation and treatment of uranium ore at the Urgeiri?a mine (north of Portugal) have been accumulated in dams (tailing ponds). To reduce the dispersion of natural radionuclides into the environment, some dams were revegetated with eucalyptus (Eucalyptus globolus) and pines (Pinus pinea). Besides these plants, some shrubs (Cytisus spp.) are growing in some of the dams. The objective of this study is to determine the 226Ra bioavailability from uranium mill tailings by quantifying the total and available fraction of radium in the tailings and to estimate its transfer to plants growing on the tailing piles. Plant and tailing samples were randomly collected and the activity concentration of 226Ra in plants (aerial part and roots) and tailings was measured by gamma-spectrometry. The exchangeable fraction of radium in tailings was quantified using one single step extraction with 1 mol dm-3 ammonium acetate (pH = 7) or 1 mol dm-3 calcium chloride solutions. The results obtained for 226Ra uptake by plants show that 226Ra concentration ratios for eucalyptus and pines decrease at low 226Ra concentrations in the tailings and appear relatively constant at higher radium concentrations. For shrubs, the concentration ratios increase at higher 226Ra solid waste concentrations approaching a saturation value. Percentage values of 16.0 +/- 8.3 and 12.9 +/- 8.9, for the fraction of radium extracted from the tailings, using 1 mol dm-3 ammonium acetate or calcium chloride solutions, respectively, were obtained. The 226Ra concentration ratios determined on the basis of exchangeable radium are one order of magnitude higher than those based on total radium. It can be concluded that, at a 95% confidence level, more consistent 226Ra concentration ratios were obtained when calculated on the basis of available radium than when total radium was considered, for all the dams.     

Recovery of foundry sands and iron fractions from an industrial waste landfill

This study was performed to analyse the technical and economical feasibility of a project concerning the recovery of foundry wastes from a landfill. In such a context, an evaluation of the total amount of residues that could be recovered was performed by using the physical chemical characterization of landfilled wastes: molding and core sands, furnace dusts, finishing dusts, muds, calcium hydroxide and refractory slags. Field tests were realized employing both geophysical methods both the digging of trenches.Two cells of the landfill were investigated by means of geophysical methods using magnetic and electromagnetic techniques. The physical and chemical characterization of wastes was employed in order to determine the best geophysical methods to locate the useful fractions of wastes in landfill and to establish the occurring treatment cycle for the recovery of useful fractions.A cost–benefit analysis was performed to evaluate the feasibility of the proposed landfill mining operation.     

Debates on Sustainable Development: Towards a Holistic View of Reality

The paper analyzes the concept of sustainable development in the light of the different interpretations existing on the issue since its appearance and establishment as an ideal to lead humanity’s line of progress. Within these interpretations, a characteristic generation of diverse debates can be appreciated, arising from different perspectives, academic as well as ideological, aiming at describing, clarifying and determining their conceptual reach. Based on these facts a model of categorization for these debates has developed, a model in which interpretations generated on the concept of sustainable development were catalogued into four realms: conceptual, contextual, academic and geopolitical. The configuration of these four areas of debate, as well as the recognition of the diversity of interpretations existing on sustainable development, is a reflection of the intrinsic complexity of the phenomena, which affect the natural and social world, both at the local and global level. The analysis of this complexity is based on the subjectivity, which is inherent to the interpretation of these phenomena, with permanent reference to the cultural context from which the diverse discourses were structured. This global perspective on the state-of-the-art controversy concerning the idea of sustainable development as an articulatory axis reveals the necessity of building epistemological models, which can give a new direction to scientific research. From these new models, based on the analysis of the holistic character of reality, the subjective and the objective must be integrated in the generation of knowledge, which contributes usefully to the unceasing reconstruction of our world-(view). Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Seat belt use in Argentina--a 10-year struggle

Can a nongovernmental organization influence or determine seat belt use in a nation? The problems that implementing such a simple, yet effective, measure for traffic safety may trigger in a developing country are impossible to imagine. Just having the right laws is not enough: A great effort is necessary to create awareness and inform the population, but the governmental authorities in Argentina are not doing this, nor do they show any interest in it. In most of the developing countries, the situation is similar. Starting from a diagnosis of seat belt use by means of systematic observations, a program of awareness and massive education was developed for national radio and TV about the advantages of seat belt use. The first stage of this program was launched at the end of 1991, and it continues to this day. Articles in newspapers and communications and requests on the same subject sent to public officials also have helped mobilize public opinion on seat belt use. After 10 years of systematic and continued work by a nongovernmental organization, seat belt use is now part of the government's agenda and there is a high rate of "almost voluntary" seat belt use. The voluntary seat belt use in the city of Buenos Aires has reached 26.9%, and in national highways 58.9%. The roads that have been traveled in Argentina (documented with follow-up statistics) may be useful as guidelines for other countries that are starting this process, and may help to shorten times, avoid pitfalls, and save lives since it is estimated that 1,100 more lives could be saved every year in Argentina when seat belts become the norm.     

Urban waste recycling behavior: antecedents of participation in a selective collection program

ABSTRACT/ The aim of this study is to analyze the antecedents of urban waste recycling behavior. To achieve this goal, a concrete urban waste management program was chosen. The study focuses on the Selective Collection Program (SCP) in Zaragoza, a medium-sized city in northeastern Spain. The research starts with a conceptual model in which the variables that potentially affect recycling behavior can be classified into two groups: incentives and barriers. Moreover, the sociodemographic characteristics of the individuals are included in our study. Given that the proposed model requires specification of latent variables or constructs, the analysis is based on the Structural Equation Models (SEM) methodology. The results revealed that environmental awareness, knowledge of the environmental impact of urban waste, and the positive perception of management by local government exercise a positive effect on individual recycling behavior, while perceived personal difficulties (space and time availability) and distance to and from the container have a negative effect. As regards sociodemographic variables, this study found that annual family income sustains a negative relationship with recycling behavior, while age maintains a positive one. The results obtained clearly show the important role that the public authorities play, especially municipal governments, in achieving the waste recycling objectives established in accordance with international legislation.     

The relationships between career concerns and political tactics in organizations

The study examined the relationships between four career concerns (Personal Success, Organizational Involvement, Skill Development and Autonomy) and two categories of political tactics in organizations (Hierarchical Tactics and Networking Tactics) in a sample of management school alumni. Career concerns were not related to the employment of hierarchical tactics but were strongly related to the use of networking tactics. ‘External’ career concerns of personal success and organizational involvement were more strongly related to political behavior than ‘internal’ career concerns of skill development and autonomy. Organization size was significantly related to the use of hierarchical tactics but not to the use of networking tactics. Type of organization structure (mechanistic versus organic) did not have a direct effect on political behavior but moderated the relationships between career concerns and political tactics. These relationships were stronger in organic than in mechanistic organizations.     

Short-term patch dynamics of macroinvertebrate colonization on decaying reed detritus in a Mediterranean lagoon (Lake Alimini Grande,Apulia, SE Italy)

In aquatic ecosystems, the ecology of macrophytal detritus aggregations has been investigated over a range of temporal scales. Yet, no attempts have been made to minimize the temporal resolution of the analysis, thus neglecting the occurrence of short-term colonization and decay dynamics for these ephemeral patches of high biological activity. The present study was carried out at two sampling sites in Lake Alimini Grande, a brackish lagoon in South-East Italy. The abundance of macroinvertebrate taxa colonizing prepared packs of reed leaf detritus and the ash-free dry mass of the packs were monitored daily for 40 days. Spectral analysis was used to investigate the fine-scale temporal dynamics of invertebrates colonization and leaf pack mass variations. The macrobenthos found on leaf packs was dominated at both sites by few taxa (i.e., the vagile Lekanesphaera monodi, Microdeutopus gryllotalpa, Neanthes caudata and the sessile Balanus sp.), whose general colonization patterns were described by unimodal curves. At a daily temporal resolution Balanus sp. was characterized by random short-term density variations, while vagile taxa showed non-random, highly site- and species-specific fluctuations generally characterized by an oscillation period comprised between 2 and 3 days. In addition, leaf packs were characterized by non-random, short-term mass oscillations, coherent and in phase with L. monodi abundance fluctuations. Our results highlight the occurrence of short-term, non-random density variations of invertebrate colonizers on leaf detritus patches. In addition, they emphasize a previously unexplored, fine-scale linkage between abundance patterns of invertebrate consumers and short-term mass variations of decaying detritus.     

Co-evolution-driven cuticular hydrocarbon variation between the slave-making ant Rossomyrmex minuchae and its host Proformica longiseta (Hymenoptera: Formicidae)

Summary. Proformica longiseta exists as two populations in the Sierra Nevada Mountains in Spain, only one of which is parasitized by the slave-maker ant Rossomyrmex minuchae. To investigate the possible effect of co-evolutionary pressures on cuticular hydrocarbon (CHC) profiles (the presumed nestmate recognition cues), we performed a comparative analysis of the CHC of R. minuchae and P. longiseta colonies from both the allopatric and sympatric populations; the latter includes samples of enslaved as well as free-living workers. Discriminant analyses based on these chemical profiles showed two clear profile groups: the first comprised R. minuchae and both enslaved and free-living P. longiseta from the sympatric population; and the second the allopatric P. longiseta workers. As expected, the profiles of the two sympatric P. longiseta groups (enslaved and free-living) were distinct; but, interestingly, those of the enslaved P. longiseta and its parasite R. minuchae were also distinguishable. This indicates that despite their cohabitation each species maintains its own chemical identity. Profile similarity between the sympatric free-living P. longiseta and its parasite may explain the lower than expected aggression observed during raids. We further speculate that in view of the differences between the sympatric and allopatric population of P. longiseta, co-evolutionary pressures have driven changes in the profile of the former to better match that of its parasite R. minuchae. Such an adjustment may have enabled nests of the sympatric P. longiseta to endure multiple raids by the parasite (due to the reduced aggression) and thus to continue to reproduce despite the damage inflicted by the raids.