Magnesium hydroxide bulk and colloid-associated 152Eu in an alkaline environment: colloid characterisation and sorption properties in the presence and absence of carbonate

The distribution of 152Eu between magnesium hydroxide bulk, colloids and solution has been assessed under alkaline conditions, such as those in nuclear fuel storage ponds. The colloidal phase has been characterised by two complementary methods: coupled ultrafiltration-ICP-AES and scanning electron microscopy. The quantity and the size distribution of the colloidal phase is strongly ionic strength-dependent. A decrease of the quantity of colloids, in particular the larger size ranges, has been observed with increasing ionic strength. Small colloids (1 kDa-10 kDa fraction) are predominant at all ionic strengths. The morphology of colloids, observed by field-emission gun scanning electron microscopy, appears to change from hexagonal prismatic (characteristic to the mineral) to spherical (energetically more favourable) as size decreases. The distribution of 152Eu between the solid and liquid/colloidal phases has been investigated at carbonate concentrations ranging from 0 to 10(-2) M by coupled ultrafiltration and gamma-spectrometry. Mg(OH)2 bulk appears to be a very strong sorbent for 152Eu, since complete sorption onto the bulk happens for carbonate concentrations as high as 10(-3) M. Scavenging of 152Eu by Mg(OH)2 colloids is negligible in the presence of Mg(OH)2 bulk. The distribution of 152Eu between liquid and colloidal phases has been investigated in the absence of bulk at various carbonate concentrations. A significant uptake of 152Eu by the colloids in solution has been observed, which decreases with increasing carbonate concentration. 152Eu appears to be mainly associated to the smallest colloids (1 kDa-10 kDa fraction). There is a strong correlation between the sorption properties and the surface area of the colloids.     

Modeling microbiological and chemical processes in municipal solid waste bioreactor,part I: Development of a three-phase numerical model BIOKEMOD-3P

The numerical computer models that simulate municipal solid waste (MSW) bioreactor landfills have mainly two components – a biodegradation process module and a multi-phase flow module. The biodegradation model describes the chemical and microbiological processes. The models available to date include predefined solid waste biodegradation reactions and participating species. Some of these models allow changing the basic composition of solid waste. In a bioreactor landfill several processes like anaerobic and aerobic solids biodegradation, nitrogen and sulfate related processes, precipitation and dissolution of metals, and adsorption and gasification of various anthropogenic organic compounds occur simultaneously. These processes may involve reactions of several species and the available biochemical models for solid waste biodegradation do not provide users with the flexibility to simulate these processes by choice. This paper presents the development of a generalized biochemical process model BIOKEMOD-3P which can accommodate a large number of species and process reactions. This model is able to simulate bioreactor landfill operation in a completely mixed condition, when coupled with a multi-phase model it will be able to simulate a full-scale bioreactor landfill. This generalized biochemical model can simulate laboratory and pilot-scale operations in order to determine biochemical parameters important for simulation of full-scale operations.     

Chemical fluxes in time through forest ecosystems in the UK - Soil response to pollution recovery

Long term trend analysis of bulk precipitation, throughfall and soil solution elemental fluxes from 12 years monitoring at 10 ICP Level II forest sites in the UK reveal coherent national chemical trends indicating recovery from sulphur deposition and acidification. Soil solution pH increased and sulphate and aluminium decreased at most sites. Trends in nitrogen were variable and dependant on its form. Dissolved organic nitrogen increased in bulk precipitation, throughfall and soil solution at most sites. Nitrate in soil solution declined at sites receiving high nitrogen deposition. Increase in soil dissolved organic carbon was detected - a response to pollution recovery, changes in soil temperature and/or increased microbial activity. An increase of sodium and chloride was evident - a possible result of more frequent storm events at exposed sites. The intensive and integrated nature of monitoring enables the relationships between climate/pollutant exposure and chemical/biological response in forestry to be explored.     

A free-enzyme catalyst for the bioremediation of environmental atrazine contamination

Herbicide contamination from agriculture is a major issue worldwide, and has been identified as a threat to freshwater and marine environments in the Great Barrier Reef World Heritage Area in Australia. The triazine herbicides are of particular concern because of potential adverse effects, both on photosynthetic organisms and upon vertebrate development. To date a number of bioremediation strategies have been proposed for triazine herbicides, but are unlikely to be implemented due to their reliance upon the release of genetically modified organisms. We propose an alternative strategy using a free-enzyme bioremediant, which is unconstrained by the issues surrounding the use of live organisms. Here we report an initial field trial with an enzyme-based product, demonstrating that the technology is technically capable of remediating water bodies contaminated with the most common triazine herbicide, atrazine.     

Social support and newcomer adjustment in organizations: Attachment theory at work?

Social support has been suggested as important for newcomer adjustment to an organization. The present paper reports a longitudinal study of 91 newcomers to three separate organizations. The effects of availability and helpfulness of 10 sources of social support on newcomers reports of psychological distress, satisfaction, intention to leave, and their supervisors assessment of their performance rating (N of supervisors = 41; n of ratings = 91) were examined. The availability of support activities such as offsite training sessions and business trips were found to be associated with decreased psychological symptoms. Helpfulness of various relationship supports were associated with positive adjustment. These results are discussed within the context of attachment theory and our knowledge of social support in work settings.     

Revitalizing neighbourhoods through sustainable brownfields redevelopment: Principles put into practice in Bridgeport, CT

This article chronicles activities and approaches carried out in working with community partners and public and private stakeholders in advancing revitalization within Bridgeport, CT. The approach described utilizes brownfields redevelopment as a focal point for a stakeholder process whose goal is neighbourhood revitalization. Two neighbourhoods—the Went End and East End—are the focus for major stakeholder-driven brownfields redevelopment processes. The article defines key elements of the stakeholder process including: involvement at several levels from neighbours to the site to the Mayor's office and beyond, a risk communication process that incorporates the broad concerns of the stakeholders including crime and violence, and the need for ongoing oversight and management throughout the redevelopment process.     

WEST AFRICA: VOLTA DISCHARGE DATA QUALITY ASSESSMENT AND USE1

ABSTRACT: Water resource management in West Africa is often a complicated process due to inadequate resources, climatic extremes, and insufficient hydrological information. Insufficient data hinder sustainable watershed management practices, one of the top priorities in the Volta River Basin. This research properly fills in missing data by modeling the hydrological distribution in the Volta River Basin. On average, discharge gages across the basin are missing 20 percent of their monthly data over 20 years. Two methods were used to supplement missing data: a statistically linear model and a conceptual hydrological model. A linear equation, developed from the regression of precipitation and runoff, was used to evaluate the quality of existing data. The hydrological model separates the system into root and groundwater zones. Measured values were used to calibrate the hydrological model and to validate the statistical model. The quality of existing data was analyzed and organized for usability. Accuracy of the hydrological model was also evaluated for its effectiveness using R² and standard error. It was found that the hydrological model was an improvement from the linear model on a monthly basis; R² values improved by as much as 0.5 and monthly error decreased. Monthly predictions of the hydrological model were used to fill gaps of measured data sets.     

Linking rights and standards: the process of developing "rights-based" minimum standards on food security, nutrition and food aid

This article examines the recent revision of the Sphere Minimum Standards in disaster response relating to food security, nutrition and food aid. It describes how the revision attempted to incorporate the principles of the Humanitarian Charter, as well as relevant human rights principles and values into the Sphere Minimum Standards. The initial aim of the revision was to ensure that the Sphere Minimum Standards better reflected the principles embodied in the Humanitarian Charter. This was later broadened to ensure that key legal standards and principles from human rights and humanitarian law were considered and also incorporated, in part to fill the "protection gap" within the existing standards. In relation to the food security, nutrition and food aid standards, it was agreed by participants in the process that the human right to adequate food and freedom from hunger should be incorporated. In relation to more general principles underlying the Humanitarian Charter, itself drawn largely from human rights and humanitarian law, it was agreed that there was a need to strengthen "protection" elements within the standards and a need to incorporate the basic principles of the right to life with dignity, non-discrimination, impartiality and participation, as well as to explore the relevance of the concept of the progressive realisation of the right to food. The questions raised in linking rights to operational standards required thought, on the one hand, about whether the technical standards reflected a deep understanding of the values expressed within the legal instruments, and whether the existing standards were adequate in relation to those legal rights. On the other hand, it also required reflection on how operational standards like Sphere could give concrete content to human rights, such as the right to food and the right to be free from hunger. However, there remain challenges in examining what a rights-based approach will mean in terms of the role of humanitarian agencies as duty-bearers of rights, given that the primary responsibility rests with state governments. It will also require reflection on the modes and mechanisms of accountability that are brought to bear in ensuring the implementation of the Minimum Standards.     

Conservation Opportunities for Securing In-Stream Flows in the Platte River Basin: A Case Study Drawing on Casper,Wyoming’s MunicipalWater Strategy

The Platte River Basin consists of tributaries largely in Wyoming, Colorado and Western Nebraska, with the main stem in Central Nebraska. Critical wildlife habitat on the main stem requires additional in-stream flows. The watershed is one hosting multiple resources, a variety of users, and managed by an array of state and federal agencies. This study proposes a basis for securing in-stream flows for the Platte River. Candidate water supply mechanisms are suggested based on the way in which Casper, Wyoming secured water for its municipal needs. Canal lining is compared to a dam project, increasing reservoir storage, and purchasing water rights, with consideration also made for water pricing to reduce municipal use. Comparisons are based on economic efficiency, potential water conservation, and property rights criteria. Canal lining, coupled with demand management, is shown to conserve water best, given the set of efficiency and cost criteria for in-stream flow enhancement. The approach offers an opportunity to organize the water supply choice context in a transboundary watershed when quantitative information is limited.