Biogeochemical relationships of arsenic in the Haor Basin of Bangladesh

Biogeochemical relationships and the level of arsenic (As) contamination of groundwater and surface sediments in the Haor Basin of Bangladesh were assessed to see if surface sediments gave any indication of underlying As cycling. The Haor areas under study have been found to be affected with high As (up to 331 μg/L) in groundwater, with contamination of both shallow and deep aquifers. Highly significant relationships of As with Dissolved Organic Carbon (DOC) in groundwater and Total Carbon (TC) and Organic Carbon (OC) in sediments are indicative of reductive dissolution of iron (Fe) and/or manganese (Mn) oxides/oxyhydroxides coupled with biodegradation of organic matter as the dominant processes to release As in groundwater. This study also reveals that As geochemistry in the surface sediments has limited influence on As geochemistry in the groundwater of the Haor Basins. © 2012 Taylor & Francis Group.

Characterizing Aquifer Heterogeneity Using Bacterial and Bacteriophage Tracers

Gravel aquifers act as important potable water sources in central western Europe yet they are subject to numerous contamination pressures. Compositional and textural heterogeneity makes protection zone delineation around groundwater supplies in these units challenging; artificial tracer testing aids characterization. This paper reappraises previous tracer test results in light of new geological and microbiological data. Comparative passive gradient testing, using a fluorescent solute (Uranine), virus (H40/1 bacteriophage), and comparably sized bacterial tracers Escherichia coli and Pseudomonas putida, was used to investigate a calcareous gravel aquifer’s ability to remove microbiological contaminants at a test site near Munich, Germany. Test results revealed E. coli relative recoveries could exceed those of H40/1 at monitoring wells 10 m and 20 m from an injection well by almost four times; P. putida recoveries varied by a factor of up to three between wells. Application of filtration theory suggested greater attenuation of H40/1 relative to similarly charged E. coli occurred due to differences in microorganism size, while estimated collision efficiencies appeared comparable. By contrast, more positively charged P. putida experienced greater attenuation at one monitoring point, while lower attenuation rates at the second location indicated the influence of geochemical heterogeneity. Test findings proved consistent with observations from nearby fresh outcrops that suggested thin open framework gravel beds dominated mass transport in the aquifer, while discrete intervals containing stained clasts reflect localized geochemical heterogeneity. Study results highlight the utility of reconciling outcrop observations with artificial tracer test responses, using microbiological tracers with well-defined properties, to characterize aquifer heterogeneity.

Street Space—North Street, Belfast

The Belfast city center is fractured, divided by motorways, parking lots, empty buildings, and big box stores. Its 19th-century heyday put it on the international map of textile production, which transformed and enriched its built structure. This tight architectural fabric was slowly destroyed in the 1940s by the Blitz, in the 1970s by road plans and “the troubles” and in the 1990s by large retail buildings. Few pedestrian streets traverse Belfast, and among them, most are recently-developed conduits for the passage of shoppers from one chain store to the next.Within this seemingly bleak urban landscape, there remain a few areas that offer a richer, more architecturally and socially diverse, more memory-laden conception of public space. Current redevelopment plans, however, threaten the mere existence of these few remaining historic streets in Belfast.This reality inspired the current project of one of the Masters in Architecture design units at Queen’s University Belfast. Our team (led by urban designer Michael Corr and myself) has been exploring North Street, one of the main arteries in Belfast City Center. Although North Street has a reputation for being run-down, derelict, and in need of redevelopment, it is one of the few intact 19th-century streets left in the area, and as such is worthy of study as an example of public space that is not strictly synonymous with commercial space.

The impact of hydrogeology on the instability of a road cutting through a drumlin in the North of Ireland

This paper describes the hydrogeological processes which caused unexpected instability and quick conditions during the excavation of a 25m deep cutting through a drumlin in County Down, Northern Ireland. A conceptual hydrogeological model of the cutting, based on pore pressures monitored during and after the excavation demonstrates how quick conditions at the toe of the cutting caused liquefaction of the till. Stability of the cutting was re-established by draining the highly permeable, weathered Greywacke which underlies the drumlin, through the use of a deep toe drain. In spite of this drainage, the cutting was only marginally stable due to the presence of a low permeability zone in the till above the bedrock which limits the reduction of elevated pore pressures within the upper to mid-depths of the drumlin. The factor of safety has been further improved by the addition of vertical relief drains at the crest and berm of the cutting to relieve the pore-pressures within the upper till by intercepting the weathered bedrock. The paper also highlights the importance of carrying out an adequate site investigation compliant with Eurocode 7 and additional monitoring in excavations in stiff, low permeability till.

Distribution of soil selenium in China is potentially controlled by deposition and volatilization?

Elucidating the environmental drivers of selenium (Se) spatial distribution in soils at a continental scale is essential to better understand it's biogeochemical cycling to improve Se transfer into diets. Through modelling Se biogeochemistry in China we found that deposition and volatilization are key factors controlling distribution in surface soil, rather than bedrock-derived Se (<0.1 mg/kg). Wet deposition associated with the East Asian summer monsoon, and dry deposition associated with the East Asian winter monsoon, are responsible for dominant Se inputs into northwest and southeast China, respectively. In Central China the rate of soil Se volatilization is similar to that of Se deposition, suggesting that Se volatilization offsets it's deposition, resulting in negligible net Se input in soil. Selenium in surface soil at Central China is roughly equal to low petrogenic Se, which is the main reason for the presence of the Se poor belt. We suggest that both deposition and volatilization of Se could play a key role in Se balance in other terrestrial environments worldwide.

Competency-Based Theory For Achieving Innovation: The Case Of Post-Disaster Reconstruction

For those working in the humanitarian sector, achieving positive outcomes for postdisaster communities through reconstruction projects is a pressing concern. In the wake of recent natural disasters, NGOs have become increasingly involved in the permanent reconstruction of affected communities. They have encountered significant barriers as they implement reconstruction programmes and this paper argues that it is important to address the visible lack of innovation that is partially to blame. The theoretical bedrock of a current research project will be used as the starting point for this argument, the overall goal of which is to design a competency-based framework model that can be used by NGOs in post-disaster reconstruction projects. Drawing on established theories of management, a unique perspective has been developed from which a competency-based reconstruction theory emerges. This theoretical framework brings together 3 distinct fields; Disaster Management, Strategic Management and Project Management, each vital
to the success of the model. The objectives of this paper are a) to investigate the role of NGOs in post-disaster reconstruction and establish the current standard of practice b) to determine the extent to which NGOs have the opportunity to contribute to sustainable community development through reconstruction c) to outline the main factors of a theoretical framework first proposed by Von Meding et al. 2009 and d) to identify the innovative measures that can be taken by NGOs to achieve more positive outcomes in their interventions. It is important that NGOs involved in post-disaster reconstruction become familiar with concepts and strategies such as those contained in this paper. Competency-based organizational change on the basis of this theory has the potential to help define the standard of best practice to which future NGO projects might align themselves.