Studies on metal α-isosaccharinic acid complexes

This thesis details the experimental work carried out during a three year project commissioned by UK-Nirex. The main objective of the project was further developing the software package STAB, a programme produced at Loughborough University for predicting stability constants. It is intended that the software will be able to predict stability constants for complexes likely to be formed in a cementitious repository for intermediate and low level nuclear waste. Cellulosic materials in the waste in such repositories are likely to be degraded into potential ligands such as isosaccharinic acid. Thus, there is a need for knowledge of the complexes that they may form with radionuclides in the waste. [Continues.

Profit, reputation and ‘doing the right thing’: Convention theory and the problem of food waste in the UK retail sector

In 2014, Tesco – one of the world’s largest food retailers – revealed that it had generated almost 57,000 tonnes of food waste in its UK operations over the previous twelve-month period. This shocking statistic added to existing evidence of a significant environmental and social problem in the UK and across the world. This paper utilises convention theory to examine the role of major retailers in the context of this global problem and assesses their motivations for acting on food waste. Drawing on interviews with key stakeholders (including major retailers), the analysis investigates their main justifications for action on food waste. It finds that retailers mostly appealed to three conventions or ‘orders of worth’ (civic, market and opinion) and used these as a basis for their commitment to food waste reduction. We argue that the combination of these different justifications is feasible and necessary in the context of the retail sector but that they may also lead to some unintended consequences (in the retail sector and beyond). Crucially, we demonstrate how the dilution of civic justifications (by their financial and reputational counterparts) might produce negative outcomes and inaction as retailers attempt to adhere to the so-called ‘food waste hierarchy’. The paper highlights the continuing significance of convention theory as a framework for analysing possible responses to the social and environmental challenges confronting global agro-food systems

Applications of proxy system modeling in high resolution paleoclimatology

AbstractA proxy system model may be defined as the complete set of forward and mechanistic processes by which the response of a sensor to environmental forcing is recorded and subsequently observed in a material archive. Proxy system modeling complements and sharpens signal interpretations based solely on statistical analyses and transformations; provides the basis for observing network optimization, hypothesis testing, and data-model comparisons for uncertainty estimation; and may be incorporated as weak but mechanistically-plausible constraints into paleoclimatic reconstruction algorithms. Following a review illustrating these applications, we recommend future research pathways, including development of intermediate proxy system models for important sensors, archives, and observations; linking proxy system models to climate system models; hypothesis development and evaluation; more realistic multi-archive, multi-observation network design; examination of proxy system behavior under extreme conditions; and generalized modeling of the total uncertainty in paleoclimate reconstructions derived from paleo-observations

Carbon sequestration and biogeochemical cycling in a saltmarsh subject to coastal managed realignment

Globally, wetlands provide the largest terrestrial carbon (C) store, and restoration of degraded wetlands provides a potentially important mechanism for climate change mitigation. We examined the potential for restored saltmarshes to sequester carbon, and found that they can provide a modest, but sustained, sink for atmospheric CO2. Rates of C and nutrient cycling were measured and compared between a natural saltmarsh (high- and low-shore locations), claimed arable land on former high-shore saltmarsh and a managed realignment restoration site (high- and low-shore) in transition from agricultural land to saltmarsh 15 years after realignment, at Tollesbury, Essex, UK. We measured pools and turnover of C and nitrogen (N) in soil and vegetation at each site using a range of methods, including gas flux measurement and isotopic labelling. The natural high-shore site had the highest soil organic matter concentrations, topsoil C stock and below-ground biomass, whereas the agricultural site had the highest total extractable N concentration and lowest soil C/N ratio. Ecosystem respiration rates were similar across all three high-shore sites, but much higher in both low-shore sites, which receive regular inputs of organic matter and nutrients from the estuary. Total evolution of 14C-isotopically labelled substrate as CO2 was highest at the agricultural site, suggesting that low observed respiration rates here were due to low substrate supply (following a recent harvest) rather than to inherently low microbial activity. The results suggest that, after 15 years, the managed realignment site is not fully equivalent to the natural saltmarsh in terms of biological and chemical function. While above ground biomass, extractable N and substrate mineralisation rates in the high-shore site were all quite similar to the natural site, less dynamic ecosystem properties including soil C stock, C/N ratio and below-ground biomass all remained more similar to the agricultural site. These results suggest that reversion to natural biogeochemical functioning will occur following restoration, but is likely to be slow; we estimate that it will take approximately 100 years for the restored site to accumulate the amount of C currently stored in the natural site, at a rate of 0.92 t C ha−1 yr−1

Arsenic's interactions with humic acid

The environmental mobility of arsenic is primarily controlled by adsorption onto metal oxide surfaces, particularly iron, aluminium and manganese. Humic acid (HA) may interfere with this adsorption, thereby increasing arsenic mobility. This study has characterised the interaction of arsenic with HA in a system consisting of HA with As(III), As(V) and DMAA. Three sets of batch experiments were performed at varying pH (3-12), ionic strength (I = 0 - 0.4), concentration of each arsenic species (0 - 100 mg dm-3) and HA concentration (0 - 10 g dm-3). Arsenic species were shown to react with humic acid. The interaction is postulated to involve bridging metals and deprotonated functional groups within the HA. The association is dependent on pH, ionic strength and arsenic concentration. The extent of the interaction was greater in the pH range 8 – 10 for As(V) and DMAA, while it extended to pH 12 for As(III). The strong pH dependency is probably due to the aqueous speciation of arsenic. The logarithmic conditional association constants for the reactions were found to be 1.97 ± 0.02, 1.58 ± 0.07 and 1.50 ± 0.10 for As(V), As(III) and DMAA respectively. These values indicate the formation of weak complexes with humic acid

Spectrophotometric determination of uranium with arsenazo-III in perchloric acid

A short, sensitive and reliable spectrophotometric method, which has advantages over all known “wet chemistry” methods for uranium determination with regard to tolerance to common interferences, has been developed for the determination of uranium. Selectivity, molar absorptivity and the determination range of uranium have been enhanced by using 0.07 % arsenazo-III as a chromogenic reagent. The use of 3 mol dm-3 perchloric acid as a medium of determination was found to be excellent in terms of good solvent compatibility on dilution, destruction of organic contamination and simplicity of operation. The uranium-arsenazo-III complex formed instantly, and was found to be stable for more than 3 weeks with constant absorbance. Beer’s law was obeyed up to a uranium concentration of 16 μg g-1, with 1 a molar absorptivity at 651 nm of 1.45 x 105 mol-1 dm3 cm -1 at 24 ± 2 °C. Only phosphate and citrate at 70-fold excess over uranium interfere seriously, whereas other anions studied could be tolerated up to a 70 fold excess over uranium. Of the cations studied, only Mn(II), Co(II), Ni(II), Cu(II) and Cr(III) decreased the normal absorbance of the complex. Iron(III), Ce(III) and Y(III) enhanced the absorbance. Other cations studied did not affect the absorbance up to a 50 fold excess. The accuracy was checked by determining uranium from standard solutions in the range 10-50 μg g-1. It was found to be accurate with a 96.0-98.6.% recovery rate. The method has been successfully applied to standard reference materials and ore samples at μg g-1 levels

Critical Exponents and Stability at the Black Hole Threshold for a Complex Scalar Field

This paper continues a study on Choptuik scaling in gravitational collapse of a complex scalar field at the threshold for black hole formation. We perform a linear perturbation analysis of the previously derived complex critical solution, and calculate the critical exponent for black hole mass, $\gamma \approx 0.387106$. We also show that this critical solution is unstable via a growing oscillatory mode.Comment: 15 pages of latex/revtex; added details of numerics, in press in Phys Rev D; 1 figure included, or available by anonymous ftp to ftp://ftp.itp.ucsb.edu/figures/nsf-itp-95-58.ep

Ectopic expression of Thy-1 in the kidneys of transgenic mice induces functional and proliferative abnormalities.

Hybrid human--mouse Thy-1.1 genes were injected into pronuclei of Thy-1.2 mice to produce transgenic animals. A hybrid gene composed of the 5' part of the mouse Thy-1.1 gene combined with the 3' human untranslated regions was expressed abnormally in the kidney podocytes, which resulted in severe protein-uria and subsequent death in several founder mice. A hybrid Thy-1 gene composed of the human coding region with the 5' and 3' flanking regions of the mouse gene was expressed abnormally in a different part of the kidney (the tubular epithelia), which resulted in a proliferative kidney disorder. In addition, a neoplasm was found in the brain of one of these mice. These results show that the Thy-1 protein can play an important role in the activation, proliferation, and differentiation of many different cell types

Understanding national variations in reusable packaging: commercial drivers, regulatory factors, and provisioning systems

Given the global environmental impacts associated with single-use plastics, alternatives are being considered, including the reuse of product packaging, which aim to retain the functionality of products while reducing waste and broader environmental impacts. Drawing on the Multi-Level Perspective approach, we analyse three national examples of reuse in Denmark, Germany, and Mexico. While the success of reuse initiatives is often attributed to heightened levels of environmental consciousness, we argue that understanding national variations in levels of reuse requires greater attention to the commercial drivers, regulatory factors, and provisioning systems in which they arise. This argument is developed through case studies of the beverage sector in the three national contexts – specifically beer, mineral water, and soft drinks – as this sector is often regarded as a successful illustration of business-to-consumer reuse systems. To conclude, we consider what the implications might be for nations such as the UK where reuse levels remain comparatively low