A l-D tidally resolving hydrodynamic model of the Tweed Estuary has been encoded using the Estuarine Contaminant Simulator, ECoS. The model results of axial and time series variations in water elevation, salinity and turbidity are compared to field data recorded during the LOIS survey programme. The organic and inorganic controls on estuarine pH have also been investigated by encoding a new template to predict the effect of changing salinity and temperature on the pH of estuarine water. The template has been coupled to the hydrodynamic model to predict pH variations in the estuary. The model results have shown conservative behaviour of the inorganic carbon system through out the majority of the estuary, but also identified an area of potentially high photosynthetic activity near the limit of saline intrusion during periods of low summer flows. Low (< 2 ^g 1"') concentrations of chlorophyll a in the water column and increases in pH correlated with tidal inundation of the river estuary banks imply that benthic photosynthetic process are important water chemistry in the upper estuary. The effects of salinity, turbidity and pH on Kd(Cd) and K<i(Zn) has been investigated using radiotracer incubation experiments and analytically determined measurements. The results show a reduction in IQ with increased salinity, but that the K<iS determined analytically are an order of magnitude higher than those measured when radiotracers are used. Analytically determined K<iS are reduced with increasing SPM concentration and increased at higher pH. Although no photosynthetically mediated control of radiotracer uptake was identified partitioning was significantly reduced (> 90 %) when a metabolic inhibitor was added. The Kd has been encoded as an exchange transfer and used to predict axial distributions and the flux of these metals from the riverine catchment to the sea. Model results indicate that the partition coefficients determined fi-om the radiotracer studies can not fully account for the analytically determined distribution between phases. It is hypothesised that colloids and Fe-Mn oxides precipitates play a significant role in trace metal transpon in low turbidity, high pH conditions. The results have implications for the measurement and modelling of chemical fluxes in low turbidity systems.

The speciation and particle-water interactions of Ni were investigated in three estuaries with contrasting pollution levels, hydrodynamics and geochemical characteristics. Samples of water and sediments were collected seasonally from the Tamar, Tweed and Mersey Estuaries. The chemical speciation of dissolved Ni was determined by adsorptive cathodic stripping voltammetry (ACSV), and the sorptive behaviour of Ni was studied under simulated estuarine conditions using " Ni coupled to liquid scintillation counting. A relatively high particle reactivity was observed only in the Tamar Estuary, where ACSV-non labile Ni was removed in the low salinity region, followed by addition of ACSV-labile Ni in the mid-estuarine region. The largely conservative behaviour of dissolved Ni in the Tweed Estuary was attributed to the combination of rapid flushing and low suspended particles concentration. In the Mersey Estuary, dissolved Ni (and Co, Zn, Cd and Pb) often showed positive deviations from conservative behaviour, which were attributed to anthropogenic and/or geochemical inputs. The fraction of ACSV-non labile Ni behaved differently in the three estuaries, with a sharp decrease from 90 to 30% from freshwater to seawater in the Tamar, scatter between 30 and 70% in the Tweed, and relatively constant values of 50-70% in the Mersey. These differences are interpreted within the context of different hydrodynamics and geochemistry of the three estuaries. Speciation modelling showed that between 30 and 70% of dissolved Ni in the Tweed, and between 50 and 70% in the Mersey, was bound to a class of strong ligands (log K'NIL = 19.0 ± 0.4 and 18.7 ± 0.5, respectively), which were saturated by the ambient concentrations of Ni throughout the estuaries, suggesting that the ligands are highly specific towards Ni. Irradiation of riverwater samples with UV light (believed to remove dissolved organic matter) significantly enhanced Ni uptake onto estuarine suspended particulate matter, with an increase in the 63Ni distribution coefficients (Kds) of up to 10 fold. Conversely, the addition of synthetic humic acids to UV-treated riverwater decreased significantly the 63Ni Kds. Complexation of Ni by dissolved natural ligands also affected the progression of sorptive reactions, with a system response time (i.e. the time required to achieve 63% of the sorptive equilibrium) between 1.6 and 8.9 hours. The results from this study suggest that the low particle reactivity generally exhibited by Ni during estuarine mixing is due to its ability to complex strongly with dissolved natural ligands (truly dissolved organic or colloidal organic/inorganic), and therefore resist adsorption onto particles.

In order to delineate the potential sources and to understand the main controls on the biogeochemical cycling of dissolved and particulate organic matter (DOM, POM) and dissolved inorganic nitrogen (DIN) during estuarine mixing, comprehensive seasonal geochemical and isotopic and surveys across the freshwater-tidal interface were carried out in the Tyne and Tweed Estuaries, NE UK. This study provided a contrast between a relatively pristine system (Tweed) with one that is heavily influenced by anthropogenic activity (Tyne). Geochemical and isotopic (13C, 14C and 15N) analyses demonstrated the predominance of terrigenous organic matter in both these estuaries, with elevated river discharges leading to enhanced terrestrial loading. High pCO2 values in the Tyne (summer) and Tweed (winter) suggested that a significant fraction of this terrestrially-derived organic matter (both DOM and POM pools) is relatively labile and can potentially undergo significant mineralization during estuarine mixing. In both estuaries in situ processing of DIN was relatively minor, with mixing between different sources being the main factor in controlling the distribution of nitrate and ammonium across the salinity gradient. However, anthropogenic ammonium discharges in the Tyne were found to have an enormous direct and indirect impact on estuarine nitrogen cycling. Large, concave removals of terrigenous high molecular weight (HMW) DOC caused by flocculation, biodegradation, and/or photochemical oxidation were associated with a non-conservative 13C-enrichment in d13C signatures. Radiocarbon dates showed an export of young (modern) HMW DOC and old (100-1000s of years), terrigenous POC to the North Sea. 14C-enriched values in coastal North Sea HMW DOC were attributed to anthropogenic discharges originating from within the coastal North Sea environment. In the Tweed, seasonal changes in soil characteristics resulted in an older age for POM during the summer. In the Tyne, decreases in POC% with increasing salinity sometimes coincided with an increase in POC age. This was attributed to mixing with older sediment and to the possible preferential loss of the younger, more labile POC fraction during mineralization. This study has shown that land use patterns, sewage inputs, and freshwater flushing time are the main influences in determining the behaviour and origin of organic matter and DIN entering the coastal North Sea in these two systems.

This essay explores ISKCON’s religious text A.C. Bhaktivedanta Swami Prabhupada’s commentary on the Bhagavad Gita, the Bhagavad Gita As It Is, as an American scripture. This commentary expressed a philosophy which attracted ISKCON’s American converts and gave voice to the protest they had against the larger American culture. Using Thomas Tweed’s theory of dissent, I show how the Bhagavad Gita As It Is gave the American converts of the 1960s and 1970s a language of dissent in the larger American conversation and allowed them to create an alternative American identity. In this way, the Bhagavad Gita is an American text.

In and around the 870s, Britain was transformed dramatically by the campaigns and settlements of the Great Army and its allies. Some pre-existing political communities suffered less than others, and in hindsight the process helped Scotland and England achieve their later positions. By the twelfth century, the rulers of these countries had partitioned the former kingdom of Northumbria. This thesis is about what happened in the intervening period, the fate of Northumbria's political structures, and how the settlement that defined Britain for the remainder of the Middle Ages came about. Modern reconstructions of the era have tended to be limited in scope and based on unreliable post-1100 sources. The aim is to use contemporary material to overcome such limitations, and reach positive conclusions that will make more sense of the evidence and make the region easier to understand for a wider audience, particularly in regard to its shadowy polities and ecclesiastical structures. After an overview of the most important evidence, two chapters will review Northumbria's alleged dissolution, testing existing historiographic beliefs (based largely on Anglo-Norman-era evidence) about the fate of the monarchy, political community, and episcopate. The impact and nature of ‘Southenglish' hegemony on the region's political communities will be the focus of the fourth chapter, while the fifth will look at evidence for the expansion of Scottish political power. The sixth chapter will try to draw positive conclusions about the episcopate, leaving the final chapter to look in more detail at the institutions that produced the final settlement.