Suspended sediments were collected from 3 rivers, the Rheidol, Ystwyth and Tywi on a regular basis. The sediment samples were studied for a number of physical and chemical properties to identify characteristics which might distinguish between source areas. These properties included mineralogy, magnetic properties, sediment colour, and the trace element composition of .sediments. Point-sources for heavy metals can be identified for all three catchments, and the metal content, and partitioning was studied. The metal content, and the site on the sediment to which the metal is bound has been found to vary with discharge. The response to discharge is not the same for all metals, but in general, at peak discharge the lead was in the Fe/Mn oxide and organic fractions, and these fractions became important for cadmium. Prior to the flood peak however, up to 70% of the cadmium was in easily exchangeable form. The organic fraction was the most important for copper throughout the flood. j Sediments which had been deposited in floodplain features and in lakes were also studied, as they recorded the pattern of sediment transport during floods over an extended period. In the Ystwyth catchment the metal content and ratios between metals was used to determine the importance of two mining areas for the supply of sediment to a floodplain during the mining period (1860-1890). Sediments from profiles in fossil alluvial channels on a floodplain in the Rheidol showed a dramatic increase in metal .concentrations in the mid-profile, and recorded the period of concerted mining in the catchment. Mining operations in the Ystwyth catchment caused widespread lateral aggradation of floodplains, as established at Trawscoed. The historic record of catchment changes as contained in the sedimentary profile of reservoirs in the Mendips was studied. The record in Blagdon and Chew Valley lakes in the Mendips was deciphered using a combination of sedimentological, magnetic and chemical data. A catastrophic flood which is documented for the area, which occurred in July 1968, caused the mobilisation and transportation of sediments from dry valleys in the catchment. Sediments deposited during the floods were distinguished by their coarse nature, by an increase in magnetic susceptibility and the parameter'S', which indicated a topsoil source, and by a change in the partitioning of lead and zinc, where the organic fraction was absent.

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Parks Canada focuses its tourism and conservation efforts in Kouchibouguac National Park along the park's diverse coastline made up of a variety of sensitive ecosystems including salt marshes, stream estuaries and a shifting barrier island lagoon system. The dynamic sediment processes in the park are not fully understood, making it difficult for Parks Canada to make informed decisions as sea-level rise in the region accelerates. In this study, extensive field data were collected in two sediment zones bordering the Kouchibouguac Lagoon. Stream data were collected and used to estimate the monthly average sediment load entering the lagoon. The maximum and minimum monthly average sediment loads were 130 g/s and 11 g/s in April and September, respectively. These freshwater sediments pass through estuaries to deposit at the coastline of the park. Changes in the barrier system surrounding the tidal inlet Little Gully were also monitored over 15 months using modern surveying techniques. The surveys showed a general southward shift in the study area and a landward migration of sediments within the flood tidal delta of the inlet. Dune surface area, volume, and vegetation cover were also examined, and the critical shear stress and velocity of the sediments were calculated. The field investigations revealed that the Kouchibouguac Lagoon was gradually filling in with sediments during the study. It is recommended that a permanent hydrometric station be installed in one of the major streams in the park and that future research along the coastline of the park complement Parks Canada's current monitoring program for the barrier island system.

Understanding of the processes of sediment transfer within, and from, glaciated catchments is of fundamental importance in order to establish rates of sediment transfer and resultant landscape evolution. Rates of glacio-fluvial sediment transfer are strongly controlled by glacier meltwater runoff and the availability of sediments for entrainment. However, it is becoming apparent that recently deglaciated forefields can modify the patterns of suspended sediment transfer. Glacier shrinkage exposes areas of unstable glacigenic sediments that can be subject to reworking and redistribution, and, as these environments become ice-free, heightened levels of geomorphological activity (so-called 'paraglacial' activity) are also likely to have a significant impact on both sediment and water yields from deglaciating catchments. Consequently, questions are raised as to the impacts of deglaciation upon contemporary and future rates of suspended sediment transfer, and the resultant fluvial sediments loads and rates of landscape adjustment. Therefore, the aim of this research was to present an integrated study of how sediment transfer in a glaciated catchment functions during, and is responding to, deglaciation. A variety of techniques were employed to examine the hydrological functioning of an Alpine glacier, the Feegletscher Nord, Switzerland, and the resultant temporal and spatial patterns of sediment transfer in light of catchment hydrology, ablation processes and forefield geomorphology. Data was collected over two field campaigns in 2010 and 2012 to capture the inputs, throughputs and outputs of meltwater and sediment. This research found that patterns of sediment transfer were modified within the proglacial zone, reinforcing previous findings that the location of proglacial monitoring is important in determining the observed patterns of sediment transfer. These patterns of sediment transfer were attributed to variations in forefield sediment availability, which appeared to demonstrate marked spatial variability. This variability was hypothesised to be influenced by the geomorphological characteristics of the forefield, including rock fall debris that appeared to limit sediment availability, and glacigenic sediment deposits that enhanced the availability of in-channel and channel-marginal sediments. These findings suggest that the investigation of rates of sediment transfer and paraglacial sedimentation may be complicated in catchments that have experienced complex geomorphological responses to deglaciation. In addition, the investigation of sediment transfer processes and the development of a glacier runoff model enabled the exploration of future suspended sediment loads with progressive deglaciation and a changing climate. Suspended sediment loads were predicted to experience rapid declines until the end of the 21st Century due to reductions in meltwater runoff as glacier extent is reduced. However, it is suggested that uncertainties in future sediment availability limit the usefulness of such forecasts. Consequently, this research highlights how the understanding of both sedimentary and hydrological processes in glaciated catchments may be enhanced by consideration of the changes that can occur in these environments associated with glacier shrinkage and a changing climate.

Rivers have been the recipients of waste for millennia. However, since the onset of industrial and urban development, major degradation of fluvial systems has been observed globally. This has encompassed a wide range of contaminants from numerous potential sources. Despite efforts to reduce inputs, contamination continues to persist in many catchments. Metal contamination of fluvial sediments is a well-established problem. Conversely, microplastics are an emerging contaminant, for which there is a paucity of data regarding their sources, behaviour, and fate. Based on the onset of industrialisation, Manchester is often heralded the 'first industrial city'. During the industrial period, the fluvial network became heavily contaminated. By the 1970s, it was amongst the most polluted river systems in Europe. Despite this background, no study has thus far undertaken a systematic, catchment-wide survey of sediment-associated contamination. This study assesses patterns of metal and microplastic contamination in fluvial sediments of the Irwell and upper Mersey catchments (1527 km2), which comprise the Manchester river network, from the onset of the industrial period to the present day. Five metal(loid)s have been studied and microplastics are assessed by type, size, and density for the first time. Metal concentrations in fine-grained bed sediments are heavily enriched across the entire fluvial network, even in headwater reaches. By examining spatial patterns, it is possible to attribute a portion of this to the reworking of historically-contaminated material; although, modern, urban sources are also important. Sources of metals to channel beds are numerous and spatially complex. This is also the case for microplastic contamination; although, microplastic particles are not bound to natural sediments and exert more transient behaviour in fluvial systems. Following an extreme flood event on Boxing Day 2015 and a sustained period of high flows (winter 2015/16), metal contamination was shown to present markedly conservative behaviour despite significant reworking of bed sediments. Metal mobility was generally low and was not affected in the long-term by hydrological processes. Despite this, the results indicate that bed sediment-associated metal contamination is likely to persist into the future at levels that exceed sediment quality guidelines. In contrast, flooding is very effective in flushing high concentrations of microplastics from channel beds. This suggests that microplastic contamination can be effectively reduced through source control. The environmental significance of microplastic contamination was directly observed through the ingestion of microplastics by freshwater Tubifex worms at the distal end of the Irwell system (Salford Quays). Microplastic concentrations within worm tissue were high, indicating an increased risk for trophic transfer. This also presents a potential link to the human food chain. Furthermore, both metals and microplastics accumulate in floodplain deposits. Floodplains are effective in preserving microplastics, recording the temporal evolution of microplastic contamination over the last 75 years. Maximum values are observed in the late 1960s/early 1970s. Conversely, elevated metal concentrations occur much earlier and reflect catchment-wide patterns of industrialisation and urban growth. Reworking of channel banks forms a secondary source of metals and microplastics to the active river channel and downstream environments that will persist long into the future. Thus far, microplastics have passed under the monitoring radar and sediment contamination is rarely given due consideration in assessments of river quality, such as in the Water Framework Directive. However, this study shows that both metals and microplastics within fluvial sediments are important contaminants and have significant implications for the health of the entire aquatic system.

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