Suspended sediments (SS) are a natural component of streams and rivers, critical for habitat heterogeneity and ecological functioning. However, human activities can cause a significant deviation in the dynamics of SS from the ‘natural’ or ‘reference’ condition, resulting in serious ecological degradation and a decline in valuable ecosystem services. In recognition of the potential for SS to cause aquatic degradation, and in an effort to minimise this, government-led environmental organisations around the world have established water quality guidelines and standards that state recommended targets for SS (sometimes referred to as suspended solids, and occasionally assessed through proxy measurements such as turbidity). However, at present these guidelines are often blanket values that do not recognise the natural spatial and temporal variation of SS in streams/rivers, are poorly linked to the biological/ecological impact evidence, and therefore ultimately may not reflect the specific requirements of the biological communities that they are designed to protect.

The aim of the research has been to determine the environments of deposition of the Grindslow Shales and Kinderscout Grit in an area north of the Derbyshire Dome. These units overly the Mam Tor Sandstones and Shale Grit, which are thought to be turbidites showing increasing proximity to scource. The Grindslow Shales had been interpreted as the slope down which the turbidity currents were generated. Little was known of the depositional environment of the Kinderscout Grit, though shallow water conditions had been suggested. The sequence, from the base of the Mam Tor Sandstones to the top of the Kinderscout Grit, falls within the zone R₁c of the Namurian. The outcrops of the Kinderscout Plateau, Derwentdale and Longendale have been mapped and numerous sections measured. In all, 17 facies have been recognised, described and interpreted in hydrodynamic terms on the basis of their internal evidence. Three silts tone facies and one of silty sandstone are thought to be largely deposited from suspension, while fine sandstone, showing ripples and cross-lamination, is interpreted as showing lower flow regime conditions. Parallel laminated fine sandstone is interpreted as an upper flow regime deposit. Facies 8, Massive Bedded Coarse Sandstone, is not, in the first instance, interpretable in hydrodynamic terms. Facies 9, Parallel Bedded Coarse Sandstone, is interpreted as an upper flow regime deposit, while Facies 10, Medium Scale Cross-Bedded Coarse Sandstone is attributed to the lower flow regime along with Facies 11, Medium Scale Cross-Bedded Fine Sandstone. Facies 12, Large Scale Cross-Bedding, consists of single tabular sets of cross-bedding up to 40 m. thick, mainly of very coarse sandstone. These are ascribed to the advance of delta-like sedimentation units into bodies of standing water. Other facies, of minor importance,are Sharp-Based Clean Sandstone Beds, Orthoconglomerates, Seat Earths and Coals, Mudstone Melange and Turbidite-like Sandstones. Three types of trace fossil have been recognised, though it is concluded that they are probably of little environmental significance. Five facies associations are recognised, in which facies succeed one another with variable predictability. The Major Channel Association involves Facies 8, 9 and 10, Massive, Parallel and Cross-Bedded Coarse Sandstones, resting in channels up to 40 m. deep. Other details of channel geometry are not clear, though widths of 300-400 m. have been calculated. There is a preferred upwards facies sequence within the channels of Erosion Surface → Facies 8 → Facies 9 → Pacies 10. From hydrodynamic considerations of the sequence, it is suggested that the Facies 8 Massive Bedded Sandstone was deposited by currents flowing in the upper part of the upper flow regime, the whole channel sequence representing a waning flow. The Large Scale Cross-Bedding Association involves Facies 12 and 10, the medium scale cross-bedded sandstone being separated from the underlying Large Scale set by an erosion surface. It is suggested that the Association represents delta cones which advanced into bodies of standing water, subsequent to sudden deepening. The Fluviatile Channel Association is a fining upwards sandstone sequence with a horizontal erosion surface at its base. Facies 10, Medium Scale Cross-Decided Coarse Sandstone forms the bulk of the association, though thin beds of Orthoconglomerate and mudflake conglomerate may occur above the erosion surface. In the top of the association, the cross- bedded sandstone passes into parallel or ripple laminated fine sandstone and sometimes into seat earths and coals. The association is interpreted as the result of the lateral migration of a fluviatile channel, probably of the meandering type. The Slope Association, which has limited stratigraphical position, is a broadly coarsening upwards silts tone and silty sandstone sequence. Thin turbidites occur in the base and burrows become abundant towards the top. It has occasional large channels, filled mainly with turbidites. The association is interpreted as the prograding slope of a coastline receiving abundant sediment supply. The Interdistributary Complex Association is a random sequence of predominantly fine grained facies, showing a variety of flow conditions. It is interpreted as forming in shallow water conditions, probably in interdistributary areas of a delta top. An analysis of the relationships of the facies associations throughout the area gives the following generalised sequence:- 'Gracile' Marine Band. Fluviatile Channel Association Slope or Interdistributary Complex Upper Kinderscout Grit Butterley Marine Band Fluviatile Channels and Interdistributary Complex Association Large Scale Cross-Bedding Lower Kinderscout Grit Major Channels Interdistributary Complex Association Grindslow Shales Slope Association From a consideration of this sequence, it is concluded that the Grindslow Shales represent the main southwards advance of the delta slope and delta top environments across the area. The major channels which erode into the Interdistributary Complex Association sediments of the top of the Grindslow Shales were non-migrating distributaries which underwent frequent diversion and cut-off. They had high flow regime currents and were possibly associated with a period of eustatically falling sea level. A subsequent eustatic rise led to the ponding up of sediment on the delta, top with the formation of delta cones. Above the delta cones, meandering river channels and interdistributary areas were the main features of the palaeogeography. The Butterley Marine Band and its overlying unit of Slope Association suggest a further eustatic rise of sea level. The Upper Kinderscout Grit is thought to be the deposit of laterally migrating rivers. Comparison with the succession further north gives additional evidence of eustatic changes of sea level and suggests ways in which the palaeogeography might have responded to these. It is suggested that the turbidity currents in the basin possibly originated as high flow regime traction currents in the major channels on the delta top, at times of flood.

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This work was carried out as part of the Natural Environment Research Council's geochemical cycling programme. Its aim was to identify the changes taking place in the constituent minerals as Silurian Gwestyn Shale weathers to a humic stagnopodsol soil at Plynlimon, mid Wales. Hand specimen appearance and chemical analyses show that the rock groups present at Plynlimon are not homogeneous. The chlorites in different rocks are also shown to have significantly different chemical compositions, and are seen to be physically intergrown with-mica. Another source of variation is that many of the soils are developed on glacial or periglacial deposits, rather than directly on rock.

Microbial biogeography explores the spatial and temporal distribution of microorganisms at multiple scales and is influenced by environmental selection and passive dispersal. Understanding the relative contribution of these factors can be challenging as their effects can be difficult to differentiate. Dormant thermophilic endospores in cold sediments offer a natural model for studies focusing on passive dispersal. Understanding distributions of these endospores is not confounded by the influence of environmental selection; rather their occurrence is due exclusively to passive transport. Sediment heating experiments were designed to investigate the dispersal histories of various thermophilic spore-forming Firmicutes in the River Tyne, a tidal estuary in North East England linking inland tributaries with the North Sea. Microcosm incubations at 50-80°C were monitored for sulfate reduction and enriched bacterial populations were characterised using denaturing gradient gel electrophoresis, functional gene clone libraries and high-throughput sequencing. The distribution of thermophilic endospores among different locations along the estuary was spatially variable, indicating that dispersal vectors originating in both warm terrestrial and marine habitats contribute to microbial diversity in estuarine and marine environments. In addition to their persistence in cold sediments, some endospores displayed a remarkable heat-resistance surviving multiple rounds of autoclaving. These extremely heat-resistant endospores are genetically similar to those detected in deep subsurface environments, including geothermal groundwater investigated from a nearby terrestrial borehole drilled to >1800 m depth with bottom temperatures in excess of 70°C. The ability of these endospores to survive extreme temperatures whilst in a dormant state may enable them to withstand adverse conditions for long periods of time and then germinate in response to changing surroundings. This was investigated further in the context of seawater injection during secondary oil recovery, where cold seawater is injected into hot oil reservoirs, resulting in a cooler reservoir temperature near the injection well bore. Microcosm experiments designed to simulate this showed that cooling triggered the germination of endospores of sulfate-reducing Desulfotomaculum leading to the onset of souring in this model system. The results presented here, indicate that bacterial endospores are transported between terrestrial and marine, surface and subsurface environments. Their survival and distribution therefore has ii relevance to understanding deep biosphere processes, and factors shaping microbial diversity in the marine environment.

Coastal deposits are often classified based on the depositional processes (wave, tide, fluvial) which operate in the depositional environment. The mix of processes operating during deposition have an effect on the size, shape, orientation and internal heterogeneities of sand- and sandstone bodies. It is important to know these properties for predicting and modelling fluid flow through aquifers. Facies models for fluvial-dominated deltas and wave-dominated shorefaces are well established and widely used. However, although there are many modern tide-influenced deltas, research in facies models for tide-influenced deltas lags behind to their better studies fluvial- and wave-dominated counterparts. This is partially because tide-dominated deposits are often interpreted in a sequence stratigraphic framework as transgressive tide-dominated estuaries. The aim of this study is to present a facies model for mixed-influence deltas, with emphasis on the preservation of channelised fluvial- and tidal channels in a progradational setting. Two case studies are part of this thesis. Firstly, outcrops of the Upper Cretaceous Sego Sandstone (Utah, USA) have been studied in order to investigate the facies architecture of a mixed tide- and wave influenced deltaic deposit. Secondly, cores of the mixed influence Lower to Middle Jurassic Ror, Tofte and Ile formation from the subsurface of the Halten Terrace (offshore mid-Norway) have been examined. Both case studies were deposited in structurally controlled embayments which favoured amplification of tides. Both case studies show an initial progradational phase with little evidence for tidal processes. In contrast, deposits on the delta plain show abundant evidence for tidal currents. In this study, it has been interpreted that these channelised tidal channels are part of continuous progradation of a tide-influenced delta. This is in contrast to sequence stratigraphic models in which tide-dominated deposits are interpreted as part of a transgressive phase. During progradation, these tidal and fluvial channels erode down in underlying deposits and they are deposited in progressively more basin-ward positions. More tide-dominated channels deposited in relatively distal or off-axis locations have a more planar geometry. More fluvial-dominated channels deposited in relatively proximal or on-axis location are more lenticular.

The erosion, transport and deposition of sediment create environmental problems and social issues worldwide. Due to these ecological, environmental and economic implications for society, the importance of protecting and managing the sediment and soil resource is increasingly recognised through legislation and government policy. These legislative drivers have inspired the development of new and innovative approaches towards applied sediment management research, to develop effective erosion and pollution control strategies and improve the understanding of sediment transport processes to inform management decisions. To implement real change and inspire a holistic view of coastal and catchment management, of which sediment is critical, it is necessary to fully understand how sediments, contaminants and microbes move around the planet and the environmental impact that this constant flux of material has on the wider environment and on specific ecosystems. As sediment and soil are a fundamental resource for humans appropriate management of these resources requires a full understanding of these issues. Crucial to this is the use of direct field techniques, practically able to identify the sediment sources, transport pathways and sink areas of different soil and sediment types. Active sediment tracing is a field technique which uses materials designed to replicate the movement of sediment, whilst remaining identifiable within the native sediment load. Active sediment tracing techniques have been developed over the last century, yet despite extensive study, the ‘perfect’ sediment tracer and field methodology remains elusive. Sediment tracing provides a unique applied sediment and soil research and management tool able to provide information which can be used to protect ecological habitats, inform sediment and soil management, and provide information and quantitative data to improve environmental modelling approaches. The development of a robust tool able to provide direct field information regarding sediment transport dynamics is important as sediment flux and deposited sediments and the associated contaminants and microbes negatively impact the environment and society as a whole. The development of informed management strategies is therefore crucial to maintain the sediment and soil resource for future generations. Sediment tracing methodologies and tracer design has progressed significantly in the last century recovering from significant setbacks (i.e. the environmental ban on the use of irradiated grains) and fluctuations in popularity due to the somewhat resource intensive nature of a sediment tracing study. Recent technological developments have reinvigorated the technique and led to original application and commercial enterprise within the sector. A variety of sediment tracers are now available. Each tracer material has unique benefits and limitations. The search for the ‘perfect’ sediment tracer is ongoing. Here the evaluation and application of a novel dual signature sediment tracer are described. The tracer has two signatures: fluorescence and ferrimagnetism which is considered an advance on previously used mono-signature tracers. The tracer provided unique opportunities to employ a variety of techniques to monitor tracer within, and recover tracer from the environment. These techniques were applied within an informed methodological framework developed to provide consistency of methodological approach within all active sediment tracing studies across disciplines. The framework provides a clear and robust step by step guide to conducting a sediment tracing study. Further it has outlined a range of techniques useful to practitioners with a focus on the practical application of the technique to the field. Field trials were conducted to investigate real world sediment management problems, these being: soil erosion within an agricultural field; sand transport on a beach within a complex anthropogenically affected environment; and, the release of fine material as part of nearshore dredging activities. The soil erosion study showed the tracer had the potential to be applied to trace multiple size classes and different soil types and explored the potential use of both passive and active sampling techniques to determine a soil erosion rate. The results indicated that the dual-signature tracer was an effective tracer of soil and showed strong potential as an applied soil management research tool. The beach face study demonstrated the utility of sediment tracing within the sediment and coastal management arena and again explored the use of passive and active sediment tracing approaches to optimise sediment monitoring and recovery from the field. The field trials successfully delineated the sediment transport pathways on the beach face in a complex environment. The study of the dispersion of fine material in the nearshore coastal zone demonstrated the critical role of tide and current in the near and far field transport of disposed dredged sediment. The spatiotemporal distribution and sedimentation pattern of the discharged particles was mapped over a tidal scale to determine the immediate, near and far field impact of disposed dredge material. The results highlighted the potential for significant redistribution of fine sediment through the nearshore coastal zone, with potentially significant environmental impacts. These three distinct field trials provide highlights the utility of active sediment tracing studies to further our understanding of sediment transport within different environments. These data are useful to manage and mitigate the associated impacts of eroded and transported sediment on the environment. The dual signature tracer was found to be an improvement over previously used, mono-signature tracers. Throughout laboratory testing and field trials the tracer upheld the key fundamental assumptions of an active sediment tracer. The tracer imitated the hydraulic properties of natural sediments, whilst not disrupting the transport system and remaining identifiable within the native sediment load. For each field application a practical, multifaceted, sampling approach was developed which increased the quantity and quality of information garnered from each tracing study: an advance since sediment tracing studies fundamentally comprise an empirical evidence-based approach. Further, the development of an analytical procedure which reduced timescales and associated costs, has improved the benefit-cost ratio of an active sediment tracing study. Continued development of the active tracing methodology can increase and enhance application of these techniques in both conventional and novel contexts. This thesis has provided baseline data for future studies utilising dual-signature tracer within laboratory or field research, or industry based studies.

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No description available.

A full understanding of the processes controlling the movement of pesticides within the soil 1 water regime is critical to the successful reduction of losses of these substances to surface waters. Until recent years the importance of absorbed phase transport of pesticides has largely been ignored with respect to drainflow and the appearance of strongly absorbed hydrophobic compounds in riverine sediments has hitherto been largely attributed to surface runoff 1 erosion. Field studies were setup for the 1994/5 winter season to investigate the hydrology and chemistry associated with drainflow from the lighter clay soils of Boarded Barns Farm, with two calcareous (Hanslope and Stretham) and two non-calcareous (Melford and Ludford) soils being chosen for study. Instrumented study plot areas were established in each field, with drainflow measurement and water sampling being automated. Laboratory based investigations (including rainfall simulation and desorption) were carried out to support, extend and clarify the field data, in particular the processes involved in the transport of isoproturon and sediment. A striking feature seen in the field studies was the appearance of large amounts of suspended sediment in drainflow from the Melford soil, in contrast to the clear drainflow from the calcareous soils. The sediments in drain flow were identified as being of surface origin, generated by rainfall impact and transported via preferential by-pass flow. Laboratory investigations have indicated that the chemical nature of the topsoil is a dominant factor controlling the transport of sediments and clay flocculation due to the presence of calcium carbonate is proposed as a mechanism for preventing sediment transport in the calcareous soils. Where sediment was found in drainflow, it was shown to be responsible for the transport and losses in the absorbed phase of not only diflufenican, a strongly absorbed pesticide, but also isoproturon, a weakly absorbed pesticide. The laboratory studies indicate that isoproturon is transported predominantly absorbed to sediment and later desorbs 1 diffuses slowly into the aqueous phase of the receiving waters. The results of the field experiments were confirmed by the rainfall simulation studies on 20cm deep (20cm diameter) topsoil cores taken from the field, which showed sediment transport only in the non-calcareous soil. The extent of this phenomena of sediment transport in the UK is not well defined, due to the historical lack of research, however soils known to show the effect have a land coverage of 6% of England and Wales. The present study highlights an additional mechanism by which pesticide losses to surface waters may occur, but the relative importance will depend heavily on the hydrological, structural and chemical nature of the soil system.