Fjord Sediments Research Articles

Ecosystem effects of materials proposed for thin‑layer capping of contaminated sediments

Ecotoxicological effects of 2 carbonaceous and 7 mineral capping materials suggested for in situ remediation of contaminated sediments in the Grenland fjords, Norway, were investigated in a mesocos ...

Geochemistry of surface sediments from the fjords of Northern Chilean Patagonia (44–47°S): Spatial variability and implications for paleoclimate reconstructions

The Patagonian fjords have a clear potential to provide high-resolution sedimentary and geochemical records of past climate and environmental change in the Southern Andes. To improve our ability to interpret these proxy records, we investigated the processes that control fjord sediment inorganic geochemistry through a geochemical, mineralogical and sedimentological analysis of surface sediment samples from the fjords of Northern Chilean Patagonia. A simple Terrestrial Index based on measurements of salinity and Fraction of Terrestrial Carbon was used to estimate the terrestrial input/river discharge at each site. Our results demonstrate that, under the cold climate conditions of Patagonia, chemical weathering is weak and the inorganic geochemical composition of the fjord sediments is primarily controlled by hydrodynamic mineralogical sorting, i.e., the intensity of river discharge. Our results suggest that the distribution of Fe, Ti and Zr in surface sediments is controlled by their association with heavy and/or coarse minerals, whereas Al is independent of hydrodynamic processes. The elemental ratios Fe/Al, Ti/Al and Zr/Al are therefore well suited for estimating changes in the energy of terrestrial sediment supply into the fjords through time. Zr/Al is particularly sensitive in proximal environments, while Fe/Al is most useful in the outer fjords and on the continental margin. In the most proximal environments, however, Fe/Al is inversely related to hydrodynamic conditions. Caution should therefore be exercised when interpreting Fe/Al ratios in terms of past river discharge. The application of these proxies to long sediment cores from Quitralco fjord and Golfo Elefantes validates our interpretations. Our results also emphasize the need to measure Al-based elemental ratios at high precision, which can be achieved using simultaneous acquisition ICP-AES technology. This study therefore constitutes a strong basis for the interpretation of sedimentary records from the Chilean Fjords.

Re-examining Southern Hemisphere westerly wind behavior: insights from a late Holocene precipitation reconstruction using New Zealand fjord sediments

The behavior of the Southern Hemisphere westerly winds (SWW) is inherently linked with climate variability. Understanding past SWW-climate feedbacks is key to predicting future climate change; however we are limited by a lack of SWW reconstructions, particularly from the southwest Pacific. Here we examine fjord sediments from Fiordland, New Zealand (44.5–46.5°S), to determine how the SWW have fluctuated in position and strength in response to regional late Holocene climate change, and we compare our record to Patagonia climate reconstructions in order to evaluate large-scale SWW behavior. SWW flow over the Southern Alps of New Zealand drives orographic rainfall that is recorded within fjord sediments as changes in the relative contributions of terrestrial to marine organic matter, which can be measured by bulk sediment δ 13C and organic C/N ratios. Using these proxies, cores from three New Zealand fjords show that precipitation decreased between 1400–1100 and 750–150 cal yr BP with short-duration shifts toward drier conditions at 1900 and 900 cal yr BP. Precipitation increased 2100–1400 and 1100–700 cal yr BP with a short interval of wetter conditions around 400 cal yr BP. These results indicate that westerly airflow over New Zealand was stronger (weaker) during intervals of relatively warm (cool) climate. Our comparison of precipitation reconstructions from Fiordland and Patagonia shows dissimilarities in SWW flow between regions. While to date, most mechanisms for changing the SWW have invoked purely zonal shifts, our results suggest that meridional changes in SWW flow occurred in addition to zonal shifts. In Fiordland, the meridional airflow associated with −SAM and/or El Niño-like climate phenomena may be responsible for wet intervals, while +SAM and/or La Niña-like phenomena may promote dry conditions.

Metal Partitioning in Ilmenite- and Barite-Based Drill Cuttings on Seabed Sections in a Mesocosm Laboratory

Summary Ilmenite and barite minerals are alternative weight materials frequently used in drilling muds and are discharged to the marine environment. These minerals contain heavy metals that may become remobilized and available for uptake in biota after deposition in sediment. Several oil companies have jointly developed a model to predict the environmental risks associated with discharges of drill cuttings and mud to sea (DREAM). This model applies partition coefficients (Kd) for estimating heavy-metal concentrations in sediment and interstitial waters from which toxic impacts are derived. Kd depend on properties of both the particulate phase and the solute and consequently on local environmental conditions such as redox potential and pH. The literature displays Kd values ranging over several orders of magnitude, and it is a challenge and a major environmental issue to determine the most representative Kd values for drilling discharges in marine offshore areas. An experiment was performed in box-core samples transferred from a fjord location to a marine soft-bottom mesocosm. Weight minerals and cuttings sampled from offshore drilling operations were added in thin layers on top of the fjord sediment in each box. During the next 3 months, the added layers were reworked by the naturally occurring benthic fauna. Environmental parameters such as dissolved oxygen, hydrogen sulfide, and redox potentials were determined as well as metals in added solids, sediments, interstitial water, and fluxes across the sediment/ water interface. Kd values were obtained for seven metals. To the extent that the experimental environment was able to mimic the offshore environment with respect to bioturbation and physicochemical gradients within the sediment surface, the Kd values obtained are considered relevant for modeling interstitial-water concentrations and toxicity in offshore cuttings deposits.

Exotic pollen as an indicator of variable atmospheric circulation over the Labrador Sea region during the mid to late Holocene

AbstractVariability in the abundance of exotic (non‐native) pollen in sediment cores has long been considered as a potential proxy for changing atmospheric circulation, but the difficulty of gaining sufficient total exotic pollen and the incomplete understanding of atmospheric pollen transport patterns has hindered its application. In light of recent advances in the study of pollen transport, we present an exotic pollen record from two fjord sediment cores taken from the west (Placentia Bay, Newfoundland) and east (Narsaq Sund, Greenland) Labrador Sea as a basis for studying variations in regional atmospheric circulation. The two cores cover the last ca. 5500 years and indicate a shift in dominant spring/summer air masses at ca. 2000 (southern Greenland) and 3000 cal a BP (Newfoundland) transporting reduced concentrations of pollen from southerly and south‐westerly vegetation zones. This may suggest a shift away from more dominantly zonal atmospheric circulation (a feature of positive North Atlantic Oscillation years) to more frequent meridional circulation. These results support sea ice/sea‐surface temperature proxy reconstructions from Newfoundland, investigated as part of the same project, which also suggest increased winter atmospheric circulation during the early part of the time period studied. In this region, more positive North Atlantic Oscillation years, and therefore more zonal atmospheric circulation, are associated with increased atmospheric circulation in both the winter and the summer seasons. Copyright © 2011 John Wiley & Sons, Ltd.

Turbiditic, clay‐rich event beds in fjord‐marine deposits caused by landslides in emerging clay deposits – palaeoenvironmental interpretation and role for submarine mass‐wasting

AbstractDistinct, clay‐rich beds are common in fjord‐marine deposits in Trondheimsfjorden near the outlet of the Nidelva River. Their characteristic light‐grey colour makes the beds easily distinguishable from the surrounding brownish, bioturbated, muddy fjord sediments. The clay‐rich beds commonly display a clear stratification in clay, silt and very fine sand. The beds are interpreted as originating primarily from large quick‐clay landslides upstream along the Nidelva River. Such events resulted in a sudden increase in the supply of fines to the fjord from disintegrating landslide debris and heavily loaded effluent plumes, possibly favouring hyperpycnal flow. Typical beds can be divided into a clay‐rich lower section, reflecting an initial surge with high concentrations of suspended mud, and a sandier upper section reflecting pulses of higher energy. This development can be explained, for example, by a lowering in the supply of mud, an increasing activity of deltaic sediment gravity flows due to a higher availability of sandy sediments in the landslide‐affected river, and by flooding and/or breaching of landslide dams. The typical, stratified beds are interpreted as the result of one quick‐clay landslide, whereas exceptionally thick, less organized, stratified beds are possibly the result of several large and/or complex landslides. Radiocarbon dating of mollusc shells has helped to establish a chronology for major terrestrial landslides in the area. The frequency of landslides increases towards the end of the Holocene. This is explained by a progressively deeper incision of rivers during glacioisostatic rebound, possibly combined with a change to a wetter climate. The marine core record displays deformation structures and hiati representing submarine mass‐wasting events, and supports the evidence that the clay‐rich beds are weak layers in the fjord‐marine stratigraphy. The inherent weakness of these layers may be explained by their composition, immature texture, loose fabric and contrasting permeabilities in the deposits. Slide‐prone layers similar to the clay‐rich beds described here may be found in other comparable fjord‐marginal settings and are considered to be of importance for geohazard assessments.

Filamentous sulfur bacteria, Beggiatoa spp., in arctic marine sediments (Svalbard, 79°N)

Fjord sediments on the west coast of the arctic archipelago Svalbard were surveyed to understand whether large filamentous sulfur bacteria of the genus Beggiatoa thrive at seawater temperatures permanently near freezing. Two sediments had abundant populations of Beggiatoa, while at six sites, only sporadic occurrences were observed. We conclude that Beggiatoa, although previously unnoticed, are widespread in these arctic fjord sediments. Beggiatoa ranged in diameter from 2 to 52 microm and, by those tested, stored nitrate in vacuoles at up to 260 mM. The 16S rRNA gene sequence of a 20-microm-wide filament is closely associated with other large, marine, nitrate-storing Beggiatoa. The Beggiatoa mostly occurred in the upper 2-5 cm of oxidized surface sediment between oxygen and the deeper sulfidic zone. In spite of a very low or an undetectable sulfide concentration, sulfate reduction provided abundant H(2)S in this zone. The total living biomass of Beggiatoa filaments at one study site varied over 3 years between 1.13 and 3.36 g m(-2). Because of their large size, Beggiatoa accounted for up to 15% of the total prokaryotic biomass, even though the filament counts at this site were rather low, comprising <1/10,000 of the bacterial numbers on a cell basis.

Role of sulfate reduction and methane production by organic carbon degradation in eutrophic fjord sediments (Limfjorden, Denmark)

The anaerobic mineralization of buried organic matter through sulfate reduction and methanogenesis was studied in 2‐m‐long piston cores of organic‐rich, silty‐clay sediment from two sites in Limfjorden, Denmark. An extended sulfate‐methane transition (SMT) zone was found at 1–1.5‐m sediment depth, accompanied by peaks in sulfide (4–6 mmol L−1) and high dissolved inorganic carbon (30–50 mmol L−1). Pore‐water acetate concentrations were 2‐10 µmol L‐1. 14C‐acetate was oxidized to 14CO2 in the sulfate zone and reduced to 14CH4 at and below the SMT. CO2 reduction was the predominant pathway of methanogenesis below the sulfate zone. Sulfate reduction rates (SRRs) determined by 35S tracer experiments decreased with depth throughout the sulfate zone from &gt; 100 nmol cm−3 d−1 near the sediment surface to &lt; 1 nmol cm−3 d−1 at depth. The depth trend of rates was equally well described by a power law function and a reactive continuum model. Only a small percentage of the total 35S‐SRR was due to anaerobic oxidation of methane. In contrast, diffusion‐reaction modeling of pore‐water sulfate indicated that sulfate reduction was insignificant throughout the sulfate zone and that most of the activity occurred at the SMT. A comparison of the burial flux of organic carbon below the sulfate zone and the returning flux of methane indicated that the diffusion modeling of pore‐water sulfate strongly underestimated in situ SRRs, whereas the 35S data may have overestimated the rates at depth. Modeled and measured SRR could be reconciled provided that bioirrigation reached to at least 20–40‐cm sediment depth, which appears realistic given the predominant burrowing polychaete fauna.

Thermophilic anaerobes in Arctic marine sediments induced to mineralize complex organic matter at high temperature

Marine sediments harbour diverse populations of dormant thermophilic bacterial spores that become active in sediment incubation experiments at much higher than in situ temperature. This response was investigated in the presence of natural complex organic matter in sediments of two Arctic fjords, as well as with the addition of freeze-dried Spirulina or individual high-molecular-weight polysaccharides. During 50 degrees C incubation experiments, Arctic thermophiles catalysed extensive mineralization of the organic matter via extracellular enzymatic hydrolysis, fermentation and sulfate reduction. This high temperature-induced food chain mirrors sediment microbial processes occurring at cold in situ temperatures (near 0 degrees C), yet it is catalysed by a completely different set of microorganisms. Using sulfate reduction rates (SRR) as a proxy for organic matter mineralization showed that differences in organic matter reactivity determined the extent of the thermophilic response. Fjord sediments with higher in situ SRR also supported higher SRR at 50 degrees C. Amendment with Spirulina significantly increased volatile fatty acids production and SRR relative to unamended sediment in 50 degrees C incubations. Spirulina amendment also revealed temporally distinct sulfate reduction phases, consistent with 16S rRNA clone library detection of multiple thermophilic Desulfotomaculum spp. enriched at 50 degrees C. Incubations with four different fluorescently labelled polysaccharides at 4 degrees C and 50 degrees C showed that the thermophilic population in Arctic sediments produce a different suite of polymer-hydrolysing enzymes than those used in situ by the cold-adapted microbial community. Over time, dormant marine microorganisms like these are buried in marine sediments and might eventually encounter warmer conditions that favour their activation. Distinct enzymatic capacities for organic polymer degradation could allow specific heterotrophic populations like these to play a role in sustaining microbial metabolism in the deep, warm, marine biosphere.

Contamination of arctic Fjord sediments by Pb–Zn mining at Maarmorilik in central West Greenland

This study focuses on heavy metal contamination of arctic sediments from a small Fjord system adjacent to the Pb–Zn “Black Angel” mine (West Greenland) to investigate the temporal and spatial development of contamination and to provide baseline levels before the mines re-opening in January 2009. For this purpose we collected multi-cores along a transect from Affarlikassaa Fjord, which received high amounts of tailings from 1973 to 1990, to the mouth of Qaumarujuk Fjord. Along with radiochemical dating by 210Pb and 137Cs, geochemical analyses of heavy metals (e.g. As, Cd, Hg, Pb, and Zn) were carried out. Maximum contents were found at 12 cm depth in Affarlikassaa. After 17 years the mine last closed, specific local hydrographic conditions continue to disperse heavy metal enriched material derived from the Affarlikassaa into Qaumarujuk. Total Hg profiles from multi-cores along the transect clearly illustrate this transport and spatial distribution pattern of the contaminated material.

Direct determination of nitrogen cycling rates and pathways in Arctic fjord sediments (Svalbard, Norway)

Results from a study of benthic nitrogen cycling in two Arctic fjords are presented. Intact sediment core incubations were used to quantify net fluxes of dissolved inorganic nitrogen, organic nitrogen, organic carbon, and oxygen across the sediment‐water interface. Rates of gross denitrification, anammox, nitrification, dissimilatory nitrate reduction to ammonium, and N2 fixation were quantified using core incubations and slurry experiments. Profiles of dissolved inorganic nitrogen in pore‐water, and organic carbon and nitrogen contents in the solid phase, were also obtained. Net nitrogen losses as N2, measured directly as changes in N2 : Ar, ranged from 152 µmol N m−2 d−1 to 453 µmol N m−2 d−1. Gross denitrification, as determined using 15N‐NO3− tracers, was 34–294 µmol N m−2 d−1. Rates of anammox ranged from 10 µmol N m−2 d−1 to 26 µmol N m−2 d−1 and contributed 5–23% of gross N2 generation. Nitrification rates were as high as 833 µmol N m−2 d−1 and sediments were a substantial source of nitrate to the water column (169–393 µmol N m−2 d−1 efflux). Uptake of ammonium (52–87 µmol N m−2 d−1), dissolved organic nitrogen (291‐486 µmol N m−2 d−1), and dissolved organic carbon (1313–2504 µmol N m−2 d−1) were observed. Nitrogen loss from the seafloor is shown to occur at rates comparable to temperate coastal environments and the sediments provide a substantial source of nitrate to the water column of Arctic fjords. In addition, anammox is confirmed as an important pathway in Arctic marine sediments, although N2 production is dominated by denitrification.

Contaminants in Norwegian fjord sediments: industrial history or future source?

Norwegian fjords have been accumulating contaminants since early industrialisation. The key question for sediment management in Norway is whether the sedimentary contaminant record is an archive of industrial history or a future source of contaminants to the fjord environment. Innovative sediment management strategies are being developed in Norway to find solutions which are both cost-effective and sustainable.

Scottish west coast fjords since the last glaciation: a review

Abstract Evidence from seismic profiles, sidescan and multibeam sonar surveys and sediment cores reveal important information about the depositional history of Scotland's fjords during the last deglacial transition and the subsequent Holocene. Devensian glaciation removed pre-existing sediments both inside and outside the fjord basins, and deposited a diamict over much of the subsequent erosional surface. Glaciomarine sequences deposited during the initial retreat of this ice margin are mainly preserved in the sea area outside the fjords. Younger glaciomarine units present within the fjord basins are often attributed to the later Younger Dryas re-advance (12.8–11.5 ka BP). Younger Dryas ice reworked Devensian sediments, depositing terminal moraines at the mouths of a number of fjords and glaciomarine units within the basins during its retreat. Ice margins oscillated throughout deglaciation, although the latter stages of post-Younger Dryas retreat may have occurred rapidly with topographic pinning an important factor in determining the style of retreat. Holocene records from the fjords are limited, but tentatively support the onshore evidence for a tundra-style landscape in the earliest Holocene, followed by a warming of the climate and, latterly ( c . 2000 ka BP), increasing humidity. In the more recent past, human activities such as deforestation, fishing, aquaculture and industry have been recorded in the fjord sediments.

Fjord systems and archives: an introduction

The current volume brings together a selection of papers which have variously, but not exclusively, been presented in recent years at one of three international meetings on the theme of Fjords. The first of these meetings on ‘Fjord Environments: Past, Present and Future’ was held as a workshop following the Challenger Society Conference hosted by The Scottish Association for Marine Science, Scottish Marine Institute, Oban, UK in June 2006. The second meeting was convened as a formal session (CGC-13) entitled ‘Fjords: Climate and Environmental Change’ during the 33rd International Geological Congress, Oslo, Norway in August 2008. The third of these meetings, representing the 2nd international workshop on the theme ‘Fjord Environments: Past, Present and Future’ was held at the University of Bergen, Norway in May 2009. The aims of these meetings were to bring together physical oceanographers, biogeochemists, biologists and earth scientists who could contribute to an improved understanding of fjord systems, both in terms of modern processes and as palaeoenvironmental archives. This publication consists of 23 papers and a glossary, dealing with various aspects of fjord systems and their associated archives. Three of the papers focus on the physics of fjord hydrography and circulation; three address aspects of fjord biology; two concern modern sediment processes; six consider fjord sediments and their depositional architecture; and eight highlight fjords as depositional archives and their palaeoenvironmental significance. The current volume therefore represents a significant contribution of both original research and reviews which we hope provides a timely update to the most recent publications in this field, namely Fjords: Processes and Products (Syvitski et al. 1987) and Fjord Oceanography (Freeland et al. 1979). The volume begins with a dedication to Harald Svendsen, who sadly passed away on 30th November 2009. Harald made a significant contribution to the investigation of Arctic fjords and it is an honour to dedicate this volume to his memory. An overview by Howe et al., highlighting some of the key features of the fjord system from modern processes to palaeo-records, provides an accessible introduction to the topic. Aspects of the major physical, chemical and biological processes within fjord systems are highlighted. The volume is subsequently divided into five main themes, comprising (a) physics and physical oceanography; (b) biology and biological indicators; (c) sediment dynamics and processes; (d) sediments and depositional architecture; and (e) depositional archives and palaeoenvironments. The paper by Inall & Gillibrand provides a useful, non-mathematical review of the dominant physical processes of mid-latitude fjords; this is likely to prove useful to non-physical oceanographers who may wish to gain an insight into some of the key fluid dynamical processes. It is followed by a review of Arctic fjords by Cottier et al., who highlight the role of fjords as ‘critical gateways’ by which glaciers are influenced by ocean conditions; the latter is a subject of increasing significance at a time of rising global sea surface temperatures. These authors show how fjord salinity plays a critical role in controlling exchange processes between the fjord and coastal ocean. The third paper on the physics of fjords by Skarðhamar & Svendsen considers short-term variability from the wide semi-enclosed Van Mijenfjorden on Svalbard. The influence of the Coriolis effect upon circulation and the development of cross-fjord gradients is illustrated. Three short papers address aspects of biological proxies as palaeoenvironmental indicators within fjords. Howe et al. review the potential of dinoflagellate cysts collected from sediment traps within Arctic (Svalbard archipelago) fjords as proxies for palaeoceanographic conditions, highlighting the significance of seasonal and inter-annual differences in cyst production. Continuing the theme of dinoflagellate cysts as palaeoceanographic proxies,

Climate proxies for recent fjord sediments in the inner Sognefjord region, western Norway

Abstract Three high-resolution sediment cores from the periodically anoxic Inner Barsnesfjord and the oxic Outer Barsnesfjord and Sogndalsfjord, Western Norway, are analysed for signals of climate variation. Sedimentation rates are 0.85, 0.75 and 0.45 cm a −1 , respectively. Sediment slices are taken of 0.3–0.5 cm thickness revealing annual resolution. Corresponding peaks of mineral clay particles, total organic matter and freshwater diatoms correlate well with maxima in regional precipitation, temperature and cloud cover over the last 20 years. This regional climate record is also correlated to the wider NAO (North Atlantic Oscillation) winter index, northern hemisphere temperature and solar activity (cosmic rays and open solar flux) based on 60 years of continuous observation. There is a strong indication that the fjord sediment record contains a climate archive spanning the last 20–100 a; it is suggested that these proxies might also work on longer timescales. A simple box model is presented describing the use of the sediment record for the interpretation of climate variability on a regional scale and at a longer timescale on a millennium scale. It is predicted that this model can be transferred to sediment settings of similar regional climate influence.

Direct determination of nitrogen cycling rates and pathways in Arctic fjord sediments (Svalbard, Norway)

Results from a study of benthic nitrogen cycling in two Arctic fjords are presented. Intact sediment core incubations were used to quantify net fluxes of dissolved inorganic nitrogen, organic nitrogen, organic carbon, and oxygen across the sediment-water interface. Rates of gross denitrification, anammox, nitrification, dissimilatory nitrate reduction to ammonium, and N2 fixation were quantified using core incubations and slurry experiments. Profiles of dissolved inorganic nitrogen in pore-water, and organic carbon and nitrogen contents in the solid phase, were also obtained. Net nitrogen losses as N2, measured directly as changes in N2 : Ar, ranged from 152 µmol N m−2 d−1 to 453 µmol N m−2 d−1. Gross denitrification, as determined using 15N-NO3− tracers, was 34–294 µmol N m−2 d−1. Rates of anammox ranged from 10 µmol N m−2 d−1 to 26 µmol N m−2 d−1 and contributed 5–23% of gross N2 generation. Nitrification rates were as high as 833 µmol N m−2 d−1 and sediments were a substantial source of nitrate to the water column (169–393 µmol N m−2 d−1 efflux). Uptake of ammonium (52–87 µmol N m−2 d−1), dissolved organic nitrogen (291-486 µmol N m−2 d−1), and dissolved organic carbon (1313–2504 µmol N m−2 d−1) were observed. Nitrogen loss from the seafloor is shown to occur at rates comparable to temperate coastal environments and the sediments provide a substantial source of nitrate to the water column of Arctic fjords. In addition, anammox is confirmed as an important pathway in Arctic marine sediments, although N2 production is dominated by denitrification.

Pollen analysis of Holocene sediments from Loch Etive, a Scottish fjord

Abstract This paper outlines one of the first attempts to analyse the detailed pollen content of the marine sediments from a fjord (sea loch) located on the west coast of Scotland. The site chosen was in the Bonawe Deep, part of the upper basin of Loch Etive, and 2.3 m depth of sediments were sampled. These sediments were examined for their fossil pollen content and a pollen diagram was constructed from the results. The interpretation of the pollen record was supported by seven radiocarbon dates which demonstrated that the sediments accumulated over the last 8–9 ka of the Holocene. The pollen diagram was divided into three pollen assemblage zones. The lowest zone ET1 ( c . 9–7.3 ka BP) was dominated by pollen of Betula , Pinus and Corylus , zone ET2 ( c . 7.3–1.2 ka BP) contained a wide range of woodland pollen taxa (mainly Betula , Pinus , Quercus , Alnus and Corylus ) and the uppermost zone ET3 (1.2–0 ka BP) was distinguished by fewer tree pollen taxa and increased values of open habitat taxa, particularly Calluna . The pollen diagram showed the development of vegetation during the Holocene which correlated well with existing results from studies of peat or freshwater lake sediments sampled in the west of Scotland. The only significant differences were the higher concentrations of Pinus pollen found in the Loch Etive site. These differences can be explained by the large catchment area of the loch which includes high ground, where it is proposed that extensive Pinus forest grew during much of the Holocene. The study demonstrates the practicality of using Scottish fjord sediments for Holocene pollen studies and potentially provides a link between terrestrial vegetation records and marine-based fossil records.

Paraglacial slope instability in Scottish fjords: examples from Little Loch Broom, NW Scotland

Abstract Lateglacial–Holocene fjord sediments in Little Loch Broom preserve evidence of extensive slope instability. The major area of reworking is in the outer loch and mid-loch sill region where ice-contact/ice-proximal deposits of the Lateglacial Assynt Glaciogenic Formation have been disrupted by sliding and mass-flow processes linked to the Little Loch Broom Slide Complex and the adjacent Badcaul Slide. Mass failure was instigated about 14–13 ka BP, and is probably the response of the landscape to deglaciation immediately following the removal of ice support during glacial retreat. An initial phase of translational sliding was followed by rotational sliding, as revealed by the superimposition of scallop-shaped slumps on a larger-scale rectilinear pattern of failure. Paraglacial landscape readjustment may also have been enhanced by episodic seismic activity linked to glacio-isostatic unloading. In the inner fjord, evidence of Holocene mass failure includes the Ardessie debris lobe and a discrete intact slide block preserved within the postglacial basinal deposits. The former is a localized accumulation linked to a fluvial catchment on the adjacent An Teallach massif. These mass-transport deposits may represent an ongoing response to paraglacial processes, albeit much reduced (relative to the major slides) in terms of sediment supply to the fjord.

Economic benefits of large-scale remediation of contaminated marine sediments—a literature review and an application to the Grenland fjords in Norway

As input to a cost-benefit analysis of large-scale remediation measures of contaminated sediments in the Grenland fjords in Norway, we conducted a contingent valuation (CV) survey of a representative sample of households from municipalities adjacent to these fjords. The CV method aimed at valuing the benefits perceived by households of removing dietary health advisories on seafood consumption currently in place through the fjords. Mean household willingness-to-pay (WTP) per year over a 10-year period was found to decrease with increased distance from the Grenland fjords and was somewhat higher than in a similar study conducted 10 years earlier than our study. Aggregating mean WTP over all households in neighbouring municipalities to the fjords resulted in total economic benefits of the same magnitude as the total remediation costs. The WTP results make the case in such a way that the high costs of remediation of contaminated marine sediments can be defended by the large economic benefits generated for households around the fjord. The research was financed by the local environmental authorities and the local industry that had caused the contaminated sediments. The WTP results were strongly contested by the industry upon completion of the study. The paper addresses the industry's critiques of this particular CV study and discusses how to better inform local stakeholders about the potential and limitations of the CV method and how to improve communication of economic valuation results.

Lateglacial ice-cap dynamics in NW Scotland: evidence from the fjords of the Summer Isles region

The seaboard of western Scotland is a classic fjord landscape formed by glaciation over at least the last 0.5 Ma. We examine the glacial geology preserved in the fjords (or sea lochs) of the Summer Isles region of NW Scotland using high-resolution seismic data, multibeam swath bathymetry, seabed sediment cores, digital terrain models, aerial photographs, and field investigations. Detailed analyses include seismic facies and lithofacies interpretations; sedimentological and palaeoenvironmental analyses; and radiocarbon dating of selected microfauna. Our results indicate that the Pleistocene sediments of the Summer Isles region, on- and offshore, can be subdivided into several lithostratigraphic formations on the basis of seismic character, geomorphology and sedimentology. These are: subglacial tills; ice-distal and glacimarine facies; ice-proximal and ice-contact facies; moraine assemblages; and Holocene basin fill. The submarine landscape is also notable for its large-scale mass-movement events – the result of glaciodynamic, paraglacial or seismotectonic processes. Radiocarbon dating of marine shells indicate that deglaciation of this part of NW Scotland was ongoing between 14 and 13 ka BP – during the Lateglacial Interstadial (Greenland Interstadial 1) – consistent with cosmogenic surface-exposure ages from previous studies. A sequence of numerous seafloor moraine ridges charts oscillatory retreat of the last ice sheet from a buoyant calving margin in The Minch to a firmly grounded margin amongst the Summer Isles in the early part of Lateglacial Interstadial (GI-1) (pre-14 ka BP). Subsequent, punctuated, frontal retreat of the ice mass occurred in the following ∼1000 years, during which time ice-cap outlet glaciers became topographically confined and restricted to the fjords. A late-stage readvance of glaciers into the inner fjords occurred soon after 13 ka BP, which calls into question the accepted limits of ice extent during the Younger Dryas Stadial (Greenland Stadial 1). We examine the wider implications of our chronostratigraphic model, discussing the implications for British Ice Sheet deglaciation, Lateglacial climate change, and the style and rates of fjord sedimentation.