ORCID Profile
0000-0003-4535-2555
Current Organisation
University of St Andrews
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Publisher: Frontiers Media SA
Date: 04-03-2021
DOI: 10.3389/FEART.2021.593324
Abstract: Continental shelf sediments are recognized as long-term stores of globally significant quantities of carbon (C) and potentially provide an important, yet largely overlooked climate regulation service via the Earth’s C cycle. Current understanding of the spatial distribution of sedimentary C across continental shelves remains poor, inhibiting the targeted management and potential inclusion of these globally significant C stores into national C budgets. Further understanding of the spatial heterogeneity of continental shelf sediments and associated C provides a foundation to quantify the organic carbon (OC) stock and better understand the role that marine sediments play in regulating the global climate and the potential for CO 2 to be released through anthropogenic disturbance of these C stores. Utilizing a spectrum of available marine data, we have created bespoke sediment maps that quantify the surficial (top 10 cm) OC stock and highlight significant spatial heterogeneity in the distribution of sediments and their associated C content across the United Kingdom’s Exclusive Economic Zone (EEZ). The surficial sediments within the UK EEZ are estimated to store 524 ± 68 Mt of organic carbon (OC) and 2,582 ± 168 Mt of inorganic carbon (IC). The spatial mapping of this C highlights well-defined OC accumulation hotspots in fjords, estuaries and coastal muds, while large accumulations of IC are found in the tidally swept areas around Orkney, Shetland and the South West of England. Within the well-defined OC hotspots, muddy sediments store the greatest quantity of OC the muds offer potentially valuable opportunities for targeted future management and protection of sedimentary C stores within the UK EEZ. In the future, if areas of the seafloor were to be managed to include the protection of these valuable sedimentary C resources, we recommend an initial focus on hotspots of high sedimentary OC density.
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-16352
Abstract: Rapid climate change (RCC) during the Holocene, particularly post-dating the demise of large Northern Hemisphere ice sheets after 8000 cal. yr BP, is a global phenomenon and is almost certainly driven by long-term changes in insolation, upon which solar variability, although a weak direct forcing mechanism, is superimposed. At least five significant intervals are identified in numerous palaeoclimate records since the major 9000-8000 cal. yr RCC, within which the intensively studied 8200 cal. yr & #8216 event& #8217 is embedded these are: 6000-5000, 4200-3800, 3500-2500, 1200-1000 and 600-150 cal. yr BP. Most of the Holocene RCCs are associated with bipolar cooling, an expansion-intensification of high latitude circulation systems and drying-aridity at low latitudes.Here, we present proxy-records from a fjord basin located on the Atlantic margins of NW Europe which contain evidence for these combined forcing mechanisms. Giant piston core (MD04-2832) from the main basin of Loch Sunart, Argyll, NW Scotland, is 22 m long and appears to contain a record of continuous sedimentation back to nearly 8000 cal. yr BP. Based upon the age-depth model for core MD04-2832, isotopic shifts recorded in the benthic foraminifera Ammonia beccarii coincide with both the rate and magnitude of the Holocene RCCs. We show that the renewal history of bottom waters in the fjord basins appear to be driven by large-scale atmospheric circulation changes that may have characterised the entire mid-latitude NE Atlantic region.
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-12008
Abstract: & & There is strong evidence that the source of terrestrial carbon and iron geochemistry play an important role in organic carbon transport and preservation in coastal and marine sediments & sup& ,2,3& /sup& . There is a global drive to increase forestry and Scotland is undergoing a period of afforestation& sup& & /sup& . A portion of this is being planted in sea loch (fjord) catchments however the effect of this increase in forestry on coastal carbon transport and storage is poorly understood. Fjord systems have recently been identified as significant terrestrial carbon stores& sup& & /sup& therefore understanding how afforestation of these catchments changes the carbon dynamics from source to sea, is key.& & & & In this study Mossbauer spectroscopy, XRD and XRF are used to examine how iron concentration and speciation differs within Scottish fjord sediments. This preliminary data provides insight of the variation in iron speciation in fjord systems, processes controlling iron transport and speciation and potential mineral binding mechanisms in coastal sediments. This enables us to start addressing key knowledge gaps in the transport of organic carbon and iron from land (forested source areas) to sea (fjords). Thus, contributing to our overarching aim of tracing the movement and interactions of organic carbon across the terrestrial - aquatic interface.& & & & Through this project, further analytical techniques such as biomarker analysis, isotopic analysis and SEM, will be used to improve our understanding of source to sea processes in fjord systems throughout the northern hemisphere. This will hopefully enable improved understanding and quantification of local and national carbon stocks. Further insights into carbon and iron burial mechanisms may allow us to tailor land use and management around fjord environments to maximise natural carbon storage.& &
Publisher: Copernicus GmbH
Date: 24-08-2016
Publisher: Copernicus GmbH
Date: 24-08-2016
Publisher: Copernicus GmbH
Date: 17-06-2016
DOI: 10.5194/BG-2016-245
Abstract: Abstract. Quantifying sedimentary carbon stocks in the coastal ocean is key to improving our understanding of long-term storage of carbon in the coastal ocean and to further constrain the global carbon cycle. Here we present a methodological approach which combines seismic geophysics and geochemical measurements to quantitatively estimate the total stock of carbon held within marine sediment. Through the application of this methodology to Loch Sunart a sea loch (fjord) on the west coast of Scotland we have created the first sedimentary carbon inventory for a fjordic system. The sediment of Loch Sunart holds 26.88 ± 0.52 Mt of carbon split between 11.05 ± 0.23 Mt and 15.02 ± 0.35 Mt of organic and inorganic carbon respectively. This quantitative estimate of carbon stored in Loch Sunart in significantly higher than previous estimates. Through comparison to Scottish peatland carbon stocks we have determined that Loch Sunart on a per are basis is a significantly more effective store of carbon. This initial work supports the concept that fjords are important environments for the burial and long-term storage of carbon and therefore should be considered as unique environments while considering coastal carbon stocks.
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-9393
Abstract: & & Fjords are recognized as globally significant hotspots for the burial (Smith et al., 2015) and long-term storage (Smeaton et al., 2017) of marine and terrestrially derived organic carbon (OC). By trapping and locking away OC over geological timescales, fjord sediments provide a potentially important yet largely overlooked climate regulation service. The proximity of fjords to the terrestrial environment in combination with their geomorphology and hydrography results in the fjordic sediments being subsidized with organic carbon (OC) from the terrestrial environment. This terrestrial OC (OC& sub& terr& /sub& ) transferred to the marine environment has traditionally be considered lost to the atmosphere in the form of CO& sub& & /sub& in most carbon (C) accounting schemes yet globally it is estimated that 55% of OC trapped in fjord sediments is derived from terrestrial sources (Cui et al., 2016). So is this terrestrial OC truly lost? Here, we estimate the quantity of OC& sub& terr& /sub& held within North Atlantic fjords with the aim of better understanding the recent and long-term role of the terrestrial environment in the evolution of these globally significant sedimentary OC stores. By understanding this subsidy of OC from the terrestrial to the marine environment we can take the first steps in quantifying the terrestrial OC stored in fjords and the wider coastal marine environment.& & & & Cui, X., Bianchi, T.S., Savage, C. and Smith, R.W., 2016. Organic carbon burial in fjords: Terrestrial versus marine inputs.& & em& Earth and Planetary Science Letters& /em& ,& & em& & /em& , pp.41-50.& & & & Smeaton, C., Austin, W.E., Davies, A., Baltzer, A., Howe, J.A. and Baxter, J.M., 2017. Scotland's forgotten carbon: a national assessment of mid-latitude fjord sedimentary stocks.& & em& Biogeosciences& /em& .& & & & Smith, R.W., Bianchi, T.S., Allison, M., Savage, C. and Galy, V., 2015. High rates of organic carbon burial in fjord sediments globally.& & em& Nature Geoscience& /em& ,& & em& & /em& (6), p.450.& & & & & & &
Publisher: Copernicus GmbH
Date: 20-05-2019
Publisher: Copernicus GmbH
Date: 15-12-2017
Abstract: Abstract. Fjords are recognised as hotspots for the burial and long-term storage of carbon (C) and potentially provide a significant climate regulation service over multiple timescales. Understanding the magnitude of marine sedimentary C stores and the processes which govern their development is fundamental to understanding the role of the coastal ocean in the global C cycle. In this study, we use the mid-latitude fjords of Scotland as a natural laboratory to further develop methods to quantify these marine sedimentary C stores on both the in idual fjord and national scale. Targeted geophysical and geochemical analysis has allowed the quantification of sedimentary C stocks for a number of mid-latitude fjords and, coupled with upscaling techniques based on fjord classification, has generated the first full national sedimentary C inventory for a fjordic system. The sediments within these mid-latitude fjords hold 640.7 ± 46 Mt of C split between 295.6 ± 52 and 345.1 ± 39 Mt of organic and inorganic C, respectively. When compared, these marine mid-latitude sedimentary C stores are of similar magnitude to their terrestrial equivalents, with the exception of the Scottish peatlands, which hold significantly more C. However, when area-normalised comparisons are made, these mid-latitude fjords are significantly more effective as C stores than their terrestrial counterparts, including Scottish peatlands. The C held within Scotland's coastal marine sediments has been largely overlooked as a significant component of the nation's natural capital such coastal C stores are likely to be key to understanding and constraining improved global C budgets.
Publisher: Elsevier BV
Date: 08-2021
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-6103
Abstract: Salt marshes sequester carbon at rates& significantly exceeding those found in terrestrial environments. This ability& arises from the in-situ production of plant& biomass and the effective trapping& and storage of both autochthonous and allochthonous organic carbon. The& importance of this blue carbon store for mitigating& increasing atmospheric& carbon dioxide depends on both the rate at which carbon is buried within& sediments and the rapidity with which that carbon is remineralised. It has been hypothesized that carbon burial rates, in turn, depend on the local rate of sea-level rise, with faster sea-level rise providing more accommodation space for carbon storage. This study addresses& these three key aspects in a salt-marsh sediment study from& Lindisfarne, northern England. We quantify rates of carbon accumulation by& combining a Bayesian age-depth model based on& Pb and& Cs& activities with centimetre-resolution organic carbon density measurements. A& Bayesian isotope& mixing model pinpoints terrestrial sources as providing the& majority of stored carbon. We compare two approaches for& assessing the relative proportions of& labile and recalcitrant carbon based on a& two-pool modelling approach and thermogravimetric analysis. Preliminary results indicate that during the 20th century more carbon was stored at Lindisfarne salt marsh during decades with relatively high rates of sea-level rise.
Publisher: Copernicus GmbH
Date: 26-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-655
Abstract: & & Scotland& #8217 s saltmarshes bury and store organic carbon (OC) for extensive periods of time, and thus, could potentially contribute as a natural solution to combat climate change. Recent studies have calculated that the top 10cm of Scottish saltmarshes hold approximately 367,888 & #177 102,278 tonnes of OC & sup& [1]& /sup& . Despite this new understanding of the surficial OC stock, the rate at which OC is buried is largely unknown. This study focusses on 10 contrasting saltmarshes around Scotland and presents an in-depth analysis of their total organic carbon (TOC) stocks and burial rates. Chronology data (provided by radioisotope analysis) provides information on the age of saltmarsh soils, as well as OC accumulation rates. Additionally, stable isotope analysis (& #948 & sup& & /sup& C and & #948 & sup& & /sup& N) allows improved understanding of carbon sources. Sediment carbon analysis, sediment descriptions and vegetation surveys were used to generate TOC stocks for each saltmarsh. The results showed that between 8,253 and 91,028 tonnes of OC is stored in these contrasting saltmarshes and OC burial rates range between 29.1 and 142.5 gC m& sup& -2& /sup& yr& sup& -1& /sup& . This work highlights the role that saltmarshes play as a natural component in coastal climate mitigation and their wider significance as blue carbon environments contributing to Scotland& #8217 s natural capital.& & & & [1] Austin, W., Smeaton, C., Riegel, S., Ruranska, P., Miller, L (2021). Blue carbon stock in Scottish saltmarsh soils. Scottish Marine and Freshwater Science, 12 (13)& &
Publisher: Pelagic Publishing
Date: 19-04-2022
DOI: 10.53061/STPP2268
Publisher: Frontiers Media SA
Date: 11-08-2022
DOI: 10.3389/FMARS.2022.959459
Abstract: A new saltmarsh soil dataset comprising of geochemical and physical property data from 752 soil s les collected through a s ling program supported by citizen scientists has been brought together with existing data to make the first national estimates of the surficial (top 10 cm) soil OC stock for Great British (GB) saltmarshes. To allow the inclusion of secondary data in the soil stock estimate a new bespoke organic matter to organic carbon conversion for GB saltmarsh soil was developed allowing organic matter data measured using loss-on-ignition to be convert to organic carbon content. The total GB surficial soil OC stock is 2.320 ± 0.470 Mt English saltmarshes hold 1.601 ± 0.426 Mt OC, Scottish saltmarshes hold 0.368 ± 0.091 Mt OC, and Welsh saltmarshes hold 0.351 ± 0.082 Mt OC. The stocks were calculated within a Markov Chain Monte Carlo framework allowing robust uncertainty estimates to be derived for the first time. Spatial mapping tools are available to accompany these stock estimates at in idual saltmarsh habitats throughout GB. This data will aid in the protection and management of saltmarshes and represents the first steps towards the inclusion of saltmarsh OC in the national inventory accounting of blue carbon ecosystems.
Publisher: Elsevier BV
Date: 03-2023
Publisher: Elsevier BV
Date: 09-2022
Publisher: Marine Scotland Science
Date: 2020
DOI: 10.7489/12262-1
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-12459
Abstract: Saltmarshes play a key role in sequestering and storing carbon, as well as providing a wide range of other ecosystem services. Assessments of both total carbon stocks and rates of carbon accumulation are vital for quantifying saltmarsh contributions to climate-change mitigation and for guiding efforts to protect and restore coastal wetlands. Current assessments of the rates at which UK saltmarshes accumulate carbon are based on a small and spatially limited dataset. To address this knowledge gap, we estimate sedimentation rates and assess organic carbon density from 22 saltmarshes distributed around the UK. Bayesian modelling quantifies the relationship between depth and age from 210Pb and 137Cs activity data. We combine these sedimentation rates with centimetre-resolution organic carbon density measurements to quantify carbon accumulation rates through time. By upscaling these estimates to the total UK saltmarsh area and fully quantifying uncertainties, we conclude that UK saltmarsh carbon burial rates are lower than previously thought.
Publisher: American Geophysical Union (AGU)
Date: 11-2017
DOI: 10.1002/2017JG003952
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-1547
Abstract: & & Annually, continental shelf sediments bury an estimated 137 Mt of organic carbon (OC) making these sedimentary systems an integral component of the global carbon (C) cycle. Within continental shelfs in idual sedimentary environments can range between inshore fjord to offshore non-deltaic settings each vastly differing in their ability to trap and lock away OC. Of these different environments fjord sediments have been shown to be hotspot for the burial and storage of OC burying and estimate 18 Mt OC yr& sup& -1& /sup& , which equates to ~11% of all marine C burial (Smith et al., 2015). In Scotland, the postglacial sediments of the mid-latitude fjords are estimated to store 252 & #177 62 Mt OC (Smeaton et al., 2017) with a further 84,000 tonnes of OC being trapped and stored each year (Smeaton et al., 2021). It is clear that fjord sediments are an integral element of the global C cycle and could potentially be crucial long-term climate mitigation. Yet these systems do not exists in isolation and how these system interact with other marine sedimentary systems remains an open question. & & & & & Current research is largely focused on the close interactions between fjord sediments and the terrestrial environment (Cui et al., 2016 Smeaton and Austin, 2017) but recent research in Scotland and Norway has indicated the marine environment can play as large if not greater role in the OC dynamics of fjords than terrestrial ecosystems (Faust and Knies, 2019 Smeaton et al., 2021).& & & & Here we explore the interactions between the sediments of the Loch Linnhe fjord complex on the West coast of Scotland and the adjacent continental shelf. Using an array of geochemical techniques the source, age and depositional history of the OC held within the sediments will be investigated to understand the geochemical processes driving OC burial and storage in both the fjord and continental shelf sediments. By integrating state-of-the-art spatial analytics with the geochemical measurements we further seek to quantify how these different sedimentary settings interact and how these processes drive OC dynamics across a continental shelf. & & & & & & & & & & & & & strong& References & /strong& & & & & Cui, X., Bianchi, T.S., Savage, C. and Smith, R.W., 2016. Organic carbon burial in fjords: Terrestrial versus marine inputs.& & em& Earth and Planetary Science Letters& /em& ,& & em& & /em& , pp.41-50.& & & & Faust, J.C. and Knies, J., 2019. Organic matter sources in North Atlantic fjord sediments.& & em& Geochemistry, Geophysics, Geosystems& /em& ,& & em& & /em& (6), pp.2872-2885.& & & & Smeaton, C., Austin, W.E., Davies, A.L., Baltzer, A., Howe, J.A. and Baxter, J.M., 2017. Scotland's forgotten carbon: a national assessment of mid-latitude fjord sedimentary carbon stocks.& & em& Biogeosciences& /em& ,& & em& & /em& (24), pp.5663-5674.& & & & Smeaton, C. and Austin, W.E., 2017. Sources, sinks, and subsidies: Terrestrial carbon storage in mid& #8208 latitude fjords.& & em& Journal of Geophysical Research: Biogeosciences& /em& ,& & em& & /em& (11), pp.2754-2768.& & & & Smeaton, C., Yang, H. and Austin, W.E., 2021. Carbon burial in the mid-latitude fjords of Scotland.& & em& Marine Geology& /em& ,& & em& & /em& , p.106618.& & & & Smith, R.W., Bianchi, T.S., Allison, M., Savage, C. and Galy, V., 2015. High rates of organic carbon burial in fjord sediments globally.& & em& Nature Geoscience& /em& ,& & em& & /em& (6), pp.450-453.& &
Publisher: American Geophysical Union (AGU)
Date: 14-03-2022
DOI: 10.1029/2021GL097481
Abstract: Disturbance of marine sediments results in the remineralization of sedimentary organic matter (OM) and impacts upon natural burial processes. Management interventions which restrict or remove activities that cause seabed disturbance may offer effective strategies to protect the most vulnerable of these shelf sea OM stores, offering new opportunities to deliver climate mitigation actions. While the largest quantities of OM are often stored in the expansive offshore regions of continental shelves and might therefore suggest appropriate zones for management interventions to protect vulnerable OM stores, our results highlight that these offshore regions generally contain OM of low reactivity. Conversely, inshore and coastal sediments store significant quantities of highly reactive OM that is at greater risk of remineralization when disturbed. The marked spatial disparities between OM reactivity across shelf sea sedimentary environments highlights the need to focus emergent policy and future management interventions toward the protection of inshore and coastal sediments.
Publisher: Copernicus GmbH
Date: 25-08-2017
Publisher: Frontiers Media SA
Date: 28-07-2020
Publisher: American Association for the Advancement of Science (AAAS)
Date: 16-11-2022
Abstract: The global carbon cycle is strongly modulated by organic carbon (OC) sequestration and decomposition. Whereas OC sequestration is relatively well constrained, there are few quantitative estimates of its susceptibility to decomposition. Fjords are hot spots of sedimentation and OC sequestration in marine sediments. Here, we adopt fjords as model systems to investigate the reactivity of sedimentary OC by assessing the distribution of the activation energy required to break OC bonds. Our results reveal that OC in fjord sediments is more thermally labile than that in global sediments, which is governed by its unique provenance and organo-mineral interactions. We estimate that 61 ± 16% of the sedimentary OC in fjords is degradable. Once this OC is remobilized and remineralized during glacial maxima, the resulting metabolic CO 2 could counterbalance up to 50 ppm of the atmospheric CO 2 decrease during glacial times, making fjords critical actors in d ening glacial-interglacial climate fluctuations through negative carbon cycling loops.
Publisher: Marine Climate Change Impacts Partnership (MCCIP), Lowestoft, UK
Date: 2020
Publisher: Copernicus GmbH
Date: 25-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-103
Abstract: & & Shelf and coastal seas hold vast quantities of sedimentary carbon, which if left undisturbed, will contribute towards long-term carbon and underpin natural ocean climate services. It is estimated that within the UK exclusive economic zone, 524 Mt of organic carbon is stored within sediments (Smeaton et al., 2021). However, the stability and potential vulnerability of this key component of global natural capital remains poorly quantified, particularly under anthropogenic stressors, such as benthic fishing activity. Benthic trawling activity is the most significant cause of anthropogenic disturbance to the seabed, leading to massive sediment resuspension events and wide scale impact to benthic communities. The impacts of trawling on benthic ecosystems and communities are well reported within the literature (e.g. Hughes et al., 2014) however, a knowledge gap remains regarding the impact of trawl-induced disturbance events on sedimentary carbon stores.& & & & In order to improve our understanding of the areas where sedimentary carbon is potentially at greatest risk from trawling events, we have developed a carbon vulnerability ranking to signify the areas of the seabed where preventative protection would be most beneficial to help maintain our current carbon stocks while further research continues to shed light on the fate of carbon after trawling (e.g. carbon remineralization, transport, and consumption etc.). These maps have been modelled within GIS via fuzzy set theory by making use of currently available fishing intensity, carbon and sediment distribution, and sediment lability datasets (ICES, 2014 Smeaton et al., 2021).& & & & Our results show that the fjordic west coast of Scotland represents one of the key areas where sedimentary carbon is highlighted as being potentially at risk from bottom trawling. This is largely due to the high lability of the sediments as a function of both sediment type and the elevated organic carbon content present within these sediments. In addition, higher occurrences of repetitive trawling activity within inshore waters may add to these pressures. Our research shows that these organic carbon hotspots are potentially at risk of disturbance from benthic trawling activity and should be prioritized for future safeguarding measures to ensure avoided emissions are minimized and to protect this natural carbon capital resource.& & & & References& & & & Hughes, K.M., Kaiser, M.J., Jennings, S., McConnaughey, R.A., Pitcher, R., Hilborn, R., Amoroso, R.O., Collie, J., Hiddink, J.G., Parma, A.M., Rijnsdorp, A., 2014. Investigating the effects of mobile bottom fishing on benthic biota: A systematic review protocol. Environ. Evid. 3. 0.1186/2047-2382-3-23& & & & ICES, 2014. OSPAR request on mapping of bottom fishing intensity using VMS data, Special request, Advice September 2014.& & & & Smeaton, C., Hunt, C.A., Turrell, W.R., Austin, W.E.N., 2021. Marine Sedimentary Carbon Stocks of the United Kingdom& #8217 s Exclusive Economic Zone. Front. Earth Sci. 9, 1& #8211 . 0.3389/feart.2021.593324& &
Publisher: Elsevier BV
Date: 12-2022
Publisher: Marine Scotland Science
Date: 2021
DOI: 10.7489/12372-1
Publisher: Springer Science and Business Media LLC
Date: 03-08-2018
Publisher: Copernicus GmbH
Date: 26-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-483
Abstract: & & Mid-latitude fjords have recently been identified as important environments for carbon storage. This research highlights the importance of the lateral transport of carbon from land to sea as we assess the influence of catchment land use (primarily forestry) on carbon transport and sediment carbon burial. Establishing the influence of land use, specifically forestry, on coastal biogeochemical cycling is particularly important if afforestation is to help mitigate climate change impacts, and to better understand the impact of deforestation. The relationship between carbon and iron in fjord sediments is the focus of this study. We provide insights into carbon and iron coupling in a mid-latitude fjord. Here we show the variability of carbon burial, and how this is influenced by terrestrial inputs and iron speciation in fjord sediments. We use bulk organic carbon and elemental data, isotopic analysis, M& #246 ssbauer spectroscopy and chemical extractions to better understand the relationship between carbon and iron. Observed decreases in organic carbon from the upper to lower basin are influenced by the input of terrestrial material. Organic carbon is up to three times higher in the upper basin and terrestrial organic carbon is ~20% higher in comparison to the lower basin of the fjord. The strength of the reactive iron signal is found to vary vertically (with depth, over time) and laterally (from upper & #8211 lower basin) within this fjord. Results highlight that there is a changing relationship between iron and carbon within this system. Understanding land-sea controls on coastal carbon transport and burial is crucial during this period of climate change.& &
Publisher: Copernicus GmbH
Date: 20-05-2019
DOI: 10.5194/BG-2019-163
Abstract: Abstract. Fjord sediments are recognized as hotspots for the burial and storage of organic carbon, yet little is known about what drives the formation of these coastal carbon stores and how this has altered over time. Here we show that fjords can act as sustained hotspots for carbon burial and storage over Holocene timescales. Further we investigate the role of North Atlantic climate and humans in the evolution of a coastal carbon store using sediment records from a temperate Scottish fjord. Our findings indicate that climate and anthropogenic activity have independently driven increases in terrestrial carbon to the marine environment. When both these drivers were coupled, the terrestrial response was pronounced and the relative proportion of terrestrial OC in the marine sediments increases from 5 % up to 70 %. We hypothesize that sustained human disturbance through the late Holocene sensitized the catchment to abrupt climate reorganizations. The results highlight the importance of fjords for carbon burial and the significance of terrestrial carbon subsidy to the long-term carbon store.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-5152
Abstract: & & Globally, fjords are recognised as hotspots for the burial and storage of organic carbon (OC). The role of fjords as nationally and globally important carbon sinks is now well established, yet the long-term drivers and evolution of OC burial and storage in these coastal systems remains largely unknown. The location of fjords at the land-ocean interface in combination with their geomorphology results in a large proportion of the OC that is trapped in their sediments deriving from the terrestrial environment, yet the processes driving the delivery of terrestrial carbon into fjords over long timescales is often poorly constrained. In order to better understand these important processes, an understanding of terrestrial landscape change in conjunction with sedimentological data for carbon storage is required. Understanding the drivers of the carbon transfer at the land-ocean interface throughout the mid- to late-Holocene can provide insights into the sensitivity of catchments to climatic and anthropogenic pressure, which will be crucial to predicting future carbon loss, burial and storage scenarios across the land-ocean interface.& & & & We present a new multiproxy palaeoenvironmental dataset developed from a core from Loch Eriboll, a large fjord in northern Scotland, spanning the last 5,000 years. Pollen data, taken to represent catchment-scale vegetation change, is used to investigate landscape change in response to natural and anthropogenic forcing mechanisms. Sedimentological and geochemical data are then used to reconstruct changes in the delivery of carbon into the fjord system via soil erosion. Comparison of two age models, developed from bulk radiocarbon dating and dating of shells, respectively, provide data on the relative age of carbon being reworked from the terrestrial system into the fjord.& & & & We present evidence for links between the terrestrial and fjord systems throughout the mid to late Holocene. Throughout the record is a consistent radiocarbon age offset of approximately 800 years in the bulk data, and increases in this offset coincide with marked changes in the terrestrial vegetation on three discrete occasions: a significant reduction in & em& Pinus& /em& , an increase in herbaceous pollen, and an expansion of heathland pollen. Complemented by a suite of geochemical proxies, including inorganic and organic geochemical signatures, these datasets provide insights into the sensitivity of fjordic systems to changes in the adjacent terrestrial system on centennial timescales.& &
Publisher: Copernicus GmbH
Date: 20-05-2019
DOI: 10.5194/BG-2019-125
Abstract: Abstract. Fjords have been described as hotspots for carbon burial, potentially playing a key role within the carbon cycle as climate regulators over multiple timescales. Nevertheless, little is known about the long-term fate of the carbon that may become stored in fjordic sediments. One of the main reasons for this knowledge gap is that carbon arriving on the seafloor is prone to post-depositional degradation, posing a great challenge when trying to discriminate between an actual change in carbon deposition rate and post depositional carbon loss. In this study, we evaluate the use of modern benthic foraminifera as bio-indicators of carbon content in six voes (fjords) on the west coast of Shetland. Benthic foraminifera are sensitive to changes in carbon content in the sediments, and changes in their assemblage composition therefore reflect synchronous variations in the quantity and quality of carbon reaching the seafloor. We identified four environments based on the relationship between benthic foraminiferal assemblages and carbon content in the sediments: 1) Land-locked regions influenced by riverine/freshwater inputs of organic matter, namely the head of fjords with a restricted geomorphology 2) Stressed environments with a heavily stratified water column and sediments rich in organic matter of low nutritional value 3) Depositional environments with moderate organic content and mild or episodic current activity 4) Marginal to coastal settings with low organic content, such as fjords with an unrestricted geomorphology. We conclude that foraminifera potentially provide a tool to disentangle primary carbon signals from post-depositional degradation and loss of carbon because of their environmental sensitivity and high preservation potential in the sedimentary record.
Publisher: Elsevier BV
Date: 11-2021
Publisher: Copernicus GmbH
Date: 16-10-2017
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-9573
Abstract: & & Coastal and shelf sediments trap and bury significant quantities carbon (Berner, 1982) and provide an conditions allowing for the long-term storage of carbon. Through burying this carbon these sediments potentially provide a climate mitigation services. Currently our understanding of the spatial distribution of C within the surficial sediments of & coastal and shelf seas is limited. Using Scotland& #8217 s EEZ as a natural laboratory in conjunction with the tiered seabed mapping methodology developed by Smeaton and Austin (2019), we show that coastal and shelf sediments are highly heterogenous in both sediment type and C content. The tiered approach utilised in this study is ideally suited to global applications where data availability may differ significantly. Improved spatial mapping of seabed C will provide policy makers with a new tool for the targeted management and protection of these globally important C stores.& & & & Berner, R. A., 1982, Burial of organic carbon and pyrite sulfur in the modern ocean: Its geochemical and environmental significance.Am. J. Sci.282,451& #8211 (1982)& & & & Smeaton, C. and Austin, W.E.N., 2019. Where& #8217 s the Carbon: Exploring the Spatial Heterogeneity of Sedimentary Carbon in Mid-Latitude Fjords. Frontiers in Earth Science, 7, p.269.& &
Publisher: Copernicus GmbH
Date: 20-05-2019
Publisher: American Geophysical Union (AGU)
Date: 11-2022
DOI: 10.1029/2022GB007434
Abstract: The sediments within fjords are critical components of the mid‐ to high‐latitude coastal carbon (C) cycle, trapping and storing more organic carbon (OC) per unit area than other marine sedimentary environments. Located at the land‐ocean transition, fjord sediments receive OC from both marine and terrestrial environments globally, it has been estimated that 55%–62% of the OC held within modern fjord sediments originates from terrestrial environments. However, the mid‐latitude fjords of the Northern Hemisphere have largely been omitted from these global compilations. Here we investigate the mechanism driving the distribution of OC originating from different sources within the sediments of 38 Scottish fjords. From an array of fjord characteristics, the tidal range and outer sill depth were identified as the main drivers governing the proportions of marine and terrestrial OC in the sediments. Utilizing this relationship, we estimate that on average 52% ± 10% of the OC held within the sediments of all Scotland's fjords is terrestrial in origin. These findings show that the Scottish fjords hold equivalent quantities of terrestrial OC as other global fjord systems. However, the analysis also highlights that the sediments within 29% of Scottish fjords are dominated by marine derived OC, which is driven by local fjord geomorphology and oceanography.
Publisher: Wiley
Date: 08-03-2021
DOI: 10.1002/LOL2.10187
Abstract: Plastic is entering the world's oceans at an unprecedented rate impacting the functioning of the natural marine environment. Yet little consideration has been given to the potential of carbon (C) in the form of plastic (C plas ) to augment the marine carbon system. Here it is shown that C plas is an integral part of the anthropogenic marine C cycle. Annually, 7.8 ± 1.73 Mt of C plas is deposited at the seabed with a further 17.2–57.1 Mt C plas already present on the seafloor. The quantity of C plas currently being deposited on the seabed annually exceeds the rate at which organic carbon (OC) is buried in some marine sediments and by 2050 it is possible that the rate at which C plas is buried will match fjord sediments which are global hotspots for OC burial. Though unwanted this new anthropogenic pathway for C to reach the marine environment cannot be ignored.
Publisher: Copernicus GmbH
Date: 17-06-2016
Publisher: Copernicus GmbH
Date: 25-08-2017
DOI: 10.5194/BG-2017-360
Abstract: Abstract. Fjords are recognised as hotspots for the burial and long-term storage of carbon (C) and potentially provide a significant climate regulation service over multiple timescales. Understanding the magnitude of marine sedimentary C stores and the processes which govern their development is fundamental to understanding the role of the coastal ocean in the global C cycle. In this study, we use the mid-latitude fjords of Scotland as a natural laboratory to further develop methods to quantify these marine sedimentary C stores at both the in idual fjord and national scale. Targeted geophysical and geochemical analysis has allowed the quantification of sedimentary C stocks for a number of mid-latitude fjords and, coupled with upscaling techniques based on fjord classification, has generated the first full national sedimentary C inventory for a fjordic system. The sediments within these mid-latitude fjords hold 640.7 ± 46 Mt of C split between 295.6 ± 52 and 345.1 ± 39 Mt of organic and inorganic C respectively. When compared, these marine mid-latitude sedimentary C stores are of similar magnitude to their terrestrial equivalents, with the exception of the Scottish peatlands, which hold significantly more C. However, when area-normalised comparisons are made, these mid-latitude fjords are significantly more effective as C stores than their terrestrial counterparts, including Scottish peatlands. The C held within Scotland's coastal marine sediments has been largely overlooked as a significant component of the nation's natural capital such coastal C stores are likely to be key to understanding and constraining improved global C budgets.
Publisher: Frontiers Media SA
Date: 04-08-2022
DOI: 10.3389/FMARS.2022.892892
Abstract: It is estimated that within the UK exclusive economic zone (UK EEZ), 524 Mt of organic carbon (OC) is stored within seabed sediment. However, the stability and potential vulnerability of OC in these sediments under anthropogenic stressors, such as bottom trawling activity, remains poorly quantified. To improve our understanding of the areas where sedimentary OC is likely to be at greatest risk from trawling events, we have developed a carbon vulnerability ranking (CVR) to identify areas of the seabed where preventative protection may be most beneficial to help maintain current OC stocks while further research continues to shed light on the fate of OC after trawling (e.g., remineralization, transport, and consumption). Predictive maps of currently available fishing intensity, OC and sediment distribution, and sediment OC lability have been generated within ArcGIS using fuzzy set theory. Our results show that the west coast of Scotland represents one of the key areas where sedimentary OC is potentially at greatest risk from bottom trawling activity. This is due mainly to the high reactivity of these OC rich sediments combined with the pressures of repetitive trawling activity within inshore waters. Our research shows that these OC hotspots are potentially at risk of disturbance from bottom trawling activity and should be prioritized for the consideration of future safeguarding (management) measures to ensure emissions are minimized and to provide greater protection of this natural carbon capital resource.
Publisher: Elsevier BV
Date: 04-2020
Publisher: Frontiers Media SA
Date: 24-10-2019
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-2836
Abstract: Fjords are recognised as important hotspots for the burial and storage of organic carbon (OC) within their sediment, which potentially provides a long-term climate regulation service. Annually, it is estimated that 18 Mt of OC is buried within fjord sediments with between 55 & #8211 62% of the OC originating from the terrestrial environment. The transfer of OC from the terrestrial environment to the fjord sediments is likely a significant pathway for aged OC to reach the coastal ocean. By estimating the quantity and mapping the spatial distribution of aged OC within the fjord sediments, we can develop a better understanding of the processes that govern the transfer of terrestrial OC from the catchment to the sediment of fjords, further constraining their role in long-term climate regulation.Here we bring together radiocarbon analysis with isotopic and biomarker measurements to investigate the age of the surficial sediments within 46 fjords across the North Atlantic. The fjords in this study range from Scottish systems with catchments dominant with OC rich peat to the glaciated systems of Svalbard and Greenland. & The results from this analysis highlight that a multiple natural and anthropogenic processes govern the quantity and distribution of aged OC across North Atlantic fjords ranging between glacial input of fossil OC to the erosion of aged terrestrial material facilitated by deforestation. & This study highlights the fundamental need to understand the processes that govern the transfer of OC across the land-ocean interface to allow the role these marine sedimentary systems play in long-term climate regulation to be constrained. & & &
Publisher: Copernicus GmbH
Date: 31-07-2023
DOI: 10.5194/EGUSPHERE-2023-1185
Abstract: Abstract. Saltmarsh environments are recognised as key components of many biophysical and biochemical processes at the local and global scale. Accurately mapping these environments, and understanding how they are changing over time, is crucial for better understanding these systems. However, traditional surveying techniques are time-consuming and are inadequate for understanding how these dynamic systems may be changing temporally and spatially. The development of Uncrewed Aerial Vehicle (UAV) technology presents an opportunity for efficiently mapping saltmarsh extent. Here we develop a methodology which combines field vegetation surveys with multispectral UAV data collected at two scales to estimate saltmarsh area and organic carbon storage at three saltmarshes in Loch Fleet (Scotland). We find that the Normalised Difference Vegetation Index (NDVI) values for surveyed saltmarsh vegetation communities, in combination with local tidal data, can be used to reliably estimate saltmarsh area. Using these area estimates, together with known plant community and soil organic carbon relationships, saltmarsh soil organic carbon storage is modelled. Based on our most reliable UAV-derived saltmarsh area estimates, we find that organic carbon storage is 15–20 % lower than previous area estimates would indicate. The methodology presented here potentially provides a cheap, affordable, and rapid method for saltmarsh mapping which could be implemented more widely to test and refine existing estimates of saltmarsh extent and is particularly well-suited to the mapping of small areas of saltmarsh habitat.
Publisher: Marine Scotland Science
Date: 2020
DOI: 10.7489/12267-1
Publisher: Frontiers Media SA
Date: 08-09-2022
DOI: 10.3389/FMARS.2022.926215
Abstract: Continental shelf sediments store large amounts of organic carbon. Protecting this carbon from release back into the marine system and managing the marine environment to maximize its rate of accumulation could both play a role in mitigating climate change. For these reasons, in the context of an expanding “Blue Carbon” concept, research interest in the quantity and vulnerability of carbon stored in continental shelf, slope, and deep ocean sediments is increasing. In these systems, carbon storage is physically distant from carbon sources, altered between source and sink, and disturbed by anthropogenic activities. The methodological approaches needed to obtain the evidence to assess shelf sea sediment carbon manageability and vulnerability within an evolving blue carbon framework cannot be transferred directly from those applied in coastal vegetated “traditional” blue carbon habitats. We present a toolbox of methods which can be applied in marine sediments to provide the evidence needed to establish where and when marine carbon in offshore sediments can contribute to climate mitigation, focusing on continental shelf sediments. These methods are discussed in the context of the marine carbon cycle and how they provide evidence on: (i) stock: how much carbon is there and how is it distributed? (ii) accumulation: how rapidly is carbon being added or removed? and (iii) anthropogenic pressures: is carbon stock and/or accumulation vulnerable to manageable human activities? Our toolbox provides a starting point to inform choice of techniques for future studies alongside consideration of their specific research questions and available resources. Where possible, a stepwise approach to analyses should be applied in which initial parameters are analysed to inform which s les, if any, will provide information of interest from more resource-intensive analyses. As studies increasingly address the knowledge gaps around continental shelf carbon stocks and accumulation – through both s ling and modelling – the management of this carbon with respect to human pressures will become the key question for understanding where it fits within the blue carbon framework and within the climate mitigation discourse.
Publisher: Copernicus GmbH
Date: 06-11-2019
Abstract: Abstract. Fjords have been described as hotspots for carbon burial, potentially playing a key role within the carbon cycle as climate regulators over multiple timescales. Nevertheless, little is known about the long-term fate of the carbon that may become stored in fjordic sediments. One of the main reasons for this knowledge gap is that carbon arriving on the seafloor is prone to post-depositional degradation, posing a great challenge when trying to discriminate between an actual change in the carbon deposition rate and post-depositional carbon loss. In this study, we evaluate the use of modern benthic foraminifera as bio-indicators of organic carbon content in six voes (fjords) on the west coast of Shetland. Benthic foraminifera are known to be sensitive to changes in organic carbon content in the sediments, and changes in their assemblage composition therefore reflect synchronous variations in the quantity and quality of carbon reaching the seafloor. We identified four environments based on the relationship between benthic foraminiferal assemblages and organic carbon content in the sediments: (1) land-locked regions influenced by riverine and/or freshwater inputs of organic matter, namely the head of fjords with a restricted geomorphology (2) stressed environments with a heavily stratified water column and sediments rich in organic matter of low nutritional value (3) depositional environments with moderate organic content and mild or episodic current activity and (4) marginal to coastal settings with low organic content, such as fjords with an unrestricted geomorphology. We conclude that foraminifera potentially provide a tool to disentangle primary organic carbon signals from post-depositional degradation and loss of organic carbon because of their environmental sensitivity and high preservation potential in the sedimentary record.
Publisher: Copernicus GmbH
Date: 19-10-2016
Abstract: Abstract. Quantifying marine sedimentary carbon stocks is key to improving our understanding of long-term storage of carbon in the coastal ocean and to further constraining the global carbon cycle. Here we present a methodological approach which combines seismic geophysics and geochemical measurements to quantitatively estimate the total stock of carbon held within marine sediment. Through the application of this methodology to Loch Sunart, a fjord on the west coast of Scotland, we have generated the first full sedimentary carbon inventory for a fjordic system. The sediments of Loch Sunart hold 26.9 ± 0.5 Mt of carbon split between 11.5 ± 0.2 and 15.0 ± 0.4 Mt of organic and inorganic carbon respectively. These new quantitative estimates of carbon stored in coastal sediments are significantly higher than previous estimates. Through an area-normalised comparison to adjacent Scottish peatland carbon stocks, we have determined that these mid-latitude fjords are significantly more effective as carbon stores than their terrestrial counterparts. This initial work supports the concept that fjords are important environments for the burial and long-term storage of carbon and therefore should be considered and treated as unique environments within the global carbon cycle.
Publisher: American Geophysical Union (AGU)
Date: 10-2019
DOI: 10.1029/2018JG004957
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Craig Smeaton.