Seasonal organic matter dynamics in a temperate shelf sea

Davis, Clare E.; Blackbird, Sabena; Wolff, George A; Woodward, Malcolm

doi:10.1016/j.pocean.2018.02.021

Cited by 19 publications

(22 citation statements)

References 49 publications

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“…DOC occupies a further 2-5% with the remainder comprising a minor contribution from POC, PIC and macrofauna (Supplementary Material). Ranges of DIC, DOC, PIC and POC concentrations were based on measurements and model results (Buitenhuis et al, 1996;Weston et al, 2004;Thomas et al, 2005;Suratman et al, 2009;Salt et al, 2013;Poulton et al, 2014;Clargo et al, 2015;Hartman et al, 2018;Painter et al, 2018;Chaichana et al, 2019;Davis et al, 2019) and were multiplied by the volume of water on the shelf (9.91 × 10 13 m 3 , Wakelin et al, 2012) to give total carbon stocks. The non-DIC component of the pelagic carbon budget (approximately 6-16 Tmol) is large relative to coastal habitats (see section "Coastal habitats") and potentially sensitive to anthropogenic influence (see section "Responses of Carbon Stocks and Flows on the NWES to Future Changes").…”

Section: Pelagic Stocks and Processesmentioning

confidence: 99%

“…In spite of much recent progress in understanding shelf carbon cycling on the NWES (e.g., Stahl et al, 2004;Thomas et al, 2005;Johnson et al, 2013;Hale et al, 2017;Hicks et al, 2017;Carr et al, 2018;Humphreys et al, 2018;Chaichana et al, 2019;Davis et al, 2019;García-Martín et al, 2019), there is still a great deal of uncertainty in both the mechanisms governing carbon dynamics and the magnitudes of contemporary carbon stocks and flows, as well as their responses to future change.…”

Section: Introductionmentioning

confidence: 99%

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Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

et al. 2020

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A carbon budget for the northwest European continental shelf seas (NWES) was synthesized using available estimates for coastal, pelagic and benthic carbon stocks and flows. Key uncertainties were identified and the effect of future impacts on the carbon budget were assessed. The water of the shelf seas contains between 210 and 230 Tmol of carbon and absorbs between 1.3 and 3.3 Tmol from the atmosphere annually. Offshelf transport and burial in the sediments account for 60-100 and 0-40% of carbon outputs from the NWES, respectively. Both of these fluxes remain poorly constrained by observations and resolving their magnitudes and relative importance is a key research priority. Pelagic and benthic carbon stocks are dominated by inorganic carbon. Shelf sediments contain the largest stock of carbon, with between 520 and 1600 Tmol stored in the top 0.1 m of the sea bed. Coastal habitats such as salt marshes and mud flats contain large amounts of carbon per unit area but their total carbon stocks are small compared to pelagic and benthic stocks due to their smaller spatial extent. The large pelagic stock of carbon will continue to increase due to the rising concentration of atmospheric CO 2 , with associated pH decrease. Pelagic carbon stocks and flows are also likely to be significantly affected by increasing acidity and temperature, and circulation changes but the net impact is uncertain. Benthic carbon stocks will be affected by increasing temperature and acidity, and decreasing oxygen concentrations, although the net impact of these interrelated changes on carbon stocks is uncertain and a major knowledge gap. The impact of bottom trawling on benthic carbon stocks Frontiers in Marine Science | www.frontiersin.org 1 March 2020 | Volume 7 | Article 143Legge et al.Carbon on the Northwest European Shelf is unique amongst the impacts we consider in that it is widespread and also directly manageable, although its net effect on the carbon budget is uncertain. Coastal habitats are vulnerable to sea level rise and are strongly impacted by management decisions. Local, national and regional actions have the potential to protect or enhance carbon storage, but ultimately global governance, via controls on emissions, has the greatest potential to influence the long-term fate of carbon stocks in the northwestern European continental shelf.

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Section: Pelagic Stocks and Processesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

et al. 2020

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“…These scaled rates provide information on the contribution of these fractions to water column metabolism. Davis et al, 2019) were used to calculate POC-specific respiration in the three fractions (suspended, slow-, and fast-sinking), and to derive relationships between the composition of the organic material (POC:PON ratio) and the metabolic rates. The specific POC and PON data used in this study are given in the supporting material (Figure S3).…”

Section: Calculation Of the Metabolic Ratesmentioning

confidence: 99%

Low Contribution of the Fast‐Sinking Particle Fraction to Total Plankton Metabolism in a Temperate Shelf Sea

García-Martín

Davidson

Davis

et al. 2021

Global Biogeochemical Cycles

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Temperate shelf seas are productive areas with the potential to export high quantities of particulate organic carbon (POC), as sinking particles, to the sediments or off‐shelf to the open ocean. The amount of carbon which can be exported depends partly on the amount of POC produced and on the remineralization processes occurring on the sinking material. Here, we assessed the relative seasonal importance of microbial respiration and bacterial production associated with suspended, slow‐ and fast‐sinking particle fractions. The three fractions were collected in the Celtic Sea above and below the seasonal thermocline in November 2014, April and July 2015 using Marine Snow Catchers. The slow‐sinking fraction had higher microbial respiration and bacterial production rates than the fast‐sinking fractions, and these two fractions sustained rates of microbial respiration and bacterial production between 1 and 3 orders of magnitude lower than the suspended fraction. This low contribution of the slow‐ and fast‐sinking fractions was consistent with their low contribution to the POC concentration at the two depths sampled. The POC‐specific respiration rates associated with the slow‐ and fast‐sinking fractions were low (median 0.17 and 0.08 d−1, respectively), indicating low‐sinking particle degradation. Our results indicate that ∼5% of the POC in surface waters can be exported below the thermocline.

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“…reliance on pre-weighed salts and reagents, moving laboratory, analyst fatigue). Precision alone for marine nutrient measurements has been reported as typically~2-3% [18,47]. In comparison, reported values for combined uncertainties associated with trace metal measurements, albeit at sub-nanomolar concentrations, range from 7.5% to 12% [20,23].…”

Section: -mentioning

confidence: 99%

Realistic measurement uncertainties for marine macronutrient measurements conducted using gas segmented flow and Lab-on-Chip techniques

Birchill

Clinton-Bailey

Hanz

et al. 2019

Talanta

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Accurate and precise measurements of marine macronutrient concentrations are fundamental to our understanding of biogeochemical cycles in the ocean. Quantifying the measurement uncertainty associated with macronutrient measurements remains a challenge. Large systematic biases (up to 10%) have been identified between datasets, restricting the ability of marine biogeochemists to distinguish between the effects of environmental processes and analytical uncertainty. In this study we combine the routine analyses of certified reference materials (CRMs) with the application of a simple statistical technique to quantify the combined (random + systematic) measurement uncertainty associated with marine macronutrient measurements using gas segmented flow techniques. We demonstrate that it is realistic to achieve combined uncertainties of~1-4% for nitrate + nitrite (ΣNOx), phosphate (PO 4 3-) and silicic acid (Si(OH) 4) measurements. This approach requires only the routine analyses of CRMs (i.e. it does not require inter-comparison exercises). As CRMs for marine macronutrients are now commercially available, it is advocated that this simple approach can improve the comparability of marine macronutrient datasets and therefore should be adopted as 'best practice'. Novel autonomous Lab-on-Chip (LoC) technology is currently maturing to a point where it will soon become part of the marine chemist's standard analytical toolkit used to determine marine macronutrient concentrations. Therefore, it is critical that a complete understanding of the measurement uncertainty of data produced by LoC analysers is achieved. In this study we analysed CRMs using 7 different LoC ΣNOx analysers to estimate a combined measurement uncertainty of < 5%. This demonstrates that with high quality manufacturing and laboratory practices, LoC analysers routinely produce high quality measurements of marine macronutrient concentrations.

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Seasonal organic matter dynamics in a temperate shelf sea

Cited by 19 publications

References 49 publications

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

Low Contribution of the Fast‐Sinking Particle Fraction to Total Plankton Metabolism in a Temperate Shelf Sea

Realistic measurement uncertainties for marine macronutrient measurements conducted using gas segmented flow and Lab-on-Chip techniques

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