Organic Carbon Origin, Benthic Faunal Consumption, and Burial in Sediments of Northern Atlantic and Arctic Fjords (60–81°N)

Włodarska‐Kowalczuk, Maria; Mazurkiewicz, Mikołaj; Górska, Barbara; Michel, Loïc; Jankowska, Emilia; Zaborska, Agata

doi:10.1029/2019jg005140

Cited by 43 publications

(37 citation statements)

References 89 publications

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“…et al, 2009). However, even in these HNLC waters there are also other concurrent factors that locally mitigate the effect of glacially derived Fe in nearshore waters, because light limitation from near-surface particle plumes may locally offset any positive effect of Fe fertilization (Wojtasiewicz et al, 2019).…”

Section: Contrasting Fe-and No 3 -Limited Regions Of the Oceanmentioning

confidence: 99%

Review article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

et al. 2020

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Abstract. Freshwater discharge from glaciers is increasing across the Arctic in response to anthropogenic climate change, which raises questions about the potential downstream effects in the marine environment. Whilst a combination of long-term monitoring programmes and intensive Arctic field campaigns have improved our knowledge of glacier–ocean interactions in recent years, especially with respect to fjord/ocean circulation, there are extensive knowledge gaps concerning how glaciers affect marine biogeochemistry and productivity. Following two cross-cutting disciplinary International Arctic Science Committee (IASC) workshops addressing the importance of glaciers for the marine ecosystem, here we review the state of the art concerning how freshwater discharge affects the marine environment with a specific focus on marine biogeochemistry and biological productivity. Using a series of Arctic case studies (Nuup Kangerlua/Godthåbsfjord, Kongsfjorden, Kangerluarsuup Sermia/Bowdoin Fjord, Young Sound and Sermilik Fjord), the interconnected effects of freshwater discharge on fjord–shelf exchange, nutrient availability, the carbonate system, the carbon cycle and the microbial food web are investigated. Key findings are that whether the effect of glacier discharge on marine primary production is positive or negative is highly dependent on a combination of factors. These include glacier type (marine- or land-terminating), fjord–glacier geometry and the limiting resource(s) for phytoplankton growth in a specific spatio-temporal region (light, macronutrients or micronutrients). Arctic glacier fjords therefore often exhibit distinct discharge–productivity relationships, and multiple case-studies must be considered in order to understand the net effects of glacier discharge on Arctic marine ecosystems.

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Section: Contrasting Fe-and No 3 -Limited Regions Of the Oceanmentioning

confidence: 99%

Review article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

et al. 2020

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“…Higher sedimentation rates and the binding of organic matter to sediment surfaces (Sholkovitz, 1976) could increase carbon burial efficiency in inner fjord areas but these processes are likely to be dominated by older, terrestrial carbon sources (Rebolledo et al, 2019). Although fjords are globally important carbon sinks (Smith et al, 2015), the probable decline in fjord primary production (Aracena et al, 2011;Włodarska-Kowalczuk et al, 2019) may mean that Patagonian fjords play a reduced role in new carbon sequestration.…”

Section: Biogeochemical Impacts Of Changing Glacier Melt Inputs On Bamentioning

confidence: 99%

Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

et al. 2021

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Biogeochemical processes in fjords are likely affected by changes in surrounding glacier cover but very little is known about how meltwater directly influences dissolved organic matter (DOM) in fjords. Moreover, the data available are restricted to a handful of northern hemisphere sites. Here we analyze seasonal and spatial variation in dissolved organic carbon (DOC) concentration and DOM composition (spectrofluorescence, ultrahigh resolution mass spectrometry) in Baker-Martinez Fjord, Chilean Patagonia (48°S), to infer the impacts of rapid regional deglaciation on fjord DOM. We show that surface layer DOC concentrations do not vary significantly between seasons, but DOM composition is sensitive to differences in riverine inputs. In summer, higher protein-like fluorescence reflects increased glacial meltwater inputs, whilst molecular level data show weaker influence from marine DOM due to more intense stratification. We postulate that the shifting seasonal balance of riverine and marine waters affects the supply of biolabile peptides and organic nitrogen cycling in the surface layer. Trends in DOM composition with increasing salinity are consistent with patterns in estuaries (i.e. preferential removal of aromatic compounds and increasing relative contribution of unsaturated and heteroatom-rich DOM from marine sources). Preliminary estimates also suggest that at least 10% of the annual organic carbon stock in this fjord is supplied by the four largest, glacially fed rivers and that these inputs are dominated by dissolved (84%) over particulate organic carbon. Riverine DOC may therefore be an important carbon subsidy to bacterial communities in the inner fjord. The overall findings highlight the biogeochemical sensitivity of a Patagonian fjord to changes in glacier melt input, which likely has relevance for other glaciated fjords in a warming climate.

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“…Fjords are notable for some of Earth's most rapid rates of sedimentation and organic carbon burial during glacial retreat (Smith et al, 2015;Syvitski et al, 1986;Włodarska-Kowalczuk et al, 2019), producing thick sediment sequences conducive to biogenic methane production. In addition, the rocks underlying many Arctic fjords support either proven or highly probable natural gas resources.…”

Section: Introductionmentioning

confidence: 99%

Open system pingos as hotspots for sub-permafrost methane emission in Svalbard

Hodson¹,

Nowak²,

Senger³

et al. 2020

Preprint

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Abstract. Methane release from beneath lowland permafrost represents an important uncertainty in the Arctic greenhouse gas budget. Our current knowledge is arguably best-developed in settings where permafrost is being inundated by rising sea level, which means much of the methane is oxidised in the water column before it reaches the atmosphere. Here we provide a different process perspective that is appropriate for Arctic fjord valleys, where local deglaciation causes isostatic uplift to out-pace rising sea level. We show how the uplift induces permafrost aggradation in former marine sediments, whose pressurisation results in methane escape directly to the atmosphere via ground water springs. In Adventdalen, Central Spitsbergen, we show how the springs are historic features, responsible for the formation of open system pingos, and capable of discharging brackish waters enriched with high concentrations of mostly biogenic methane (average 18 mg L−1). Thermodynamic calculations show that the methane concentrations sometimes marginally exceed the solubility limit for methane in water at 0 °C (41 mg L−1). In our case study, emissions from just four pingo springs with a combined discharge of less than 2 L s−1 increase the land-atmosphere methane flux by 16 %. This confirms that sub-permafrost methane migration deserves more attention for improved forecasting of Arctic greenhouse gas emissions.

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Organic Carbon Origin, Benthic Faunal Consumption, and Burial in Sediments of Northern Atlantic and Arctic Fjords (60–81°N)

Cited by 43 publications

References 89 publications

Review article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

Review article: How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?

Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

Open system pingos as hotspots for sub-permafrost methane emission in Svalbard

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