Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

Mol, J.P.; Thomas, Helmuth; Myers, Paul G.; Hu, Xianmin; Mucci, Alfonso

doi:10.5194/bg-15-1011-2018

Cited by 10 publications

(6 citation statements)

References 58 publications

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“…The Mackenzie Shelf in the southeastern Beaufort Sea (Arctic Ocean) is subject to great seasonal and interannual variability in its sea ice coverage (Galley et al, 2008;Yang, 2009;Stroeve et al, 2014), freshwater input (McClelland et al, 2012), and atmospheric forcing (Yang, 2009;Asplin et al, 2012;Moore, 2012;Kirillov et al, 2016), all of which strongly influence the water circulation and particle dynamics. The shelf is about 120 km wide, 500 km long, < 80 m deep, and is estimated to receive on average about 330 km 3 yr −1 of freshwater from the Mackenzie River with a sediment load of 130 Tg yr −1 (Macdonald et al, 1998;O'Brien et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Patterns of suspended particulate matter across the continental margin in the Canadian Beaufort Sea during summer

et al. 2019

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Abstract. The particulate beam attenuation coefficient at 660 nm, cp(660), was measured in conjunction with properties of suspended particle assemblages in August 2009 within the Canadian Beaufort Sea continental margin, a region heavily influenced by freshwater and sediment discharge from the Mackenzie River, but also by sea ice melt. The mass concentration of suspended particulate matter (SPM) ranged from 0.04 to 140 g m−3, its composition varied from mineral to organic dominated, and the median particle diameter determined over the range 0.7–120 µm varied from 0.78 to 9.45 µm, with the fraction of particles <1 µm in surface waters reflecting the degree influenced by river water. Despite this range in particle characteristics, a strong relationship between SPM and cp(660) was found and used to determine SPM distributions across the shelf based on measurements of cp(660) taken during summer seasons of 2004, 2008, and 2009. SPM spatial patterns on the stratified shelf reflected the vertically sheared two-layer estuarine circulation and SPM sources (i.e., fluvial inputs, bottom resuspension, and biological productivity). Along-shelf winds generated lateral Ekman flows, isopycnal movements, and upwelling or downwelling at the shelf break. Cross-shelf transects measured during three summers illustrate how sea ice meltwater affects river plume extent, while the presence of meltwater on the shelf was associated with enhanced near-bottom SPM during return flow of upwelled Pacific-origin water. SPM decreased sharply past the shelf break with further transport of particulate matter occurring near the bottom and in interleaving nepheloid layers. These findings expand our knowledge of particle distributions in the Beaufort Sea controlled by river discharge, sea ice, and wind, each of which is sensitive to weather and climate variations.

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Section: Introductionmentioning

confidence: 99%

Patterns of suspended particulate matter across the continental margin in the Canadian Beaufort Sea during summer

et al. 2019

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“…According to this parameterization, the model was able to correctly reproduce the DOC concentrations retrieved by satellite (Figure S4 in Supporting Information , r = 0.65; Matsuoka et al., 2017, 2022). In our simulations, tDIC plays a greater role than tDOC in the air‐sea CO 2 balance in the Beaufort Sea (see Mol et al., 2018; Tank et al., 2012). This contrasts with results from Terhaar et al.…”

Section: Contribution Of River Components To Mackenzie Plume Air‐sea ...mentioning

confidence: 63%

“…In addition to tDOC, pan‐Arctic rivers also act as large conveyor belts of terrestrial dissolved inorganic carbon (tDIC) to the ocean (Tank et al., 2012). While DIC upwelled from depth is known to trigger outgassing in coastal regions (Mol et al., 2018), quantification of tDIC release and associated CO 2 outgassing driven by Arctic river plumes has received far less attention and remains highly uncertain.…”

Section: Introductionmentioning

confidence: 99%

Biogeochemical River Runoff Drives Intense Coastal Arctic Ocean CO₂ Outgassing

Bertin

Carroll

Menemenlis

et al. 2023

Geophysical Research Letters

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Arctic warming alters land‐to‐sea fluxes of nutrients and organic matter, which impact air‐sea carbon exchange. Here we use an ocean‐biogeochemical model of the southeastern Beaufort Sea (SBS) to investigate the role of Mackenzie River biogeochemical discharge in modulating air‐sea CO2 fluxes during 2000–2019. The contribution of six biogeochemical discharge constituents leads to a net CO2 outgassing of 0.13 TgC yr−1, with a decrease in the coastal SBS carbon sink of 0.23 and 0.4 TgC yr−1 due to riverine dissolved organic and inorganic carbon, respectively. Years with high (low) discharge promote more CO2 outgassing (uptake) from the river plume. These results demonstrate that the Mackenzie River modulates the capacity of the SBS to act as a sink or source of atmospheric CO2. Our work suggests that accurate model representation of land‐to‐sea biogeochemical coupling can be critical for assessing present‐day Arctic coastal ocean response to the rapidly changing environment.

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“…During May-June, the Mackenzie River flow exceeds that for January-April by about four times (Yang et al, 2015). Wind forcing controls the diversion of the river plume over the Beaufort Sea shelf (Mulligan et al, 2010;Mol et al, 2018;Mulligan and Perrie, 2019). The along-shore easterly (anticyclonic) wind diverges the Mackenzie River riverine water westward, and also favours upwelling of the Pacific-and Atlantic-derived Arctic water onto the Beaufort Sea shelf.…”

Section: Study Areamentioning

confidence: 99%

Contrasting two major Arctic coastal polynyas: the role of sea ice in driving diel vertical migrations of zooplankton in the Laptev and Beaufort Seas

Dmitrenko,

Petrusevich,

Preußer

et al. 2024

Preprint

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Abstract. The diel vertical migration (DVM) of zooplankton is one of the largest species migrations to occur globally and is a key driver of regional ecosystems and the marine carbon pump. Previously thought to be hampered by the extreme light regime prevailing in the Arctic Ocean, observations have revealed that DVM does occur in ice-covered Arctic waters and suggest the decline in Arctic sea ice may thereby impact DVM and its role in the Arctic ecosystem. However, coastal polynyas present a unique environment where open water or thin, nearly translucent, ice prevail when offshore winds advect the ice pack away from the coast, allowing light into the surface waters and potentially disrupting DVM. Here, four yearlong time series of acoustic backscatter collected by moored acoustic Doppler current profilers at two opposite sides of the circumpolar polynya system at the Laptev Sea shelf (2007–08) and the Beaufort Sea shelf (2005–06) were used to examine the annual cycle of acoustic scattering, and therefore the annual cycle of DVM in these areas. The acoustic time series were used along with atmospheric and oceanic reanalysis and satellite data to interpret the results. Our observations show that DVM started to occur once the ice-free surface or under-ice layer irradiance exceeds a certain threshold (from ~0.3 to 3.3 lux), which is about two to ten times lower in the Beaufort Sea compared to the Laptev Sea. In the Laptev Sea, DVM does not occur during polar night, while civil twilight in the Beaufort Sea is sufficient to trigger DVM through polar night. This difference in DVM between the Laptev and Beaufort Seas is not entirely assigned to the 3° difference in latitude between the mooring positions, but also to the different light threshold required to trigger DVM, different zooplankton communities' composition, and potentially different depths and predation pressure. We find examples in both the Laptev and Beaufort Seas where the formation of polynyas and large leads caused DVM to abruptly cease or be disrupted, which we attribute to predator avoidance by the zooplankton in response to higher polar cod abundance near the open water. Finally, light attenuation by sea-ice in the Beaufort Sea caused DVM to extend onto the polar day until summer solstice. Overall, our results highlight the role of sea ice in disrupting synchronized DVM, the spatial variability in the relationship between sea ice and DVM, and the potential ecological impact of significant trends toward a more extensive circumpolar Arctic coastal polynya as part of changing ice conditions in the Arctic Ocean.

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Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

Cited by 10 publications

References 58 publications

Patterns of suspended particulate matter across the continental margin in the Canadian Beaufort Sea during summer

Patterns of suspended particulate matter across the continental margin in the Canadian Beaufort Sea during summer

Biogeochemical River Runoff Drives Intense Coastal Arctic Ocean CO₂ Outgassing

Contrasting two major Arctic coastal polynyas: the role of sea ice in driving diel vertical migrations of zooplankton in the Laptev and Beaufort Seas

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Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

Cited by 10 publications

References 58 publications

Patterns of suspended particulate matter across the continental margin in the Canadian Beaufort Sea during summer

Patterns of suspended particulate matter across the continental margin in the Canadian Beaufort Sea during summer

Biogeochemical River Runoff Drives Intense Coastal Arctic Ocean CO2 Outgassing

Contrasting two major Arctic coastal polynyas: the role of sea ice in driving diel vertical migrations of zooplankton in the Laptev and Beaufort Seas

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Biogeochemical River Runoff Drives Intense Coastal Arctic Ocean CO₂ Outgassing