Sedimentation on the Canadian Beaufort Shelf

Hill, Philip R.; Blasco, Steve; Harper, John R.; Fissel, David B.

doi:10.1016/0278-4343(91)90081-g

Cited by 84 publications

(124 citation statements)

References 8 publications

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“…The total sediment mass stored in the delta regions with an average Holocene accumulation rate in the Mackenzie Delta of ca. 136Á163 Tg/y (Lewis 1988) appeared to be three times higher than the deposition on the shelf (Hill et al 1991). In shelf areas influenced by the Mackenzie outflow, sedimentation rates have reached ca.…”

Section: Sinksmentioning

confidence: 91%

“…This highlights the potential of coastal erosion to generate fluctuations in sediment supply of greater magnitude than rivers, which react to environmental forcing in a much smoother way, as shown by the current trends in river discharge constrained to a 95% window. Sediment supply from coastal erosion in the past, beyond observational timescales, is difficult to quantify as it depends on erosion of a coastline whose original configuration is not known (Hill et al 1991), as well as a variety of mechanisms that are difficult to assess in the geological past. Large parts of the shallow circum-Arctic shelves were subaerially exposed during the LGM (Svendsen et al 2004;Jakobsson et al 2014) and became flooded rapidly.…”

Section: Coastal Erosionmentioning

confidence: 99%

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Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Wegner

Bennett

Vernal³

et al. 2015

Polar Research

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Arctic coastal zones serve as a sensitive filter for terrigenous matter input onto the shelves via river discharge and coastal erosion. This material is further distributed across the Arctic by ocean currents and sea ice. The coastal regions are particularly vulnerable to changes related to recent climate change. We compiled a pan-Arctic review that looks into the changing Holocene sources, transport processes and sinks of terrigenous sediment in the Arctic Ocean. Existing palaeoceanographic studies demonstrate how climate warming and the disappearance of ice sheets during the early Holocene initiated eustatic sea-level rise that greatly modified the physiography of the Arctic Ocean. Sedimentation rates over the shelves and slopes were much greater during periods of rapid sea-level rise in the early and middle Holocene, as a result of the relative distance to the terrestrial sediment sources. However, estimates of suspended sediment delivery through major Arctic rivers do not indicate enhanced delivery during this time, which suggests enhanced rates of coastal erosion. The increased supply of terrigenous material to the outer shelves and deep Arctic Ocean in the early and middle Holocene might serve as analogous to forecast changes in the future Arctic.To access the supplementary material for this article, please see supplementary files under Article Tools online.Rapid changes in the environmental conditions of the Arctic have been observed over recent decades. These include decreasing summer and winter sea-ice extent, increasing annual river discharge, increasing areal extent of open-water areas over the Arctic shelves and lengthening of the open-water season Serreze et al. 2007;Kwok et al. 2009;Wagner et al. 2011;Stroeve et al. 2012;Fichot et al. 2013;Zhang et al. 2013). These changes will likely lead to important transformations in sedimentary environments and the pathways and processes of terrigeneous particulate cycling. In particular, they could play a role in sediment resuspension and coastal erosion (e.g., Atkinson 2005;Eicken et al. 2005; Carmack et al. 2006; Anisimov et al. 2007;Lantuit et al. 2012).The impact of increased export of turbid waters from rivers and coastal regions on Arctic marine ecosystems remains uncertain; it could either increase delivery of nutrients and promote productivity or suppress photosynthesis in the light-limited algal populations by scattering absorbing sunlight (Retamal et al. 2008). An adequate understanding of the pathways of terrigenous material is needed to elucidate connections between sediment and ecosystem dynamics under a changing climate. Research efforts assessing recent trends and variability of terrigenous particulate matter inputs into the Arctic Ocean have been carried out during the past decades and discussed in reviews by Rachold et al. (2004), Macdonald et al. (2010), Forbes (2011) and Goñ i et al. (2013). However, the ability to forecast the future significance of land-derived sedimentary inputs into the Arctic Ocean also needs to account for th...

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Section: Sinksmentioning

confidence: 91%

Section: Coastal Erosionmentioning

confidence: 99%

Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Wegner

Bennett

Vernal³

et al. 2015

Polar Research

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“…The Mackenzie River is the largest river draining into the Arctic in terms of sediment and particulate organic carbon supply (127 × 10 12 g y −1 of sediment and 2.1 × 10 12 g y −1 of particulate organic carbon respectively; Macdonald et al, 1998) and the fourth largest in terms of freshwater discharge (3.3 × 10 11 m 3 y −1 ; Milliman and Meade, 1983;Brunskill, 1986;Macdonald et al, 1998). The Mackenzie River supplies about 95-99 % of the sediment to the Beaufort Shelf, with coastal erosion and other rivers (Hill et al, 1991;Rachold et al, 2004). The main river load occurs between end of May and the end of August with considerable interannual variance (O'Brien et al, 2006).…”

Section: Study Areamentioning

confidence: 99%

Intense photooxidative degradation of planktonic and bacterial lipids in sinking particles collected with sediment traps across the Canadian Beaufort Shelf (Arctic Ocean)

et al. 2012

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Abstract. The lipid content of seven samples of sinking particles collected with sediment traps moored at ∼ 100 m depth in summer and fall across the Canadian Beaufort Shelf (Arctic Ocean) was investigated. Our main goal was to quantify and characterize the biotic and abiotic degradation processes that acted on sinking material during these periods. Diatoms, which dominated the phytoplanktonic assemblage in every trap sample, appeared to be remarkably sensitive to Type II (i.e. involving singlet oxygen) photodegradation processes in summer, but seemed to be relatively unaffected by biotic degradation at the same time. Hence, the relative recalcitrance of phytodetritus towards biodegradation processes during the Arctic midnight sun period was attributed to the strong photodegradation state of heterotrophic bacteria, which likely resulted from the efficient transfer of singlet oxygen from photodegraded phytoplanktonic cells to attached bacteria. In addition, the detection in trap samples of photoproducts specific to wax ester components found in herbivorous copepods demonstrated that zooplanktonic faecal material exported out of the euphotic zone in summer were affected by Type II photodegradation processes as well. By contrast, sinking particles collected during the autumn were not influenced by any light-driven stress. Further chemical analyses showed that photodegraded sinking particles contained an important amount of intact hydroperoxides, which could then induce a strong oxidative stress in underlying sediments.

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“…In addition, the potential impact of bacterial activity on the isotopic signature of the sinking material due to longer deployment time at this station is considered negligible. Storms have increased in frequency and intensity in the Beaufort Sea over the past decade (Yang et al 2004;Barber et al 2008), leading to increases in coastal erosion/horizontal advection near the coast (Hill et al 1991;Dunton et al 2006;Walker et al 2008). We cannot evaluate if the terrigenous signature at Stn CA16 was of transient nature or if it reflects such broader changes in Arctic coastal dynamics.…”

Section: Sedimentation Of Phytoplankton-derived Materialsmentioning

confidence: 99%

Summertime primary production and carbon export in the southeastern Beaufort Sea during the low ice year of 2008

2011

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Following the extreme low ice year of 2007, primary production and the sinking export of particulate and gel-like organic material, using short-term particle interceptor traps deployed at 100 m, were measured in the southeastern Beaufort Sea during summer 2008. The combined influence of early ice retreat and coastal upwelling contributed to exceptionally high primary production (500 ± 312 mg C m -2 day -1 , n = 7), dominated by large cells ([5 lm, 73% ± 15%, n = 7). However, except for one station located north of Cape Bathurst, the sinking export of particulate organic carbon (POC) was relatively low (range: 38-104 mg C m -2 day -1 , n = 12) compared to other productive Arctic shelves. Estimates indicate that 80% ± 20% of the primary production was cycled through large copepods or the microbial food web. Exopolymeric substances were abundant in the sinking material but did not appear to accelerate POC sinking export. The use of isotopic signatures (d 13 C, d 15 N) and carbon/nitrogen ratios to identify sources of the sinking material was successful only at two stations with a strong marine or terrestrial signature, indicating the limitations of this approach in hydrographically and biologically complex Arctic coastal waters such as in the Beaufort Sea. At these two stations influenced by either coastal upwelling or erosion, the composition and magnitude of particulate sinking fluxes were markedly different from other stations visited during the study. These observations underscore the fundamental role of mesoscale circulation patterns and hydrodynamic singularities on the export of particulate organic material on Arctic shelves.

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Sedimentation on the Canadian Beaufort Shelf

Cited by 84 publications

References 8 publications

Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Variability in transport of terrigenous material on the shelves and the deep Arctic Ocean during the Holocene

Intense photooxidative degradation of planktonic and bacterial lipids in sinking particles collected with sediment traps across the Canadian Beaufort Shelf (Arctic Ocean)

Summertime primary production and carbon export in the southeastern Beaufort Sea during the low ice year of 2008

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