Seasonal variations in Arctic sediment dynamics—evidence from 1-year records in the Laptev Sea (Siberian Arctic)

Wegner, Carolyn; Hölemann, Jens; Dmitrenko, Igor; Kirillov, Sergey; Kassens, Heidemarie

doi:10.1016/j.gloplacha.2004.12.009

Cited by 58 publications

(53 citation statements)

References 47 publications

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“…Generally, along the outer parts of Arctic Ocean continental margins and across topographic highs in deep basins, sea ice is assumed to be the main contributor seasonal sea-ice formation, ice rafting, peak riverine input shortly after spring break-up, pulsed productivity during ice-free months and increased resuspension of bottom sediments and current transport during ice-free conditions and freeze-up (e.g., Macdonald 2000; McClimans et al 2000; Bauch et al 2001;Sternberg et al 2001; Baskaran et al 2003; Bauch et al 2004;Stein, Schubert et al 2004;Wegner et al 2005). Today, shelf currents experience a strong seasonality with wind and ice as limiting factors (e.g., Harms & Karcher 1999;McClimans et al 2000;Sternberg et al 2001;Wegner et al 2005;Schulze & Pickart 2012).…”

Section: Transport Processesmentioning

confidence: 99%

“…Today, shelf currents experience a strong seasonality with wind and ice as limiting factors (e.g., Harms & Karcher 1999;McClimans et al 2000;Sternberg et al 2001;Wegner et al 2005;Schulze & Pickart 2012). The surface distribution of riverine water and river-derived material shows strong interannual variability, mainly attributed to atmospheric vorticity variations over the adjacent Arctic Ocean in summer (Guay et al 2001;Macdonald et al 2002; ViscosiShirley et al 2003;Dmitrenko et al 2005; Bauch et al 2009;Yamamoto-Kawai et al 2009;Wegner et al 2013).…”

Section: Transport Processesmentioning

confidence: 99%

“…Riverine waters are not only a critical source for low salinity waters, but they also carry high nutrient loads and fuel biological production (e.g., Smith et al 2003;Trimble & Baskaran 2005). The terrestrial material delivered to the Arctic Ocean by riverine input and coastal erosion either accumulates on the shelf or is transported further offshore by currents or sea ice (e.g., Stein 2000Stein , 2008Wegner et al 2005). Throughout the Holocene, as more of the shelf seas were inundated, formation of shore-fast sea ice and the incorporation of sediments into newly formed sea ice became more widespread.…”

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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: Transport Processesmentioning

confidence: 99%

Section: Transport Processesmentioning

confidence: 99%

mentioning

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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“…A similar range of PM concentrations was observed along the Lena River after breakup time (late June-August), as discussed in this paper. Another "mooring-based" study (Wegner et al, 2005) shows that the main river PM transport onto the midshelf occurs during and shortly after river-ice breakup (Juneearly July), with peak PM concentrations of up to 6.5 mg l −1 . Surprisingly, events with the highest PM concentrations (up to 9.1 mg l −1 ) were recorded over the mid-shelf during the ice-free period and at the time of freeze up.…”

Section: Introductionmentioning

confidence: 99%

Carbon transport by the Lena River from its headwaters to the Arctic Ocean, with emphasis on fluvial input of terrestrial particulate organic carbon vs. carbon transport by coastal erosion

et al. 2011

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Abstract. The Lena River integrates biogeochemical signals from its vast drainage basin, and the integrated signal reaches far out over the Arctic Ocean. Transformation of riverine organic carbon (OC) into mineral carbon, and mineral carbon into the organic form in the Lena River watershed, can be considered to be quasi-steady-state processes. An increase in Lena discharge exerts opposite effects on total organic (TOC) and total inorganic (TCO 2 ) carbon: TOC concentration increases, while TCO 2 concentration decreases. Significant inter-annual variability in mean values of TCO 2 , TOC, and their sum (total carbon, TC) has been found. This variability is determined by changes in land hydrology which cause differences in the Lena River discharge. There is a negative correlation in the Lena River between TC in September and its mean discharge in August; a time shift of about one month is required for water to travel from Yakutsk to the Laptev Sea. Total carbon entering the sea with the Lena discharge is estimated to be almost 10 Tg C yr −1 . The annual Lena River discharge of particulate organic carbon (POC) can be as high as 0.38 Tg (moderate to high estimate). If we instead accept Lisytsin's (1994) statement that 85-95 % of total particulate matter (PM) (and POC) precipitates on the marginal "filter", then only about 0.03-0.04 Tg of Lena River POC reaches the Laptev Sea. The Lena's POC export would then be two orders of magnitude less than the annual input of eroded terrestrial carbon onto the shelf of the Laptev and East SiberianCorrespondence to: I. P. Semiletov (igorsm@iarc.uaf.edu) seas, which is estimated to be about 4 Tg. Observations support the hypothesis of a dominant role for coastal erosion (Semiletov, 1999a, b) in East Siberian Arctic Shelf (ESAS) sedimentation and the dynamics of the carbon/carbonate system. The Lena River is characterized by relatively high concentrations of the primary greenhouse gases, dissolved carbon dioxide (CO 2 ) and methane (CH 4 ). During all seasons the river is supersaturated in CO 2 compared to the atmosphere, by up to 1.5-2 fold in summer, and 4-5 fold in winter. This results in a significant CO 2 supersaturation in the adjacent coastal sea. Localized areas of dissolved CH 4 along the Lena River and in the Lena delta channels may reach 100 nM, but the CH 4 concentration decreases to 5-20 nM towards the sea, which suggests that riverborne export of CH 4 plays but a minor role in determining the ESAS CH 4 budget in coastal waters. Instead, the seabed appears to be the source that provides most of the CH 4 to the Arctic Ocean.

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“…Because the strong vertical density gradient (pycnocline) separates the fresh surface layers from the more saline bottom waters and impedes the exchange of energy and matter between both water masses, it was assumed that*particularly in the eastern Laptev Sea* the temperature below 20-m water depth is not affected by the distinct seasonal cycle of temperature variations in the surface layer. This assumption was mainly based on the first year-round mooring observations (1998Á99) from the mid-shelf of the Laptev Sea at 44-m water depth (Dmitrenko et al 2002;Wegner et al 2005) and the analysis of the Russian historical oceanographic record (see below).…”

Section: Introductionmentioning

confidence: 99%

Near-bottom water warming in the Laptev Sea in response to atmospheric and sea-ice conditions in 2007

et al. 2011

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In this paper we present new data from ship-based measurements and two-year observations from moorings in the Laptev Sea along with Russian historical data. The observations from the Laptev Sea in 2007 indicate that the bottom water temperatures on the mid-shelf increased by more than 3°C compared to the long-term mean as a consequence of the unusually high summertime surface water temperatures. Such a distinct increase in near-bottom temperatures has not been observed before. Remnants of the relatively warm bottom water occupied the mid-shelf from September 2007 until April 2008. Strong polynya activity during March to May 2007 caused more summertime open water and therefore warmer sea surface temperatures in the Laptev Sea. During the ice-free period in August and September 2007, the prevailing cyclonic atmospheric circulation deflected the freshwater plume of the River Lena to the east, which increased the salinity on the mid-shelf north of the Lena Delta. The resulting weaker density stratification allowed more vertical mixing of the water column during storms in late September and early October, leading to the observed warming of the near-bottom layer in the still ice-free Laptev Sea. In summer and autumn 2008, when the density stratification was stronger and sea surface temperatures were close to the long-term mean, no near-bottom water warming was observed. Warmer water temperatures near the seabed may also impact the stability of the shelf's submarine permafrost

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Seasonal variations in Arctic sediment dynamics—evidence from 1-year records in the Laptev Sea (Siberian Arctic)

Cited by 58 publications

References 47 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

Carbon transport by the Lena River from its headwaters to the Arctic Ocean, with emphasis on fluvial input of terrestrial particulate organic carbon vs. carbon transport by coastal erosion

Near-bottom water warming in the Laptev Sea in response to atmospheric and sea-ice conditions in 2007

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