scholarly journals Interannual variability of surface and bottom sediment transport on the Laptev Sea shelf during summer

2012 ◽  
Vol 9 (9) ◽  
pp. 13053-13084 ◽  
Author(s):  
C. Wegner ◽  
D. Bauch ◽  
J. A. Hölemann ◽  
M. A. Janout ◽  
B. Heim ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Interannual Variability ◽  
Water Column ◽  
Atmospheric Circulation ◽  
Surface Waters ◽  
Laptev Sea ◽  
Nepheloid Layer ◽  
Transport Dynamics ◽  
Spm Concentration ◽  
The Laptev Sea

Abstract. Sediment transport dynamics were studied during ice-free conditions under different atmospheric circulation regimes on the Laptev Sea shelf (Siberian Arctic). To study the interannual variability of suspended particulate matter (SPM) dynamics and their coupling with the variability in surface river water distribution on the Laptev Sea detailed oceanographic, optical (turbidity and Ocean Color satellite data), and hydrochemical (nutrients, SPM, stable oxygen isotopes) process studies were carried out continuously during the summers of 2007 and 2008. Thus, for the first time SPM and nutrient variations on the Laptev Sea shelf under different atmospheric forcing and the implications for the turbidity and transparency of the water column can be presented. The data indicate a clear link between different surface distributions of riverine waters and the SPM transport dynamics within the entire water column. The summer of 2007 was dominated by shoreward winds and an eastward transport of riverine surface waters. The surface SPM concentration on the south-eastern inner shelf was elevated, which led to decreased transmissivity and increased light absorption. Surface SPM concentrations in the Central and Northern Laptev Sea were comparatively low. However, the SPM transport and concentration within the bottom nepheloid layer increased considerably on the entire eastern shelf. The summer of 2008 was dominated by offshore-winds and northwards transport of the river plume. The surface SPM transport was enhanced and extended onto the mid-shelf whereas the bottom SPM transport and concentration was diminished. This study suggests that the SPM concentration and transport in both, the surface and bottom nepheloid layers, are associated with the distribution of riverine surface waters which are linked to the atmospheric circulation patterns over the Laptev Sea and the adjacent Arctic Ocean during open water season. A continuing trend toward shoreward winds, weaker stratification and higher SPM concentration throughout the water column might have severe consequences for the ecosystem on the Laptev Sea shelf.

scholarly journals Interannual variability of surface and bottom sediment transport on the Laptev Sea shelf during summer

2013 ◽  
Vol 10 (2) ◽  
pp. 1117-1129 ◽  
Author(s):  
C. Wegner ◽  
D. Bauch ◽  
J. A. Hölemann ◽  
M. A. Janout ◽  
B. Heim ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Interannual Variability ◽  
Water Column ◽  
Atmospheric Circulation ◽  
Surface Waters ◽  
Laptev Sea ◽  
Nepheloid Layer ◽  
Transport Dynamics ◽  
Spm Concentration ◽  
The Laptev Sea

Abstract. Sediment transport dynamics were studied during ice-free conditions under different atmospheric circulation regimes on the Laptev Sea shelf (Siberian Arctic). To study the interannual variability of suspended particulate matter (SPM) dynamics and their coupling with the variability in surface river water distribution on the Laptev Sea shelf, detailed oceanographic, optical (turbidity and Ocean Color satellite data), and hydrochemical (nutrients, SPM, stable oxygen isotopes) process studies were carried out continuously during the summers of 2007 and 2008. Thus, for the first time SPM and nutrient variations on the Laptev Sea shelf under different atmospheric forcing and the implications for the turbidity and transparency of the water column can be presented. The data indicate a clear link between different surface distributions of riverine waters and the SPM transport dynamics within the entire water column. The summer of 2007 was dominated by shoreward winds and an eastward transport of riverine surface waters. The surface SPM concentration on the southeastern inner shelf was elevated, which led to decreased transmissivity and increased light absorption. Surface SPM concentrations in the central and northern Laptev Sea were comparatively low. However, the SPM transport and concentration within the bottom nepheloid layer increased considerably on the entire eastern shelf. The summer of 2008 was dominated by offshore winds and northward transport of the river plume. The surface SPM transport was enhanced and extended onto the mid-shelf, whereas the bottom SPM transport and concentration was diminished. This study suggests that the SPM concentration and transport, in both the surface and bottom nepheloid layers, are associated with the distribution of riverine surface waters which are linked to the atmospheric circulation patterns over the Laptev Sea and the adjacent Arctic Ocean during the open water season. A continuing trend toward shoreward winds, weaker stratification and higher SPM concentration throughout the water column might have severe consequences for the ecosystem on the Laptev Sea shelf.

Application of ADCPs for Long-Term Sediment Transport Monitoring in Arctic Environments: Examples From the Laptev Sea

2006 ◽  
Author(s):  
Carolyn Wegner ◽  
Jens A. Ho¨lemann ◽  
Torben Klagge ◽  
Leonid Timokhov ◽  
Heidemarie Kassens
Keyword(s):  
Sediment Transport ◽  
Water Samples ◽  
Acoustic Doppler Current Profiler ◽  
Laptev Sea ◽  
Transport Dynamics ◽  
Shelf Seas ◽  
Current Profiler ◽  
Spm Concentration ◽  
Optical Turbidity ◽  
The Laptev Sea

For offshore constructions the knowledge on sediment transport dynamics is essential and the quantification of suspended particulate matter (SPM) is of major importance. The Laptev Sea shelf is one of the largest Siberian shelf seas and ice-covered for about nine months a year. In order to use indirect measuring devices for the quantification of SPM concentration on the Laptev Sea shelf, optical (turbidity meter) and acoustic (ADCP; Acoustic Doppler Current Profiler) backscatter sensors were compared to assess their potential for the investigation of SPM dynamics in an arctic environment. To estimate SPM concentrations from optical backscatter signals, these were converted using the linear relation between the backscatter signals and SPM concentrations derived from water samples. Applying the theoretical interaction of sound in the water with SPM the acoustic backscatter signals were transformed adapting a previously established approach. SPM concentrations estimated from the backscattered signals of both sensors showed a close similarity to SPM concentrations obtained from filtered water samples. While the ADCP offers distinct advantages over the turbidity meter in that it allows measurement of the complete concentration profile, bottom location, and currents, co-deployment of both sensors are recommended for improved SPM measurements.

scholarly journals On the Variability of Stratification in the Freshwater-Influenced Laptev Sea Region

2020 ◽  
Vol 7 ◽  
Author(s):  
Markus A. Janout ◽  
Jens Hölemann ◽  
Georgi Laukert ◽  
Alexander Smirnov ◽  
Thomas Krumpen ◽  
...  
Keyword(s):  
Sea Ice ◽  
Interannual Variability ◽  
Water Column ◽  
River Water ◽  
Heat Storage ◽  
Mixed Layer Depth ◽  
Laptev Sea ◽  
Layer Depth ◽  
Freshwater Influence ◽  
The Laptev Sea

In this paper, we investigate the seasonal and spatial variability of stratification on the Siberian shelves with a case study from the Laptev Sea based on shipboard hydrographic measurements, year-round oceanographic mooring records from 2013 to 2014 and chemical tracer-based water mass analyses. In summer 2013, weak onshore-directed winds caused spreading of riverine waters throughout much of the eastern and central shelf. In contrast, strong southerly winds in summer 2014 diverted much of the freshwater to the northeast, which resulted in 50% less river water and significantly weaker stratification on the central shelf compared with the previous year. Our year-long records additionally emphasize the regional differences in water column structure and stratification, where the northwest location was well-mixed for 6 months and the central and northeast locations remained stratified into spring due to the lower initial surface salinities of the river-influenced water. A 26 year record of ocean reanalysis highlights the region’s interannual variability of stratification and its dependence on winds and sea ice. Prior the mid-2000s, river runoff to the perennially ice-covered central Laptev Sea shelf experienced little surface forcing and river water was maintained on the shelf. The transition toward less summer sea ice after the mid-2000s increased the ROFI’s (region of freshwater influence) exposure to summer winds. This greatly enhanced the variability in mixed layer depth, resulting in several years with well-mixed water columns as opposed to the often year-round shallow mixed layers before. The extent of the Lena River plume is critical for the region since it modulates nutrient fluxes and primary production, and further controls intermediate heat storage induced by lateral density gradients, which has implications for autumnal freeze-up and the eastern Arctic sea ice volume.MAIN POINTS1.CTD surveys and moorings highlight the regional and temporal variations in water column stratification on the Laptev Sea shelf.2.Summer winds increasingly control the extent of the region of freshwater influence under decreasing sea ice.3.Further reductions in sea ice increases surface warming, heat storage, and the interannual variability in mixed layer depth.

Viruses in the water column and the sediment of the eastern part of the Laptev Sea

2020 ◽  
Vol 242 ◽  
pp. 106836
Author(s):  
Alexander I. Kopylov ◽  
Elena A. Zabotkina ◽  
Anna V. Romanenko ◽  
Dmitriy B. Kosolapov ◽  
Andrey F. Sazhin
Keyword(s):  
Water Column ◽  
Laptev Sea ◽  
The Laptev Sea

Interannual Variability of Primary Production in the Laptev Sea

Oceanology ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 50-61 ◽  
Author(s):  
A. B. Demidov ◽  
S. V. Sheberstov ◽  
V. I. Gagarin
Keyword(s):  
Primary Production ◽  
Interannual Variability ◽  
Laptev Sea ◽  
The Laptev Sea

Heterotrophic nanoflagellates in the pelagic zone and sediments of the eastern Laptev sea

2019 ◽  
Vol 59 (6) ◽  
pp. 974-986
Author(s):  
N. G. Kosolapova ◽  
D. B. Kosolapov ◽  
A. I. Kopylov ◽  
A. V. Romanenko
Keyword(s):  
Water Column ◽  
Heterotrophic Nanoflagellates ◽  
Heterotrophic Flagellates ◽  
Laptev Sea ◽  
Freshwater Input ◽  
Water Layers ◽  
Quantitative Characteristics ◽  
Taxonomic Groups ◽  
First Time ◽  
The Laptev Sea

For the first time, the species composition of heterotrophic nanoflagellates, their quantitative characteristics, as well as the abundance and biomass of their main food objects: bacteria and picophytoplankton, were determined in the water column and sediments of the Laptev Sea. On a meridional transect from the Lena delta to the deep-sea zone in early autumn an increase in the number and biomass of planktonic flagellates was recorded in the area of the internal shelf, which is impacted by Lena's freshwater input. The pattern of vertical distribution of planktonic flagellates differed in the different parts of the sea, but everywhere their greatest number was confined to either the surface or the near-bottom water layers. Quantitative parameters of planktonic flagellates positively correlated with the temperature, bacterial abundance and biomass and negatively correlated with the water salinity. The abundance and biomass of heterotrophic flagellates in the surface sediments was 34 orders of magnitude higher than in the water column and exceeded those of planktonic flagellates in the shallow sites under 1 m2. A total of 28 species and forms of heterotrophic flagellates have been identified. Representatives of two taxonomic groups: Kinetoplastea and Stramenopiles, which were the most tolerance to the salinity, dominated in the community. The species richness of the flagellates decreased with the water depth and was minimal in the less saline coastal waters and increased in the deep-see area.

scholarly journals Halocline water modification and along-slope advection at the Laptev Sea continental margin

Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 141-154 ◽  
Author(s):  
D. Bauch ◽  
S. Torres-Valdes ◽  
I. Polyakov ◽  
A. Novikhin ◽  
I. Dmitrenko ◽  
...  
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Continental Slope ◽  
Shelf Break ◽  
Laptev Sea ◽  
Frontal System ◽  
Ice Melt ◽  
Sea Bottom ◽  
Bottom Waters ◽  
The Laptev Sea

Abstract. A general pattern in water mass distribution and potential shelf–basin exchange is revealed at the Laptev Sea continental slope based on hydrochemical and stable oxygen isotope data from the summers 2005–2009. Despite considerable interannual variations, a frontal system can be inferred between shelf, continental slope and central Eurasian Basin waters in the upper 100 m of the water column along the continental slope. Net sea-ice melt is consistently found at the continental slope. However, the sea-ice meltwater signal is independent from the local retreat of the ice cover and appears to be advected from upwind locations. In addition to the along-slope frontal system at the continental shelf break, a strong gradient is identified on the Laptev Sea shelf between 122° E and 126° E with an eastward increase of riverine and sea-ice related brine water contents. These waters cross the shelf break at ~ 140° E and feed the low-salinity halocline water (LSHW, salinity S < 33) in the upper 50 m of the water column. High silicate concentrations in Laptev Sea bottom waters may lead to speculation about a link to the local silicate maximum found within the salinity range of ~ 33 to 34.5, typical for the Lower Halocline Water (LHW) at the continental slope. However brine signatures and nutrient ratios from the central Laptev Sea differ from those observed at the continental slope. Thus a significant contribution of Laptev Sea bottom waters to the LHW at the continental slope can be excluded. The silicate maximum within the LHW at the continental slope may be formed locally or at the outer Laptev Sea shelf. Similar to the advection of the sea-ice melt signal along the Laptev Sea continental slope, the nutrient signal at 50–70 m water depth within the LHW might also be fed by advection parallel to the slope. Thus, our analyses suggest that advective processes from upstream locations play a significant role in the halocline formation in the northern Laptev Sea.

Going with the flow: Experimental simulation of sediment turbid transport from a foraminifera perspective

2021 ◽  
Author(s):  
Anat Ash-Mor ◽  
Ahuva Almogi-Labin ◽  
Vincent M. P. Bouchet ◽  
Laurent Seuront ◽  
Tamar Guy-Haim ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Water Column ◽  
Deep Ocean ◽  
Thin Layers ◽  
Experimental Simulation ◽  
Threshold Velocity ◽  
Transport Pathway ◽  
Lower Velocity ◽  
Transport Dynamics ◽  
Shelf Sediments

&lt;p&gt;Transport of continental shelf sediments to the deep ocean can be studied from displaced symbiont-bearing larger benthic foraminifera (LBF) found in turbidite deposits. The LBF habitat depth, physical characteristics and preservation serve as indicators for understanding sediment transport dynamics near the seabed and in the water column. Here, an experiment was designed to explore turbulent sediment transport in a closed flume system using simulated high current velocities. Shelf sediments from the Gulf of Eilat/Aqaba (GEA), dominated by Amphistegina papillosa and Operculina ammonoides, were subjected to 60 and 80 cm/sec current velocities while collected in a 10-cm vertical sediment trap. LBF abundance, shell physical properties and preservation state were analyzed and compared with the original bulk shelf sediments. The experiment results showed that at 80 cm/sec velocity LBF shells of all sizes and preservation states are efficiently resuspended and transported in large quantities throughout the water column, as opposed to their transport as bedload by the lower velocity current. LBF shape also has a role in the transport distances and accumulation depths. O. ammonoides shells were found more portable, compared to A. papillosa, due to their flatter discoid shape. The results suggest that a threshold velocity of ~80 cm/sec was needed to generate the thick coarse deposits found in the GEA slope sedimentary record, which were previously suggested to be triggered by large magnitude seismic events. Lower velocities probably winnowed minor amounts of LBF shells (with little or no coarser sediments) that were deposited as thin layers and may point to lower magnitude seismic triggers. In conclusion, LBF shells are transported and deposited in turbidites according to their hydrodynamic properties, resulting in assemblage differentiation along the transport pathway. This study shows the fossil biogenic composition in turbidites &amp;#160;includes valuable information on current velocities, transport dynamics and possible triggers in the geological record.&amp;#160;&amp;#160;&lt;/p&gt;

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