CDOM Optical Properties and DOC Content in the Largest Mixing Zones of the Siberian Shelf Seas

Notable changes in the Arctic ecosystem driven by increased atmospheric temperature and ice cover reduction were observed in the last decades. Ongoing environmental shifts affect freshwater discharge to the Arctic Ocean, and alter Arctic land-ocean fluxes. The monitoring of DOC distribution and CDOM optical properties is of great interest both from the point of view of validation of remote sensing models, and for studying organic carbon transformation and dynamics. In this study we report the DOC concentrations and CDOM optical characteristics in the mixing zones of the Ob, Yenisei, Khatanga, Lena, Kolyma, and Indigirka rivers. Water sampling was performed in August–October 2015 and 2017. The DOC was determined by high-temperature combustion, and absorption coefficients and spectroscopic indices were calculated using the seawater absorbance obtained with spectrophotometric measurements. Kara and Laptev mixing zones were characterized by conservative DOC behavior, while the East Siberian sea waters showed nonconservative DOC distribution. Dominant DOM sources are discussed. The absorption coefficient aCDOM (350) in the East Siberian Sea was two-fold lower compared to Kara and Laptev seawaters. For the first time we report the DOC content in the Khatanga River of 802.6 µM based on the DOC in the Khatanga estuary.

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Optical Characterization of Homogeneous and Heterogeneous Intralipid-Based Samples

Applied Sciences ◽

10.3390/app10186234 ◽

2020 ◽

Vol 10 (18) ◽

pp. 6234

Author(s):

Ines Delfino ◽

Maria Lepore ◽

Rosario Esposito

Keyword(s):

Optical Properties ◽

Light Scattering ◽

Scattered Light ◽

Industrial Applications ◽

Point Of View ◽

Turbid Media ◽

Time Resolved ◽

Propagation Of Light ◽

First Time

Different scattering processes take place when photons propagate inside turbid media. Many powerful experimental techniques exploiting these processes have been developed and applied over the years in a large variety of situations from fundamental and applied research to industrial applications. In the present paper, we intend to take advantage of Static Light Scattering (SLS), Dynamic Light Scattering (DLS), and Time-Resolved Transmittance (TRT) for investigating all the different scattering regimes by using scattering suspensions in a very large range of scatterer concentrations. The suspensions were prepared using Intralipid 20%, a material largely employed in studies of the optical properties of turbid media, with concentrations from 10−5% to 50%. By the analysis of the angular and temporal dependence of the scattered light, a more reliable description of the scattering process occurring in these samples can be obtained. TRT measurements allowed us to obtain information on the reduced scattering coefficient, an important parameter largely used in the description of the optical properties of turbid media. TRT was also employed for the detection of inclusions embedded in Intralipid suspensions, by using a properly designed data analysis. The present study allowed us to better elucidate the dependence of scattering properties of Intralipid suspensions in a very large concentration range and the occurrence of the different scattering processes involved in the propagation of light in turbid media for the first time to our knowledge. In so doing, the complementary contribution of SLS, DLS, and TRT in the characterization of turbid media from an optical and structural point of view is strongly evidenced.

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Seasonal and Regional Manifestation of Arctic Sea Ice Loss

Journal of Climate ◽

10.1175/jcli-d-17-0427.1 ◽

2018 ◽

Vol 31 (12) ◽

pp. 4917-4932 ◽

Cited By ~ 76

Author(s):

Ingrid H. Onarheim ◽

Tor Eldevik ◽

Lars H. Smedsrud ◽

Julienne C. Stroeve

Keyword(s):

Sea Ice ◽

Barents Sea ◽

Arctic Sea Ice ◽

The Arctic ◽

Sea Ice Concentration ◽

Sea Ice Extent ◽

The Barents Sea ◽

East Siberian Sea ◽

Shelf Seas ◽

Perennial Ice

The Arctic Ocean is currently on a fast track toward seasonally ice-free conditions. Although most attention has been on the accelerating summer sea ice decline, large changes are also occurring in winter. This study assesses past, present, and possible future change in regional Northern Hemisphere sea ice extent throughout the year by examining sea ice concentration based on observations back to 1950, including the satellite record since 1979. At present, summer sea ice variability and change dominate in the perennial ice-covered Beaufort, Chukchi, East Siberian, Laptev, and Kara Seas, with the East Siberian Sea explaining the largest fraction of September ice loss (22%). Winter variability and change occur in the seasonally ice-covered seas farther south: the Barents Sea, Sea of Okhotsk, Greenland Sea, and Baffin Bay, with the Barents Sea carrying the largest fraction of loss in March (27%). The distinct regions of summer and winter sea ice variability and loss have generally been consistent since 1950, but appear at present to be in transformation as a result of the rapid ice loss in all seasons. As regions become seasonally ice free, future ice loss will be dominated by winter. The Kara Sea appears as the first currently perennial ice-covered sea to become ice free in September. Remaining on currently observed trends, the Arctic shelf seas are estimated to become seasonally ice free in the 2020s, and the seasonally ice-covered seas farther south to become ice free year-round from the 2050s.

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Molecular and radiocarbon constraints on sources and degradation of terrestrial organic carbon along the Kolyma paleoriver transect, East Siberian Sea

Biogeosciences ◽

10.5194/bg-7-3153-2010 ◽

2010 ◽

Vol 7 (10) ◽

pp. 3153-3166 ◽

Cited By ~ 91

Author(s):

J. E. Vonk ◽

L. Sánchez-García ◽

I. Semiletov ◽

O. Dudarev ◽

T. Eglinton ◽

...

Keyword(s):

Particulate Matter ◽

Surface Water ◽

Organic Carbon ◽

Coastal Waters ◽

Coastal Erosion ◽

Surface Soil ◽

Mixing Model ◽

The Arctic ◽

East Siberian Sea ◽

Shelf Seas

Abstract. Climate warming in northeastern Siberia may induce thaw-mobilization of the organic carbon (OC) now held in permafrost. This study investigated the composition of terrestrial OC exported to Arctic coastal waters to both obtain a natural integration of terrestrial permafrost OC release and to further understand the fate of released carbon in the extensive Siberian Shelf Seas. Application of a variety of elemental, molecular and isotopic (δ13C and Δ14C) analyses of both surface water suspended particulate matter and underlying surface sediments along a 500 km transect from Kolyma River mouth to the mid-shelf of the East Siberian Sea yielded information on the sources, degradation status and transport processes of thaw-mobilized soil OC. A three end-member dual-carbon-isotopic mixing model was applied to deduce the relative contributions from riverine, coastal erosion and marine sources. The mixing model was solved numerically using Monte Carlo simulations to obtain a fair representation of the uncertainties of both end-member composition and the end results. Riverine OC contributions to sediment OC decrease with increasing distance offshore (35±15 to 13±9%), whereas coastal erosion OC exhibits a constantly high contribution (51±11 to 60±12%) and marine OC increases offshore (9±7 to 36±10%). We attribute the remarkably strong imprint of OC from coastal erosion, extending up to ~500 km from the coast, to efficient offshoreward transport in these shallow waters presumably through both the benthic boundary layer and ice-rafting. There are also indications of simultaneous selective preservation of erosion OC compared to riverine OC. Molecular degradation proxies and radiocarbon contents indicated a degraded but young (Δ14C ca. −60‰ or ca. 500 14C years) terrestrial OC pool in surface water particulate matter, underlain by a less degraded but old (Δ14C ca. −500‰ or ca. 5500 14C years) terrestrial OC pool in bottom sediments. We suggest that the terrestrial OC fraction in surface water particulate matter is mainly derived from surface soil and recent vegetation fluvially released as buoyant organic-rich aggregates (e.g., humics), which are subjected to extensive processing during coastal transport. In contrast, terrestrial OC in the underlying sediments is postulated to originate predominantly from erosion of mineral-rich Pleistocene coasts (i.e., yedoma) and inland mineral soils. Sorptive association of this organic matter with mineral particles protects the OC from remineralization and also promotes rapid settling (ballasting) of the OC. Our findings corroborate recent studies by indicating that different Arctic surface soil OC pools exhibit distinguishing susceptibilities to degradation in coastal waters. Consequently, the general postulation of a positive feedback to global warming from degradation of permafrost carbon may be both attenuated (by reburial of one portion) and geographically displaced (degradation of released terrestrial permafrost OC far out over the Arctic shelf seas).

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Ordovician turbidites and black shales of Bennett Island (De Long Islands, Russian Arctic), and their significance for Arctic correlations and palaeogeography

Geological Magazine ◽

10.1017/s0016756819001341 ◽

2020 ◽

Vol 157 (8) ◽

pp. 1207-1237

Author(s):

Maria K. Danukalova ◽

Alexander B. Kuzmichev ◽

Nikolai V. Sennikov ◽

Tatiana Yu. Tolmacheva

Keyword(s):

Carbonate Platform ◽

Black Shales ◽

The Arctic ◽

New Siberian Islands ◽

Faunal Assemblages ◽

Lower Palaeozoic ◽

Early Palaeozoic ◽

First Time ◽

Remote Part ◽

Siberian Shelf

AbstractBennett Island stands alone in a remote part of the Arctic and information on its geology is essential to ascertain relations with other terranes in order to restore the early Palaeozoic Arctic palaeogeography. Lower Palaeozoic sedimentary rocks throughout the island were studied thoroughly for the first time. The Ordovician section (> 1.1 km thick) comprises three units: Tremadocian, lowest Floian black shale (130–140 m); Floian, lower Dapingian carbonate turbidite (> 250 m); and Dapingian, lower Darriwilian siliciclastic turbidite (> 730 m). Ordovician deposits conformably overlie Cambrian rocks deposited within the Siberian shelf, as shown earlier. Most of the Ordovician succession was formed in a deep trough that received carbonate debris from a nearby carbonate platform and silicate material from a distant landmass located to the NE (present coordinates). The Bennett Island Ordovician rocks have much in common with those of both the Central and Northern Taimyr belts. It could be tentatively suggested that both belts merged at their eastern continuation in the vicinity of De Long Islands. The whole system probably extends further eastwards. The Ordovician facies patterns and faunal assemblages in the New Siberian Islands are notably similar to those of northwestern Alaska, where the same lateral transition from turbidites to shelf limestones was reported.

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Floating marine macro-litter distribution in the Russian Arctic Seas in relation to oceanographic characteristics

10.5194/egusphere-egu21-2028 ◽

2021 ◽

Author(s):

Maria Pogojeva ◽

Evgeniy Yakushev

Keyword(s):

Barents Sea ◽

Average Density ◽

The Arctic ◽

Initial Assessment ◽

Russian Arctic ◽

Arctic Seas ◽

East Siberian Sea ◽

Atlantic Origin ◽

Shelf Seas ◽

Floating Objects

<p>The main objectives of this work was the acquisition of new data on floating marine macro litter (FMML) and natural floating objects in the Arctic seas, an initial assessment of the level of pollution by FMML and an analysis of potential sources. The results of this study present the first data on FMML distribution in Russian Arctic shelf seas in relation to oceanographic conditions (i.e. position of water masses of different origin as described by temperature, salinity, dissolved oxygen and pH). The main finding of this study is that FMML was found only in the water of Atlantic origin, inflowing from the Barents Sea, where FMML average density on the observed transects was 0.92 items/ km2. Eastern parts of the study, Kara Sea, Laptev Sea and East Siberian Sea were practically free from FMML. The input from rivers appears to be negligible, at least in autumn.</p>

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Molecular and radiocarbon constraints on sources and degradation of terrestrial organic carbon along the Kolyma paleoriver transect, East Siberian Sea

Biogeosciences Discussions ◽

10.5194/bgd-7-5191-2010 ◽

2010 ◽

Vol 7 (4) ◽

pp. 5191-5226

Author(s):

J. E. Vonk ◽

L. Sánchez-García ◽

I. P. Semiletov ◽

O. V. Dudarev ◽

T. I. Eglinton ◽

...

Keyword(s):

Particulate Matter ◽

Surface Water ◽

Organic Carbon ◽

Coastal Waters ◽

Coastal Erosion ◽

Surface Soil ◽

Mixing Model ◽

The Arctic ◽

East Siberian Sea ◽

Shelf Seas

Abstract. Climate warming in Northeastern Siberia may induce thaw-remobilization of the organic carbon (OC) now held in permafrost. This study investigated the composition of terrestrial OC exported to Arctic coastal waters to both obtain a natural integration of terrestrial permafrost OC release and to further understand the fate of remobilized carbon in the extensive Siberian Shelf Seas. Application of a variety of elemental, molecular and isotopic (δ13C and Δ14C) analyses of both surface water suspended particulate matter and underlying surface sediments along a 500 km transect from Kolyma River mouth to the mid-shelf of the East Siberian Sea yielded information on the sources, degradation status and transport processes of thaw-remobilized soil OC. A three end-member dual-carbon-isotopic mixing model was applied to deduce the relative contributions from riverine, coastal erosion and marine sources. The mixing model was solved numerically using Monte Carlo simulations to obtain a fair representation of the uncertainties of both end-member composition and the end results. Riverine OC contributions to sediment OC decrease with increasing distance offshore (35±15 to 13±9%), whereas coastal erosion OC exhibits a constantly high contribution (51±1 to 60±12%) and marine OC increases offshore ward (9±7 to 36±10%). We attribute the remarkably strong imprint of OC from coastal erosion, extending up to ~500 km from the coast, to efficient offshoreward transport in these shallow waters presumably through both the benthic boundary layer and ice-rafting. There are also indications of simultaneous selective preservation of erosion OC compared to riverine OC. Molecular degradation proxies and radiocarbon contents indicated a degraded but young (Δ14C ca. −60‰ or ca. 500 14C yr) terrestrial OC pool in surface water particulate matter, underlain by a less degraded but old (Δ14C ca. −500‰ or ca. 5500 14C yr) terrestrial OC pool in bottom sediments. We suggest that the terrestrial OC fraction in surface water particulate matter is mainly derived from surface soil and recent vegetation fluvially released as buoyant organic-rich aggregates (e.g., humics), which are subjected to extensive processing during coastal transport. In contrast, terrestrial OC in the underlying sediments is postulated to originate predominantly from erosion of mineral-rich Pleistocene coasts (i.e., yedoma) and inland mineral soils. Sorptive association of this organic matter with mineral particles protects the OC from remineralization and also promotes rapid settling (ballasting) of the OC. Our findings corroborate recent studies by indicating that different Arctic surface soil OC pools exhibit distinguishing susceptibilities to degradation in coastal waters. Consequently, the general postulation of a positive feedback to global warming from remineralization of permafrost carbon may be both attenuated (by reburial of one portion) and geographically displaced (degradation of released terrestrial permafrost OC far out over the Arctic shelf seas).

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Theoretical And Practical Design Considerations for Ultra-High Resolution Electron Lenses

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600001161 ◽

1980 ◽

Vol 38 ◽

pp. 266-269

Author(s):

Y. Harada ◽

K. Tsuno ◽

Y. Arai

Keyword(s):

Optical Properties ◽

High Resolution ◽

Chromatic Aberration ◽

Point Of View ◽

Pole Piece ◽

Axial Field ◽

Design Considerations ◽

Resolution Electron ◽

Practical Design ◽

Peak Flux

Magnetic objective lenses, from the point of view of pole piece geometry, can he roughly classified into two types, viz., symmetrical and asymmetrical. In the case of the former, the optical properties have been calculated by several authors1-3) and the results would appear to suggest that, in order to reduce the spherical and chromatic aberration coefficients, Cs and Cc, it is necessary to decrease the half-width value of the axial field distribution and to increase the peak flux density. The expressions for either minimum Cs or minimum Cc were presented in the form of ‘universal’ curves by Mulvey and Wallington4).

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Environmental and legal problems of ensuring biological safety in the Arctic zone of the Russian Federation

Sociopolitical sciences ◽

10.33693/2223-0092-2020-10-1-66-69 ◽

2020 ◽

Vol 10 (1) ◽

pp. 66-69

Author(s):

Natalia Zhavoronkova ◽

Vyacheslav Agafonov

Keyword(s):

Russian Federation ◽

Environmental Law ◽

Point Of View ◽

The Arctic ◽

Arctic Zone ◽

Federal Law ◽

Biological Safety ◽

Legal Problems ◽

Potential Risks ◽

The Russian Federation

The article is devoted to the study of modern theoretical and legal problems of ensuring biological security in the Arctic zone of the Russian Federation. The published Draft of Federal law No. 850485-7“On biological security of the Russian Federation”provides an opportunity to take a closer look at the problem of legal provision of biological security in relation to the most vulnerable ecosystems, and, first of all, the Arctic. The article considers the most important features and potential risks of the Arctic zone of the Russian Federation of critical importance from the point of view of biological hazards, the features (specificity) of biological safety problems from the point of view of organizational-legal features and, in particular, from the perspective of environmental law. It is proved that, given the special situation of the Arctic zone of the Russian Federation, in addition to the base Federal law“About biological safety” required a specific law on biological and ecological safety of the Arctic zone of the Russian Federation, which should be generated on a slightly different model than the draft Federal law «On biological safety”, to wear the most specific, applied nature.

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