Elemental and Mineral Composition of the Barents Sea Recent and Late Pleistocene−Holocene Sediments: A Correlation with Environmental Conditions

Abstract

A comprehensive examination of the elemental (including radionuclides and heavy metals), mineral, and grain-size composition of sediments from different areas of the Barents Sea was performed. Sediment cores were sampled in the Central Deep, Cambridge Strait (Franz Josef Land Archipelago), Russkaya Gavan’ Bay (Novaya Zemlya Archipelago), and Bear Island Trough. We aim to evaluate how the modern and more ancient environmental conditions are reflected in the elemental and mineral composition, as well as to test indicative elemental ratios. The applied methods include elemental analysis using gamma-ray spectroscopy, X-ray fluorescence (XRF), Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), and X-Ray Difractometry XRD analysis of minerals. Difference in sedimentation rates, grain-size composition, and sources of material, are reflected in downcore variation of Si/Al, Mn/Fe, P/Al, Ti/K, and quartz-feldspar ratios. At boundary Early Holocene/Late Deglaciation, intensive bottom currents from the West-Southern shelf areas contributed to increase of Si/Al and Zr/Ca ratios. Distinct growth of the Si/Fe ratio within the sediments deposited over Late Pleistocene to Mid Holocene may be caused by increased contents of the coarse sand material, as well as by abundant fluxes of clay-mineral-loaded glacial meltwater during the main deglaciation phase. The Mn/Fe ratio used as redox proxy, displayed peaks at different depths related to oxygen concentration growth in bottom water.

Benthic Organic Matter Transformation Drives pH and Carbonate Chemistry in Arctic Marine Sediments

“…$${Ca}^{2+}$$ denotes the concentration of dissolved calcium (see Section 2.2.2). While we acknowledge that our analyses may underrepresent the contributions of aragonite and dolomite to the benthic pool of $${CaCO}_{3}$$, we are confident that the contribution of these minerals is minimal here based on literature data (e.g., Demina et al., 2020; Pautova et al., 2020; Solheim & Elverhoi, 1996). Calcite dissolution (Equation 5) and authigenic precipitation (Equation 6) are described by a kinetic‐thermodynamic rate law with a linear dependency on saturation state (e.g., Morse, 1983): $$${R}_{dissolution}={k}_{diss}\cdot \,(1-\Omega)\,\cdot \,CaC{O}_{3}\qquad \mathrm{if}\,\Omega\,< \,1$$$ $$${R}_{dissolution}=0\qquad \mathrm{if}\,\Omega\ge 1$$$ $$${R}_{precipitation}={k}_{prec}\,\cdot \,(\Omega-1)\qquad \mathrm{if}\,\Omega\ge 5$$$ …”

“…𝐴𝐴 𝐴𝐴𝐴𝐴 2+ denotes the concentration of dissolved calcium (see Section 2.2.2). While we acknowledge that our analyses may underrepresent the contributions of aragonite and dolomite to the benthic pool of 𝐴𝐴 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴3 , we are confident that the contribution of these minerals is minimal here based on literature data (e.g., Demina et al, 2020;Pautova et al, 2020;Solheim & Elverhoi, 1996). Calcite dissolution (Equation 5) and authigenic precipitation (Equation 6) are described by a kinetic-thermodynamic rate law with a linear dependency on saturation state (e.g., Morse, 1983):…”

“…Carbonate contents within the Barents Sea surface sediments reveal higher values on the SW and Norwegian shelves (>5 wt%), relatively lower contents in the vicinity of the Polar Front (<1.5 wt%), and moderate amounts on the northern shelf (3–5 wt%) (Faust et al., 2020 and references therein). Biogenic calcite is the predominant form of calcium carbonate ($${CaCO}_{3}$$) across the Barents Sea; dolomite is only present in small amounts and linked to coarse detrital sediment input (Demina et al., 2020; Pautova et al., 2020; Solheim & Elverhoi, 1996).…”

Benthic Organic Matter Transformation Drives pH and Carbonate Chemistry in Arctic Marine Sediments

“…Carbonate contents within the Barents Sea surface sediments reveal higher values on the SW and Norwegian shelves (>5 wt%), relatively lower contents in the vicinity of the Polar Front (<1.5 wt%), and moderate amounts on the northern shelf (3-5 wt%) (Faust et al, 2020 and references therein). Biogenic calcite is the predominant form of calcium carbonate ( 𝐴𝐴 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴3) across the Barents Sea; dolomite is only present in small amounts and linked to coarse detrital sediment input (Demina et al, 2020;Pautova et al, 2020;Solheim & Elverhoi, 1996).…”

The Features of Distribution of Chemical Elements, including Heavy Metals and Cs-137, in Surface Sediments of the Barents, Kara, Laptev and East Siberian Seas

“…For the Barents Sea surface sediments, estimation of a regional background content of some heavy metals and their anthropogenic loads was performed [21]. In the Barents Sea surface sediments, the element distribution exhibited a noticeable dependence on grain size composition, which in turn is related to bottom topography and hydrodynamics conditions; for potentially toxic elements, such as Pb, Cu, and Zn, a rather weak anthropogenic influence was recorded, except for As, whose average content (19 ppm) exceeds the UCC values (8 ppm) [22]. The high concentrations of Cr, Zn, Ni, Cu, and As were detected in the deeper parts of the East Siberian and Laptev Seas and the estuarine shelves of the Lena and Yana Rivers, while the high Cd content was observed in sediments of the eastern East Siberian Sea [23].…”