Quantitative knowledge about the burial of sedimentary components at the seafloor has wide‐ranging implications in ocean science, from global climate to continental weathering. The use of ²³⁰Th‐normalized fluxes reduces uncertainties that many prior studies faced by accounting for the effects of sediment redistribution by bottom currents and minimizing the impact of age model uncertainty. Here we employ a recently compiled global data set of ²³⁰Th‐normalized fluxes with an updated database of seafloor surface sediment composition to derive atlases of the deep‐sea burial flux of calcium carbonate, biogenic opal, total organic carbon (TOC), nonbiogenic material, iron, mercury, and excess barium (Ba_xs). The spatial patterns of major component burial are mainly consistent with prior work, but the new quantitative estimates allow evaluations of deep‐sea budgets. Our integrated deep‐sea burial fluxes are 136 Tg C/yr CaCO₃, 153 Tg Si/yr opal, 20Tg C/yr TOC, 220 Mg Hg/yr, and 2.6 Tg Ba_xs/yr. This opal flux is roughly a factor of 2 increase over previous estimates, with important implications for the global Si cycle. Sedimentary Fe fluxes reflect a mixture of sources including lithogenic material, hydrothermal inputs and authigenic phases. The fluxes of some commonly used paleo‐productivity proxies (TOC, biogenic opal, and Ba_xs) are not well‐correlated geographically with satellite‐based productivity estimates. Our new compilation of sedimentary fluxes provides detailed regional and global information, which will help refine the understanding of sediment preservation.

An area of cold methane seeps at the bottom of the Laptev Sea was investigated. High rates of methane oxidation were revealed in the sediments and in the water column. Anaerobic methane oxidation carried out by the ANME-2 a/b consortium was coupled to sulfate reduction. Bacteria of the genera Sulfurovum and Arcobacter were the agents of the sulfur cycle. Methane unconsumed in the sediments diffused into the near-bottom water, where it was oxidized by methanotrophic bacteria. Methanotrophic activity was essential for development of symbiotrophic tubeworms of the upper sediment layers, which were responsible for the process of bioturbation.

Studies have been performed on a transect along 130°30′ E from the Lena River delta (71°60′ N) to the continental slope and adjacent deepwater area (78°22′ N) of the Laptev Sea in September 2015. The structure of phytoplankton communities has distinct latitudinal zoning. The southern part of the shelf (southward of 73°10′ N), the most desalinated by riverine discharge, houses a phytoplankton community with a biomass of 175–840 mg/m², domination of freshwater Aulacoseira diatoms, and significant contribution of green algae (both in abundance and biomass). The northern border for the distribution range of the southern complex of phytoplankton species lies between the 8 and 18 psu isohalines (~73°10′ N). The continental slope and deepwater areas of the Laptev Sea (north of 77°30′ N), with a salinity of >27 psu in the upper mixed layer, are populated by the community prevalently composed of Chaetoceros and Rhizosolenia diatoms, very abundant in the Arctic, and dinoflagellates. The phytoplankton number in this area fall in the range of 430–1100 × 10⁶ cell/m², and the biomass, in the range of 3600 mg/m². A moderate desalinating impact of the Lena River discharge is observed in the outer shelf area between 73°20′ and 77°30′ N; the salinity in the upper mixed layer is 18–24 psu. The phytocenosis in this area has a mosaic spatial structure with between-station variation in the shares of different alga groups in the community, cell number of 117–1200 × 10⁶ cells/m², and a biomass of 1600–3600 mg/m². As is shown, local inflow of “fresh” nutrients to the euphotic layer in the fall season leads to mass growth of diatoms.

New data on the elemental composition of the Severnaya Dvina River, the largest one in the White Sea region, are presented. The elemental composition of the river water in May, the period of the...

The biogeochemical processes participating in the transformation of the particulate matter into sediment along the Yenisei River-St. Anna Trough (Kara Sea) meridional profile were studied using...