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.

The mineral composition of the suspended particulate matter (SPM) was studied for the White Sea area. The comparative analysis of the composition of the marine SMP and the SPM of the rivers of the White Sea catchment area was performed, including the Severnaya Dvina River, one of the major sources of the terrigenous suspended matter to the sea. The research of such kind is faced with numerous methodological difficulties, which slows down the study process. Data on the mineral composition of the SPM are scarce. Applying the method of X-ray powder diffractometry, we assessed the bulk mineral composition of the SPM with special regard to its clay fraction.

This paper seeks to generalize the data obtained over 4 years of investigation of the suspended sediment mineral composition in Severnaya Dvina River. The sampling of the river water to isolate suspended particulate matter (SPM) using the method of sedimentation from large water volumes (200–800 L) was carried out at two points of the delta with different hydrological regimes every month for four years. SPM samples weighing 1 g and more allowed us to obtain and preserve for different analytical procedures the grain size fractions from 1.0–0.5 to <0.001 mm (from sands to pelit). The analyses of fractions revealed a sharp prevalence of pelitic fractions (<0.01 mm) (near 90% on average), while the share of silt was 4%–5%. Coarse fractions were found in the SPM of the main stream of the river but were absent in the samples taken at the point near the river–sea boundary. The determinations of clastic, clay, and some other minerals using the method of X-ray diffraction analysis have shown that in the group of clastic minerals, quartz and plagioclase prevail. Among the clay minerals, smectite and illite were present in high quantities, and chlorite and kaolinite were in lower quantitative. The distribution of minerals in the grain size fractions showed that the sum of clastic minerals reached its highest content of up to 84% in silt fractions (0.05–0.01 mm), while the sum of clay minerals in this fraction was minimal (about 15%). Investigations of seasonal variations of clastic and clay minerals during the whole period showed that the contents of minerals in the SPM of the Severnaya Dvina did not change much over the year. As a result of this work, the following trend was established on the behavior of all kinds of minerals: during the periods of high water in spring and autumn, a slightly increased quantity of clastic minerals was detected in comparison to winter and summer, while the variations in the quantities of clay minerals were insignificant.

Despite the importance of river suspended matter (RSM) for carbon, nutrient, and trace metal transfer from the land to the ocean, the mineralogical control on major and trace element speciation in the RSM remains poorly constrained. To gain a better understanding of environmental and seasonal factors controlling the mineral and chemical composition of riverine suspended load, we studied, over several hydrological seasons, including winter baseflow, the RSM of a large boreal river in Western Siberia (Ob in its middle course) and its two small tributaries. The concentration of RSM increased from 2–18 mg/L in winter to 15–105 mg L⁻¹ during the spring flood. Among the dominant mineral phases of the RSM in the Ob River, quartz (20–40%), albite (4–18%), smectite (2–14%), and chlorite (6–16%) increased their relative proportions with an increase in discharge in the order “winter ≤ summer < spring flood”; illite (5–15%) was not affected by seasons or discharge, whereas the abundance of calcite (0–30%) decreased with discharge, from winter to summer and spring. Seasonal variation of elemental composition of the Ob River’s RSM allowed distinguishing three main groups of elements. Sodium, K, Si, Al, trivalent, and tetravalent hydrolysates increased their concentrations in the RSM with an increase in discharge, reflecting enhanced contribution of lithogenic material during high flow, whereas the concentration of alkaline-earth metals (Ca, Sr, Ba), P, Mn, and As decreased with discharge, reflecting accumulation of these elements in the suspended matter under ice. At the same time, a number of nutrients and trace elements demonstrated progressive accumulation in the RSM during winter (Ca, P, Cu, Zn, Mo, As, Cd, Sb). Micronutrients (V, Co), Fe, and Cr exhibited a minimum during summer, which could reflect both the uptake of these elements by the biota during baseflow (micronutrients) and their enhanced export during winter and spring compared to summer (Fe). The RSM of small tributaries demonstrated quite a different pattern compared to the Ob River main stem. Maximal concentration of suspended matter was observed at low discharges during the winter. During this period, the RSM was dominated by amorphous Fe hydroxides. Overall, the obtained results confirm the overwhelming impact of peatlands on element export in suspended form in small rivers of Western Siberia, and strong seasonal variations of both mineralogy and chemistry of the RSM in the Ob River main stem. Elemental yields (watershed-normalized export), assessed for the first time for the middle course of the Ob River and tributaries, were shifted towards the more important role of particulate vs. dissolved export for a number of trace elements, compared to that of the small and medium-sized rivers of Western Siberia, draining the taiga forest and peatlands of the boreal zone. The contrasting pattern of RSM chemical composition across the year demonstrated the importance of seasonal approach for sampling river suspended matter and calls a need for addressing strongly understudied RSM sources during winter baseflow, under ice.