In support of efforts to reconstruct relative sea level (RSL), we investigated the utility of foraminifera, diatoms and bulk-sediment geochemistry (d 13 C, C:N and parameters measured by Rock-Eval pyrolysis) as sea-level indicators in Eurasian sub-Arctic salt marshes. At three salt marshes (<15 km apart) in Dvina Bay (White Sea, Russia), we collected surface sediment samples along transects from subtidal to Taiga forest environments. Foraminifera at all sites formed bipartite assemblages, where elevations below mean high higher water (MHHW) were dominated by Miliammina spp. and elevations between MHHW and the highest occurrence of foraminifera were dominated by Jadammina macrescens and Balticammina pseudomacrescens. Five high-diversity groups of diatoms were identified and they displayed pronounced variability amongst the study sites. Bulk-sediment geochemistry recognized two groups (clastic-dominated environments below MHHW and organic-rich environments above MHHW). As one group included subtidal elevations and the other included supratidal elevations, we conclude that the measured geochemical parameters are not stand-alone sea-level indicators. Core JT2012 captured a regressive sediment succession of clastic, tidal-flat sediment overlain by salt-marsh organic silt and freshwater peat. The saltmarsh sediment accumulated at 2804AE52 years before present and preserved foraminifera (Jadammina macrescens and Balticammina pseudomacrescens) with good analogy to modern assemblages indicating that RSL was +2.60AE0.47 m at this time. Diatoms confirm that marine influence decreased through time, but the lack of analogy between modern and core assemblages limited their utility as sea-level indicators. Geochemical parameters also indicate a reduction in marine influence through time. We conclude that RSL reconstructions derived from salt-marsh sediment preserved beneath Eurasian sub-Arctic peatlands can provide valuable insight into the spatio-temporal evolution of the Fennoscandian and Eurasian ice sheets.

The generation of reliable age models for palaeoenvironmental and archaeological records in the Eurasian Arctic is often problematic when using conventional dating techniques. Tephrochronology can potentially improve the chronologies of such records and synchronise disparate sedimentary archives. However, to date, systematic tephra studies are lacking for this region. This paper presents the first cryptotephra data from the White Sea region (northwestern Russia) based on a peat core spanning the past~1800 years. We identify seven geochemical glass populations that derive from six Icelandic volcanoes and correlate four of them to north European tephra isochrons; these include Askja AD 1875, the basaltic component of the AD 877 Landnám tephra, and tephras BTD-15 (c. AD 1750-1650) and SL-2/SB-2 (AD 803-767) from unknown eruptions of Katla and Snaefellsjökull, respectively. The remaining three populations originate from Grímsvötn, Hekla and Katla; however, their attribution to individual eruptions remains ambiguous. These findings highlight the potential to extend the Late Holocene tephrochronological framework of northern Europe to the west Eurasian Arctic. The detection of at least three basaltic tephras in the core suggests that basaltic shards can be transported over larger distances than previously known and that peatlands are well suited to preserve such components.

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The distribution of diatoms in the core of bottom sediments of the small meromictic Lake Kislo-Sladkoe on the Karelian Coast of White Sea was studied. The changes in diatom associations in the column show the isolation of the lagoon from the sea and its transformation into a meromictic lake. First alteration of dominant species marks the decrease of hydrodynamic activity as a result of the formation of spit and transformation of the lagoon into semi-closed bay. Second shift in species composition reflects the onset of the strong stratification and occurrence of a bottom anoxic layer.