A high-resolution record of carbon accumulation rates during boreal peatland initiation

Boreal peatlands are a major global C sink, thus having important feedbacks to climate. A decreased concentration in atmospheric CO<sub>2</sub> 7000–10 000 yr ago has been linked to variations in peatland C accumulation rates attributed to a warm climate and increased productivity. Yet, this period also corresponds to early stages of peatland development (as peatland was expanding) following retreat of ice sheets and increases in C storage could be associated with wetland evolution via lake filling or following marine shoreline emergence. Unravelling past links amongst peatland dynamics, C storage, and climate will help us assess potential feedbacks from future changes in these systems, but most studies are hampered by low temporal resolution. Here we provide a decadal scale C accumulation record for a fen that has begun transformation from salt marsh within the last 70 yr on the isostatically rebounding coast of James Bay, Québec. We determined time frames for wetland stages using palynological analyses to reconstruct ecological change and <sup>210</sup>Pb and <sup>137</sup>Cs to date the deposit. The average short-term C accumulation rates during the low and high tidal marsh and incipient fen stage (42, 87 and 182 g C m<sup>−2</sup> yr<sup>−1</sup>, respectively) were as much as six times higher than the global long-term (millennial) average for northern peatlands. We suggest that the atmospheric CO<sub>2</sub> flux during the early Holocene could be attributed, in part, to wetland evolution associated with isostatic rebound, which makes land for new wetland formation. Future climate warming will increase eustatic sea level, decrease rates of land emergence and formation of new coastal wetlands, ultimately decreasing rates of C storage of wetlands on rebounding coastlines

The Middle and Late Pleniglacial (Weichselian) malacofauna of the Zemun loess–paleosol sequence, Serbia

The aim of our study was to describe the succession of malacological assemblages along the exposed loess profile located in Belgrade, along the banks of the Danube River (municipality of Zemun). Deposits that belong to the composite loess unit L1 were sampled. Loess unit L1 included two subunits: L1SS1 (a Middle Pleniglacial subunit with two weakly developed initial pedogenic horizons) and L1LL1 (a Late Pleniglacial loess subunit). Three malacological zones were distinguished. Malacological results imply a change in climatic conditions and subsequently in vegetation structure. The molluscs indicate an environment with a moderate (warm and dry) climate and a mosaic vegetation type composed of grasslands and forest steppe. Gradual cooling was inferred within the Late Pleniglacial period. Our findings concur with the results of earlier studies indicating that the Zemun site and the adjacent area served as a transition zone between the refuge areas within the southeastern part of the Carpathian Basin during the Late Pleistocene

Atmospheric Dust Variations in the Ili Basin, Northwest China, During the Last Glacial Period as Revealed by a High Mountain Loess-Paleosol Sequence

Atmospheric dust emission is closely related to conditions in the source area. Typically, loess deposits represent the accumulation of locally derived dust, providing the opportunity to reconstruct past variations in dust emission and hence insights into dust-climate linkages and the underlying mechanisms of dust mobilization, transport, and deposition. As yet, however, information on patterns of dust emission in Central Asia is sparse. Here we present the last glacial sedimentological data of a loess section from the Ili Basin, northwest China. Our results show that the variations in sand-sized fraction can indicate frequencies of occurring strong winds, which was likely driven by the Eurasian ice sheets during Marine Isotope Stage Stage 2 (MIS2) and MIS4 and by the boreal summer insolation during MIS3. The mass accumulation rate (MAR) reflects an integration of sediment availability in the provenance, vegetation cover in the deposition area, and wind regime. The differences of driving factors potentially explain the observed mismatches between variations in grain size and MAR. Comparison of dust fluxes observed in Greenland ice core and the North Pacific deep-sea sediment with the Central/East Asian MAR records supports the idea that the high flux of long-distance export of Asian dust is closely associated with the Siberian High and also influenced by changes in the atmospheric transport efficiency and likely by the source strength