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Glacier recession is creating new water bodies in proglacial forelands worldwide, including Antarctica. Yet, it is unknown how microbial communities of recently formed "young" waterbodies (originating decades to a few centuries ago) compare with established "old" counterparts (millennia ago). Here, we compared benthic microbial communities of different lake types on James Ross Island, Antarctic Peninsula, using 16S rDNA metabarcoding and light microscopy to explore bacterial and diatom communities, respectively. We found that the older lakes host significantly more diverse bacterial and diatom communities compared to the young ones. To identify potential mechanisms for these differences, linear models and dbRDA analyses suggested combinations of water temperature, pH, and conductivity to be the most important factors for diversity and community structuring, while differences in geomorphological and hydrological stability, though more difficult to quantify, are likely also influential. These results, along with an indicator species analysis, suggest that physical and chemical constraints associated with individual lakes histories are likely more influential to the assembly of the benthic microbial communities than lake age alone. Collectively, these results improve our understanding of microbial community drivers in Antarctic freshwaters, and help predict how the microbial landscape may shift with future habitat creation within a changing environment. [ABSTRACT FROM AUTHOR]

Increasing temperatures in Antarctica have resulted in the enlargement of proglacial regions on the Antarctic Peninsula, following glacier melt. This melt has increased river activity yet direct runoff measurements remain scarce in Antarctica, despite it acting as a proxy for glacial ablation. Here, we present discharge and water temperature data from 2013 for three streams on Vega Island and discuss their relationship with air temperature. The average discharge at the largest stream was 0.523 m3s−1 with a maximum of 5.510 m3s−1 – among the highest recorded in Antarctica. The rivers continued to flow even when temperatures dropped to −7°C, indicating that a large proportion of the total runoff originated sub-glacially. This is supported by the one-day time lag between air and water temperatures. Using river discharge as a proxy, we measured 124.5 ± 14.4 mm w.e. of ablation. This indirect measurement proved an effective tool to complement classic glaciological observations. [ABSTRACT FROM AUTHOR]

With the ongoing climate change and the prolongation of the summer melting season and increasing air temperature that this entails, fluvial transport is likely to become a more important process shaping the deglaciated areas of Antarctica. Quantification of suspended sediment transport in the deglaciated catchment of the Bohemian Stream is presented in this study. It was shown that a large amount of fine-grained material is being transported even in the relatively small catchment during the short period of the Antarctic summer. The average calculated suspended sediment concentration during the 2018 austral summer reached 274.6 mg l−1, which corresponded to an average suspended sediment load of 3662 kg day−1 and suspended sediment yield of 68 t km−2 year−1 when considering the flow season to be approximately 4 months per year. Such values are considerably higher than those reported from continental Antarctica; however, they are lower compared to most of the Arctic catchments. [ABSTRACT FROM AUTHOR]

High‐latitude dust (HLD) depositions on four glaciers of James Ross Island (the Ulu Peninsula) were analysed. The deposition rate on the selected glaciers varies from 11.8 to 64.0 g m−2, which is one order of magnitude higher compared to the glaciers in Antarctica or elsewhere in the world. A strong negative relationship between the sediment amount and altitude of a sampling site was found. This is most likely caused by the higher availability of aeolian material in the atmospheric boundary layer. General southerly and south‐westerly wind directions over the Ulu Peninsula – with exceptions based on local terrain configuration – help to explain the significantly lower level of sediment deposition on San Jose Glacier and the high level on Triangular Glacier. X‐ray fluorescence (XRF) spectrophotometry was used to estimate the relative proportions of the main and trace (lithophile) elements in the sediment samples. Both the sediment amount and the XRF results are analysed in a depth profile at each locality and compared among the glaciers, suggesting long‐range transport of fine mineral material from outside James Ross Island. The distribution of aeolian sediment among the glaciers corresponds well with the prevailing wind direction on the Ulu Peninsula. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Lentic waterbodies provide terrestrial sedimentary archives of palaeoenvironmental change in deglaciated areas of the Antarctic. Knowledge of the long-term evolution of Antarctic palaeoenvironments affords important context to the current marked impacts of climate change in the Polar regions. Here, we present a comprehensively dated, multi-proxy sedimentary record from Monolith Lake, a distal proglacial lake in one of the largest ice-free areas of the Antarctic Peninsula region. Of the two defined sedimentary units in the cores studied, the lower Unit 1 exhibits a homogeneous composition and unvarying proxy data profiles, suggesting rapid clastic deposition under uniform, ice-proximal conditions with a sedimentation rate of ∼1 mm yr−1. 14C and optically stimulated luminescence (OSL) dating bracket the deposition interval to 1.5–2.5 ka BP, with the older age being more probable when compared to independent dating of the local deglaciation. The uppermost 11 cm of the record spans the last ∼2.2 ka BP (maximum age), suggesting a markedly decreased sedimentation rate of ∼0.05 mm yr−1 within Unit 2. Whereas Unit 1 shows only scarce evidence of biological activity, Unit 2 provides an uninterrupted record of diatoms (with 29 species recorded) and faunal subfossils, including the fairy shrimp Branchinecta gaini. Concentrations of organically-derived elements, as well as diatoms and faunal remains, are consistent, implying a gradual increase in lake productivity. These results provide an example of long-term Antarctic 'greening' (i.e. increasing organic productivity in terrestrial habitats) from a palaeolimnological perspective. The boundary between Units 1 and 2, therefore, marks the timing of local deglaciation at the final stages of a period of negative glacier mass balance, i.e. the Mid-Late Holocene Hypsithermal. Subsequent Neoglacial cooling is evidenced by the abated influence of glacial meltwater streams and turbidity decline linked to reduced glacier runoff, although most proxy responses mirror the natural proglacial lake ontogeny. • Antarctic lake sediments record rapid deglaciation ∼2.5 ka ago and subsequent lake ontogeny. • Portable optically stimulated luminescence (pOSL) enhanced absolute OSL and 14C dating. • For the last ∼2.2 ka, biodiversity hotspot persisted despite the Neoglacial cooling. • Fairy shrimp Branchinecta gaini did not become extinct on James Ross Island. • We present an example of long-term Antarctic greening from a palaeolimnological perspective. [ABSTRACT FROM AUTHOR]

• Sediment load for the Bohemian Stream was 1.18 ± 0.63 t km−2 d−1 over the 50 day study period. • Sediment load for the Algal Stream was 1.73 ± 1.02 t km−2 d−1 in the austral summer of 2021/2022. • Sediment load from the Bohemian catchment is primarily controlled by air temperature. • Algal catchment sediment load appear to be driven by changes in active layer thaw and snow. • Differences between the catchments are primarily due to differing glacier and snowfield coverage. Proglacial regions are enlarging across the Antarctic Peninsula as glaciers recede in a warming climate. However, despite the increasing importance of proglacial regions as sediment sources within cold environments, very few studies have considered fluvial sediment dynamics in polar settings and spatio-temporal variability in sediment delivery to the oceans has yet to be unravelled. In this study, we show how air temperature, precipitation, and ground conditions combine to control sediment loads in two catchments on James Ross Island, Antarctica. We estimate that the sediment load for the Bohemian Stream and Algal Stream over the 50 day study period, the average sediment load was 1.18 ± 0.63 t km−2 d−1 and 1.73 ± 1.02 t km−2 d−1, respectively. Both catchments show some sensitivity to changes in precipitation and air temperature, but the Algal catchment also shows some sensitivity to active layer thaw. The downstream changes in sediment provenance are controlled by underlying lithology, while differences in sediment load peaks between the two catchments appear to be primarily due to differing glacier and snowfield coverage. This identification of the controls on sediment load in this sub-polar environment provides insight into how other fluvial systems across the Antarctic Peninsula could respond as glaciers recede in a warming climate. [ABSTRACT FROM AUTHOR]

The Arctic and Antarctic regions include large areas of High Latitude Dust sources, from where dust is transported long distances. The first estimates are that all high latitude dust sources cover > 500,000 km2 and contribute to at least 5 % of global dust budget. Iceland is the largest Arctic as well as European desert with high dust event frequency (~135 dust days annually). Icelandic volcanic dust can be transported distances > 1700 km towards the Arctic and deposited on snow, ice and sea ice. It is estimated that about 7% of Icelandic dust can reach the high Arctic (N>80°). Total extent of the deserted areas is about 44,000 km2. This represents that > 40% of Iceland is poorly vegetated and with high erosion rates, not including the 10% extent of the glaciers. These areas used to be, however, vegetated while forests covered at least 25% of the country about 800 years ago. Woodlands were reduced due to medieval agricultural methods to almost total elimination about 100 years ago. Cold climate and massive erosion caused a collapse turning vegetated ecosystem into desert. Today dust events frequently occur in the winter and during sub-zero temperatures.Icelandic dust was compared to local dust sources in Ny-Alesund, Svalbard, showing that it contains of large fractions of fine dust. Metal oxide particles and volcanic glass are the most representative markers to identify Icelandic dust. In 2011, Icelandic dust reached Svalbard, over 1700 km from the dust source, and deposited in Ny-Alesund. This study confirms our theory that Icelandic volcanic dust can have a significant influence on the cryosphere in Greenland and elsewhere. Active dust sources were monitored also in the Southern Hemisphere. In situ measurements in the Antarctic Peninsula showed that the air is polluted by local dust sources, as well as due to long-range transport from Patagonia. The PM10 concentrations in Antarctica were higher than those in natural areas of the Northern Europe. We present newly identified HLD sources as well as the first evidence that Icelandic volcanic dust reaching the High Arctic, Svalbard Islands. Impacts of High Latitude Dust on climate should be investigated and incorporated into climate scenarios. [ABSTRACT FROM AUTHOR]