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The paper presents a new monitoring station DIAMIS for continuous precisious observations of atmospheric carbon dioxide (CO2) and methane (CH4) mole fractions over the Yenisei Gulf, on the southwestern coast of the Taimyr Peninsula at the edge of the Dikson settlement. Here, we summarize technical details of the instrumental setup, give an overview of calibration and data processing algorithms, describe local environments of the study area, and analyze the seasonal footprint of the measurement station. Based on the observations in September 2018–February 2020, a comparative analysis of the atmospheric CO2 and CH4 annual variations in the polar belt (DIAMIS) and middle-taiga subzone (ZOTTO observatory) of near-Yenisei Siberia is presented. [ABSTRACT FROM AUTHOR]

Summary Current predictions of the effects of climate change indicate that the Arctic may experience a larger than average increase in temperature with consequent changes to the length of the snow-free active summer period, winter snow depth and amount and frequency of summer precipitation being highly probable. This paper reports on measurements of carbon dioxide flux at a high arctic site at Ny-Ålesund (78° 56′ N, 11° 55′ E), Svalbard and the physical climate variables that largely control this flux. It is shown that during three important precipitation-free periods of the active summer period, namely post snowmelt, high summer, and early autumn, the net balance between CO2 flux from the soil (due to respiration of roots and soil organisms) and CO2 assimilation by the vegetation is controlled largely by soil temperature and solar radiation. A simple combined photosynthetic assimilation-soil respiration model is shown to be capable of simulating the net CO2 flux during mid-summer, but is less proficient in the post snowmelt period and in early autumn when the simple models’ inability to simulate the effects of emergent growth and ponding during the former and senescence, freezing temperatures and dew during the latter indicates the need for a more complex descriptive model. The net CO2 flux during the measurement periods progresses from a net CO2 source of 0.3 gC m-2 d-1 during late snowmelt to a mid summer net CO2 sink of -0.39 gC m-2 d-1, returning to a net CO2 source of 0.1 gC m-2 d-1 in the early autumn. Simple extrapolation of the data indicates that, during the active summer season in 1995, this site was a net sink of CO2 of approximately - 9 gC m-2. [ABSTRACT FROM AUTHOR]

Ocean acidification from the uptake of anthropogenic carbon dioxide (CO) is regarded as a critical threat particularly to marine calcifying organisms. The arctic pteropod Limacina helicina may be one of the first polar organisms that are expected to display early sensitivity to ocean acidification, but a molecular approach as a foundation for understanding the effect of ocean acidification on this pteropod has rarely been reported. In this study, we examined the sublethal effects of CO-driven seawater acidification at the transcriptome level in L. helicina. cDNAs, treated under control (pH 8.2), high-CO (pH 7.5), and extreme-CO (pH 6.5) conditions, generated a total of 31,999,474 reads, comprising a total of 2,271,962,654 bp, using the Illumina platform. De novo assembly yielded 53,121 transcripts comprising 31.79 Mbp. Among the upregulated genes, 346 (0.7 %) and 655 (1.2 %) genes responded to extreme-level CO (pH 6.5) and high-level CO (pH 7.5), respectively. Also, 76 (0.1 %) transcripts were commonly upregulated in both conditions. Among the downregulated genes, 690 (1.3 %) and 739 (1.4 %) genes were in response to extreme-level CO and high-level CO, respectively. Also, 270 downregulated genes (0.5 %) were affected in both acidic stress conditions. Moreover, 504 transcripts (1 %) of biomineralization-related genes were identified; 16 of these genes showed differential expression in response to acidified seawater. The dataset provides the first comprehensive overview of changes in transcript levels in the arctic pteropod L. helicina in response to increased CO, emphasizing the potential impact of future environmental change and ocean acidification on Arctic species with external calcified structures. [ABSTRACT FROM AUTHOR]

Permafrost thawing in lowland Arctic tundra results in a polygonal patterned landscape and the formation of numerous small ponds. These ponds emit biologically mediated carbon dioxide (CO) and methane (CH). Their greenhouse gas (GHG) emissions are variable, for reasons that are not well understood. Emissions are related to a balance between GHG producers and consumers, as well as to physical properties of the water column controlling gas exchange rates with the atmosphere. Here, we investigated the bacterial diversity of polygonal and runnel ponds, two geomorphologically distinct pond types commonly found in continuous permafrost regions. Using a combination of 16S rRNA Sanger sequencing and high-throughput amplicon sequencing, we found that bacterial communities in overlying waters were clearly dominated by carbon degraders and were similar in both pond types, despite their variable physical and chemical properties. However, surface sediment communities in the two pond types were significantly different. Polygonal pond sediment was colonized by carbon degraders (46-29 %), cyanobacteria (20-27 %) that take up CO and produce oxygen, and methanotrophs (11-20 %) that consume CH and require oxygen. In contrast, cyanobacteria were effectively absent from the surface sediment of runnel ponds, which in addition to carbon degraders (65-81 %), were colonized by purple non-sulfur bacteria (5-21 %), and by fewer methanotrophs (1-5 %). The link between the methanotrophic community and the type of ponds could potentially be used to improve upscale estimates of GHG emissions based on landscape morphology in such remote regions. [ABSTRACT FROM AUTHOR]