cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.1594/pangaea.952486
title: Alkenone sea surface temperature estimates of gravity core M40/4_SL71 (eastern Mediterranean Sea)

description: Water column stratification increased at climatic transitions from cold to warm periods during the late Quaternary and led to anoxic conditions and sapropel formation in the deep eastern Mediterranean basins. Here we report downcore sea surface temperature estimates of gravity core M40-4/71 taken SW of Crete (eastern Mediterranean Sea) that elucidate the influence of glacial/interglacial temperature changes in determining density of surface waters and isolation of deep waters.
description: Methods:Samples were obtained from cores taken aboard r/v Meteor either during the expedition or in the Core Repository of the Institute of Baltic Sea Research. Samples were punched out of the working halves with sawn-off syringes, wrapped in plastic, and stored frozen until freeze-drying in the shore-based laboratory.Subsamples (~1-2 g dry weight) of the homogenized bulk samples were used to extract lipids and to estimate the alkenone unsaturation index, a SST indicator (Brassell et al., 1986). Weighted splits of freeze-dried and homogenized sediments were extracted by ultrasonic agitation with 35-mL CH2Cl2 (2 ' 10 min). Elemental sulfur was removed by the addition of copper foil during the extraction. After each extraction step, samples were centrifuged, and the solvent was collected by pipette. The two lipid extracts were combined and dried in a rotary evaporator. The extracts were redissolved in CH2Cl2 and precleaned over a silica gel column (conditioned with 30-mL CH2Cl2) by elution with 14-mL CH2Cl2 and dried again in a rotary evaporator. The extracts were redissolved in n-hexane and subsequently fractionated using high-pressure liquid chromatography (HPLC). The HPLC column, packed with silica gel was MERCK LiChrospher Si 100-5. Four fractions were obtained using 5.5-mL n-hexane, 14-mL n-hexane/dichloromethane, 9-mL dichloromethane, and 9-mL acetone as eluents. The ketones (here: alkenones) were isolated in the second fraction. The first fraction contained the aliphatic hydrocarbons, and the third and fourth fractions yielded the more polar compounds.Gas chromatographic (GC) analyses were carried out on a HR 8000 Fisons gas chromatograph (FID, cold on-column injection) equipped with a 30-m (0.32 mm ID) glass capillary column (DB5HT). Helium was used as a carrier gas (column head pressure 110 kPa). Oven temperature programming conditions were from 35°C to 300°C at 15°C min-1 followed by an isothermal period of 15 min at 300°C and from 300°C to 330°C at 15°C min-1 followed by an isothermal period of 10 min at 330°C. Alkenones were identified by comparing retention times with those of standards. Peak areas were converted to the UK'37 index, and SSTs calculated according to a global coretop calibration (Müller et al., 1998): SST (°C) = (C37:2 / (C37:2 + C37:3) - 0.044) / 0.033. Alkenone concentrations were determined from GC analyses of the ketone fractions based on peak responses relative to 5alpha-cholestane as an external standard. Results of duplicate analyses (n = 21) are also given.
DOI: 10.15468/dl.pk1wql
title: Occurrence Download

description: A dataset containing 8 species occurrences available in GBIF matching the query:
{
 "DatasetKey" : [
 "is (Table 1) Proportion of Toxoplasma gondii seropositive arctic foxes (Alopex lagopus) by age group and geographic area"
 ]
}

 The dataset includes 8 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0027701-180131172636756/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.t0g7qf
title: Occurrence Download

description: A dataset containing 8 species occurrences available in GBIF matching the query:
{
 "DatasetKey" : [
 "is (Table 1) Proportion of Toxoplasma gondii seropositive arctic foxes (Alopex lagopus) by age group and geographic area"
 ]
}

 The dataset includes 8 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0017253-160910150852091/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.1594/pangaea.953119
title: Atmospheric methane consumption by upland soils - dataset 2: campaign-based manual chamber measurements

description: This dataset includes campaign-based, manual chamber measurements at sites displaying net methane (CH4) uptake. These manual measurements were conducted during the growing season at typical, well-drained upland sites, which included, besides Trail Valley Creek, three additional sites in the Canadian and European Arctic (Havikpak Creek, Scotty Creek, Kilpisjärvi). Besides CH4 flux observations, the dataset contains measured greenhouse gas concentration profiles of CH4, carbon dioxide (CO2) and nitrous oxide (N2O) at 2 cm, 5 cm, 10 cm, and 20 cm soil depths, as well as site meteorological data.
description: Further funding awards: NSERC Discovery Grants program (DGPIN-2018-05743 and RGPIN-2022-05347), Atmosphere and Climate Competence Center (ACCC, no. 337550), Northern Water Futures (Global Water Futures, Canada First Research Excellence Fund's Global Water Futures program, doi:10.13039/501100013380), Polar Continental Shelf Program (608-20, 602-21)Dates are given in local timezone, which are:- Canadian sites (Trail Valley Creek, Havikpak Creek, Scotty Creek): times in MST = Mountain standard time (no daylight saving time), i.e. UTC-07- Finnish sites (Kilpisjärvi): Eastern European Summer Time, i.e. UTC+03
DOI: 10.1594/pangaea.953126
title: Diatom species from sediment core EN18218, Lake Rauchuagytgyn, expedition to Chukotka 2018, Russian Arctic

description: These dataset contains multi proxy data from sediment core EN18218 obtained from Arctic glacial lake Rauchuagytgyn (67.7922°N, 168.7312°E) by piston coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 53 samples along a ca. 5.5 m interval in the sediment core, next to nitrogen and mercury concentrations. The data are complementary to the sedimentological and radiocarbon data published in an earlier data set by Vyse et al. 2021. The data sets provides, calculated from the original data, estimated accumulation rates based on a revised age model explained in the manuscript for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
description: Zeiss Axioscope 5 Light microscope with an Axiocam 208 color camera attached, equipped with a Plan-Apochromat 100x/1.4 Oil Ph3 objective at 1000x magnification. The data provided here describe original count data of diatom valves attributed to diatom species.
DOI: 10.1594/pangaea.953129
title: Nitrogen from sediment core EN18218, Lake Rauchuagytgyn, expedition to Chukotka 2018, Russian Arctic

description: These dataset contains multi proxy data from sediment core EN18218 obtained from Arctic glacial lake Rauchuagytgyn (67.7922°N, 168.7312°E) by piston coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 53 samples along a ca. 5.5 m interval in the sediment core, next to nitrogen and mercury concentrations. The data are complementary to the sedimentological and radiocarbon data published in an earlier data set by Vyse et al. 2021. The data sets provides, calculated from the original data, estimated accumulation rates based on a revised age model explained in the manuscript for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
description: TN was measured using a rapid MAX N exceed (Elementar Analysensysteme GmbH).
DOI: 10.1594/pangaea.953130
title: Mercury from sediment core EN18218, Lake Rauchuagytgyn, expedition to Chukotka 2018, Russian Arctic

description: These dataset contains multi proxy data from sediment core EN18218 obtained from Arctic glacial lake Rauchuagytgyn (67.7922°N, 168.7312°E) by piston coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 53 samples along a ca. 5.5 m interval in the sediment core, next to nitrogen and mercury concentrations. The data are complementary to the sedimentological and radiocarbon data published in an earlier data set by Vyse et al. 2021. The data sets provides, calculated from the original data, estimated accumulation rates based on a revised age model explained in the manuscript for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
description: We determined the THg in solid material by thermal decomposition, amalgamation and atomic absorption spectrophotometry using a Direct Mercury Analyzer (DMA-80 evo; MLS-MWS GmbH).
DOI: 10.1594/pangaea.953132
title: Accumulation rates from sediment core EN18218, Lake Rauchuagytgyn, expedition to Chukotka 2018, Russian Arctic

description: These dataset contains multi proxy data from sediment core EN18218 obtained from Arctic glacial lake Rauchuagytgyn (67.7922°N, 168.7312°E) by piston coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 53 samples along a ca. 5.5 m interval in the sediment core, next to nitrogen and mercury concentrations. The data are complementary to the sedimentological and radiocarbon data published in an earlier data set by Vyse et al. 2021. The data sets provides, calculated from the original data, estimated accumulation rates based on a revised age model explained in the manuscript for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
DOI: 10.1594/pangaea.953134
title: Geochemistry data from sediment core 16-KP-04-L19B, Lake Rauchuagytgyn, expedition to Chukotka 2016, Russian Arctic

description: These dataset contains multi proxy data from short sediment core 16-KP-04-L19B obtained from Arctic glacial lake Rauchuagytgyn (N 67.7888, E 168.7380) by gravity coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 20 samples along a ca. 10.5 cm interval in the sediment core, next to organic carbon, nitrogen, and mercury concentrations. The data sets provides, calculated from the original data, estimated accumulation rates for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
description: TOC and TIN measured using Vario SoliTOC cube elemental analyzer - Detection limit: 0.1; TC estimated from sum of TOC and TIC; TN measured using a rapid MAX N exceed analyzer; THg determined using Direct Mecury Analyzer DMA-80 evo
DOI: 10.1594/pangaea.953138
title: Diatom species from sediment core 16-KP-04-L19B, Lake Rauchuagytgyn, expedition to Chukotka 2016, Russian Arctic

description: These dataset contains multi proxy data from short sediment core 16-KP-04-L19B obtained from Arctic glacial lake Rauchuagytgyn (N 67.7888, E 168.7380) by gravity coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 20 samples along a ca. 10.5 cm interval in the sediment core, next to organic carbon, nitrogen, and mercury concentrations. The data sets provides, calculated from the original data, estimated accumulation rates for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
description: Diatom valves were identified using a Zeiss Axioscope 5 light microscope with a Plan-Apochromat 100x/1.4 Oil Ph3 objective at 1000x magnification and Axiocam 208 color camera.
DOI: 10.1594/pangaea.953139
title: 210Pb and 137Cs dating data from sediment core 16-KP-04-L19B, Lake Rauchuagytgyn, expedition to Chukotka 2016, Russian Arctic

description: These dataset contains multi proxy data from short sediment core 16-KP-04-L19B obtained from Arctic glacial lake Rauchuagytgyn (N 67.7888, E 168.7380) by gravity coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 20 samples along a ca. 10.5 cm interval in the sediment core, next to organic carbon, nitrogen, and mercury concentrations. The data sets provides, calculated from the original data, estimated accumulation rates for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
description: 210Pb and 137Cs activities analyzed by direct gamma assay in the Liverpool University Environmental Radioactivity Laboratory, using Ortec HPGe GWL series well-type coaxial low background intrinsic germanium detectors - gamma emissions at 46.5 keV (210Pb) and at 662 keV (137Cs).
DOI: 10.1594/pangaea.953298
title: Cladocera counts of sediment core from Lake Bayan Nuur

description: Cladocera analysis 25 samples from lake Bayan Nuur (Core BN2016-1) were prepared for сladoceran analysis using the methods described in Korhola and Rautio (2001, doi:10.1007/0-306-47671-1_2). Each sample (0.5-1 gr of dry sediment) was heated for approximately 30 minutes at 75 °C in 10% KOH. The KOH sediment mixture was then poured onto a 50-μm mesh sieve. A few drops of ethanol and safranin-glycerin solution were added to prevent fungal growth and to stain the cladoceran remains. The identification of Cladocera remains was conducted using a light Carl Zeiss Axiolab microscope at magnification x100-400. The remains of 200-343 (mean 244) Cladocera were analyzed of each sample. The number of specimens of each genus was taken to be equal to the maximum number of the encountered remains of the body (mostly headshields, carapaces, postabdomens). The chitinous remains of cladoceran were identified with both subfossil and modern cladoceran identification keys. Cladocera were subdivided into two groups based on their habitats (planktonic and benthic).
DOI: 10.1594/pangaea.953299
title: Pollen counts of sediment core from Lake Bayan Nuur

description: A total of 94 samples (0.8-1.2 g of dry sediment) from lake Bayan Nuur (Core BN2016-1) were used for pollen and non pollen palynomorphs analysis. The samples were chemically treated according to the methodology suggested by Faegri and Iversen (1989, doi:10.1016/j.gloplacha.2014.11.015), including treatment with a 10% solution of hydrochloric acid to dissolve carbonates, a 10% solution of potassium hydroxide to remove humic acids, and high concentration hydrofluoric acid to remove silicates. Acetolysis was not performed. A Lycopodium spore tablet (batch 483216) was added to each sample to calculate the total palynomorph concentration. Pollen grains mounted in glycerine were analyzed under a transmitted light microscope AxioImagerD2 with x400 magnification. In addition to pollen and spores, other non-pollen palynomorphs (NPPs), including spores and the fruit bodies of coprophilous fungi, were counted, and are included in the total sum. Pollen percentages were calculated based on the pollen sum of all detected taxa, taken as 100%. NPP percentages were calculated on the basis of the total sum taken as 100%. In the pollen diagram, dung fungi Sordaria, Sporormiella, and single coprophypous Ascomycetes (Podospora and Gelasinospora) are combined in one group, “coprophilous 40 fungi”. The coprophilous fungi were calculated in the pollen slides simultaneously with pollen. As fungi spore production and incorporation into sediments is independent of vegetation or pollen deposition; we calculated the coprophilous fungi concentrations and accumulation rates (influx) that would be the most reliable way to assess the real herbivore population and grazing trends (according to Wilmshurst and Wood, 2013, doi:10.5305/amerjintelaw.107.2.0390).
DOI: 10.1594/pangaea.953142
title: Accumulation rates from sediment core 16-KP-04-L19B, Lake Rauchuagytgyn, expedition to Chukotka 2016, Russian Arctic

description: These dataset contains multi proxy data from short sediment core 16-KP-04-L19B obtained from Arctic glacial lake Rauchuagytgyn (N 67.7888, E 168.7380) by gravity coring during the Chukotka 2018 expedition (Siberia). We provide original count data of diatom species from 20 samples along a ca. 10.5 cm interval in the sediment core, next to organic carbon, nitrogen, and mercury concentrations. The data sets provides, calculated from the original data, estimated accumulation rates for diatom valves (diatom accumulation rate, DAR), organic carbon (organic carbon accumulation rates, OCAR), and mercury (Hg accumulation rates, HgAR).
DOI: 10.1594/pangaea.953300
title: Diatom abundance of sediment core from Lake Bayan Nuur

description: 25 samples from the lake Bayan Nuur sediment core ( BN2016-1) bottom sediments were processed for diatom analysis in the range from 0 to 110.4 cm (Appendix 2). The samples of sediments were treated using the water bath method. We used high refracting Naphrax resin for the preparation of slides. The species were identified by key books. The valves were counted by parallel transects up to 300 pieces in a sample, using a light microscope and immersion oil. The total number of valves was considered to be 100%. Dominant species were defined as those which accounted for 10% of the total amount or more; subdominants were species which accounted for 5–10%. The pH and total phosphorus (µg/l) values were reconstructed using the European diatom algae database. The trophic status was assessed according to the reconstructed value of total phosphorus. Biogeographical and ecological characteristics of the taxa concerning preferences of habitat, pH, water salinity, geographical distribution were described following Van Dam et al. (1994, doi:10.1007/BF02334251) and Barinova et al. (2006).
DOI: 10.1594/pangaea.953303
title: Reconstruction of the amount of annual precipitation (PANN; mm/year) for Lake Bayan Nuur

description: The modern pollen data from arid central Asia (Bordon et al., 2009, doi:10.1016/j.quaint.2008.05.014) and our newly completed modern pollen data from southwest Siberia (unpublished) was homogenized and combined into the modern pollen dataset (Cao et al., 2014, doi:10.1016/j.revpalbo.2014.08.007). In this study, the 808 modern pollen sites 1000-km around Bayan Nuur were selected to establish pollen-climate calibration-sets. PANN was selected as the target climatic variable for past climate 206 reconstruction. The model performance of cross-validation for the pollen-PANN calibration-set has high R2 (0.79) and low RMSEP (71 mm). A quantitative PANN reconstruction was performed using the WAPLS function in rioja package version 0.7-3 (Juggins, 2012) for R with square-root transformed pollen data.
DOI: 10.1594/pangaea.953305
title: Pollen based annual precipitation for Lake Bayan Nuur

description: Method for quantitative reconstruction of mean July air temperatures (Tjuly). The quantitative reconstruction of mean July air temperatures (TJuly) is based on calibration chironomid data sets for lakes from northern Russia (Nazarova et al., 2015, doi:10.1016/j.gloplacha.2014.11.015). Mean July air temperatures were inferred using a North Russian (NR) chironomid-based temperature inference model (WA-PLS, 2 component; r 2 boot = 0.81; RMSEP boot =1.43 °C) based on a modern calibration data set of 193 lakes and 162 taxa from East and West Siberia (61-75°N, 50-140 °E, T July range 1.8 - 18.8 °C). The mean July air temperature of the lakes for the calibration data set was derived from New et al. (2002, doi:10.3354/cr021001). The TJuly NR model was previously applied to palaeoclimatic inferences in Europe, arctic Russia, East and West Siberia, and demonstrated a high reliability of the reconstructed parameters. The chironomid-inferred TJuly were corrected to 0 m a.s.l. using a modern July air temperature lapse rate of 6 oC km-1. Chironomid-based reconstructions were performed in C2 version 1.7. The chironomid data was square-rooted to stabilize species variance. To assess the reliability of the chironomid-inferred TJuly reconstruction, we calculated the percentage abundances of the fossil chironomids that are rare or absent in the modern calibration data set. A taxon is considered to be rare in the modern data when it has a Hill N2 below 5. Optima of the taxa that are rare in modern data are likely to be poorly estimated. Goodness-of-fit statistics derived from a canonical correspondence analysis (CCA) of the modern calibration data and down-core passive samples with TJuly as the sole constraining variables was used to assess the fit of the analyzed down-core assemblages to TJuly. This method shows how unusual the fossil assemblages are in respect to the composition of the training set samples along the temperature gradient. Fossil samples with a residual distance to the first CCA axis larger than the 90th and 95th percentile of the residual distances of all the modern samples were identified as samples with a 'poor fit' and a 'very poor fit' with the reconstructed variable (TJuly). CCA was performed using CANOCO 5. In the evaluation of goodness-of-fit, the CCA scaling focused on inter-sample distances with Hill's scaling selected to optimize inter-sample relationships.
DOI: 10.1594/pangaea.953306
title: Total organic carbon from sediment core BN2016-1 of for Lake Bayan Nuur

description: The composition of organic matter (TOC, δ13C) in lacustrine sediments is an approach for reconstructions of lake environments and climate fluctuations. In lacustrine sediments, organic matter is comprised of detritus which arises from terrestrial and aquatic vascular plants and algae, as well as other organic producers (cladoceran, chironomids, etc.). Carbon isotopic compositions indicate changes in lake productivity and carbon recycling (Meyers and Ishiwatari, 1993, doi:10.1016/0146-6380(93)90100-P). Core BN2016-1 from lake Bayan Nuur was studied for stable carbon isotopes and total organic carbon (TOC) content in bulk sediments. Were measured TOC (39 sediment samples) and δ13C (42 samples) from the BN2016-1 core. The sediment samples were leached by 0.5 N HCl to remove inorganic carbon, then washed with distilled water and freeze-dried. The TOC and δ13C were measured using the (IRMS) Delta V Advantage with EA 2000 HT.
DOI: 10.1594/pangaea.953334
title: Fish and invertebrate length frequencies of three bottom trawl hauls in 2022, southern North Sea

description: During a MARSYS student training cruise (HE600) three bottom trawl hauls were conducted on 2022 June 3., 7. and 10. in the southern North Sea. The length frequency data originate from bottom trawl hauls, conducted with the Schollennetz from RV Heincke. The trawl ground rope was approx. 17 m, the vertical opening approx. 2 m and the cod end mesh size 1 cm. Tow duration was recorded for effort standardization. Fish size was measured to the next lower centimeter (“cm below”). Fish and invertebrate catch per unit of effort and biomass of three bottom trawl hauls in 2022, southern North Sea.
DOI: 10.1594/pangaea.953345
title: Fish and invertebrate catch per unit of effort and biomass of three bottom trawl hauls in 2022, southern North Sea

description: During a MARSYS student training cruise (HE600) three bottom trawl hauls were conducted on 2022 June 3., 7. and 10. in the southern North Sea. The catch per unit of effort and biomass data originate from bottom trawl hauls (RV Heincke Schollensack, AWI), conducted with the Schollennetz from RV Heincke. The trawl ground rope was approx. 17 m, the vertical opening approx. 2 m and the cod end mesh size 1 cm. Tow duration was recorded for effort standardization.