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Charcoal counts of sediment core LLCore2 from Lost Lake, British Columbia in 2020
No full textThis dataset provides charcoal counts for the Holocene lacustrine sedimentary sequence retrieved from Lost Lake, Canada (49.4038, -122.9756, 235 m above sea level). The LLCore2 composite sediment core was collected from Lost Lake, in the Lower Seymour Conservation Reserve, North Vancouver, British Columbia, Canada in fall 2020. The composite core is composed of a 0.41 meter surface core, collected using a Glew gravity corer, and a 2.41 meter sediment core collected using a Livingstone piston corer. The chronology was established using 210Pb, 137Cs, and accelerator mass spectrometry 14C radiometric dating. 1-cm³ volumetric charcoal samples were collected at 1-cm intervals along the core and isolated according to Hallett et al. (2003, doi:10.1139/x02-177), Walsh et al. (2008, doi:10.1016/j.yqres.2008.05.002), and Murphy et al. (2019, doi:10.3389/fevo.2019.00090). Charcoal fragments were counted using a Leica M205C stereomicroscope and measured against depth (m) and age (ka BP). These data were collected to provide information about local and regional changes in ecosystem composition and fire activity throughout the Holocene in the Lower Mainland of British Columbia
Mendenhall Glacier basal ice-sediment outcrop samples, 2021
No full textWe gathered field observations of debris-rich ice layers from an alpine glacier margin to help inform models of glacial sediment transport across landscapes. Basal ice and entrained sediment samples were taken from the margin of Mendenhall Glacier, Juneau, AK, in August 2021. Along the land-terminating margin of the glacier, we identified five representative outcrops of debris-rich ice with obvious stratigraphic layers. Samples were taken in duplicate at intervals from the base of the debris-rich layers to the clean ice above. After removing the outermost layer of sediment, which is typically enriched by surface melt, we weighed the samples in the field, then transported them back to the Sedimentology and Plant Lab at the Institute of Arctic and Alpine Research in Boulder, Colorado. In the lab, samples were freeze-dried to remove the ice fraction, then weighed again to obtain sediment mass, and thus sediment concentration
REVEALS reconstruction of past vegetation cover with optimized RPP values for African samples
No full textThis data set presents the reconstructed vegetation cover for 164 African sites based on harmonized pollen data from the data set LegacyPollen 2.0 and optimized RPP values. Sugita's REVEALS model (2007) was applied to all pollen records using REVEALSinR from the DISQOVER package (Theuerkauf et al. 2016). Pollen counts were translated into vegetation cover by taking into account taxon-specific pollen productivity and fall speed. Additionally, relevant source areas of pollen were also calculated using the aforementioned taxon-specific parameters and a gaussian plume model for deposition and dispersal and forest cover was reconstructed. In this optimized reconstruction, relative pollen productivity estimates for the ten most common taxa were first optimized by using reconstructed tree cover from modern pollen samples and LANDSAT remotely sensed tree cover (Sexton et al. 2013) for Africa. Values for non-optimized taxa for relative pollen productivity and fall speed were taken from the synthesis from Wiezcorek and Herzschuh (2020). The average values from all Northern Hemisphere values were used where taxon-specific continental values were not available. We present tables with optimized reconstructed vegetation cover for all records in Africa. As further details we list a table with the taxon-specific parameters used and a list of parameters adjusted in the default version of REVEALSinR
pCO2 and turbulence data from an autonomous drifting buoy in 2016 during FALKOR cruise FK161010
No full textPalynomorph and dinoflagellate cyst assemblage counts at OPD Site 145-887 from 5.3 to 0.4 Ma
No full textThis dataset contains raw palynomorphs counts at ODP Holes 887A and 887C, including dinocyst assemblage, as well counts of others palynomorphs such as acritarchs, pollen grains and tasmanites. Precise depths and estimated age are also provided for each sample
Magnetic susceptibility borehole logging of MeBo sediment core GeoB23702-5
No full textLogging was performed with the sea floor drill rig MARUM-MeBo70 in a borehole drilled with a 103 mm diameter bit. The 1188 Slimhole Memory Magnetic Susceptibility instrument developed by ANTARES Datasystems GmbH was used. Three coils are used for measuring the apparent magnetic susceptibility with an alternating magnetic field tuned to resonate at 1 kHz. The accuracy is within 5 %. The vertical resolution is about 20 cm. The probe was deployed in the memory mode with the logging string being inserted into the drill string and the sensors located below the drill bit. The measurement was conducted as upcast while the drill string was pulled back to the seafloor out of the borehole. The trip out speed was about 1 cm/s and the logging frequency was 0.5 Hz. Data Processing was conducted using the Antares software GeoBase 6.22.
Soil properties, carbon composition, microbial community, and potential CO2 production from a typical thaw slump on the northern Qinghai-Tibet Plateau
No full textRapid warming of permafrost regions leads to the widespread development of thaw slumps and accelerates the decomposition and release of soil organic carbon. Yet, how the evolution of thaw slump affects carbon dioxide (CO2) release remains unclear. This dataset presents soil properties, carbon composition, microbial community, and potential CO2 production from a typical thaw slump located in the northeastern Qinghai-Tibet Plateau (37°28′N, 100°17′E, 3597m). In the field, we set up a control area and three collapse areas (including 1, 12, and 23 years of collapse) along the thaw sequence. In each plot, we set up three quadrats (~4 m × 5 m) along a diagonal line. Three replicates of topsoil (0–15 cm) and subsoil (15–30 cm) were collected from each quadrate and mixed by depth as one composite sample for subsequent analyses. The soil sampling was carried out in July 2020. Each of the collected soil samples was divided into three subsamples after sieving (2-mm mesh) and removal of stones, root fragments, and plant material. The first subsample was stored at −80 °C for biomarker phospholipid fatty acids (PLFAs) and enzyme activities analysis, the second subsample used laboratory incubation, and the third subsample was air-dried to determine soil physical and chemical properties, including soil moisture, texture, pH, SOC content, total nitrogen content, stable carbon isotopes, and carbon composition; this data is presented here. All samples were further analyzed for potential CO2 production rate and cumulative CO2 release using aerobic incubations for 189 days at 10 °C
Drill hole measurements of land-fast sea ice and sub-ice platelet layer thicknesses, fast ice freeboard, and snow depth in Gerlache Inlet, north Terra Nova Bay, Antarctica in November 2021
No full textHere, we present drill hole measurements of land-fast sea ice and sub-ice platelet layer thicknesses, fast ice freeboard, and snow depth collected at 6 drill sites distributed over a 60 km^2 fast ice area in Gerlache Inlet, north Terra Nova Bay, western Ross Sea, Antarctica between 3 and 7 November 2021. At each site, five holes were drilled in the fast ice at the centre and end points of two cross‐profile lines, each 30 m long. Sea ice and SIPL thicknesses were measured with a suspended thickness probe and metal bar using the procedure described in Price et al. (2014). Snow depth measurements at centimetre accuracy were made at the drill holes using a metal ruler. Sea ice freeboard (i.e., the height of the sea ice surface above sea level) was measured in each of the drill holes. The average value for each parameter at a field site was calculated from the five drill hole measurements to provide a representative measurement over the 30 m cross-profile fast ice area. The drill hole measurements were used to underpin spatial distribution surveys of the aforementioned parameters, to calibrate electromagnetic induction forward and inverse models, and to ground-validate satellite altimetry assessments of fast ice freeboard and derived ice thickness
The concentration of humic substances and their contribution to iron speciation in waters of the Atlantic sector of the Arctic Ocean and the North Atlantic Ocean
No full textIn this dataset, we present findings on concentrations (< 0.2 μm) of humic substances, dissolved iron, and humic iron (the fraction of dissolved iron complexed by humic substances) in samples gathered during three distinct cruises across the North Atlantic and Arctic oceans. Our objective was to track the migration of humic substances originating from Siberian river outflows, as they traverse from surface waters of the Arctic Ocean into the North Atlantic Ocean, and to understand their impact on dissolved iron transport in the region. The dataset encompasses results from three cruises: the TransArcII expedition aboard the RV Polarstern (PS94) in the central basins and Atlantic sector of the Arctic Ocean, the GN05 expedition (PS100) in waters of the Fram Strait, and the Metalgate expedition aboard the RV Pelagia (64PE474) in waters surrounding Iceland. Dissolved iron concentrations were determined using ICP-MS (Middag et al. 2023), while humic substances and iron bound to humic substances were measured via Adsorptive Cathodic Stripping Voltammetry following the method outlined by Sukekava et al. (2018). Our findings reveal significant regional variations in the role of humic substances, influencing the prevention of dissolved iron precipitation and facilitating its transport.
Middag, R., R. Zitoun, and T. Conway, Trace Metals, in Marine Analytical Chemistry, J. Blasco and A. Tovar-Sánchez, Editors. 2023, Springer International Publishing: Cham. p. 103-198.
Sukekava, C., et al., Determination of the contribution of humic substances to iron complexation in seawater by catalytic cathodic stripping voltammetry. Talanta, 2018. 189: p. 359-364
2D multichannel seismic reflection raw data (GI Gun) of RV Petr Kottsov in 1998 to the Agulhas Plateau, seismic reflection profile AWI-98012
No full textSeismic reflection data collected on the Agulhas Plateau during with RV Petr Kottsov in 1998. 2 GI-guns were used a seismic source, the data were recorded with a 2400 m (active length) long analog streamer. The data are demultiplexed and unprocessed. No gain, filter or mute have been applied. The data are in SEGY format. See cruise report or ReadMe file for more information on acquisition parameters