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Sediment fluxes and biotic C cycling from stable isotope tracer incubation experiments under climate change projections in the Cabo Verde Basin, NE Atlantic
No full textAn experimental approach was developed to assess the individual and combined effects of two climate change stressors (temperature and POC quality) on soft sediments in the bathyal continental margin of the Cabo Verde Basin (CVB, Equatorial Atlantic). The study used stable isotope tracer incubation experiments with 13C and 15N labelled diatoms Phaeodactylum tricornutum, to simulate climate change projections for the next century. A balanced experimental design was employed to examine the impacts of increased temperature (+2 °C), reduced POC quality (dialysed labile fraction), or both, compared to a control treatment. The experiments were carried out onboard the research vessel Sarmiento de Gamboa during the iMirabilis2 campaign in August 2021 (Orejas et al., 2022). A total of 19 sediment samples were collected by four multi-corer (MUC) deployments. From each MUC deployment, four cores with clear overlying water were randomly selected and assigned among the four different treatments (total n= 4 for each of 4 treatments), and the remaining three cores were used as background for natural stable isotopes. The upper 15-18 cm of sediment from each core was extruded to an incubation core (inner diameter 10 cm) closed airtight at the bottom. The incubation cores were placed in buckets with filtered seawater at the experimental temperature. After an equilibration period of 147 to 173 hours, the stable isotope experiment began with the injection of 12.5 mg of fresh or partially degraded diatoms into each core, representing approximately 10% of the average annual POC flux for the region (Sweetman et al., 2017). The experiment lasted 48 hours after the algae injection, with the cores maintained under constant aeration. During the incubation, Sediment Community Oxygen Consumption (SCOC) rates and DI13C production rates were measured twice (at T10 and at T45). At the experiment's conclusion, sediment samples were stored at -80°C for Phospho Lipid derived Fatty Acid (PLFA) analysis or fixed in 10% borax-buffered formalin seawater for macrofauna analysis (Gaurisas et al. 2024). Phospho Lipid derived Fatty Acid (PLFA) extraction according to Shahbaz et al. (2020) followed by Gas Chromatography Isotope Ratio Mass Spectrometry (GC-IRMS) according to Thornton et al. (2011), utilising bacterial biomarker C15:0i and related biomarker-specific fraction (7.4%) from Rajendran et al. (1993). Followed by adjustment for sediment Dry Bulk Density (DBD = 2.50 g cm-3) and sediment porosity (= 0.61) according to Thiede et al. (1982); followed by adjustment for bacterial-cell specific PLFA concentration (= 0.056 g C PLFA g-1 C) according to Brinch-Iversen & King (1990)
Geothermal heat flow data collected during PS134
No full textThe geothermal heat flow in the Bellingshausen Sea, West Antarctica, is not well constrained, but a crucial parameter, as it can influence sliding conditions at the ice-bed contact and englacial temperatures and consequently, the ice-sheet flow dynamics. Furthermore, the magnitude and spatial variability of geothermal heat flow can provide insights into regional tectonic and magmatic development. However, bottom water variations of the modified Circumpolar Deep Water are presumably affecting the upper meters of the sub-seafloor sediment temperatures and thus, the measurement-derived heat flow estimates. For these purposes, we conducted heat flow measurements during cruise PS134 in the Bellingshausen Sea at stations located in Ronne Entrance, Eltanin Bay, and in front of the Abbot Ice Shelf. The dataset comprises in situ sediment temperatures measured using a heat flow probe with six Miniaturized Temperature Data-Loggers. Thermal conductivities were measured on split sediment cores using the KD2 Thermal Property Analyzer. During the deployment of the heat flow probe, water column temperatures were recorded
Results of direct shear experiments on intact and powdered samples from the submarine flank of Kilauea volcano (Hawaii, USA)
No full textWe performed laboratory friction experiments on simulated fault gouges and intact samples from the submarine flank of Kilauea volcano (Hawaii, USA) and measured the velocity-dependence of friction in velocity-step tests. Moreover, we have directly measured cohesion on the fault gouge and intact samples from Kilauea's submarine flank. The experiments were carried out using a single-direct shear device at room temperature. For the shearing tests, the samples simulating fault gouge were crushed and sieved to a grain size of < 125 µm. The intact samples were tested as mini-cores. All experiments were carried out under fluid-saturated conditions (3.5 % NaCl brine) and under an effective normal load of 10 MPa
Basic measurements of radiation at station De Aar (2000-06 - 2020-01)
No full textThis is a compilation of all short-wave and long-wave radiation datasets from De Aar that were and are published in the frame of BSRN. New data will be added regularly.
The data are subject to the data release guidelines of BSRN (https://bsrn.awi.de/data/conditions-of-data-release/)
Basic measurements of radiation at station Goodwin Creek (1995-01 et seq)
No full textThis is a compilation of all short-wave and long-wave radiation datasets from Goodwin Creek that were and are published in the frame of BSRN. New data will be added regularly.
The data are subject to the data release guidelines of BSRN (https://bsrn.awi.de/data/conditions-of-data-release/)
Processed physical properties measured on sediment core GeoB22306-2
No full textSound knowledge about the petrophysical characteristics of a sediment core is a prerequisite for any subsequent paleoenvironmental study relying on sediment proxies. Physical properties of whole-round sediment cores are acquired as a first step of sediment core description, prior to slicing of sediment cores into two halves. Here, we present processed physical-properties data of core GeoB22306-2 acquired with a Geotek MSCL-S system on the unsplit core, retrieved RV Maria S. Merian expedition MSM66 WESTBAFF to the Baffin Bay, Canada/Greenland, in 2017. Cores were processed according to the standard protocol given by the manufacturer Geotek Ltd
Processed physical properties measured on sediment core GeoB22331-2
No full textSound knowledge about the petrophysical characteristics of a sediment core is a prerequisite for any subsequent paleoenvironmental study relying on sediment proxies. Physical properties of whole-round sediment cores are acquired as a first step of sediment core description, prior to slicing of sediment cores into two halves. Here, we present processed physical-properties data of core GeoB22331-2 acquired with a Geotek MSCL-S system on the unsplit core, retrieved RV Maria S. Merian expedition MSM66 WESTBAFF to the Baffin Bay, Canada/Greenland, in 2017. Cores were processed according to the standard protocol given by the manufacturer Geotek Ltd
Natural abundance of stable carbon and nitrogen isotopes of small pelagic fishes from the northern Iberian shelf (NE Atlantic) between 1998 and 2024
No full textThis dataset contains the values of natural abundance of stable carbon and nitrogen isotopes in bulk muscle and gut contents, and nitrogen isotopes in muscle amino acids measured in 1801 samples of 10 small pelagic fish species sampled during the PELACUS spring cruises in the northwestern Iberian shelf and in adjacent waters of the southern Bay of Biscay. Length, weight, sex and maturity stage data for each individual analyzed are also provided. Fishes were collected by midwater trawls of ca. 30 m2 pelagic net equipped with a graded-mesh netting (starting with 30 mm and ending with 4 mm). The duration of each trawl was between 25 and 40 min. Different species occurred in the same trawls. Samples of muscle tissue and gut contents were preserved dried (50°C, 48 h) or freeze-dried. No treatments for lipid removal were used prior to carbon analyses. Stable isotope determinations in bulk samples (also carbon and nitrogen contents) were made by isotope-ratio mass spectrometry coupled to an elemental analyzer (Bode et al. 2018). Stable nitrogen isotopes in amino acids were determined by isotope-ratio mass spectrometry couples to a gas chromatograph (Bode et al., 2021)
Total carbon, total organic carbon, and total inorganic carbon (solid-phase discrete samples) from IODP Hole 389-M0097B
No full textTotal carbon (TC), total organic carbon (TOC), and total inorganic carbon (TIC) content from solid-phase discrete samples from the above given hole of International Ocean Discovery Program (IODP) Expedition 389 (Hawaiian Drowned Reefs). The offshore phase of this expedition took place between 2023-08-31 and 2023-10-31 onboard multipurpose vessel MMA Valour sailing from and to Barbers Point Harbor, Hawai'i, USA, followed by the onshore phase from 2025-02-06 to 2025-02-26 at the Bremen Core Repository (BCR) hosted at MARUM – Center for Marine Environmental Sciences, University of Bremen. During the onshore phase a set of solid-phase samples were taken from the work halves of core sections, with a volume of approx. 10 cubic centimeters each, were taken with the purpose to be later on split into aliquots for the following three analyses: X-ray diffraction, carbon and X-ray fluorescence. Bulk samples were subsequently freeze-dried, ground and homogenized to a fine powder (<20 µm particle size) by ECORD Science Operator staff using a pestle and an agate mortar or a ball mill. Sample aliquots of approx. 100 mg (TC) and 1 g (TOC) were processed through a CS744 LECO carbon-sulfur analyzer to obtain the respective concentrations. TIC was calculated as the difference between TC and TOC.
For further methodological information see methods chapter in Webster, J.M. et al., 2025 https://doi.org/10.14379/iodp.proc.389.202
Physical properties (MSCL) of IODP Hole 389-M0097A
No full textMulti-Sensor Core Logger (MSCL) data (P-wave velocity, magnetic susceptibility, natural gamma radiation (NGR), noncontact resistivity (NCR), gamma ray attenuation (GRA) density) from the above given hole of International Ocean Discovery Program (IODP) Expedition 389 (Hawaiian Drowned Reefs). These data were obtained from whole round core sections by means of a Geotek MSCL during the offshore phase of the expedition. The offshore phase of this expedition took place between 2023-08-31 and 2023-10-31 onboard multipurpose vessel MMA Valour sailing from and to Barbers Point Harbor, Hawai'i, USA. During expedition 389 offshore operations, the recovered cores were transferred from aluminum to plastic liners, thereby draining and to some extent further disturbing the core sections. Thus, partial fluid saturation and drilling-induced core damage on top of natural vugs and fractures common in carbonates and volcanic lava rocks negatively impacted the data quality. GRA density, P-wave velocity, NCR, and magnetic susceptibility were measured every 2 cm, and NGR measurements were obtained every 10 cm. Note, in contrast to standard IODP syntax in this data set the depth value at the end of the sample label identifier, gives the depth in core. For instance, a sample label like 389-M0101B-19-2,126 identifies a measurement from 126 cm depth in core 19 (corresponding to section 2) within hole M0101B of expedition 389.
For further methodological information see methods chapter in Webster, J.M. et al., 2025 https://doi.org/10.14379/iodp.proc.389.202