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Found 12 results.

Concentrations and loadings of fatty acids in surface sediments of Helgoland Mud Area in the North Sea

Surface sediment were extracted 4 times by ultrasonication with dichloromethane: methanol (9:1, v/v) for 15 min for FAs and alkanes. For quantification of FAs and alkanes, known amounts of 19-methylarachidic acid and squalane were added as internal standards prior to extraction. Supernatants from each extraction were obtained by centrifugation and combined. The total lipid extracts were concentrated and evaporated under a nitrogen stream. The total lipid extracts were saponified for 2 h at 80 °C with 1 mL of KOH (0.1 M) in methanol: H2O (9:1, v/v). After saponification, the neutral fractions were liquid-liquid extracted with n-hexane and alkanes were eluted from the neutral fractions by silica gel column chromatography with n-hexane. The remaining KOH solution was acidified to pH 1, from which FA were liquid-liquid extracted into dichloromethane. The extracted and dried FAs were converted to methyl ester derivatives (FAMEs) in methanol: HCl (95:5, v/v) at 60 °C for 12 h. After methylation, the FAME fraction was further purified by silica gel column chromatography using dichloromethane: hexane (2:1, v/v) to remove residual polar compounds. FAMEs and alkanes were analyzed on a 7890A gas chromatograph (GC) equipped with a DB-5MS fused silica capillary column (60 m, 250 µm, 0.25 µm) and a flame ionization detector (FID). Peak areas were determined by integrating the respective peaks and concentrations were calculated against the internal standards. FAME contents were subsequently corrected for the derivative methyl carbon to determine FA contents. FAs and alkanes were normalized to OC content.

Concentrations and loadings of alkanes in surface sediments of Helgoland Mud Area in the North Sea

Surface sediment were extracted 4 times by ultrasonication with dichloromethane: methanol (9:1, v/v) for 15 min for FAs and alkanes. For quantification of FAs and alkanes, known amounts of 19-methylarachidic acid and squalane were added as internal standards prior to extraction. Supernatants from each extraction were obtained by centrifugation and combined. The total lipid extracts were concentrated and evaporated under a nitrogen stream. The total lipid extracts were saponified for 2 h at 80 °C with 1 mL of KOH (0.1 M) in methanol: H2O (9:1, v/v). After saponification, the neutral fractions were liquid-liquid extracted with n-hexane and alkanes were eluted from the neutral fractions by silica gel column chromatography with n-hexane. The remaining KOH solution was acidified to pH 1, from which FA were liquid-liquid extracted into dichloromethane. The extracted and dried FAs were converted to methyl ester derivatives (FAMEs) in methanol: HCl (95:5, v/v) at 60 °C for 12 h. After methylation, the FAME fraction was further purified by silica gel column chromatography using dichloromethane: hexane (2:1, v/v) to remove residual polar compounds. FAMEs and alkanes were analyzed on a 7890A gas chromatograph (GC) equipped with a DB-5MS fused silica capillary column (60 m, 250 µm, 0.25 µm) and a flame ionization detector (FID). Peak areas were determined by integrating the respective peaks and concentrations were calculated against the internal standards. FAME contents were subsequently corrected for the derivative methyl carbon to determine FA contents. FAs and alkanes were normalized to OC content.

Organic carbon (OC) content, nitrogen content, C/N ratio, carbonate content, δ13C of OC, mean grain size, surface area, calculated fraction, content and loading of terrestrial and marine OC in surface sediments of Helgoland Mud Area in the North Sea

The grain size of sediments was determined with a Cilas 1180 laser-diffraction particle analyzer (range 0.04–2500 μm) and the mean grain size was calculated. The surface area (SA) was calculated from the grain size distribution of the sediments. The OC content of surface sediments was determined using a carbon-sulfur analyzer (CS-125, Leco) after decarbonization with HCl. The total carbon (TC) and nitrogen (TN) contents of the samples were analyzed using a carbon-nitrogen-sulfur analyzer (Elemental III, Vario) and used to calculate carbonate contents (CaCO3= (TC − OC) × 8.333) and the mass ratio of OC to TON content ((C/N)OC), which was corrected for mineral-associated inorganic N. The stable carbon isotope composition of OC in surface sediments (δ13COC) was measured using a Thermo Delta isotope ratio mass spectrometer coupled to a Carlo Erba elemental analyzer. δ13COC values are given in per mil notation relative to the Vienna Pee Dee Belemnite standard. The standard deviation of duplicate analyses ranged from 0.01‰ to 0.18‰, with an average of 0.10‰. See details in related publication (Wei et al., 2025).

Geochemical properties in surface sediments of the Helgoland Mud Area and surrounding sandy areas taken during HEINCKE cruise HE595 in the North Sea

In March 2022, 56 surface sediments were collected from the Helgoland Mud Area and surrounding sandy areas in the North Sea. These surface sediments were analyzed for grain size, organic carbon (OC) content, total nitrogen content (TN), stable carbon isotope of OC, and abundances of source-specific alkanes and fatty acids, in aim to determine and quantify composition and sources of OC, to understand the degradation and sequestration of marine and terrestrial OC in sediments, and to estimate the burial fluxes and burial efficiencies of marine and terrestrial OC in the Helgoland Mud Area. Detailed dataset interpretation can be found in Wei et al. (2024, in preparation).

Pore-water pH, H2S, Cl-, SO42-, SiO2, NO2-, PO43-, NH4+, NO3-, major and trace element data from MUC cores taken during RV HEINCKE cruises HE575 and HE595 in the Helgoland Mud Area, German Bight

This dataset includes downcore measurements of pH values, H2S, Cl-, SO42-, SiO2, NO2-, PO43-, NH4+, NO3-, As, Ba, Ca, Cu, Fe, K, Li, Mg, Mn, Mo, P, Si and Sr concentrations for sediment cores retrieved using multi-corer sampling during RV Heincke expeditions HE575 and HE595 in 2021 and 2022, respectively. The samples were collected in the framework of the Project APOC (Anthropogenic impacts on particulate organic carbon cycling in the North Sea). All measurements were performed in the laboratories of the Alfred Wegener Institute (AWI) in Bremerhaven, Germany, except pH values, which were determined onboard the research vessel.

Pore-water DIC and δ13C-DIC data, as well as solid-phase porosity and TOC data from a MUC core from RV HEINCKE cruise HE595 at Tonne E3 in the Helgoland Mud Area, SE German Bight

This dataset includes downcore measurements of dissolved inorganic carbon (DIC) and its stable carbon isotopic composition (δ13C-DIC), as well as solid-phase porosities and total organic carbon (TOC) contents from a sediment core retrieved using multi-corer sampling during RV Heincke expedition HE595 in 2022. The samples were collected in the framework of the Project APOC (Anthropogenic impacts on particulate organic carbon cycling in the North Sea). DIC contents were determined in the laboratories of the Alfred Wegener Institute (AWI) in Bremerhaven, Germany. The δ13C-DIC data were produced at MARUM—Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany. Solid-phase porosity data were produced in the laboratories of the Alfred Wegener Institute (AWI) in Bremerhaven, Germany. Total organic carbon contents were determined at the Faculty of Geosciences at the University of Bremen, Bremen, Germany.

Solid phase geochemistry of a multicorer core and a gravity core at Station HE443/10, North Sea

Solid-phase samples were collected onboard (RV Heincke expedition HE443) using cut-off syringes. The MUC was sliced and sampled. For sampling the GC, small windows were drilled into the liner through which the syringes were introduced. All samples were stored anoxically and frozen at -20°C until processing. The processing involved freeze-drying and grinding before splitting the samples for the different kinds of analyses.

Solid phase iron isotopic composition of a gravity core at Station HE443/10, North Sea

Solid-phase samples were collected onboard (RV Heincke expedition HE443) using cut-off syringes. The MUC was sliced and sampled. For sampling the GC, small windows were drilled into the liner through which the syringes were introduced. All samples were stored anoxically and frozen at -20°C until processing. The processing involved freeze-drying and grinding. Extracts deriving from the sequential extraction of Fe phases were processed for stable Fe isotope analysis after Henkel et al. (2016).

Pore-water data of a multicorer core and a gravity core at Station HE443/10, North Sea

Pore water was collected onboard (RV Heincke expedition HE443) by use of rhizons that were inserted into the cores through drilled holes in the core liners. Samples were preserved and analyses were performed onshore (at AWI) shortly after the expedition.

Radiographs of the gravity core HE443/10-3 from North Sea

Radiographs of gravity core HE443/10-3 that was collected in the Helgoland mud area. The radiographs were produced about 8 months after coring and sampling. The white spots derive from previous sediment sampling that was performed onboard through windows that were cut into the core liner. The core shows intervals with intact sedimentary structures, but also intervals that are strongly mixed by bioturbation.

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