ALBERT

Description: In the marine realm, microorganisms are responsible for the bulk of primary production, thereby sustaining marine life across all trophic levels. Longhurst provinces have distinct microbial fingerprints; however, little is known about how microbial diversity and primary productivity change at finer spatial scales. Here, we sampled the Atlantic Ocean from south to north (~50°S–50°N), every ~0.5° latitude. We conducted measurements of primary productivity, chlorophyll-a and relative abundance of 16S and 18S rRNA genes, alongside analyses of the physicochemical and hydrographic environment. We analysed the diversity of autotrophs, mixotrophs and heterotrophs, and noted distinct patterns among these guilds across provinces with high and low chlorophyll-a conditions. Eukaryotic autotrophs and prokaryotic heterotrophs showed a shared inter-province diversity pattern, distinct from the diversity pattern shared by mixotrophs, cyanobacteria and eukaryotic heterotrophs. Additionally, we calculated samplewise productivity-specific length scales, the potential horizontal displacement of microbial communities by surface currents to an intrinsic biological rate (here, specific primary productivity). This scale provides key context for our trophically disaggregated diversity analysis that we could relate to underlying oceanographic features. We integrate this element to provide more nuanced insights into the mosaic-like nature of microbial provincialism, linking diversity patterns to oceanographic transport through primary production.

Description: Isotropic three-dimensional (3-D) inversion has become a standard tool in the interpretation of magnetotelluric (MT) data. 3-D anisotropic inversion codes are under development, yet the number of unknowns increases by a factor of 6 rendering the problem extremely ill-posed. The presence of anisotropy is usually inferred from (i) spurious sequences of conductive and resistive bodies or (ii) comparison with two-dimensional anisotropic modelling approaches. Here, we investigate the 3-D structure of the Gawler Craton down to ∼250 km depth using 282 sites of the AusLAMP array located in the southern half of South Australia. Inversions of the MT impedance as phase tensors and real and imaginary parts result in diverging structures at depths 〉 70 km. We demonstrate that a unifying model that explains all data types similarly well is suggestive of an anisotropic resistivity structure at the base of the Gawler Craton lithosphere at depths of 120–210 km. Depth location and orientation of the anisotropy agree well with results from the analysis of seismic receiver functions. We suggest that electric anisotropy in the Gawler Craton is a result of lattice-preferred orientation of olivine crystals and metasomatic processes with macroscopic preferential orientation. Our results illustrate that inversion of phase tensor data is superior for the direct imaging of anisotropic resistivity contrasts in otherwise isotropic resistivity models; inversion models obtained with impedances may miss such structures. “Comparable” overall RMS misfits are often meaningless when comparing inversion results for various data types since sensitivities differ between data types. Reliable inversion results consistent with the entire data set can only be recovered if data fits are assessed systematically for all data representations. We also discuss the influence of error settings for phase tensors on the inversion. Our study also revealed that, if persistent across large areas, (i) parallel orientation of phase tensor major axes, (ii) constantly high phase tensor maximum phases or (iii) diverging directions of phase tensor major axes and induction arrows are suggestive of anisotropic structures and corresponding hypotheses should be evaluated.

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen-consuming processes are promoted, driving oxygen depletion that favours trace gases i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. Also, gas-rich subsurface waters are transported towards the surface waters during upwelling, enhancing trace gas sea-air fluxes. Within the EVAR project, we investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system as the source of these greenhouse gases relative to the atmosphere. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise SO283 (March 19th – May 25th, 2021) onboard the R/V SONNE from and to Emden (Germany). The main area of the sampling was the Namibian shelf between 18°S and 25°S which is suggested to represent some regional hotspots of trace gas emissions to the atmosphere, in particular in the vicinity of the upwelling cells. Over 260 discrete water samples were collected from the Niskin bottles at different stations for the determination of the concentrations of CH4, N2O, and dissolved inorganic carbon (DIC). 200ml seawater samples were fixed with 200 µL of saturated HgCl2 solution straight after sampling and trace gas was quantified in return. Dissolved CH4 and N2O were measured by an in-house designed purge and trap system with a dynamic headspace method back on land. In brief, a subsample is purged with an inert ultrapure carrier gas of Helium, and the gases are focused on a cryo-trap operated at about -120°C. The volatile compounds are desorbed by rapid heating and analyzed by a gas chromatograph (GC; Agilent 7890B), equipped with capillary columns and a Deans Switch, which directed the components to the flamenionization detector for CH4 detection and electron capture detector ECD for N2O detection. To explore the carbonate system Dissolved Inorganic Carbon (DIC) was measured in the institute. About 5.00 ml of each fixed discrete sample was acidified by 10 % phosphoric acid, resulting in release of inorganic carbon content of the sample. An automated infra-red inorganic carbon analyzer (AIRICA, Marianda, Tulpenweg 28, D-24145 Kiel) equipped with an infrared detector LICOR 7000 (LI-COR Environmental – GmbH, Homburg, Germany) was used to quantify DIC. A 3-fold measurement of the pH was also carried out in 120 ml of discrete samples directly after sampling using the HydroFIA pH system (4H Jena Engineering, 24148 Kiel, Germany). We calculated the average pH value of the corresponding sample after Müller and Rehder (2018) and corresponding total alkalinity and pCO2 after Dickson et al. (2007).

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen-consuming processes are promoted, driving oxygen depletion that favours trace gas i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. Also, gas-rich subsurface waters are transported towards sea surface during upwelling, enhancing trace gas sea-air fluxes. Within the EVAR project, we investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system as the source of the greenhouse gases relative to the atmosphere. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise MSM105 (January 11th – February 23rd, 2022) onboard the R/V MARIA S. MERIAN, which encompassed close-coastal and open ocean regions between Mindelo (Cape Verde) and Walvis Bay. The working area of the cruise MSM105 was the Namibian shelf between 18°S and 27°S which are suggested to represent some regional hotspots of trace gas emissions to the atmosphere, in particular in the vicinity of the upwelling cells. Over 260 discrete water samples were collected from the Niskin bottles at different stations for the determination of dissolved CH4, N2O, and dissolved inorganic carbon (DIC). 200ml seawater samples were fixed with 200 µL of saturated HgCl2 solution straight after sampling and dissolved trace gas was quantified in return. The dissolved gases were measured by an in-house designed purge and trap system with a dynamic headspace method back on land. In brief, a subsample is purged with an inert ultrapure carrier gas of Helium, and the gases are focused on a cryo-trap operated at about -120°C. The volatile compounds are desorbed by rapid heating and analyzed by a gas chromatograph (GC; Agilent 7890B), equipped with capillary columns and a Deans Switch, which directed the components to the flamenionization detector for CH4 detection and electron capture detector ECD for N2O detection. To explore the carbonate system, Dissolved Inorganic Carbon (DIC) was measured on board by an automated infra-red inorganic carbon analyzer (AIRICA, Marianda, Tulpenweg 28, D-24145 Kiel) equipped with an infrared detector LICOR 7000 (LI-COR Environmental – GmbH, Homburg, Germany. A 3-fold measurement of the pH was also carried out in 120 ml of discrete samples directly after sampling using the HydroFIA pH system (4H Jena Engineering, 24148 Kiel, Germany). We calculated the average pH value of the corresponding sample after Müller and Rehder (2018) and corresponding total alkalinity and pCO2 after Dickson et al. (2007).

Description: Abyssal holothurians were collected during SO242-2 in the Peru Basin in 2015 with ROV Kiel 6000 (Geomar, Germany). Aboard the vessel, holothurians were measured (length, width, height), dissected and stored frozen (-20°C). At the shore-based laboratory of NIOZ-Yerseke, samples were weight before and after freeze-drying and organic (org.) C/ δ13C and N/ δ15N content of freeze-dried, finely-ground holothurian body wall tissue were measured with an elemental analyzer coupled with an isotope ratio mass spectrometer. Total hydrolizable amino acids (THAA) from holothurian body wall tissue were extracted following a modified protocol of Veuger et al. 2005. Phospholipid-derived fatty acids (PLFAs) and neutral lipid-derived fatty acids (NLFAs) were extracted from holothurian body wall tissue and gut content following a modified Bligh and Dyer extraction method.

Description: Abyssal holothurians were collected during SO242-2 in the Peru Basin in 2015 with ROV Kiel 6000 (Geomar, Germany). Aboard the vessel, holothurians were measured (length, width, height), dissected and stored frozen (-20°C). Feces and gut content of individual holothurian specimens were also kept frozen. At the shore-based laboratory of NIOZ-Yerseke, samples were weight before and after freeze-drying and organic (org.) C/ δ13C and N/ δ15N content of freeze-dried, finely-ground holothurian gut content and feces were measured with an elemental analyzer coupled with an isotope ratio mass spectrometer. Sediment grain size of holothurian gut content was determined by laser diffraction on freeze-dried and sieved (〈1 mm) sediment samples in a Malvern Mastersizer 2000.

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen consuming processes are promoted, driving oxygen depletion that favors trace gases i.e. methane (CH4) and nitrous oxide (N2O) production at relatively shallow depths. During upwelling, gas-rich subsurface waters are also transported towards the surface waters, enhancing trace gas sea-air fluxes. We investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system in gas emissions. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise MSM105 (January 11th – February 23rd, 2022) onboard the R/V MARIA S. MERIAN, which encompassed close-coastal and open ocean regions between Mindelo (Cape Verde) and Walvis Bay. The working area of the cruise MSM105 was the Namibian shelf between 18°S and 27°S which are suggested to represent some regional hotspots of trace gas emissions to the atmosphere.The underway mesurement of partial pressures of CH4, N2O, and CO2 in sea surface and atmosphere were determined using IOW's self-built Mobile Equilibrator Sensor System (MESS). The system was described in details elsewhere (Sabbaghzadeh et al., 2021) but in brief, it consists of a custom-built equilibrator (combined shower-head/bubble type) and a control unit lined up with two Los Gatos Research off-axis laser absorption spectroscopy (oa-ICOS) analyzers. In this study, a Model # 908-0011-0001(CO2/CH4/H2O) and a Model # 908-0014-0000 (N2O/CO/H2O) were used. To quantify sea-air gas fluxes, the atmospheric concentration of studied trace gases was measured at several positions during the cruise using a tube with the inlet positioned at front of the bow to minimize ship contamination. All other ancillary parameters out of the MESS system were synchronized with D-ship data with a simultaneous data reduction to one-minute intervals.

Description: The southern North Sea (German Bight) is influenced by the inflowing water in the Tide-Elbe area and how it is further modified. For a better understanding of the different branches of relevant events it is necessary to investigate which are the main impacting factors for the terrestrial and coastal water quality. Therefore, during different cruises between 2019 and 2022 a group of parameters was continuously traced from the Elbe River basin (Czech/German border) to Tide-Elbe and Elbe estuary (Hamburg, Germany) until the German Bight. This dataset is about the cruise "Sternfahrt 5" from August 31 to September 03 in 2020, with the objective to detect the spatial extension of the riverine influence of Elbe and Weser. Therefore, three research vessels have been involved to cover a broad area of the German Bight between Hamburg, Heligoland and Sylt. All three research vessels (Littorina, Ludwig Prandtl and Mya II) started together on the first day from Cuxhaven to Heligoland. The first day and whenever two or three of the ships met, one measuring was made together as inter-calibration station (for more details, see file description), in total four. From the second day the ship Littorina travelled between Heligoland and Büsum, one track each day. The Ludwig Prandtl headed the second day towards Wyk auf Föhr. Afterwards the crew navigated further north towards Sylt and turning back to Wyk on the same day. The last day they went back from there to Cuxhaven meeting with the vessel Littorina for a last inter-calibration station. The vessel Mya II instead was navigating on the second and third day first to Bremerhaven and on a more western track back to Heligoland. To also cover the northern part of the research area, on the last day the crew travelled to Sylt, the home harbour of the vessel. Therefore, it was not participating on the last inter-calibration station off Cuxhaven. All ships took measurements of basic hydrographic parameters (salinity, temperature, oxygen saturation, pH) and atmospheric and dissolved greenhouse gases (methane and carbon dioxide). The parameters were measured continuously on the way by specific sensors submerged in a water reservoir on deck which was supplied with surface water (about 1m depth) from the underway water supply of the vessel. Methane and carbon dioxide were measured in the surface water and in the atmosphere with the sensors "LosGatos" and "Picarro". Ferrybox systems measured physical and chemical oceanographic parameters including salinity, temperature, pH. At specific stations along the tracks additionally vertical profiles were taken as well as water samples from the surface. The respective data can be found in: Bussmann, Ingeborg, Flöser, Götz, Geißler, Felix (2021): Carbon compounds, nutrients and pigments from water samples from MOSES project's cruise Sternfahrt 5. PANGAEA, https://doi.org/10.1594/PANGAEA.934894. Further profile data can be found in the AWI O2A-Database as download. Additional information about the whole campaign and different cruises can be found in the article(s) cited.

Description: The high surface productivity triggered by nutrient-rich Benguela upwelled waters results in significant enrichment of organic carbon in the sub-surface waters due to enhanced mineralization in the water column and benthic fluxes. Hence, microbial oxygen demand processes are promoted, driving oxygen depletion that favors trace gas production at relatively shallow depths. During upwelling, gas-rich subsurface waters are transported towards the surface waters, enhancing trace gas sea-air fluxes. We investigate the variability of these fluxes on seasonal and shorter timescales to understand the intensity of the Benguela upwelling system in gas emissions. The data might serve as a base for projections under a changing climate. The fieldwork took place during the cruise MSM105 (January 11th – February 23rd, 2022) onboard the R/V MARIA S. MERIAN, which encompassed close-coastal and open ocean regions between Mindelo (Cape Verde) and Walvis Bay. The working area of the cruise MSM105 was the Namibian shelf between 18°S and 27°S which is suggested to represent some regional hotspots of trace gas emissions to the atmosphere. The partial pressures of CH4, N2O, and CO2 in the sea surface and atmosphere were determined using IOW's self-built Mobile Equilibrator Sensor System (MESS). The system was described in detail elsewhere (Sabbaghzadeh et al., 2021) but in brief, it consists of a custom-built equilibrator (combined shower-head/bubble type) with a water flow rate of about 5 l min-1 and an airflow rate of ~ 4.00 - 5.00 L min-1. The system is linked to two off-axis integrated cavity output laser spectrometers (oa-ICOS, Los Gatos Instruments) for the detection of CH4 / CO2 and N2O / CO. To operate the system, seawater was supplied by a deep-well pump (CAPRARI Desert E4XP30-4 with CAPRARI XPBM1 control unit, ~ 100 L min-1, Italy), installed in the moon-pool at ∼ 6.00 m water depth on board of the R/V MARIA S. MERIAN. All gas analyzers were calibrated against three standard gasses at the beginning and end of each survey daily for data recalibration and drift correction. In addition, one "zero" gas (i.e. Nitrogen 5.00, LINDE) was measured infrequently throughout the survey to check any system deficiency like leakage detection. To quantify sea-air gas fluxes, the atmospheric concentration of studied trace gas was measured at several positions during the cruise using a tube with the inlet positioned at the front of the bow to minimize ship contamination. All other ancillary parameters were synchronized with D-ship data with a simultaneous data reduction to one-minute intervals.

Description: The present dataset contains results from magnetic data measurements – data files and plots –on sediment cores collected during the M162 marine campaign, conducted onboard the R/V Meteor (Geomar, Germany) from 06/03/2020 to 11/04/2020 along the Gloria Fault - the Atlantic plate boundary between the Africa and the Eurasia plates. 46 gravity cores (39 with successful recovery) were collected on 6 geographically defined working areas (WA1 to WA6), from the Azores plateau to the Josephine seamount area. Magnetic susceptibility was measured onboard after core opening, using a KT10 magnetic hand susceptibilimeter (Bartington). Generally, one measurement was taken at each 5 cm, except when the core was very monotonous (each 10 cm) or when singular sedimentary horizons occurred in between each 5 cm mark. In addition to onboard measurements, 26 cores were also sampled using 2×2 cm3 plastic boxes, standard for laboratory magnetic analysis. Magnetic measurements were later conducted on the Paleomagnetism Laboratory of Instituto Dom Luiz (FCUL, Lisbon, Portugal), and included: anisotropy of magnetic susceptibility (AMS), using a MFK1 Kappabridge (Agico), natural remanent magnetization (NRM) using a JR6 spinner magnetometer (Agico), and its alternating field demagnetization, using a LDA-3 AF demagnetizer (Agico).