Mixing and Circulation in the Tropical Atlantic Cruise No. M98

July 01 – July 28, 2013 Fortaleza (Brazil) – Walvis Bay (Namibia

Character and environmental lability of cyanobacteria-derived dissolved organic matter

Autotrophic dissolved organic matter (DOM) is central to the carbon biogeochemistry of aquatic systems, and the full complexity of autotrophic DOM has not been extensively studied, particularly by high-resolution mass spectrometry (HRMS). Terrestrial DOM tends to dominate HRMS studies in freshwaters due to the propensity of such compounds to ionize by negative mode electrospray, and possibly also because ionizable DOM produced by autotrophy is decreased to low steady-state concentrations by heterotrophic bacteria. In this study, we investigated the character of DOM produced by the widespread cyanobacteriaMicrocystis aeruginosausing high-pressure liquid chromatography-electrospray ionization-high-resolution mass spectrometry.M. aeruginosaproduced thousands of detectable compounds in axenic culture. These compounds were chromatographically resolved and the majority were assigned to aliphatic formulas with a broad polarity range. We found that the DOM produced byM. aeruginosawas highly susceptible to removal by heterotrophic freshwater bacteria, supporting the hypothesis that this autotroph-derived organic material is highly labile and accordingly only seen at low concentrations in natural settings

South American Hydrological Balance and Paleoceanography during the Late Pleistocene and Holocene (SAMBA) – Cruise No. M125, March 21 – April 15, 2016 - Rio de Janeiro (Brazil) – Fortaleza (Brazil)

R/V METEOR expedition M125 (“SAMBA”) focused on the influence of paleoceanographic changes off NE Brazil on the continental hydrological cycle. For this purpose, we obtained 202 m of gravity (24 stations) and piston cores (9) at seven sections on the shelf and continental slope close to river mouths from Cabo Frio in the south to the Rio Sao Francisco in the north. Coring stations were determined after intensive echosounder surveys (total: 1221 NM). On-board foraminiferal biostratigraphy, as well as color and XRF-scanning already provided first stratigraphic constraints, indicating the preservation of different regional paleoclimatic signals at the respective sections. Based on the preliminary stratigraphy, we retrieved high-resolution archives, covering Holocene sediments on the shelf and late Pleistocene sediments on the slope. These high-resolution archives are complemented by long-term records covering up to 900 ka of continuous sedimentation at deeper sites at smaller rivers. For proxy-calibration and the study of present-day sedimentation dynamics and biogeochemical processes, surface sediments were sampled via multicorer (47), Van Veen Grab (6) and box corer (3). Water samples for determination of the water chemistry (trace elements, stable and radiogenic isotopes) and nutrient composition were retrieved by 55 CTD/Rosette casts. In addition, we run multinet-hauls at seven stations to investigate the planktonic foraminiferal communities in the water column down to 700 m water depth, complemented by filtering water from the ship’s pump twice a day

Photoinduced Isomerization of Lycopene and Application to Tomato Cultivation

The present study aimed to investigate if growth conditions have an impact on the isomeric composition of lycopene in tomatoes. First a model system for photoinduced isomerization was established. Tomato extracts were irradiated with a halogen lamp, whose wavelength spectrum is close to the spectrum of daylight and thus mimics field-grown cultivation. Different optical filters were interposed between lamp and samples to simulate greenhouse conditions. 5-<i>cis</i>-Lycopene was formed preferentially while the concentration of 7-<i>cis</i>-lycopene decreased in field-grown model systems. The change of isomerization in greenhouse model systems led to a significantly different ratio. Consequently 5-<i>cis</i>- and 7-<i>cis</i>-lycopene were identified as potent markers for the differentiation of various lighting conditions during cultivation. This result was verified in biological samples. Authentic field-grown tomatoes (<i>var. Lycopersicon esculentum Mill. var. commune L. H. Bailey “Harzfeuer”</i>) showed a significantly higher content of 5-<i>cis</i>-lycopene 5.90 ± 0.45% compared to tomatoes of the same variety grown under electric lighting 4.11 ± 0.10%. Additionally, the ratio of 7-<i>cis</i>-lycopene was significantly lower under field-grown conditions

METEOR Fahrtbericht / Cruise Report M146, Henry Seamount Seepage Exploration (HESSE), Recife (Brazil) - Las Palmas de Gran Canaria (Spain), March 17 - April 16, 2018

The main objective of cruise M146 was the discovery and documentation of inferred fluid venting sites at Henry Seamount, an extinct 126 Ma old volcano located 40 km to the southeast of El Hierro island. Evidence of recent fluid discharge at this seamount was provided by rock and shell samples from a reconnaissance dredging campaign during METEOR cruise M66/1. Such discharge could reflect hydrothermal circulation of seawater through the old oceanic crust, a globally important process. This type of circulation requires basement outcrops through the impermeable sediment cover, which can be provided by seamounts and island flanks. To achieve the goals, we carried out a hydroacoustic survey of Henry Seamount using the ship's multibeam echosounder and PARASOUND system, and mapped an area of 31 km² in detail during seven AUV dives. About 600 km of reflection seismic profiles were shot across the seamount and its vicinity to reveal sub-bottom structures and basement outcrops. As a potential tracer for fluid discharge or recharge sites, the heat flow in the area was determined by more than 50 measurements along four profiles using a heat flow probe. During seven TV sled surveys we explored the seafloor on the top and flanks of Henry Seamount, and logged temperature, turbidity and geochemical potential of the bottom water. Five gravity cores and 13 grabs provided samples of sediment, shells and other biota, and revealed conspicuous basaltic ash and lapilli layers. Our data show that surprisingly large areas of the seamount are covered with Abyssogena clam shells, testifying widespread past fluid discharge, even though this is not reflected in the heat flow data. Oxydation-reduction potential (ORP) anomalies in the bottom water indicate that in some areas fluids are still discharging