ALBERT

Description: Long-chain diols (LCDs) occur widespread in marine environments and also in lakes and rivers. Transport of LCDs from rivers may impact the distribution of LCDs in coastal environments, however relatively little is known about the distribution and biological sources of LCDs in river systems. In this study, we investigated the distribution of LCDs in suspended particulate matter (SPM) of three river systems (Godavari, Danube, and Rhine) in relation with precipitation, temperature, and source catchments. The dominant long-chain diol is the C32 1,15-diol followed by the C30 1,15-diol in all studied river systems. In regions influenced by marine waters, such as delta systems, the fractional abundance of the C30 1,15-diol is substantially higher than in the river itself, suggesting different LCD producers in marine and freshwater environments. A change in the LCD distribution along the downstream transects of the rivers studied was not observed. However, an effect of river flow is observed; i.e., the concentration of the C32 1,15-diol is higher in stagnant waters such as reservoirs and during seasons with river low stands. A seasonal change in the LCD distribution was observed in the Rhine, likely due to a change in the producers. Eukaryotic diversity analysis by 18S rRNA gene sequencing of SPM from the Rhine showed extremely low abundances of sequences (i.e., 〈0.32% of total reads) related to known algal LCD producers. Furthermore, incubation of the river water with 13C-labeled bicarbonate did not result in 13C incorporation into LCDs. This indicates that the LCDs present are mainly of fossil origin in the fast flowing part of the Rhine. Overall, our results suggest that the LCD producers in rivers predominantly reside in lakes or side ponds that are part of the river system.

Description: Samples were obtained during the Schmidt Ocean Institute cruise "Exploring Fronts With Multiple Robots" to the Pacific Ocean in 2018 (https://schmidtocean.org/cruise/exploring_fronts_with_multiple_aerial-surface-underwater-vehicles/). This expedition target the Subtropical Front, located approximately 1,000 nautical miles off the coast of Southern California. A SEABIRD SBE 9 PLUS CTD profiler with sensors for water temperature, salinity, oxygen, fluorescence and turbidity was used during this expedition. CTD profiles were taken within water depths between 300 m and 500 m. In total, 126 CTD casts at different stations were run. The achieved data have been converted using the software SBE Data Processing. Water samples for microplankton analysis were also collected in some of the CTD stations using a multi water sampler (rosette) from the research vessel "Falkor" and concentrated on board in a 0.2 um Sterivex filter. Results from 18S and 16S amplicon sequencing are public available in ENA-EMBL archive with the project accession number PRJEB32783.

Description: Methane is a very effective greenhouse gas, but the role of the Polar Regions in the methane budget and its sources there is subject to discussion. The sparse surface network data and satellite data indicate significant source regions above the polar oceans. The remotely piloted quadrocopter ALICE was developed for taking air samples to study methane isotopic composition related to different polar atmospheric boundary layer conditions above sea ice and open water (German Research Foundation, DFG, grant No. LA2907/8-1, DA 2907/5-1). Adapted to rough polar conditions the quadrocopter carries twelve 100 ml glass bottles for air sampling and sensors for air temperature, humidity, irradiation and surface temperature up to 1000 m above ground. The samples can be taken by opening the evacuated glass bottles at any point of the trajectory, at predefined positions or manually triggered by the operator. The quadrocopter is a tool to get vertical profiles of air samples easier than with other methods. The initially tested prototype was field operated for the first time during Polarstern cruise PS109 (ARK-XXXI/4) in September/October 2017. A scientific case study was done at rewetted peatland area at Zarnekow (Northeast Germany), by probing the atmosphere above this known methane source during the morning transition at one day in late spring 2018 and at one day in early autumn 2018 (Lampert et al., https://www.atmos-meas-tech-discuss.net/amt-2019-111/) The data set includes 5 flights of the initial operational field testing during the PS109 expedition and two days of surveying a rewetted peatland area at Zarnekow. In the PANGAEA data set, different parameters characterizing the measurement system, the meteorological conditions and the air sampling system are provided: Time of the measurements, coordinates and altitude of the quadrocopter based on global navigation satellite systems (GNSS) and barometric pressure, three-dimensional velocity of the quadrocopter, raw data of air temperature and humidity measured by several temperature and humidity sensors, surface temperature, upward and downward solar radiation, and the pressure inside the twelve glass bottles, to control at which altitude the sample was taken. For the Zarnekow data set, the methane isotopic composition of each sample is included, as well as the corresponding sampling altitude. Methane concentration and methane isotopic composition for additional water samples are provided in Lampert et al. (2019).