• European Marine Science
• 2018-2022close
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• Other ORP type close
• PANGAEA - Data Publisher for Earth and Environmental Science close

The presented daily mean sea ice draft time series are derived from bottom track mode measurements from multiple upward-looking Workhorse 300 kHz Sentinel Acoustic Doppler Current Profilers (ADCPs, manufactured by Teledyne RDI). ADCP moorings were deployed and recovered during multiple TRANSDRIFT expeditions to the Laptev Sea (2003 to 2016). A total of 13 data files, named to indicate the location of the deployment (station name) and the sampling period, provide values of daily mean sea ice draft (in m) and time. Sea ice draft is derived from ADCP bottom track data following Belter et al. (in review). An additional info file provides the coordinates of the stations, expedition specifics and serial numbers of the instruments.

In an enclosure experiment, we employed two levels of inorganic NP ratios (10 and 5) for three distinct plankton communities collected along the coast of central Chile (33ºS). Each combination of community and NP level was replicated three times. The experiment lasted 12 days, and the data set include inorganic nutrients (NO3, PO4, DSi), particular organic carbon (POC), nitrogen (PON) and phosphorus (POP), Chlorophyll a, a range of fluorescence based measurements such as photochemical efficiency (Fv/Fm) and community data. The primary effect of the NP treatment was related to different concentrations of NO3, which directly influenced the biomass of phytoplankton. Additionally, low inorganic NP ratio reduced the seston NP and Chl a-C ratios, and there were some effects on the plankton community composition, e.g. benefitting Synechococcus spp in some communities.

Atmospheric _p_CO~2~ is a critical component of the global carbon system and is considered to be the major control of Earth's past, present and future climate. Accurate and precise reconstructions of its concentration through geological time are, therefore, crucial to our understanding of the Earth system. Ice core records document _p_CO~2~ for the past 800 kyrs, but at no point during this interval were CO~2~ levels higher than today. Interpretation of older _p_CO~2~ has been hampered by discrepancies during some time intervals between two of the main ocean-based proxy methods used to reconstruct _p_CO~2~: the carbon isotope fractionation that occurs during photosynthesis as recorded by haptophyte biomarkers (alkenones) and the boron isotope composition (δ^11^B) of foraminifer shells. Here we present alkenone and δ^11^B-based _p_CO~2~ reconstructions generated from the same samples from the Plio-Pleistocene at ODP Site 999 across a glacial-interglacial cycle. We find a muted response to _p_CO~2~ in the alkenone record compared to contemporaneous ice core and δ^11^B records, suggesting caution in the interpretation of alkenone-based records at low _p_CO~2~ levels. This is possibly caused by the physiology of CO~2~ uptake in the haptophytes. Our new understanding resolves some of the inconsistencies between the proxies and highlights that caution may be required when interpreting alkenone-based reconstructions of _p_CO~2~.

Tropical peatlands are important for the global carbon cycle as they store 18% of the total global peat carbon. As they are vulnerable to changes in temperature and precipitation, a rapidly changing environment endangers peatlands and their carbon storage potential. Understanding the mechanisms of peatland carbon accumulation from studying past developments may, therefore, help to assess the future role of tropical peatlands. Using a multi-proxy palaeoecological approach, a peat core taken from the Sungai Buluh peatland in Central Sumatra has been analyzed for its pollen and spore, macro charcoal and biogeochemical composition. The result suggests that peat and C accumulation rates were driven mainly by sea level change, river water level, climatic variability and anthropogenic activities. It is also suggested that peat C accumulation in Sungai Buluh is correlated to the abundance of Freycinetia, Myrtaceae, Calophyllum, Stemonuraceae, Ficus and Euphorbiaceae. Sungai Buluh has reasonable potential for being a future global tropical peat C sinks. However, considering the impact of rapid global climate change in addition to land-use change following rapid economic growth in Indonesia, such potential may be lost. Taking advantage of available palaeoecological records and advances made in Quaternary studies, some considerations for management practice such as identification of priority taxa and conservation sites are suggested.

This dataset compiles in-situ temperature measurements for geothermal heat flow estimates and water temperature profiles of the water column, extracted from Miniaturized Temperature data-Logger (MTL). The data were collected during RV POLARSTERN cruise PS104 in 2017 in Amundsen Sea.

The geochemical measurements within the long-lived, crustose coralline red alga Clathromorphum compactum in calibration experiments, and the environmental conditions selected for the controlled laboratory aquaria.

During the 1967-1968 period chemical analysis of both major and trace elements was performed on manganese nodules, crusts and micronodules on a large number of cores taken by the Lamont-Doherty Observatory during various cruises of the R/V Vema and the R/V Robert D. Conrad. Methods of analysis were a combination of Wet chemistry and Atomic Absorption Analysis (AAS). Most of the samples are related to buried deposits inside sediment columns. This data was released to Dr. W. M. Ewing, the then Director of Lamont Geological Observatory who handed the results to S. K. Addy for his review and research work (see, related document: S. K. Addy, 1978). It was later included in the SIO Nodule Database and finally transferred into the NOAA-MMS database.

High-resolution 2D seismic reflection data during research cruise MSM63 in April/May 2017 onboard RV Maria S. Merian. The seismic profiles were acquired with a two-105/105-in3-GI-Gun-array shot at 210 bar every 5 seconds and a 150 m-long streamer with 96 channels and 1.5625 m channel spacing. The resulting shot point distance is approximately 8.75-12.5 m at 3.5-5 kn ship speed. The frequency range of the two-GI-Gun-array is 15-500 Hz. The processing included geometry and delay corrections, static corrections, binning to 1.5625 m and bandpass filtering with corner frequencies of 25, 45, 420, and 500 Hz. Furthermore, a normal-move-out-correction (with a constant velocity of 1488 m/s calculated from CTD measurements) was applied and the data were stacked and then migrated using a 2D Stolt algorithm (1500 m/s constant velocity model). Sub-bottom profiler data acquired during cruise MSM63 using Parasound P70 with 4 kHz as the secondary low frequency to obtain seismic images of the upper 100 m below the seafloor with very high vertical resolution (< 15 cm). We applied a frequency filter (low cut 2 kHz, high cut 6 kHz, 2 iterations) and calculated the envelope within the seismic interpretation software IHS Kingdom. Bathymetric data were acquired with the EM712 system mounted to the hull of RV Maria S. Merian. The survey was designed to provide high-resolution bathymetry with 5 x 5 m resolution. We processed the data using MB Systems software (Caress & Chayes, 2017) and included statistical evaluation of soundings that increased the signal-to-noise ratio. The sound velocity profile for multibeam processing was measured at the beginning and at the end of the cruise.

In permafrost areas, seasonal freeze-thaw cycles result in upward and downward movements of the ground. For some permafrost areas, long-term downward movements were reported during the last decade. We measured seasonal and multi-year ground movements in a yedoma region of the Lena River Delta, Siberia, in 2013–2017, using reference rods installed deep in the permafrost. The seasonal subsidence was 1.7 ± 1.5 cm in the cold summer of 2013 and 4.8 ± 2 cm in the warm summer of 2014. Furthermore, we measured a pronounced multi-year net subsidence of 9.3 ± 5.7 cm from spring 2013 to the end of summer 2017. Importantly, we observed a high spatial variability of subsidence of up to 6 cm across a sub-meter horizontal scale. In summer 2013, we accompanied our field measurements with Differential Synthetic Aperture Radar Interferometry (DInSAR) on repeat-pass TerraSAR-X (TSX) data from the summer of 2013 to detect summer thaw subsidence over the same study area. Interferometry was strongly affected by a fast phase coherence loss, atmospheric artifacts, and possibly the choice of reference point. A cumulative ground movement map, built from a continuous interferogram stack, did not reveal a subsidence on the upland but showed a distinct subsidence of up to 2 cm in most of the thermokarst basins. There, the spatial pattern of DInSAR-measured subsidence corresponded well with relative surface wetness identified with the near infra-red band of a high-resolution optical image. Our study suggests that (i) although X-band SAR has serious limitations for ground movement monitoring in permafrost landscapes, it can provide valuable information for specific environments like thermokarst basins, and (ii) due to the high sub-pixel spatial variability of ground movements, a validation scheme needs to be developed and implemented for future DInSAR studies in permafrost environments.

This dataset contains the results of a lab experiment performed in Ny Ålesund (Arctic, Svalbard, 78° 55′ N, 11° 56′ O) from 22.–29. August 2013. We collected early-stage thecosome pteropods (Limacina spp.) in Kongsfjord to investigate the response of their lipid metabolism (response variables: total lipids, lipid classes, fatty acids, fatty alcohols) to ocean warming and acidification (OWA). Pteropods were collected on August 21 with a 100 µm plankton net (0.2 square meter mouth opening, 1 L cod end) integrated from 300 m depth in Kongsfjord. The OWA experiment was designed to cover end-of the century projections for temperature and pCO2 and included two temperature treatments (3.5°C = mean in situ temperature averaged over the depth range where pteropods where collected from, and 5.5°C resembling a 2°C temperature increase projected for the Arctic Ocean in the upper 100-200 m, Steinacher et al. 2009, https://doi.org/10.5194/bg-6-515-2009) and three pCO2 levels chosen according to the RCP 8.5 scenario (present day = 400 µatm, year 2080 = 750 µatm, and >2100 = 1100 µatm). Temperature treatments were realized in temperature controlled rooms. pCO2 levels were established by bubbling filtered seawater (20 µm filtered) with Wösthoff gas mixing pumps (Wösthoff, Germany). For each treatment level six replicates (one vessel á 300 ml = one experimental unit = one replicate) were established with 200 incubated early-stage pteropods (ca. 300 µm shell length of individual pteropods). To assure that oxygen concentrations in the vessels did not fall below critical saturation levels of oxygen partial pressure for marine mollusks due to respiration of the incubated pteropods, the experimental seawater was changed regularly. Along with the analyzed lipid data, this dataset also includes the carbonate chemistry data of the perturbed experimental seawater and of that in the experimental units (start/end measurements as well as pH development in the experimental units).