ALBERT

Description: Marine sedimentary archives are routinely used to reconstruct past environmental changes. In many cases, bioturbation and sedimentary mixing affect the proxy time-series and the age-depth relationship. While idealized models of bioturbation exist, they usually assume homogeneous mixing, thus that a single sample is representative for the sediment layer it is sampled from. However, it is largely unknown to which extent this assumption holds for sediments used for paleoclimate reconstructions. To shed light on 1) the age-depth relationship and its full uncertainty, 2) the magnitude of mixing processes affecting the downcore proxy variations, and 3) the representativity of the discrete sample for the sediment layer, we designed and performed a case study on South China Sea sediment material which was collected using a box corer and which covers the last glacial cycle. Using the radiocarbon content of foraminiferal tests as a tracer of time, we characterize the spatial age-heterogeneity of sediments in a three-dimensional setup. In total, 118 radiocarbon measurements were performed on defined small- and large-volume bulk samples ( ∼ 200 specimens each) to investigate the horizontal heterogeneity of the sediment. Additionally, replicated measurements on small numbers of specimens (10 × 5 specimens) were performed to assess the heterogeneity within a sample volume. Visual assessment of X-ray images and a quantitative assessment of the mixing strength show typical mixing from bioturbation corresponding to around 10 cm mixing depth. Notably, our 3D radiocarbon distribution reveals that the horizontal heterogeneity (up to 1,250 years), contributing to the age uncertainty, is several times larger than the typically assumed radiocarbon based age-model error (single errors up to 250 years). Furthermore, the assumption of a perfectly bioturbated layer with no mixing underneath is not met. Our analysis further demonstrates that the age-heterogeneity might be a function of sample size; smaller samples might contain single features from the incomplete mixing and are thus less representative than larger samples. We provide suggestions for future studies, optimal sampling strategies for quantitative paleoclimate reconstructions and realistic uncertainty in age models, as well as discuss possible implications for the interpretation of paleoclimate records.

Description: This is a compilation of all short-wave and long-wave radiation datasets from Budapest that were and are published in the frame of BSRN. New data will be added regularly. The data are subject to the data release guidelines of BSRN (https://bsrn.awi.de/data/conditions-of-data-release/).

Description: Raw data acquired by GPS1 position sensors on board research aircraft Polar 5 during the campaign P6_231_HALO_P6_2022 were processed to receive a validated master track which can be used as reference of further expedition data. Novatel FlexPak6 GPS receiver was used as navigation sensors during the campaign. Data were downloaded from DAVIS SHIP data base (https://dship.awi.de) with a resolution of 1 sec. Processed data are provided as a master track with 1 sec resolution and a generalized track with a reduced set of the most significant positions of the master track. A detailed report on processing is also available for each flight.

Description: 499 emerging chemicals (ECs) were investigated in 56 effluent samples from 52 European wastewater treatment plants (WWTPs). The samples were collected between August 2017 and April 2019, using on-site large volume solid phase extraction (LVSPE) (Schulze et al., 2017). Chemical target screening by liquid chromatography high-resolution mass spectrometry (LC-HRMS) resulted in 366 detected compounds. Different capacities and conventional treatment technologies, as well as two advanced treatment technologies are included. One sample was taken at a WWTP with activated carbon (AC) treatment. Three WWTPs applying ozonation were sampled before and after this treatment step, providing two samples each. One of these WWTPs had already been sampled before the upgrade, resulting in a total of 56 (52+4) samples. More information can be found in Finckh et al. (2022). The two main objectives were (1) to extend our knowledge on chemicals occurring in treated wastewater, and (2) to identify and prioritize compounds of concern based on three different risk assessment approaches for the identification of consensus mixture risk drivers of concern.

Description: The Landscape Fire Scars Database for Chile makes publicly available for the first time a historical high-resolution (~30 m) burned area and fire severity product for the country. The georeferenced database is a multi-institutional effort containing information on more than 8,000 fires events between July 1984 and June 2018. Using Google Earth Engine (GEE), we reconstructed the fire scar area, perimeter, and severity for each fire. We also provide the Landsat mosaic image of pre- and post-fire events, including the NDVI and NBR indexes. In the related paper, we release the GEE code to reproduce our database or enable the international community to reconstruct another individual burned areas and fire severity data, with minimum input requirements. In the summary file is the list of reconstructed fire events. The identification number (ID) relates the initial information of the wildfires with fire scar and severity data.

Description: The inter-reef Halimeda bioherms of the northern Great Barrier Reef (GBR) have accumulated up to 25 m of positive relief throughout the Holocene. Covering 〉 6000 km2, the Halimeda bioherms represent a significant contribution to the development of the northeast Australian continental shelf geomorphology, neritic carbonate factory, and sedimentary archive of post-glacial environmental changes. Previously, the chronological record of initiation and development of the Halimeda bioherm carbonate factory was poorly constrained and based on very few age data points. A comprehensive new age dataset is presented, comprising sixty-three AMS radiocarbon measurements of Halimeda and foraminifera grains, mollusc shells and bulk soil from twelve inter-reef sediment cores, and ten previously published Halimeda ages that are newly calibrated. Radiocarbon measurements were undertaken at the ANSTO Centre for Accelerator Science in 2018, 2019 and 2020 from cores collected by the Bureau of Mineral Resources in 1983. Halimeda growth had established by 11,143 +237/-277 cal. yr BP, just ~450 years after the marine transgression commenced and approximately 1000 years earlier than previous inferred estimates. The outer-shelf carbonate factory was initially dominated by benthic foraminifera, then Halimeda was productive for at least 2100 years prior to the turn-on of Holocene coral reefs in the study area. Inter-reef Halimeda bioherm sediments including foraminiferal communities, might record a 〉10,000-year near-continuous geochemical record of northeast Australian Holocene oceanographic and climatic changes, potentially filling spatial and temporal gaps not covered by coral and other marine sediment proxies.

Description: This data set comprises radiogenic neodymium (Nd) isotope signatures of past deep water masses and detrital matter in the Early Cretaceous (Barremian-Albian) South Atlantic Ocean and Southern Ocean, recorded at Deep Sea Drilling Project (DSDP) Sites 249, 327, 361, and 511 and Ocean Drilling Project (ODP) Site 693. Deep water Nd isotope compositions were leached from authigenic ferromanganese coatings of bulk sediment particles. Detrital Nd isotope signatures were obtained from residues of the sediment leaching procedures after dissolution via alkaline fusion. Age estimates for individual samples were calculated based on biostratigraphic and carbon isotope stratigraphic age constraints and calibrated to the time GTS2012 time scale of Gradstein et al. (2012).

Description: This data set presents the results of an automated cluster analysis using Gaussian mixture models of the entire Atlantic seafloor environment. The analysis was based on eight global datasets and their derivatives: Bathymetry, slope, terrain ruggedness index, topographic position index, sediment thickness, POC flux, salinity, dissolved oxygen, temperature, current velocity, and phytoplankton abundance in surface waters along with seasonal variabilities (see Source data set). We obtained nine seabed areas (SBAs) that portray the Atlantic seafloor that are shown as polygons in the data set. The attribute table holds short descriptions of each SBA as well as about the colours used in the accompanying paper publication. Data sets like this can be used for further analysis like e.g. for landscape ecology metrics to identify regions of interest. The compressed file further contains a style file that can be used to directly load the correct style in the QGIS software package.