ALBERT

Description: High-resolution multi-proxy records from two lakes on the southern Tibetan Plateau, Nam Co and Tangra Yumco, are used to infer long-term variations in the Asian monsoon system. We examine the moisture evolution during the Late Glacial Maximum and Holocene using the trace element and stable isotope composition of ostracod shells. The sediment records covering the past 24 cal. ka BP and 18 cal. ka BP, respectively, demonstrate the suitability of ostracod shell chemistry as paleoenvironmental proxy. We analysed (i) Mg/Ca, Ba/Ca and Sr/Ca ratios as salinity proxies, (ii) Fe/Ca, Mn/Ca and U/Ca ratios representing redox conditions and microbial activity, and (iii) rare earth elements (REEs) reflecting weathering and changes in provenance.

Description: iButton (24) loggers measuring soil temperature were deployed in the Kaldoaivi Wilderness Area in August/September 2016 and retrieved in August 2018. They were installed in a very shallow depth in different locations, covering a wide range of landscape types, exposure and suspected snow conditions. Sensors were deployed approximately 3-5cm below the surface to avoid direct influence by the sun. Near surface soil moisture measurements were taken during late August/early September of 2016, 2017 and 2019 at the locations of the deployed iButtons. Snow depth and snow water equivalent measurements were taken during March 2018 at or near most measurement points. The field work and research was supported by the Austrian Science Fund (Fonds zur Förderung der wissenschaftlichen Forschung, FWF) through the Doctoral College GIScience (DK W1237-N23).

Description: Previous studies suggest that, during the late Pleistocene ice ages, surface-deep exchange was somehow weakened in the Southern Ocean's Antarctic Zone (AZ), reducing the leakage of deeply sequestered CO2 and thus contributing to the lower atmospheric CO2 levels of the ice ages. To better understand the surface nutrient consumption in the Antarctic ocean during glacial intervals and its implication on atmospheric CO2 changes, we measured diatom-bound nitrogen isotopes (d15N_db) extending back to 150 thousand years ago (150ka) in two sediment cores in the Indian sector of the AZ. The data series include d15N_db, TEX86L-based SST, d18O of planktonic foraminifera Neogloboquadrina pachyderma (sin.), sediment Ba/Fe and the age model of MD12-3394 (48°23' S, 64°35' E, 2320m water depth), d15N_db and updated age model of MD11-3353 (50°34' S, 68°23' E, 1568m water depth), as well as the mean d15N_db of the two sediment cores, and the d15N_db offset calculated using the mean d15N_db and MD12-3394 d15N_db alone. The age model for MD12-3394 was based on 7 Holocene radiocarbon dates measured with planktonic foraminifera Neogloboquadrina pachyderma (sin.) and Globigerina bulloides hand-picked from the 〉 63µm fraction, and correlation of reconstructed SST by TEX86L to the Antarctic temperature stack (ATS) (adjusted to AICC2012 age scale) compiled from ice core data. Ages were linearly interpolated between the stratigraphic tie points. The age model of MD11-3353 is based on the age model published in Thöle et al. (2019), with modifications of the youngest age tie point and the tie point at Marine Isotope Stage (MIS) 5-6 transition, and two additional tie points during MIS 3 based on correlation of d15N_db to MD12-3394 d15N_db. Monte Carlo simulation and Kalman filter were combined to generate a mean d15N_db time series for the two sediment cores on a 500-year time grid, following the method in Wang et al. (2017). For the d15N_db offset, a linear fit was first applied to glacial (20-27 ka,140-155 ka) and interglacial (0-10 ka, 115-126 ka) extreme values of d15N_db (or calculated mean d15N_db) and ATS. Using this linear regression, we calculated the ATS-predicted d15N_db. The d15N_db offset was obtained by subtracting the ATS-predicted d15N_db from measured d15N_db (or calculated mean d15N_db).

Description: By means of a multiproxy data set combining biomarker (alkenones, n-alkanes), microfossil (diatoms) and sedimentological (ice rafted debris, XRF) data obtained from sediments from IODP Site U1417 in the Gulf of Alaska, we elucidate the paleoenvironmental setting in this area during the Mid Pleistocene Transition. The data point to a stimulation of the marine primary productivity through the input of nutrients (e.g. iron) via aeolian dust and icebergs. These fertilization pulses were likely triggered by the dynamic behaviour of the Cordilleran Ice Sheet during the Pleistocene.

Description: Dataset 1 shows the dissolved iron (dFe) values of an iron release experiment performed in the Southern Ocean at the tip of the Western Antarctic Peninsula. Krill and salp fecal pellets (FP) were incubated in filtered seawater (FSW) and seawater with phytoplankton (SWP). After 48 hours of incubation the dFe concentrations were measured. Numbers marked in red have been recognized as outliers (due to contamination or analytic error) and have been excluded from statistical analysis. Dataset 2 shows the uptake of iron into Southern Ocean phytoplankton cells from the pre-incubated water. The uptake was measured using the radiotracer 55Fe into two size classes of plankton (0.2-2µm and 〉2µm). Total dFe uptake is the sum of the two size classes. Lines marked in orange have been excluded from statistical analysis because respective dissolved iron concentrations were not reliable. The data for both datasets was collected between 04/11/2018 and 04/14/2018 (campaign PS112) at the Western Antarctic Peninsula (60° 44.455 S 54° 30.477 W) from a depth of 25 m. The data was collected in order to compare the bioavailability of iron from salp and krill FP to a Southern Ocean plankton community. All sampling steps were performed in trace metal clean ways.

Description: During expedition SCAN 2013, two gravity cores were collected in the Ona High slope, central Ona Basin, NE prolongation of the Antarctic Peninsula. Core TG-01 is 400 cm long and was collected from 2160 m water depth at 60º22'23.9314''S, 53º02'15.2501''W; core TG-03 is 295 cm long and was obtained from 2789 m water depth at 60º11'23.4003''S, 53º10'49.0810''W. Non-destructive analyses (i.e., physical properties measurements and X-ray fluorescence scanning) were performed on the archive halves. Both, physical properties (magnetic susceptibility, gamma-ray density, electrical resistivity and P-wave velocity) and major element compositions were determined at 1-cm resolution on split core surfaces of the archive halves using a GEOTEK Multi-Sensor Core Logger (MSCL) 81 at the Spanish Geological Survey (IGME, Spain).

Description: In laboratory culture experiments, calcified and decalcified coccolithophore cells were offered as prey to a phagotrophic predator, both in separate pure cultures with calcified or decalcified cells only, and in mixed cultures that contained both cell types. Overall, three experiments were conducted, each with a different coccolithophore species. The prey and predator concentrations were monitored over the course of each experiment by flow cytometry and microscopic counting.

Description: Carbon and hydrogen isotope values with molecular distributions of normal-alkanes (n-alkanes), carbon and nitrogen isotope values of bulk leaf material, as well as xylem water hydrogen and oxygen isotope values are presented from five co-occurring tree species. Species were collected during the 2006-growing season from a climate transect along the East Coast of the United States where high-resolution temperature, precipitation, and humidity data were available. Efforts focused on Acer rubrum, Platanus occidentalis, Juniperus virginiana, Pinus taeda, and Pinus strobus. In addition, meteoric water samples were collected from rivers, streams, and other bodies of water along the transect. Leaf wax n-alkanes were extracted, isolated, identified, and quantified following Tipple and Pagani, 2013 (Geochimica et Cosmochimica Acta, 111, 64-77). The average chain length of n-alkanes, carbon preference index, among other indices were calculated. The carbon and hydrogen isotope values of leaf wax n-alkanes were conducted following Tipple et al., 2018 (Oecologia, 187, 1053-1075) and Tipple and Pagani, 2013, respectively. The carbon and nitrogen isotope values of bulk leaf materials were measured according to Tipple et al., 2018. Xylem waters were extracted from woody stems and both the hydrogen and oxygen isotope values of xylem and meteoric waters were measured following Tipple and Pagani, 2013. The purpose of this study was to compare leaf wax distributions and isotope values along a climate transect to better understand the environmental factors and species' effects responsible for the carbon and hydrogen isotopic compositions of terrestrial plant materials, as well as the factors that influence n-alkane chain length. This study focused on species that inhabit the same environments and co-occur along a climate transect. This design allowed for interspecies and intraspecies variation to be explored. Site selections for this study allowed for an assessment of the importance of precipitation and temperature, while limiting the effects of humidity and elevation.

Description: Aircraft measurements of profiles in the katabatic wind during the experiment KABEG (Katabatic wind and boundary-layer front experiment around Greenland) in April and May 1997. The aircraft used was the research aircraft POLAR2 (Dornier 228) owned by the Alfred Wegener Institute (Bremerhaven, Germany). The vertical profiles were flown as slantwise aircraft profiles (ascents or descents). The data represent averages of consecutive vertical profiles representing a horizontal scale of about 15km for three locations in relatively homogeneous terrain in west and southeast Greenland. The vertical resolution is 10 m for the lowest 200m and 20m between 200 and 340m. A total of 14 profiles of potential temperature, specific humidity, wind speed and direction are included in the data set.

Description: The year 2020 marks the 200th anniversary of European settlers first encountering the 'noble expanse of water' of Lake George in New South Wales. Since 1820, unofficial observations and official measurements of the lake's water level have been recorded almost continuously by various individuals, research teams, government departments and private companies. The lake's recent hydrographic history has been characterised by periods of flood and drought, which correspond with the prevailing rainfall conditions of SE Australia. This is the longest water level record of its sort in the Southern Hemisphere and hence of great scientific and historic value. Here, we have compiled all available historic water level data for Lake George, referenced them to common datums and presented a methodology for continuing the record using satellite imagery in lieu of on-site measurements.