ALBERT

Description: In this work we used controlled microcosms to study the effect of temperature and pH on brGDGTs in lake water. We collected surface water from Kennedy Lake, Tucson, AZ, a shallow eutrophic artificial reservoir previously described by Martínez-Sosa & Tierney (2019). From the collected samples we set up a series of microcosms, consisting of 1L glass flasks filled with lake water, and manipulated single environmental factors including temperature and pH. For our temperature incubations, we selected four conditions (9C, 18C, 27C and 35C) and incubated 3 1L flasks under each condition for two periods of time (4 or 6 weeks). For the pH incubations, we used commercially available freshwater aquarium non-phosphate buffers (Proprietary composition, Seachem, Madison, GA, USA) to manipulate the pH of the microcosms. For these experiments we targeted four pH conditions (4, 5, 6 and 7), and included two control samples: one where we added enough buffer to maintain the initial pH (Control + Buffer), and another to which we added no buffer (Control - Buffer). GDGTs were analyzed on an Agilent 1260 Infinity HPLC coupled to an Agilent 6120 single quadrupole mass spectrometer using two BEH HILIC silica columns (2.1 x 150 mm, 1.7 um; Waters) and the methodology of Hopmans et al. (2016). We calculated peak areas using the MATLAB package software ORIGAmI (Fleming et al. 2016) and estimated the concentration of brGDGTs by comparing the obtained peaks with a C46 internal standard (Huguet et al. 2006) normalized to the volume of each sample.

Description: Instrumental data suggest that major shifts in tropical Pacific atmospheric dynamics and hydrology have occurred within the past century, potentially in response to anthropogenic warming. To better understand these trends, we use the hydrogen isotopic ratios of terrestrial higher plant leaf waxes (DDwax) in marine sediments from southwest Sulawesi, Indonesia, to compile a detailed reconstruction of central Indo-Pacific Warm Pool (IPWP) hydrologic variability spanning most of the last two millennia. Our paleodata are highly correlated with a monsoon reconstruction from Southeast Asia, indicating that intervals of strong East Asian summer monsoon (EASM) activity are associated with a weaker Indonesian monsoon (IM). Furthermore, the centennial-scale oscillations in our data follow known changes in Northern Hemisphere climate (e.g., the Little Ice Age and Medieval Warm Period) implying a dynamic link between Northern Hemisphere temperatures and IPWP hydrology. The inverse relationship between the EASM and IM suggests that migrations of the Intertropical Convergence Zone and associated changes in monsoon strength caused synoptic hydrologic shifts in the IPWP throughout most of the past two millennia.

Description: Soil profiles were collected along a transect across the Serengeti ecosystem, in Tanzania from 2-3S and 34-35.5E, 1153 to 1677 m above sea level and 0 to 1.6 m soil depth. The samples are modern soils and the temporal span of the soil depth profiles is unconstrained, likely centuries to millennia. The survey is intended to observe soil microbial lipid biomarkers that are commonly used as proxies for temperature and pH and to assess their robustness in alkaline carbonate-precipitating soil profiles, where soil carbonate proxies can also be applied. These modern calibrations can inform reconstructions of Eastern African paleoenvironments using the same proxies in geological archives. Lipid extractions and purifications were performed at USC in 2018-2019 and abundances of branched and isoprenoidal glycerol dialkyl glycerol tetraethers were obtained by high pressure liquid chromatography mass spectrometry, performed in 2020-2021 at the University of Arizona. Contextual data include total dissolved solids and pH measurements at the University of Houston in 2020-2021. For more information, please consult associated manuscript on the GDGTs within these soil profiles: Peaple et al., (2022) Identifying the drivers of GDGT distributions in alkaline soil profiles within the Serengeti ecosystem, Organic Geochemistry, in review. A publication on the bulk organics and compound specific carbon isotopic composition of plant waxes in the same soils: Zhang, et al. (2021) Carbon isotopic composition of plant waxes, bulk organics and carbonates from soils of the Serengeti grasslands, Geochimica et Cosmochimica Acta, 311, 316-331, doi:10.1016/j.gca.2021.07.005. That study includes stable hydrogen isotopic data on plant wax, available from doi:10.1594/PANGAEA.921002. A publication on multiple oxygen isotopes within carbonates in the same soil profiles can be found at: Beverly, E.J., Levin, N.E., Passey, B.H., Aron, P.G., Yarian, D.A., Page, M. and Pelletier, E.M. (2021) Triple oxygen and clumped isotopes in modern soil carbonate along an aridity gradient in the Serengeti, Tanzania. Earth and Planetary Science Letters, 567, 116952, doi:10.1016/j.epsl.2021.116952. That study includes stable carbon isotopic data on soil carbonates, available from doi:10.5281/zenodo.4919027.

Description: This dataset contains a modern core top collection of Mg/Ca in planktic foraminifera; the same dataset averaged to 1 x 1 grids; a collection of Mg/Ca in culture experiments with planktic foraminifera; a collection of Mg/Ca and Mg/Ca of seawater in culture experiments with planktic and benthic foraminifera; and a collection of geological estimates of the Mg/Ca of seawater.

Description: The stable hydrogen isotopes of C30-Alkanoic acids were measured from marine sediment core MD98-2152, collected off the southern coast of Sumatra, likely reflecting rainfall over southern Sumatra and western Java. The record extends to ~450,000 years before present and includes the five most recent glacial periods. To purify the leaf wax fatty acids for analysis, organic material was extracted from the sediment using an Accelerated Solvent Extractor, leaf waxes were isolated from each total lipid extract using column chromatography then methylated with methanol of a known isotopic composition to form fatty acid methyl esters, and purified with a final column. Hydrogen isotopes were measured using a gas chromatography-isotope ratio-monitoring mass spectrometer against Vienna Standard Mean Ocean Water (VSMOW). The hydrogen isotopes of the leaf wax fatty acids were then used in tandem with previously measured carbon isotopes of the same samples to calculate the hydrogen isotope values of precipitation, accounting for vegetation changes, through time following the methods in Tierney et al. (2017). This data was collected with the purpose of examining rainfall variability in the southern Indo-Pacific Warm Pool during glacial climates and to improve the spatial coverage of precipitation isotope records in the region. The age model and leaf wax carbon isotopes for MD98-2152 are available in Windler et al. (2019).

Description: This dataset presents measurements of individual foraminiferal analyses (IFA) of stable oxygen and carbon isotopes in tests of planktic foraminifera Globigerinoides ruber, obtained from a series of four eastern tropical Indian Ocean sediment cores. The IFA dataset focuses on two time periods: the Late Holocene (0-2 ka) and the Last Glacial Maximum (19-21 ka).