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Autotrophic community composition based on chlorophyll-a concentrations in lakes and streams in South Greenland in August 2022
No full textThis dataset contains measurements of physico-chemical parameters, biofilm, and watershed characteristics from subarctic lakes and streams in the Narsaq area, Greenland, collected in August 2022. Water samples were collected and analyzed for temperature, conductivity, alkalinity, and nutrient concentrations. Biofilm samples were collected from stones, with chlorophyll a (Chl a), ash-free dry weight (AFDW), and carbon-to-nitrogen (C:N) ratios measured. Algal pigments were analyzed using HPLC for taxonomic composition. Watershed delineation was performed using a digital elevation model (DEM), and vegetation greenness was quantified via the normalized difference vegetation index (NDVI) using Sentinel-2 satellite imagery. This dataset contributes to understanding the environmental drivers of biofilm biomass and community composition in Arctic freshwater ecosystems
Mineralogical characterisation from XRD analysis of sediments and soils in the catchment of Lashmars Lagoon, Kangaroo Island (Karti/Karta), southern Australia
No full textThese data comprise XRD mineralogical analysis of twelve soil and sediment samples from the catchment surrounding Lashmars Lagoon, Kangaroo Island (Karti/Karta), southern Australia. To assess possible changes of sediment sources to Lashmars Lagoon over the past 7 kyr that could impact the interpretation of the palaeoenvironmental history of the site, these data were compared to the downcore XRD data from the composite lake sediment core (see 'Chronology, µXRF, XRD and bulk organic geochemistry from a lake sediment core from Lashmars Lagoon, Kangaroo Island (Karti), southern Australia, for the last 7 kyr'). The catchment soil and sediment samples were collected during field campaigns in November and December 2021. Soil samples were taken of the different surrounding surface geologies and sediment samples were taken from the creek inflows and one outflow to the lake, as well as a mudline sample from the northern basin of the lake. Mineralogy was determined by semi-quantitative XRD analysis using a Bruker D8 ADVANCE Powder X-ray Diffractometer with a Cu-radiation source operating at 40 KV and 40 amps, scanning 2 theta from 5 to 65 degrees with sample rotation of 30 rotations per minute. Data were interpreted using the software package DIFFRAC.EVA (Bruker, Karlsruhe, Germany) and Crystallography Open Database (www.crystallography.net/cod/) reference patterns for identifying mineral phases. Semi-quantitative estimates of mineral composition were obtained by Rietveld modelling using the program DIFFRAC.TOPAS 4.2 (Bruker, Karlsruhe, Germany)
A new helium isotope recored of the Paleocene-Eocene Thermal Maximum from ODP Site 198-1209 (S2)
No full textThe Paleocene-Eocene Thermal Maximum (PETM; around 56 Ma ago) is arguably the most intensively studied event of rapid greenhouse warming of the geological past. The duration and age of the PETM, however, remains vividly debated, limiting our understanding of the response of the Earth System dynamics to rapid warming. Here we present new extraterrestrial helium 3 (3HeET) data across the PETM at ODP Site 198-1209 (N Pacific) that document a drop in 3HeET fluxes from 0.56 ± 0.02 pcm³/cm²/ka ~1 Ma prior to the PETM to values of 0.37 ± 0.02 pcm³/cm²/ka before and after the PETM. Our 3HeET-based chronology, optimized through spectral analysis and orbital tuning, indicates a duration of 160±10 ka for the PETM body/core, consistent with previous 3HeET estimates from ODP Site 208-1266 (Walvis Ridge). The PETM started at the onset of a 100 ka eccentricity maxima at 56080 ka BP and ended abruptly during a marked decline in eccentricity at 55883 ka, providing strong support for an orbital trigger of both its onset and termination. The reevaluation of the 3HeET age models of the high paleo-latitude ODP Site 113-690 shows that the prominent sedimentary and carbon isotope steps at this site were controlled by obliquity instead of precession. Our revised chronology suggests that obliquity was also the dominant driver of the repeated drops to lower δ13C values during the PETM in otherwise precession-dominated low latitude sites, possibly reflecting the repeated destabilization of methane hydrate or permafrost carbon stocks at high latitudes.
This dataset contains the grayscale reflectance logs obtained on core photographs for ODP Site 198-1209A, B and C, new records of helium isotope and non-carbonate fraction data for ODP Site 198-1209 and the reconstructed apparent 3HeET fluxes (FET), instantaneous sedimentation rates (ISR) and ages. We also report new bulk carbonate carbon and oxygen stable isotope data for ODP Site 198-1209 that are included in a compilation of published bulk carbonate data from the same site along with their corresponding 3HeET ages. We include a compilation of published benthic foraminifera carbon and oxygen stable isotope data for ODP Site 198-1209 with their corresponding 3HeET ages. We also report a compilation of Fe and Ca concentrations, stable isotope data measured on bulk sediment, planktonic and benthic foraminifera from ODP Site 113-690 that are reported against a revised 3HeET-based age model we developed for this site using published 3HeET data and a revised 3HeET flux of 0.42 ± 0.02 pcm³/cm²/ka and an age of 55916 ka BP for point F (169.05 mbsf)
Chironomid determination of sediment core from Lake Prata (São Miguel, Azores, Portugal)
No full textThe location of the Azores Archipelago makes this group of islands an excellent setting for investigating past long-term temperature and precipitation changes in the central North Atlantic region. Lake Prata (37º48'23''N, 25°44'12''W; 520 m a.s.l.) is found on the island of São Miguel, more precisely in the western sector of the Picos fissure system, 5 km SE of the Sete Cidades caldera, and it fills the crater of a scoria cone older than 5000 years. The lake is currently a Sphagnum/Eleocaris-dominated peatland. In January 2021, a 4.5-m long core was collected from Lake Prata using a Russian corer with a 50 cm long and 7 cm diameter sampler. The core was packed in PVC trays and covered in plastic film before being transported to the CIBIO's paleolimnology laboratory (University of Azores). The core was dated using ¹⁴C and produced a multi-proxy dataset of geochemical and biological analyses that we used to uncover paleoenvironmental changes on Lake Prata in the last ca. 1200 years
Sea-floor videos (benthos) along ROV profile PS111_063-2 during POLARSTERN cruise PS111, links to videos
No full textImproved Estimates of Monthly Land Surface Temperature from MODIS using a Diurnal Temperature Cycle (DTC) Model
No full textThe data associated with the experiment to construct monthly Land Surface Temperature(LST) using a diurnal temperature cycle (Duan et al 2013, 2014, Göttsche and Olesen 2001) from MODIS observations at the 32 sites of flux towers over relatively homogenous sites globally. The methodology is summarized in the manuscript under review.
The data include three files of monthly LST estimates in Celsius Degree over the land and coordinates are included in each file
Benthic stable carbon and oxygen isotopes of Cibicidoides wuellerstorfi from ODP Hole 130-806B 0-4 m.y
No full textODP Leg 130 - Site 806B benthic stable carbon and oxygen isotopes have been measured using the epibenthic foraminifer species Cibicidoides wuellerstorfi in cores cores 1H to 11H of Hole B, only. Stratigraphy is based on correlation to the benthic oxygen isotope stack of Lisiecki and Raymo 2005 (Paleoceanography vol 20, PA1003, doi:10.1029/2004PA001071)
The impacts of grassland restoration and drought on biodiversity metrics in a coastal prairie in Santa Cruz, CA, USA in 2019 and 2021
No full textThis data provides support for a research project assessing the impacts of restoration and drought on taxonomic, functional and phylogenetic diversity. Restoration seeks to recover damaged habitats through improving taxonomic diversity but does not often consider functional or phylogenetic diversity. Integrated approaches with taxonomic, functional, and phylogenetic diversity can improve our mechanistic understanding of restoration outcomes. Projected droughts may lead to shifts in functional diversity that will influence species coexistence. I utilized a drought design (excluding 60% of rainfall) that was experimentally restored in a California coastal grassland and measured plant community composition four- and six-years post-treatments. I collected leaf traits to determine shifts in community weighted trait means (CWT) and functional diversity metrics (richness, evenness, dispersion). To assess phylogenetic relationships, I calculated nearest taxon distance, phylogenetic distance at the 10th quantile (PD10) and mean phylogenetic distance. Restoration increased taxonomic diversity, functional richness and functional dispersion but decreased phylogenetic diversity at large (MPD) and small (PD10) evolutionary scales. Restored communities had lower CWT for absolute and specific leaf area. Drought intensified environmental filtering by selecting for plants with key drought management strategies (via CWT shifts) resulting in lower functional evenness. Grassland restoration was effective in improving native cover and richness six years later with minimal maintenance indicating that restoration outcomes may be resistant to the impacts of drought in coastal California. This could be caused by increased niche complementarity as indicated via higher functional dispersion and richness
Biodiversity metrics during experimental drought and restoration in a coastal prairie in Santa Cruz, CA, USA in 2019 and 2021
No full textVarious biodiversity metrics of restored, unrestored, droughted and ambient rainfall plots derived from plant community data in 2021 and trait data from 2019. Different facets of metrics include: taxonomic, functional and phylogenetic, that is, the average relative total native cover in a plot determined from an average of six 0.25 m² quadrats; the total number of unique native plant species in a plot (richness); the total number of unique plant taxa in a plot (alpha); the nearest taxon distance, i.e. the abundance weighted phylogenetic distance at the 0th quantile; the abundance weighted phylogenetic distance at the 10th quantile; the mean phylogenetic distance; i.e. the abundance weighted phylogenetic distance at the 50th quantile; functional richness, a measure of the total trait space occupied; functional evenness, a measure of the relative distribution of traits in an occupied trait space; functional divergence, a measure of the relative divergence of traits in an occupied trait space, and functional dispersion, a measure of the relative disperion of traits in an occupied trait space determined through relative abundances and dominance
Foraminiferal stable carbon isotope and trace element ratios at IODP Site 383-U1540 during Marine Isotope Stage 11
No full textThis dataset presents foraminiferal stable carbon isotope (δ¹³C) and trace element data from sediment samples of International Ocean Discovery Program Site U1540 (55° 8.47ʹ S, 114° 50.52ʹ W, 3580 m), located in the central South Pacific Ocean. The records cover the timespan between Marine Isotope Stage 11 and 10 (~420-360 ka before present). Foraminiferal δ¹³C was measured on the epibenthic foraminifera Cibicidoides wuellerstorfi and Cibicides kullenbergi and on the planktic foraminifera Globigerina bulloides. The trace element ratios were measured on Cibicides kullenbergi. This dataset provides insights into sub-millennial carbon cycle dynamics in the central South Pacific Ocean during the climatic optimum of Marine Isotope Stage 11 and the following glacial inception