ALBERT

Description: Albedo – the reflectivity of a surface - is an important component in the energy budget, impacting the local to global climate. Data from nadir-viewing satellites can be combined with bidirectional reflectance distribution function (BRDF) data from multi-angular observation platforms to achieve realistic albedo values that acknowledge anisotropy. In my thesis, I evaluated how the land surface albedo varied on spatial and temporal scales during the snow-free period on Disko Island, Greenland. I examined how the albedo differed among the vegetation classes. Concerning the methodology, I assessed how the combination of MODIS BRDF data with Landsat 8 (L8) or Sentinel-2 (S2) influenced the albedo. The study area was located at the southern tip of Disko Island (69.27 °N, -53.47 °E) in West Greenland and covered a wetland and a range of tundra vegetation. I analysed automatic weather station (AWS) data from 2013 to 2022 and conducted mobile albedo measurements in August and September 2022 to examine the temporal and spatial variability. For the period from June to September 2022, I derived the L8 and S2 based albedo with inclusion of MODIS BRDF and narrow to broadband conversion and analysed their variability with regard to vegetation classes. In the snow-free period, the albedo increased from a monthly mean of 0.16 in June to 0.19 in September in the AWS data. The mobile measurements ranged from 〈 0.10 above bare soil and water to 〉 0.23 above areas dominated by lichen, Salix glauca or Equisetum arvense. The satellite-based albedo revealed temporally variable, significant correlations to normalised difference vegetation and moisture indices that reached values 〉 0.5 in the fen and wet heath class on several days. The albedo of shrubs was not notably smaller than other vegetation types but partly 0.01-0.05 above them in both the mobile measurements and the satellite-derived albedo. This finding challenges the assumption that shrubification causes climate forcing in all circumstances. The albedo of L8 and S2 differed to each other and the local data (root-mean-square error 0.04-0.14). The BRDF correction increased the albedo by 0.01 on average compared to nadir reflectance. L8 was better in reproducing the expected temporal and spatial variability of albedo than S2, which displayed less variability. S2 seemed to be more sensitive to atmospheric effects of haze and clouds influencing albedo. Thus, L8 seemed more suitable to calculate albedo in the study area. Though there were some methodological limitations, this thesis highlights aspects that should be considered when analysing albedo or jointly using L8 and S2 in high latitude regions.

Description: The origin, transport pathway, and spatial variability of total organic carbon (OC) in the western Himalayan glaciers are poorly understood compared to those of black carbon (BC) and dust, but it is critically important to evaluate the climatic role of OC in the region. By applying the distribution of OC activation energy; 14C activity; and radiogenic isotopes of 208Pb/204Pb, 207Pb/204Pb, and 206Pb/204Pb in glacial debris and atmospheric particulate matter (PM10 size fraction), we demonstrate that 98.3 ± 1.6 and 1.7 ± 1.6% of OC in western Himalayan glaciers are derived from biomass and petrogenic sources, respectively. The δ13C and N/C composition indicates that the biomass is a complex mixture of C3 vegetation and autochthonous photoautotrophic input modified by heterotrophic microbial activity. The data set reveals that the studied western Himalayan glacier has negligible contributions from fossil-fuel-derived particles, which contrasts to the central and eastern Himalayan glaciers that have significant contributions from fossil fuel sources. We show that this spatial variability of OC sources relates to regional differences in air mass transport pathways and precipitation regimes over the Himalaya. Moreover, our observation suggests that biomass-derived carbon could be the only primary driver of carbon-induced glacier melting in the western Himalaya.

Description: Fluoride contamination in groundwater is a worldwide phenomenon. Excess fluoride in drinking water causes serious health risks, and as a result, fluoride contamination of water resources is a global concern. In this study, an attempt has been made to provide the distribution of fluoride and related non-carcinogenic health hazards to local individual groups (males, females, and children separately) in the fluoride endemic region of Patiala, Punjab located in the Northern Indo-Gangetic Plain (IGP). The study shows that the dissolved groundwater fluoride concentration ranged between 1.5 and 9.2 mg/L with ∼98% of the sampling locations having fluoride levels higher than the permissible limit. Samples collected from deeper aquifers (〉284 m bgl) showed ∼27% more fluoride contamination compared to those collected from 〈284 m bgl. Maximum incidence of elevated fluoride concentrations was observed in the eastern part of the study area in-sync with groundwater movement. The hazard quotient of fluoride (HQFluoride) calculated to assess the non-carcinogenic health risk was higher than the unitary value in all individual groups suggesting a prevalence of distressful fluorosis and chronic health risk. Results show that the children are the most vulnerable to fluoride toxicity followed by males and females. Our results are consistent with the recent trends in an increase in dental, skeletal fluorosis, and liver functional damage problems reported in children and adults of the studied region. The study area, therefore, needs the urgent attention of policymakers and government agencies to implement proper water management and cost-effective fluoride remedial measures to reduce the current and future chronic health risks associated with high fluoride intake.

Description: Data derived from Core SG-1b (coordinates: 38°21'9.46'' N, 92°16'24.72'' E) which was drilled within the framework of a Sino-German cooperation project in 2008. Attached Excel spreadsheet contains to data sets: 1. Data: Depth, Age, Sedimentation Rate and ln(Rb/Sr) ratio 2. Age model: Depth, Age Abstract: To contribute to a better understanding of Neogene climate evolution in Central Asia, we here present the first orbitally tuned time scale for a drillcore record from the Qaidam Basin (NE Tibetan Plateau) that consists of lacustrine sediments and spans the late Pliocene to early Pleistocene (~3.3 to 2.1 Ma). Our tuning of Core SG-1b is based on the ln(Rb/Sr) ratio derived from XRF core scanning and grain-size distribution data that trace wet-dry climate alternations predominantly paced by orbital obliquity. Based on our ln(Rb/Sr) record, obliquity-precession interferences persisted during the mid-Pliocene warm period, but disappeared during the early Pleistocene. This could indicate that over the course of the late Pliocene a low-latitude-derived climate modulator gained an increasingly prominent role in shaping the environment of the Qaidam paleolake. At the same time, the consistent presence of the precession signal during the early Pleistocene hampers a refinement of the entire tuning on precession time scales. The inferred changes in sedimentation rate from the late Pliocene to the early Pleistocene indicate a long-term decrease in sediment supply into the Qaidam paleolake. This finding is in line with the previously proposed notion of a long-term aridification trend across the Plio-Pleistocene transition in Central Asia.

Description: Bulk-rock carbon isotopes (d13C), redox-sensitive trace elements and carbonate content measured in the Bodudd section in Gotland, Sweden. The age of the section is Ludfordian (Ludlow, Silurian) and it was deposited on a tropical carbonate platform. Funded by Deutsche Forschungsgemeinschaft project JA 2718/3-1.

Description: These are the supplementary datasets for the manuscript: Drury, A.J., Liebrand, D., Westerhold, T., Beddow, H., Hodell, D., Rohlfs, N., Wilkens, R.H., Lourens, L., 'History of South Atlantic carbonate deposition since the Oligocene (30-0 Ma)', in final preparation for submission Climate of the Past

Description: Sediment properties of a 223-m-long drill core from the Ejina basin, NW China, for reconstructing the palaeoenvironmental history of a part of the Gobi Desert. The sediment study is part of the Q-TiP project (Quaternary Tipping Points of Lake Systems in the Arid Zone of Central Asia) in the frame of the CAME II program (BMBF funded).

Description: This dataset includes planktic foraminifera (Globigerinoides ruber sensu-stricto) stable oxygen isotope and Mg/Ca data from IODP Expedition 353, Sites U1446 and U1448 across Marine Isotope Stage 5 (140-70 ka). Additionally, included is a time-series of annual change in precipitation as emulated by PaleoPGEM across 6 large-scale low-latitude regions throughout Marine Isotope Stage 5 (140-70 Ka).

Description: We compiled modern and fossil relative abundance of coccolithophore species Florisphaera profunda from published and unpublished datasets, along with ocean environmental variable data from satellite remote sensing and physical measurements. The database includes relative abundances of F. profunda in sediment trap (n = 26) and core-top (n = 1258), and sediment core samples (n = 104). Downcore data covers the Last Glacial Maximum (n = 94, 24-19 ka) or the Mid-to-Late Holocene (n = 77, 〈6 ka). This database allows studying modern and past biogeography of F. profunda as a response to changing ocean and climate conditions, “Quantitative reconstruction of primary productivity in low latitudes during the last glacial maximum and the mid-to-late Holocene from a global Florisphaera. profunda calibration dataset” (Hernández-Almeida et al., 2018).

Description: This dataset presents the XRF core-scanning record from International Ocean Discovery Program (IODP) Site U1478 off the Limpopo River mouth (Mozambique Channel, SW Indian Ocean) spanning the past c. 4 Ma. Site U1478 was drilled in the northernmost Natal Valley, on the Inharrime Terrace (25°49.26′ S; 34°46.16′ E) at a water depth of 488 m below sea level. The XRF core scanning of the ~257-m-long splice for Site U1478 was carried out using an Itrax Core Scanner at Lamont-Doherty Earth Observatory Core Repository, Columbia University (USA). In total, 239 sections (archive halves) were scanned at a voltage of 30 kV and a tube current of 55 mA using a Cr tube and employing an exposure time of 2 seconds. Measurement spacing was set at 2 mm, with downcore and crosscore slit sizes set at 2 mm and 2 cm, respectively. The individual element counts were normalized using the ratio of raw total counts of a given element to the total counts of all processed elements for the respective measurement position. To eliminate non-linear matrix effects and constant-sum constraints, log ratios were applied on the elemental ratios. The age model of Site U1478 is based on cyclostratigraphic analysis of the XRF-based log(Ti/Ca) record and its tuning to ice-volume, precession and eccentricity cycles.