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Research subject and methods. The work is based on a comparative study of the data obtained by the authors and those published in literature on U-Pb ID-TIMS and “in-situ” isotopic examination of zircons extracted from a number of Ural geological objects (volcanogenic rocks of the Mashak Formation of the Bashkir Meganticlinorium, granitoid massifs of the Northern part of the Uraltau Ridge, Kumba gabbro-norite massif Platinum-bearing belt), as well as Australian diorites and South African mafic xenoliths. Results. Since the methods of ID-TIMS (ID-MC-ICP/MS) and SIMS dating of zircon are fundamentally different, their advantages and disadvantages should be taken into account when solving the corresponding geochronological problems. Conclusions. U-Pb ID-TIMS (ID-MC-ICP/MS) methods allow the analysis of individual crystals, as well as their fragments, with an unprecedented level of uncertainty concerning age dating (up to 0.05%). The main drawback of the U-Pb SIMS method consists in a significant error when dating U-Pb (2–5%), which might disguise possible Pb losses (and / or U-contribution) and lead to appearance of artifacts when interpreting U-Pb zircon data. This, in turn, leads to the identification of non-existent stages of magmatism, metamorphism, false ideas about the length of evolutionary processes, etc. The use of U-Pb SIMS methods should be limited to solving geological problems that do not require a high accuracy of dating (i.e., allowing rough estimation) but involving the need to study a large number of samples and corresponding zircon grains. Such problems arise during examination of clastic material in the process of reconstructing sources and geological conditions of sedimentary basin formation. U-Pb SIMS methods can be used for studying the heterogeneity of zircon crystals having a complex structure under preliminary selection of materials for subsequent high-precision dating using U-Pb ID-TIMS and / or ID-MC-ICP/MS methods. The expansion of the number of laboratories using these high-precision methods seems to be the most important direction in the development of Russian isotope geochronology.

Detailed organic and inorganic geochemical analyses were used to assess the depositional environment and source rock potential of the Upper Albian to Turonian oil shale deposits in the Tarfaya Basin. This study is based on core samples from the Tarfaya Sondage-4 well that penetrated over 300m of Mid Cretaceous organic matter-rich deposits. A total of 242 samples were analyzed for total organic and inorganic carbon and selected samples for total sulfur and major elements as well as for organic petrology, Rock-Eval pyrolysis, Curie-Point-pyrolysis-gas-chromatography-Mass-Spectrometry and molecular geochemistry of solvent extracts. Based on major elements the Albian and Lower Cenomanian differ from the other intervals by higher silicate and lower carbonate contents. Moreover, the molecular geochemistry suggests marine anoxic bottom water conditions during the Cenomanian-Turonian boundary event (CTBE; oceanic anoxic event 2: OAE2). As a proxy for the Sorg/Corg ratio, the ratio total thiophenes/total benzenes compounds was calculated from pyrolysate compositions. The results suggest that Sorg/Corg is low in the Albian, moderate in the Cenomanian, very high in the CTBE and high in the Turonian samples. Rock-Eval data reveal that the Albian is a moderately organic carbon-rich source rock with good potential to generate oil and gas upon thermal maturation. On the other hand, the samples from the Cenomanian to the Turonian exhibit higher organic carbon contents and can be classified as oil-prone source rocks. Based on Tmax data, all rocks are thermally immature. The microscopic investigations suggest dominance of submicroscopic organic matter in all samples and different contents of bituminite and alginite. The Albian samples have little visible organic matter and no bituminite. The Cenomanian and CTBE samples are poor in bituminite and have rare visible organic matter, whereas the Turonian samples change from bituminite-fair to bituminite-rich and to higher percentages of visible organic matter towards the younger interval. These differences in the organic matter type are attributed to 1) early diagenetic kerogen sulfurization and 2) the upwelling depositional environment. Moreover, kerogen sulfurization was controlled by the relationship between carbonate, iron and sulfur as well as the organic matter. Thus, the organic carbon-rich deposits can be grouped into: 1) low Sorg and moderately organic matter-rich oil prone source rocks, 2) moderate Sorg and organic-carbon-rich oil prone source rocks, 3) high Sorg and organic carbon-rich oil prone source rocks and 4) very high Sorg and organic carbon-rich oil prone source rocks, the latter being represented by the CTBE. Types 2 to 4 will generate sulfur-rich petroleum upon maturation or artificial oil shale retorting.

Total element concentrations by themselves are not always good predictors of toxicity and are therefore not suitable for eco- and/or human toxicological risk determination. In addition, despite the growing call for harmonization, countries show significant variation in risk assessment tools, screening/background values, protocols and legal management of soils. By incorporating mobility and bioaccessibility/availability into soil risk assessments, location-specific physico-chemical and geological conditions can be considered in routinely applied general risk assessment methodologies. Minette soils and rocks are a great case in point since they often are associated with high geogenic As concentrations and consequently potential risks. Minette iron ores form the world largest Fe ore deposits since the "great oxidation". For the first time, oral bioaccessibility during direct ingestion was assessed on Minettes from Luxembourg by applying the in vitro Solubility/Bioavailability Research Consortium (SBRC) method. Out of > 180 samples, 25 representative samples were selected providing a unique dataset which showed an average gastric bioaccessibility of ∼10% (7.8 ± 4.0 mg/kg) of the total As-concentration, with a maximum of 45% (17.9 mg/kg). Of importance is that bioaccessibility of As in Minette rocks and soils are controlled by, and can be estimated from, lithology, mineralogy and total Ca content. Soils and ooid grainstones with an iron oxide or clayey matrix, are characterized by average gastric bioaccessible As concentrations < 6 mg/kg. Gastric As bioaccessibility is highest in Fe-bearing calcite-cemented bioclastic grainstones (∼12 mg/kg). Importantly, for all samples the maximal bioaccessible As concentrations remain below the threshold from which significant adverse non-carcinogenic and/or carcinogenic health effects are expected. These new results are in strong contrast with what total As concentrations might suggest. Considering bioaccessibilities, consequently, can help to avoid disproportionate, costly and environmentally impacting risk management strategies. Furthermore, this study illustrates the importance of cross-disciplinary collaboration between geo- and health scientists., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Hannes Claes reports financial support was provided by Environment Agency Luxembourg. Pol Tock reports a relationship with Environment Agency Luxembourg that includes: employment., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Sediment geochemistry of the Jakarta region, a densely populated tropical coast, is studied - with particular focus on rivers discharging to Jakarta Bay. Weathering volcanics in the river catchment area control the composition of major elements, As, Cr and in part Cu. In contrast, Zn, Ni, Pb and partly Cu are affected by anthropogenic sources, mainly in central Jakarta City. The data reflect a high variability of local emission sources, among which metal processing industries, fertilizers or untreated animal waste may be important. In particular, the role of street dusts is emphasized. Locally, heavy metals reach levels considered to have adverse biological effects. River discharge leads to anthropogenic enrichment of heavy metals in the coastal sediments. Element data also show geogenic effects on the composition of the coastal sediments, such as mixing of detrital silicates with biogenic carbonates as well as suspended particulate matter from the ocean., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The Ethiopian Rift Valley Lakes host populations of edible fish species including Oreochromis niloticus, Labeobarbus intermedius and Clarias gariepinus, which are harvested also in other tropical countries. We investigated the occurrence of six heavy metals in tissues of these fish species as well as in the waters of Lake Koka and Lake Awassa. Both lakes are affected by industrial effluents in their catchments, making them ideal study sites. Mercury concentrations were very low in the water samples, but concentrations in the fish samples were relatively high, suggesting a particularly high bioaccumulation tendency as compared with the other investigated metals. Mercury was preferentially accumulated in the fish liver or muscle. It was the only metal with species-specific accumulation with highest levels found in the predatory species L. intermedius. Lower mercury concentrations in O. niloticus could be attributed to the lower trophic level, whereas mercury values in the predatory C. gariepinus were unexpectedly low. This probably relates to the high growth rate of this species resulting in biodilution of mercury. Accumulation of lead, selenium, chromium, arsenic and cadmium did not differ between species, indicating that these elements are not biomagnified in the food chain. Values of cadmium, selenium and arsenic were highest in fish livers, while lead and chromium levels were highest in the gills, which could be related to the uptake pathway. A significant impact of the industrial discharges on the occurrence of metals in the lakes could not be detected, and the respective concentrations in fish do not pose a public health hazard.

A new method to continuously change the buffer conditions in samples prior to electrophoresis by counter-current dialysis has been developed using a hollow fiber membrane module (VariPerm M, bitop, Witten). It is demonstrated that the collected fractions of a column eluate after hydrophobic interaction chromatography cannot be analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) due to the high content of ammonium sulfate. In contrast, when the hollow fiber membrane module is used for on-line desalting of the eluate during chromatography, it is possible to detect distinct bands on SDS-gels even after sample concentration by evaporation. Moreover, adding polyethyleneglycol 20,000 to the counter-current dialysis buffer the hollow fiber membrane module is suitable for combined on-line sample desalting and sample concentration of living organisms during free flow electrophoresis (FFE): a culture of Nitrosomonas eutropha which could not significantly be detected by FFE without conditioning was successfully analyzed when concentrated and desalted on-line during sample application.