S and O isotope ratios of sulfate suggest enhanced monosulfides oxidation in a historical Pb–Zn mine site

© 2021 Elsevier LtdAqueous and solid tailings geochemistry of two contrasting depositional sites (water-saturated and subaerial) in a historical Pb–Zn mine tailings in Balya, Turkey were chemically and isotopically (δ34S and δ18O) characterized to trace source of sulfate and elucidate oxidation pathways of sulfide mixtures. Aqueous geochemistry data of water-soluble fractions (n = 15) obtained from the batch leaching tests applied on the subaerial mine tailings (SA-MT) revealed three geochemically distinct zones: i) oxidized zone (OXZ, 10–75 cm), ii) transition zone (TZ, 75–125 cm) and iii) unoxidized zone (U-OXZ, 125–350 cm). The OXZ is characterized by a sharp decrease in sulfur and metals contents of the tailing rocks while high sulfate and metals concentrations in their water-soluble fractions. In contrast, the TZ and U-OXZ zones are mainly characterized by low sulfate but relatively high metal concentrations with slightly acidic pH values (4.9–6.2). Compared to the SA-MT tailings geochemical profiles of the pore waters of the water-saturated tailings (S-MT) showed remarkably high sulfate, Fetot and metals concentrations with strong acidic pH values (1.9–3.8). The δ34S and δ18O values of sulfate suggest that galena and/or sphalerite are the main source of sulfate and metals at the tailings site. The differences in sulfur isotope values (Δ34SSO4-sulfide) appear to be reflective of the extend of oxidation of monosulfides (e.g. galena) under two contrasting conditions of the tailings. The large sulfur isotope differences (Δ34SSO4-sulfides ~ -4.5 ± 0.2‰) imply incomplete oxidation of monosulfides to sulfate with aqueous geochemistry record of low sulfate, high metal and slightly acidic pH values. In contrast, the small Δ34SSO4-sulfide (<1 ± 0.2‰) values indicate the tailings site where complete oxidation of monosulfides to sulfate occurred resulting in acidic condition having with high sulfate, metal concentrations. The δ18OSO4 values were enriched than those of background water in tailings sites with the similar Δ18OSO4–H2O values (+8.9 to +11‰). Based on field data revealing enhanced galena and/or sphalerite oxidation relative to pyrite, the observed Δ18OSO4–H2O (avg., 9‰) values coupled with the relationship between δ34SSO4 values and sulfate concentration can be reflective of oxidation of monosulfides in contrast to disulfide minerals (e.g, pyrite) within polymetallic rich AMD systems

Jerusalem artichoke diversity in Türkiye: comparative analysis of clone and organ-based biochemical composition

In this study, biochemical analyses were performed for the first time on 22 different Jerusalem artichokes clones collected from different regions of Turkiye and samples from three different organs of each clone, considering the interaction effects. As a result of the study, the interaction effect of clones and sampled organs was found significant for total flavonoids, ascorbic acid, total chlorophyll, pH, H2O2 removal capacity, total dry matter, water soluble dry matter and antioxidant capacity via FRAP. According to the correlation analysis, the highest coefficient among the parameters in the tuber was between titratable acidity and total phenolic matter (0,576). Principal component analysis was used to assess the degree to which the parameters explained the variation in the gene pool. Factors directly and indirectly affecting the amount of water-soluble dry matter in the tuber were examined by path analysis

Genotypes and virulence factors of Candida species isolated from oral cavities of patients with type 2 diabetes mellitus

Background/aim: This study compared the genotypes and virulence factors of Candida species isolated from oral cavities of healthy individuals and patients with diabetes mellitus (DM)

Comparison of chemotherapy and hematopoietic stem cell transplantation pre and postterm DMFT scores: a preliminary study.

Aims: Chemotherapy is frequently used as a conditioning regimen to destroy malignant marrow cells before transplantation. Xerostomia, dysphagia, altered taste perception, mucositis, soft-tissue ulceration, and infection are common adverse oral effects of chemotherapy. The study was aimed to compare decayed, missing, filled teeth (DMFT) scores before and after hematopoietic stem cell transplantation (HSCT) and chemotherapy

Community Report from the Biosignatures Standards of Evidence Workshop

The search for life beyond the Earth is the overarching goal of the NASA Astrobiology Program, and it underpins the science of missions that explore the environments of Solar System planets and exoplanets. However, the detection of extraterrestrial life, in our Solar System and beyond, is sufficiently challenging that it is likely that multiple measurements and approaches, spanning disciplines and missions, will be needed to make a convincing claim. Life detection will therefore not be an instantaneous process, and it is unlikely to be unambiguous-yet it is a high-stakes scientific achievement that will garner an enormous amount of public interest. Current and upcoming research efforts and missions aimed at detecting past and extant life could be supported by a consensus framework to plan for, assess and discuss life detection claims (c.f. Green et al., 2021). Such a framework could help increase the robustness of biosignature detection and interpretation, and improve communication with the scientific community and the public. In response to this need, and the call to the community to develop a confidence scale for standards of evidence for biosignature detection (Green et al., 2021), a community-organized workshop was held on July 19-22, 2021. The meeting was designed in a fully virtual (flipped) format. Preparatory materials including readings, instructional videos and activities were made available prior to the workshop, allowing the workshop schedule to be fully dedicated to active community discussion and prompted writing sessions. To maximize global interaction, the discussion components of the workshop were held during business hours in three different time zones, Asia/Pacific, European and US, with daily information hand-off between group organizers