Browsing by Subject "Redox conditions"
Now showing items 1-3 of 3
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(2018)Anthropogenic nutrient input has caused a rapid expansion of bottom water hypoxia in the Baltic Sea over the past century. Two earlier intervals of widespread hypoxia, coinciding with the Holocene Thermal Maximum (HTMHI; 8-4 ka before present; BP) and the Medieval Climate Anomaly (MCA(HI); similar to 1200-750 years BP), have been identified from Baltic Sea sediments. Here we present sediment records from two sites in the Baltic Sea, and compare the trace metal (As, Ba, Cd, Cu, Mo, Ni, Pb, Re, Sb, Tl, U, V, Zn) enrichments during all three hypoxic intervals. Distinct differences are observed between the intervals and the various elements, highlighting the much stronger perturbation of trace metal cycles during the modern hypoxic interval. Both Mo and U show a strong correlation with C-org and very high absolute concentrations, indicative of frequently euxinic bottom waters during hypoxic intervals. During the modern hypoxic interval (Modern(HI)) comparatively less Mo is sequestered relative to C-org than in earlier intervals. This suggests partial drawdown of the water column Mo inventory in the modern water column due to persistent euxinia and only partial replenishment of Mo through North Sea inflows. Molybdenum contents in modern sediments are likely also affected by the recent slowdown in input of Mo in association with deposition of Fe and Mn oxides. Strong enrichments of U in recent sediments confirm that the Modern(HI) is more intense than past intervals. These results suggest that U is a more reliable indicator for the intensity of bottom water deoxygenation in the Baltic Sea than Mo. Sedimentary Re enrichment commences under mildly reducing conditions, but this element is not further enriched under more reducing conditions. Enrichments of V are relatively minor for the MCA(HI) and Modern(HI), possibly due to strong reservoir effects on V in the water column, indicating that V is unreliable as an indicator for the intensity of bottom water hypoxia in this setting. Furthermore, Ba profiles are strongly influenced by post-depositional remobilization throughout the Holocene. The strong relationship between C-org and Ni, Tl and particularly Cu suggests that these trace metals can be used to reconstruct the C-org flux into the sediments. Profiles of As, Sb and Cd and especially Pb and Zn are strongly influenced by anthropogenic pollution.
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(2020)Lung cancer is a deadly disease, typically caused by known risk factors, such as tobacco smoke and asbestos exposure. By triggering cellular oxidative stress and altering the antioxidant pathways eliminating reactive oxygen species (ROS), tobacco smoke and asbestos predispose to cancer. Despite easily recognizable high-risk individuals, lung cancer screening and its early detection are hampered by poor diagnostic tools including the absence of proper biomarkers. This study aimed to recognize potential lung cancer biomarkers using induced sputum noninvasively collected from the lungs of individuals in risk of contracting lung cancer. Study groups composed of current and former smokers, who either were significantly asbestos exposed, had lung cancer, or were unexposed and asymptomatic. Screening of potential biomarkers was performed with 52, and five differentially abundant proteins, peroxiredoxin 2 (PRDX2), thioredoxin (TXN), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), extracellular matrix protein 1 (ECM1), and protein S100 A8 (S100A8), were chosen to undergo validation, for their previously known connection with oxidative stress or cancer. Results from the validation in 123 sputa showed that PRDX2, TXN, and GAPDH were differentially abundant in sputa from individuals with lung cancer. TXN had a negative correlation with asbestos exposure, yet a positive correlation with smoking and lung cancer. Thus, tobacco smoking, asbestos exposure, and lung carcinogenesis may disturb the cellular redox state in different ways. A strong correlation was found among PRDX2, TXN, GAPDH, and S100A8, suggesting that these proteins may present a diagnostic biomarker panel to aid recognizing individuals at high risk of contracting lung cancer.
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(2021)Unusually high uranium (U) concentrations (up to 175 mu g/L) have been measured in groundwater at depths between 400 and 650 m at the Forsmark site, eastern Sweden. Since it is unlikely that such high concentrations formed under the stagnant and low redox groundwater conditions that currently prevail, this study employs Useries isotopes to understand how the recent evolution (
