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"Sedimentation"
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Correction: Comparative study of impaction and sedimentation in an aerosol chamber using defined fungal spore and bacterial concentrations
[This corrects the article DOI: 10.1371/journal.pone.0187039.].
Journal Article
Sediment Depositional History and Processes for the Eurasian Basin Since 54 Ma, Arctic Ocean
The Eurasian Basin in the Arctic Ocean, comprising the Amundsen and Nansen Basins separated by the Gakkel Ridge, has sediment deposits up to 4–5 km thick. However, its sedimentation history and processes remain poorly understood. Using 31 seismic profiles, we have estimated deposition rates for 54 Ma. From 54 to 45 Ma, the Nansen Basin averaged ∼15 cm/kyr, while the Amundsen Basin exhibited higher but variable rates (15–50 cm/kyr). From 45 to 20 Ma, the Amundsen Basin's rates decreased significantly, dropping to 6–7 cm/kyr (34–45 Ma) and ∼3.5 cm/kyr (20–34 Ma). Meanwhile, the Nansen Basin maintained higher rates (∼12 cm/kyr to ∼5 cm/kyr). After 20 Ma, sedimentation rates diverged further. The Nansen Basin stabilized at ∼5 cm/kyr and was significantly influenced by glaciation and iceberg rafting, while the Amundsen Basin continued to decline to ∼2 cm/kyr, with pelagic sediments dominated by sea‐ice and iceberg rafting, and debris flows near the Lomonosov Ridge. The Nansen Basin's higher rates are likely due to its proximity to the Barents and Laptev Sea shelves, while the general declined rates across the basin are related to basin expansion, climate cooling, and reduced tectonic activity. Additionally, the Eurasian Basin's sedimentation is shaped by two phases of Siberian river activity. Before 45 Ma, the Lena and Indigirka rivers dominated, particularly near the eastern Laptev Sea Shelf. After 45 Ma, the Pyasina and Yenisey rivers became the main contributors, with significant sediment delivery through the St. Anna Trough. Sediment deposits (0.6–1 km) along the Gakkel Ridge (70°E−100°E) are also caused by these processes.
Journal Article
Effects of B-cell directed therapy on the preclinical stage of rheumatoid arthritis: the PRAIRI study
ObjectivesWe explored the effects of B-cell directed therapy in subjects at risk of developing autoantibodypositive rheumatoid arthritis (RA), who never experienced inflammatory arthritis before, and explored biomarkers predictive of arthritis development.MethodsIndividuals positive for both anti-citrullinated peptide antibodies and rheumatoid factor but without arthritis were included in a randomised, double-blind, placebo-controlled study to receive a single infusion of 1000 mg rituximab or placebo.ResultsEighty-one individuals received treatment and were followed up for a mean of 29.0 (0–54) months, during which 30/81 (37%) individuals developed arthritis. The observed risk of developing arthritis in the placebo-treated group was 40%, which was decreased by 55% (HR 0.45, 95% CI 0.154 to 1.322) in the rituximab-treated group at 12 months. Rituximab treatment caused a delay in arthritis development of 12 months compared with placebo treatment at the point when 25% of the subjects had developed arthritis (p<0.0001). Erythrocyte sedimentation rate and the presence of anti-citrullinated α-enolase peptide 1 at baseline were significant predictors of arthritis development.ConclusionsA single infusion of 1000 mg rituximab significantly delays the development of arthritis in subjects at risk of developing RA, providing evidence for the pathogenetic role of B cells in the earliest, prearthritis stage of autoantibody positive RA.
Journal Article
Pyrite sulfur isotopes reveal glacial–interglacial environmental changes
The sulfur biogeochemical cycle plays a key role in regulating Earth’s surface redox through diverse abiotic and biological reactions that have distinctive stable isotopic fractionations. As such, variations in the sulfur isotopic composition (δ34S) of sedimentary sulfate and sulfide phases over Earth history can be used to infer substantive changes to the Earth’s surface environment, including the rise of atmospheric oxygen. Such inferences assume that individual δ34S records reflect temporal changes in the global sulfur cycle; this assumption may be well grounded for sulfate-bearing minerals but is less well established for pyrite-based records. Here, we investigate alternative controls on the sedimentary sulfur isotopic composition of marine pyrite by examining a 300-m drill core of Mediterranean sediments deposited over the past 500,000 y and spanning the last five glacial–interglacial periods. Because this interval is far shorter than the residence time of marine sulfate, any change in the sulfur isotopic record preserved in pyrite (δ34Spyr) necessarily corresponds to local environmental changes. The stratigraphic variations (>76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial–interglacial sea level and temperature changes. In this case, the dominant control appears to be glacial–interglacial variations in sedimentation rates. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records, especially associated with intervals of substantial sea level change. This work provides an important perspective on the origin of variability in such records and suggests meaningful paleoenvironmental information can be derived from pyrite δ34S records.
Journal Article
Estimating Reservoir Sedimentation Rates and Storage Capacity Losses Using High‐Resolution Sentinel‐2 Satellite and Water Level Data
In nearly all reservoirs, storage capacity is steadily lost due to trapping and accumulation of sediment. Despite critical importance to freshwater supplies, reservoir sedimentation rates are poorly understood due to sparse bathymetry survey data and challenges in modeling sedimentation sequestration. Here, we proposed a novel approach to estimate reservoir sedimentation rates and storage capacity losses using high‐resolution Sentinel‐2 satellites and daily in situ water levels. Validated on eight reservoirs across the central and western United States, the estimated reservoir bathymetry and sedimentation rates have a mean error of 4.08% and 0.05% yr−1, respectively. Estimated storage capacity losses to sediment vary among reservoirs, which overall agrees with the pattern from survey data. We also demonstrated the potential applications of the proposed approach to ungauged reservoirs by combining Sentinel‐2 with sub‐monthly water levels from recent satellite altimeters. Plain Language Summary Reservoir storage capacity is steadily lost due to sediment filling, which threatens freshwater supplies both now and in the future. Yet, lost reservoir storage capacities to sediment are largely unknown. Here, we develop a generic method to estimate capacity losses and reservoir sedimentation rates by leveraging remote sensing techniques. We tested on eight reservoirs across the central and western United States and found capacity losses and sedimentation rates vary across reservoirs. The proposed method offers a promising alternative to evaluate and predict capacity losses in reservoirs nationwide and globally, and thus supports effective water managements and planning for sustainable freshwater supplies in the future. Key Points High‐resolution Sentinel‐2 images and daily in situ water levels were used to estimate reservoir sedimentation rates and capacity losses Estimated reservoir sedimentation rates and storage capacity losses have a mean error of 0.05% yr−1 of full storage capacity Potential applications of this method to ungauged reservoirs are feasible with sub‐monthly level data from recent satellite altimeters
Journal Article