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• Scirpus olneyi plants fed 5 mM (15NH 4) 2 SO 4 recorded lower 15N in stems, roots plus rhizomes, and whole plants under elevated CO 2 than ambient CO 2. • 15N concentration decreased by 51 % in stems, 63 % in roots plus rhizomes, and 74 % in whole plants exposed to elevated CO 2. • 15N uptake by S. olneyi plants was decreased by 78 % in elevated CO 2. • Under elevated CO 2 , total amino acid pool was decreased by 50 % in stems and 23 % in roots plus rhizomes of S. olneyi plants. Isotopic analysis of ambient and elevated CO 2 -treated S. olneyi plants receiving 5 mM 99 atom % excess (15NH 4) 2 SO 4 for 19 h showed significantly lower 15N in stems, roots plus rhizomes, and whole plants than ambient CO 2. The 15N concentration decreased by 51 % in stems, 63 % in roots plus rhizomes, and 74 % in whole plants of S. olneyi under elevated CO 2. 15N uptake was reduced by 78 % in elevated CO 2 , resulting in 79 % decrease in 15N content. The N concentration of the rooting medium supporting S. olneyi growth was 2.27 %, suggesting that the plants were not N-starved. The combined evidence from the 15NH 4 + assimilation data and the sediment N analysis clearly showed that the decline in N of S. olneyi under elevated CO 2 was due to inhibition of N uptake, and not low N concentration in the marsh sediment. The elevated CO 2 -induced decrease in 15N uptake and assimilation resulted in significantly reduced concentrations of amino acids in organs of S. olneyi plants. The observed decreases in stem composition of individual amino acids (e.g. serine, glycine, alanine, Gaba and lysine) ranged from 25.6 % for glycine to 65.0 % for serine. Similarly, root concentrations of aspartate, serine, glutamate, glycine, alanine, cysteine, isoleucine, and Gaba were decreased by elevated CO 2 from 2 % for Gaba up to 80 % for glutamate. Given its role as a precursor for glutamine biosynthesis via the GS/GOGAT pathway, the big decrease in glutamate concentration of roots and rhizomes under elevated CO 2 resulted in 50 % decrease in total amino acid pool of stems and 23 % in roots plus rhizomes of S. olneyi plants. The decreased NH 4 + uptake under elevated CO 2 in this study has implications for human nutrition and health in Africa, where agricultural soils are inherently low in N for production of adequate and nutritious grain, and/or development of ecotourism and animal protein from grass pastures (which have a strong preference for NH 4 + nutrition). [ABSTRACT FROM AUTHOR]

Lake Tennyson's basin and sedimentary record were assessed for multiple branches of paleoenvironmental research. A geophysical investigation of the lake depositional setting was supported by physical and chemical analysis of multiple sediment cores. The basin reaches 60 m depth and several subaerial landforms identified were likely deposited from seismic activity. Deformed sediments and turbidites in gravity cores are attributed to one or more large (pre)historic earthquakes, and episodic grain size changes in sediment cores are related to either seismic and/or climatic/meteorological processes. A hummocky slump deposit located on the western lake bed margin is linked to widespread sediment deformation that was likely caused by movement of the Awatere Fault. Radiocarbon dating constrains the most recent major deformation event between the late thirteenth century CE and mid-twentieth Century. Folded turbidites in the stratigraphy suggest multiple sedimentary deformation episodes occurred during the last millennium. Micro-XRF elemental signatures suggest proxies of past water column mixing (windiness proxy) can be reconstructed via identification of changing redox conditions. Records from Lake Tennyson show potential for several palaeoenvironmental research applications, and combining them with basin morphostratigraphy and land-based palaeoclimate and palaeoseismic evidence can enhance understanding of environmental change in the northern South Island. [ABSTRACT FROM AUTHOR]

In the geochemical review based on records from cruises of the International Deep Marine Drilling Project (DSDP, ODP, and IODP phases) and other literature data on the main types of Pleistocene sediments in the Atlantic, tables of average arithmetic chemical composition, mean weighted chemical composition, accumulation rates, and mass accumulation rates of chemical components are presented. These tables can be used for the comparative analysis with sediments of the same or other stratons in different oceanic basins, as well as with paleoceanic sediments on the continents. The terrigenous matrix dominates within the lithogenic matter. Using methods of mathematical statistics, we revealed the main geochemical associations and major factors determining the chemical composition of studied sediments. Masses of oxides of petrogenic elements and several trace elements have been calculated for Pleistocene sediments. Average chemical composition of Pleistocene sediments is proposed for the Atlantic. [ABSTRACT FROM AUTHOR]

Background and aim: Organic C stocks in lacustrine sediments can be an important C sink. We therefore addressed the drivers of the sediment organic carbon (SOC) and labile organic carbon (LOC) concentrations after submerged aquatic vegetation (SAV) reestablishment by sowing in a eutrophic lake. Methods: We conducted a field experiment in Lake Datong, a eutrophic lake in the Dongting Lake basin. There are two distinct areas in the lake: the DX area, where the reestablished SAV persisted for three years; the MN area, where SAV persisted for 1.5 years. Our investigation focused on assessing SOC and LOC concentrations within the 0–20 cm sediment layers, and examining their correlations with sediment physicochemical properties and potential enzyme activities. Results: SOC and LOC concentrations were higher in the DX than MN area. Sediment total nitrogen (TN) concentrations, porosity, and potential BG and NAG enzyme activities were higher in the DX than MN area. While dry bulk density (DBD) and sediment pH were lower in the DX than MN area. Those sediment physicochemical properties and potential enzyme activities in different reestablished areas explained variations in SOC and LOC concentrations to varying extents. Conclusion: Our findings indicate that SAV reestablishment time holds great potential for accumulating SOC and LOC concentrations by altering the stability of SOC and enhancing sediment nutrient levels. [ABSTRACT FROM AUTHOR]

The evolution of submarine canyons is primarily controlled by turbidity currents, which erode and fill them over time; however, many other hydrodynamic currents operate within canyons. Bottom currents from these other hydrodynamic processes, including internal tides, can be dominant processes, but their deposits are seldom recognized in sediment cores or the rock record. This study combines autonomous underwater vehicle swath bathymetry imagery and sub‐bottom profiles, high‐resolution sediment core analyses (X‐ray imagery and thin sections), and previously collected seabed video and flow measurements within Logan Canyon head (eastern Canada) to provide a detailed, modern record of facies associated with hydrodynamic processes in a canyon head. These results suggest that bottom currents are responsible for maintaining gullies on canyon sidewalls and an axial channel on the canyon floor. Thin sections of sediment cores reveal that muddy sand in the canyon head consists of mud aggregates and silt and fine‐grained sand, both behaving similarly in terms of flow dynamics. Three facies are present at macro‐scale and micro‐scale: laminated, partially laminated and bioturbated sandy mud. Sedimentary structures include rhythmic sand and mud aggregate couplets, planar to wavy laminations, current ripple cross‐laminations and fining‐upward successions, which are attributed to bottom currents induced by internal tides. Bioturbated facies, characterized by discrete biogenic structures and cross‐cutting relationships, predominate and overprint a mottled background. A mottled bioturbation fabric also alternates with or locally disrupts layering within the partially laminated facies. Internal tide currents, capable of bedload transport and forming ripples, were measured during a monitoring period in the canyon head, followed by rapid re‐establishment of benthos and associated biogenic structures, supporting the core interpretations. Preservation of sedimentary facies associated with these internal tides occurs when the sedimentation rate outpaces the rate of bioturbation, likely during stormier conditions on the shelf. These results represent observations of sedimentary facies associated with modern bottom currents and internal tides, and can be used to interpret similar occurrences within the rock record. [ABSTRACT FROM AUTHOR]

To understand the role of the East Asian summer monsoon (EASM) and the East Asian winter monsoon (EAWM) on the hydroclimate in northern Taiwan, a multiproxy study has been conducted. This study aims to achieve its goal by using micro-XRF data of Ti and sulfur (S), carbon isotopic compositions (δ13C) along with elemental concentrations of carbon (C), nitrogen (N) and S, and diatom analyses in the sediment core extracted from the Dream Lake (DL; 25°10′01.9″ N, 121°33′36.0″ E and elevation = 588 m above sea level), northern Taiwan. The radiocarbon dates revealed that the DL core covered the time interval from 4.5 to 0.4 cal kyr BP. The current records revealed wetter phases during 4.5–3.0 cal kyr BP, 2.0–1.7 cal kyr BP, and 1.0–0.4 cal kyr BP, characterized by the dominance of C3 plants in the DL catchment, increased runoff, and higher lake levels. Drier climates observed in the current study during 3.0–2.0 cal kyr BP and 1.7–1.0 cal kyr BP, marked by a reduction in C3 plants, decreased runoff, and lower lake levels. The northern Taiwan climate during the late Holocene was observed to be regulated by the interplay of EASM and EAWM. The wet climate conditions during 4.5–3.0 were due to the La Niña-like conditions, which led to a strong EASM resulting in high precipitation conditions. The dry climate conditions during 3.0–2.0 cal kyr BP have coincided with El Niño-like conditions during 3.0–2.4 cal kyr BP and a subsequently strong EAWM during 2.4–2.0 cal kyr BP. Both situations led to a reduction in precipitation in the region. Unlike the time frame from 4.5 to 3.0 cal kyr BP, wet climate conditions during 2.0–1.7 and 1.0–0.4 cal kyr BP have coincided with weak EAWM conditions, which led to an increase in precipitation in northern Taiwan. The dry climate noticed between 1.7 and 1.0 cal kyr BP appeared to be the impact of both El Niño-like conditions and strong EAWM. [ABSTRACT FROM AUTHOR]

Both modern and historical data show that lake systems are undergoing profound changes because of human impacts from local to global scales. Research on this topic shows that human pressure on water systems can take various forms and is highly variable in time and space. This article presents the results of Ostracoda fauna research as an indicator of anthropogenic changes covering the time span from 7000 BP to the Mediaeval Period. The palaeoecological information (abundance and habitat preferences of Ostracoda assemblages) obtained in studies of fossil Ostracoda fauna communities amplified by palynological and archaeological data allowed to answer the following questions: (1) to what extent the impact of successive archaeological settlement cultures caused ecological changes in the lake catchment areas without directly affecting the lakes themselves, and when anthropogenic pressure caused transformations in the functioning of lake ecosystems and (2) whether the neolithization, as the first clearly legible stage of anthropopression, had a decisive influence on the functioning of lake ecosystems. Results of Ostracoda fauna studies have been compared with archaeological data available in the literature and multiproxy paleoenvironmental data previously published in a study of lake sediments in the Chełm Hills in South-Eastern Poland. Presented results of study of Ostracoda in lake sediments as a bioindicators of anthropogenic impact suggest that the pressure of prehistoric settlement in older phases (up to the early Middle Ages) was most clearly reflected in the landscape, while the functioning of lake ecosystems was disturbed only by the periodic increase in lake trophic status. A substantial change resulting from the analysis of the subfossil Ostracoda in all the studied lake ecosystems occurred in the phase of settlement related to the Early Middle Ages, which was reflected in the permanently changed species composition of the fauna. [ABSTRACT FROM AUTHOR]

Investigations into the microbial community of bottom sediments in the karst Lake Black Kichier were conducted. These sediments exhibited elevated levels of sulfide, dissolved methane, and organic matter. Direct radiotracer experiments revealed substantial rates of microbial processes involved in the decomposition of organic matter. Uncultivated archaea belonging to the phylum Thermoplasmatota were identified within the microbial community. Metagenomic analysis unveiled representatives from five orders: Methanomassiliicoccales, Thermoprofundales (formerly known as Marine Benthic Group D and DHVEG-1), DTX01, SG8-5, and Candidatus Gimiplasmatales (formerly UBA10834). These archaea were previously believed to occur exclusively in deep marine sediments characterized by extreme organic matter scarcity. This discovery reshapes our understanding of the role played by Thermoplasmatota archaea, spanning five orders, in the degradation segment of the carbon cycle. [ABSTRACT FROM AUTHOR]

The issues of the environmental evolution of the western sector of the Khanka valley and the evolution of Lake Khanka are considered for the maxima of the last glaciation and Late Pleistocene lacustrine transgression. The lithological indicators and results of diatom analysis of lacustrine sediments of Lake Khanka indicate two sedimentation conditions over the period of 24.0–19.0 cal ka BP: an oligotrophic–mesotrophic moderately swampy shallow reservoir with an unstable level and a relatively deep lake. The maximum of the transgression occurred at ~19.6 cal ka BP, when the lake level was 1.5–2.0 m higher than at present for the first time. Four phases of the vegetation evolution in the western sector of the Khanka valley are distinguished: I, birch–larch mari with alder and frigid shrubs (23.8–22.8 cal ka BP); II, dark coniferous taiga with dwarf pine and a small amount of broad-leaved trees (22.8–20.6 cal ka BP); III, spruce forests with dwarf pine, fir, larch, and rare oak (20.6–20.1 cal ka BP); and IV, light birch forests and larch mari with frigid shrubs (20.1–19.0 cal ka BP). Two cooling phases are registered at the Khanka valley (~24.0 cal ka BP (cooling maximum) and 20.6 cal ka BP) and one warming phase (∼22.8 cal ka BP), which are correlated with the detailed global Greenland glacier records. The driest periods occurred at 21.7–21.2 cal ka BP. The quantitative characteristics of climate events are reconstructed from modern plant analogs. [ABSTRACT FROM AUTHOR]

The McMurdo Dry Valleys of Antarctica provide a testbed for alteration processes on Mars due to the cold, arid, and windy conditions. Analysis of three sediment cores collected from Don Juan Basin, Wright Valley, Antarctica, reveals that surface sediment formation is primarily dominated by physical alteration. Chemical alteration occurs sporadically in this region and is frequently indicated by the accumulation of sulfates and Cl-bearing salts. We investigated the effects of physical and chemical alteration in Don Juan Basin by considering major and trace element abundances in the sediments based on depth and location. Our results indicate inversely related chemical- and physical-alteration gradients with proximity to Don Juan Pond where the current center of the pond represents a more chemically altering environment and the perimeter a more physically altering one. Comparing calculated sulfate abundances for Don Juan Basin cores to rock and soil samples taken by the rover Curiosity at Gale crater, we observed that the core from within Don Juan Pond best matches Curiosity soil sulfate abundances. A new Chemical Index of Alteration equation that adjusts for salt dilution was also applied to the Antarctic cores and Curiosity rocks and soils. Our analysis indicates a significantly higher degree of chemical alteration than originally reported for most Antarctic and martian samples. Our investigation provides evidence for aqueous-based chemical alteration under cold, hyperarid conditions in Don Juan Basin, Antarctica. Our work also demonstrates the analogous nature of terrestrial microenvironments to similar, local-scale sample sites on Mars, thereby supporting past or present chemical alteration on Mars. [ABSTRACT FROM AUTHOR]

The sediment erosion of Pelton turbine components is a major challenge in the operation and development of high-head water resources, especially in mountainous areas with high sediment yield. In this paper, a study using numerical simulation was conducted with different sediment particle sizes in the fine sand range. And the erosion mechanism of the Pelton turbine injector was analyzed. The Eulerian Lagrange method was adopted to simulate the gas–liquid–solid flow. The Mansouri's model was applied to estimate the injector erosion. The predicted erosion results were in accord with field erosion photographs. In particular, the asymmetrical erosion distribution on the needle surface was physically reproduced. With the sediment particle size increasing from 0.05 mm, the needle erosion rate decreased, while the nozzle casing erosion rate increased dramatically. In order to clarify this tendency, the characteristics of the three-phase flow were analyzed. Interestingly, the results show that with the rise in particle size, the separation of particles and water streamlines became more serious in the contraction section of the nozzle mouth. Consequently, it caused the enhancement of erosion of the nozzle surfaces and weakened the erosion of the needle surfaces. Significant engineering insights may be provided for weakening Pelton injector erosion with needle guides in the current study. [ABSTRACT FROM AUTHOR]

Forests, serving as natural barriers in mountainous regions, can reduce surface erosion, enhance water flow resistance and facilitate sedimentation. While extensive research has been conducted for forests and their capacity to withstand debris flows, there has been relatively little investigation into the interactions between riparian forests and debris flows. In this paper, a field investigation of Keze gully was conducted through section surveys, quadrat surveys and unmanned aerial vehicle field investigations. Based on the flow calculation results, analysis of sediment characteristics, gully morphology change and analysis of stand characteristics, the interaction model between the riparian forest and debris flow in the complex channel was discussed. The results further emphasise the role of forests in mitigating debris flows. Furthermore, the results show that the identified critical slope for the study area provides a threshold to explain two different flow interaction dynamics with riparian forests. Above the critical slope, debris flows predominantly follow the main channel, where the root-soil complex of riparian forests reduces channel bank erosion. However, this erosion can also lead to the uprooting and destruction of trees. Below the critical slope, floodplains are vital in accommodating overflow. Debris flows interact not only with the roots of trees near the riverbank but also with the trunks of trees on floodplains. Trees with a diameter less than 30 cm may also suffer damage due to broken stems. [ABSTRACT FROM AUTHOR]

Paleoecological analysis of three lake sediment cores from the Roraima savannas in northern Brazil revealed systems dominated by Poaceae pollen throughout most of the Holocene. A slight increase of palms and woody taxa, probably linked to wetter conditions, is observed during the last 1000 years but is more noticeable after 300 and 150 calibrated years BP (yr BP) respectively. Charcoal was present throughout affirming the importance of fire for the landscape but showed the highest values mostly in the last millenium. Poaceae pollen size spectra varied considerably, showing more variability than the overall pollen record. Despite evidence of some climate change in the Holocene, these savannas were stable systems. The sedimentary records showed gaps in deposition between 10,000 and 7800 yr BP and between 2500 and 1200 yr BP, suggesting dry periods during which lakes most likely dried out or became impermanent and highlighting the sensitivity of these lakes to local water table variation. The establishment of the modern climate in the region is evident after 1000 yr BP. [ABSTRACT FROM AUTHOR]

Turbulent bursting events have been classified into outward interactions ( Q 1 ) , ejections ( Q 2 ) , inward interactions ( Q 3 ) , and sweeps ( Q 4 ) in various studies. Ejections ( Q 2 ) and sweeps ( Q 4 ) have been identified as significant contributors to time consumption, momentum flux, and sediment flux. Additionally, research has shown that the distribution of these events varies nonuniformly at different bed elevations. Despite extensive investigations into the nonuniform distribution of turbulent bursting events, their impact on sediment transport has been rarely explored. In this work, we developed a modified stochastic diffusion particle tracking model (SD-PTM) driven by skew Brownian motion (SBM) using the stochastic Lagrangian approach to scrutinize sediment particle movement in turbulent flows. The model incorporates turbulent characteristics derived from a direct numerical simulation dataset, allowing for a comprehensive analysis of sediment particle dynamics. Moreover, the proposed model accounts for the nonuniform spatial distribution of ejection and sweep events, as well as the particle movement direction during these events. Numerical simulations of the model were conducted to trace sediment particle trajectories in the streamwise and vertical directions. The analysis of sediment transport involved calculating the variance of particle trajectories to examine anomalous diffusion. The model's performance was evaluated by comparing it with flow velocity and sediment concentration profiles obtained from measurements in previous studies. In conclusion, our study suggests that the motion of sediment particles in turbulent flow can be thoroughly investigated under extreme flow conditions using the modified SD-PTM driven by SBM. [ABSTRACT FROM AUTHOR]

Lake Nasser is a freshwater lake that supplies over 95% of Egypt's freshwater budget. Therefore, the quality of water in the lake is critical for its conservation. In addition to assessing the metal pollution load, the quality of water and sediment in the lake was assessed by collecting water and sediment samples for metal content analysis. Lake Nasser is a warm monomictic water body with a single circulation cycle in the cold months. Dissolved oxygen content in bottom water samples often dropped significantly to levels below international guidelines, reflecting reduced rates of photosynthetic activity. Although 50% of the lake's water samples contained Pb concentrations slightly above the World Health Organization's (WHO) limit for drinking water, the metal pollution index did not exceed the critical level and was classified as low metal water pollution. Based on the geoaccumulation index (I-geo), the enrichment factor (EF) and the pollution load index, the sediments of Lake Nasser are practically uncontaminated with metals. Ni has the highest EF and I-geo values, while Ni and Cd contributed the most to the ecological risk and toxic risk index. The obtained results revealed that Cd and Ni in the sediments may pose a threat to organisms living in Lake Nasser. [ABSTRACT FROM AUTHOR]

Human impacts on lakes can lead to nutrient release, increased algal productivity and consequently low oxygen concentrations in deepwater environments. Here we report the unexpected and contrasting finding of a pronounced shift to chironomid and invertebrate assemblages suggesting oligotrophication and oxygen increase in Lac de Champex, a Swiss mountain lake, due to human activities during the Mediaeval period. Chironomid assemblages in the lower part of the lake sediment record show changes that agree with known climatic shifts during the Lateglacial period and early Holocene and a progressively stronger influence of peat development, and possibly humic conditions, from ca. 8500 calibrated 14C years BP (cal. BP) onwards. This resulted in low chironomid influx and assemblages with high abundances of Procladius and Chaoborus ca. 2000–3000 cal. BP. These assemblages resemble those found in relatively nutrient-rich, oxygen-poor lakes and may have developed due to natural, long-term development to more nutrient-rich and possibly humic conditions, and from the Bronze Age (ca. 4000 cal. BP) onwards, due to human activities such as pasturing. Ca. 1000 cal. BP, an abrupt increase in sediment accumulation, chironomid influx and distinct changes in the chironomid assemblage composition were observed, coinciding with evidence for local human activities from pollen data. A major transition in chironomid and invertebrate assemblages followed ca. 500 cal. BP with the disappearance of Chaoborus, a decrease in Procladius, and the increase or appearance of several chironomid taxa, including several rheophilous groups. We conclude that Late-Holocene human impact led to re-oligotrophication and increased oxygen availability for invertebrates in the lake. This reversal of the long-term Holocene trend was possibly promoted by increased erosion from the Mediaeval period onwards and from ca. 500 cal. BP likely by the construction of an irrigation canal (bisse), leading to inflow of clear, cool water which changed the lake's hydrological characteristics. [ABSTRACT FROM AUTHOR]

Estuarine sediment transport is driven by the combined action of a multitude of influencing factors, including astronomical tides, waves dynamics, and river discharges. This study focuses on the effects of wave forces on sediment transport patterns in micro-tidal estuaries near Wanbao Beach, China. Numerical simulations are carried out using Delft3D. Modeling scenarios are configured using different wave characteristics, spanning from typical waves to those with a return period of 50 years. Results show that waves have a positive effect on landward sediment transport, resulting a larger active range of sediment. By comparing the spatial geomorphic variations under varying wave conditions, we find that modifications in significant wave height (Hs) primarily impact the position of erosion and deposition zones, whereas alterations in spectral peak period (Tp) predominantly influence the magnitude of these changes. The finding is further demonstrated by a comparison of residual currents under different wave intensities. Analysis of sediment transport rates in different transects indicates that the sediment transport rate is highest at the mouth transects and lowest at the alongshore transects. Moreover, variations in sediment transport rates exhibit distinctive patterns between the two outlet transects, even when subjected to identical wave conditions. The disparities are attributed to differences in runoff and the topographical features in proximity to the estuaries. Additionally, we find the sediment transport rate becomes insensitive to the variations in Hs when Hs is larger than a threshold value. The threshold decreases with increasing Tp. [ABSTRACT FROM AUTHOR]

The ever-increasing applications of metabarcoding analyses for environmental samples demand a well-designed assessment of the stability of DNA and RNA contained in cells that are deposited or buried in marine sediments. We thus conducted a qPCR quantification of the DNA and RNA in the vegetative cells of three microalgae entrapped in facsimile marine sediments and found that >90% of DNA and up to 99% of RNA for all microalgal species were degraded within 60 days at 4 °C. A further examination of the potential interference of the relic DNA of the vegetative cells with resting cyst detection in sediments was performed via a metabarcoding analysis in artificial marine sediments spiked with the vegetative cells of two Kareniaceae dinoflagellates and the resting cysts of another three dinoflagellates. The results demonstrated a dramatic decrease in the relative abundances of the two Kareniaceae dinoflagellates in 120 days, while those of the three resting cysts increased dramatically. Together, our results suggest that a positive detection of microalgae via metabarcoding analysis in DNA or RNA extracted from marine sediments strongly indicates the presence of intact or viable cysts or spores due to the rapid decay of relic DNA/RNA. This study provides a solid basis for the data interpretation of metabarcoding surveys, particularly in resting cyst detection. [ABSTRACT FROM AUTHOR]

Compounded assessment of heavily polluted areas can be a challenge, especially in mostly heavy industrial region such Upper Silesia (Poland). The main and the biggest river flowing through this region is Kłodnica River. This study presents an application of multivariate data analysis in the field of river sediments pollution. The dataset consists of As, Cd, Cr, Cu, Fe, Ni, Mn, Pb, and Zn contents in sediment samples collected from the Kłodnica River (Poland) in sampling campaigns (2013 and 2014). As chemometric statistic tools cluster analysis (CA), multivariate analysis of variance and discriminant analysis (MVDA) and factor analysis (FA) were used to investigate the matrix of 32 sampling points. The cluster analysis presents that pollution can be distinguished into three groups which were strongly dependent of the contamination's concentrations (As, Cd, Cu, Pb, and Zn) and the localization of the samples. Multivariate analysis of variance and discriminant analysis confirms the results from the CA. This method was used also to apply real reduction in the tested matrix dimension by use of forward strategy. In the 4th step of that strategy the variables As, Cd, Cu, Pb, and Zn are sufficient to describe the variability in the river sediments and to separate the groups of sampling points. Two factors obtained from the factor analysis explained approximately 61 % of the total variance of the river system and allow distinguish of the dominant anthropogenic pollution sources in the river system. Factor 1 describes 36.74 % of the common variance and is highly loaded by As, and Cd. Factor 2 induces pollution with Cu, Pb and Zn and explains 24.67 % of the common variance. The interpretation of factor analysis was presented by the representation of factor scores as a function of the Kłodnica River-kilometers. [ABSTRACT FROM AUTHOR]

Shallow thermokarst lakes are important sources of greenhouse gases (GHGs) such as methane (CH4) and carbon dioxide (CO2) resulting from continuous permafrost thawing due to global warming. Concentrations of GHGs dissolved in water typically increase with decreasing lake size due to coastal abrasion and organic matter delivery. We hypothesized that (i) CH4 oxidation depends on the natural oxygenation gradient in the lake water and sediments and increases with lake size because of stronger wind‐induced water mixing; (ii) CO2 production increases with decreasing lake size, following the dissolved organic matter gradient; and (iii) both processes are more intensive in the upper than deeper sediments due to the in situ gradients of oxygen (O2) and bioavailable carbon. We estimated aerobic CH4 oxidation potentials and CO2 production based on the injection of 13C‐labeled CH4 in the 0–10 cm and 10–20 cm sediment depths of small (~300 m2), medium (~3000 m2), and large (~106 m2) shallow thermokarst lakes in the West Siberian Lowland. The CO2 production was 1.4–3.5 times stronger in the upper sediments than in the 10–20 cm depth and increased from large (158 ± 18 nmol CO2 g−1 sediment d.w. h−1) to medium and small (192 ± 17 nmol CO2 g−1 h−1) lakes. Methane oxidation in the upper sediments was similar in all lakes, while at depth, large lakes had 14‐ and 74‐fold faster oxidation rates (5.1 ± 0.5 nmol CH4‐derived CO2 g−1 h−1) than small and medium lakes, respectively. This was attributed to the higher O2 concentration in large lakes due to the more intense wind‐induced water turbulence and mixing than in smaller lakes. From a global perspective, the CH4 oxidation potential confirms the key role of thermokarst lakes as an important hotspot for GHG emissions, which increase with the decreasing lake size. [ABSTRACT FROM AUTHOR]

Background: Lupus nephritis (LN) is one of the most severe manifestations of systemic lupus erythematosus (SLE). There are increased studies examining the role of different markers that would facilitate diagnosis, LN activity' monitoring, relapse occurrence, and the right time to introduce maintenance therapy. We aimed to examine the importance of determining the neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), systemic immune-inflammatory index (Sil) and systemic inflammatory response index (SIRI) in LN, comparing their significance with other standard parameters of active disease. Methods: The clinical examination included 66 patients (34 with active and 32 with LN in remission) and 23 healthy controls. The investigated parameters were CRR CBC, creatinine, albumin, GFR, C3, C4, ANA, anti-ds DNA Ab, in urine: sediment analysis, SLEDAI/r, proteinuria 24h and Up/cre. We determined the derived markers: NLR, PLR, SIRI, and Sil and their correlation with other parameters of active disease. Results: Comparing the group with active LN with LN in remission and the control group, a statistically significant difference was obtained for CRP (p=0.004) and RBW and haemoglobin, albumin, C3, ANA and anti-ds DNA Ab (p<0.001) and for urinary parameters, SLEDAI/r, proteinuria 24h and Up/cre ratio. Comparing the markers: NLR, PLR, SIRI, and Sil between the groups, a significant difference can be observed for all selected parameters; for NLR, it was the most pronounced (p<0.001). In active LN, NLR correlated with CRR creatinine, SLEDAI/r and proteinuria 24h, PLR with ANA, SIRI with CRR creatinine, GFR, C5, anti-ds DNA Ab, and SI I with CRR NLR in collective group LN, was the parameter with the highest significance in correlations with C3, albumin, SLEDAI/r and proteinuria (p=0.000), ANA (p=0.001), anti-ds DNA Ab (p=0.004) and Up/cre (p=0.018). Conclusion: Our results indicate that NLR, PLR, SIRI, and Sil are elevated in the group of patients with active LN and that the correlations of those biomarkers with other activity parameters can be significant for evaluating renal lesions in LN. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) belong to the persistent organic pollutant class and are ubiquitously present in the environment. As a consequence of their high hydrophobicity, PAHs in aquatic environments tend to rapidly sink down to the bottom sediments which are the most important reservoirs of PAHs in the aquatic environment. This paper presents the validation and further performance evaluation of a method modified in-house for PAHs' sample preparation and analysis in sediment using gas chromatography-mass spectrometry (GC-MS). The method validation covers determining the calibration linear range, method detection and quantitation limits, method recovery and precision, method uncertainty and further internal and external quality control steps. Principal component analysis was used to identify the influence of different variables on method performance and indicated main clustering by PAH molecule size. The results of a two-year quality control programme show that the variations in method performance were not statistically significant in comparison to the parameters set during the validation experiments. Trueness expressed as recovery was very similar for spiked sediment samples and the analysed certified reference material (CRM) (70.6–113%). Expanded uncertainty ranged from 40.4% to 50.9% with higher values noted for the highly hydrophobic PAHs benzo(a)pyrene and benzo(g,h,i)perylene. [ABSTRACT FROM AUTHOR]

The preliminary results of geochemical analyses of the surface sediments from 4 lakes on Robert Island, South Shetland, Antarctica, are presented herein. The samples were collected during the Turkish Antarctic Expedition (TAE-II) in 2018. Sediment samples were obtained from the littoral zone (approximately 20 cm) of 4 different lakes exposed on the glacier-free land area on Robert Island. The lake sediments predominantly consist of fine-grained sand, clay, and silt particles. These particles include Fe-shale and graywacke geochemical characteristics. Their plagioclase index of alteration, chemical index of weathering, chemical index of alteration, and other weathering index values, suggest that the studied sediments have likely undergone low to moderate weathering and alteration processes. The Th/U ratios generally indicated a lower distribution relatively to the upper continental crust, and they displayed slight enrichment in alkali elements, indicating a low degree of chemical weathering that has slightly influenced the sediment chemistry. Moreover, the Gd/Yb, Zr/Y, and La/Yb ratios exhibited similarities with the surrounding volcanic rocks on Robert Island. Additionally, their chondrite-normalized rare earth element (REE) patterns exhibited a similar trend, implying that the REE composition of the sediments is predominantly controlled by the local source rocks. Nevertheless, there were slight differences in the Y/Ho ratios and heavy REE (HREE) contents, suggesting the presence of additional sources contributing to the REE supply in the lake basins. The Co/Th, La/Sc, Th/Sc, and Zr/Sc ratios mostly resembled those of basic volcanic rocks, while the Rb, K, HREE, and Ni values dominantly indicated basic rocks with a minor input from felsic magmatic or quartzose sedimentary rocks. Considering the geomorphology and location of the basins, which are mostly situated along the coast where foehn winds have a limited influence over ice-free areas, it is likely that locally resuspended materials have had a significant impact. This factor may mask any potential signals of modern dust fallout and accumulation. However, possible dust sources include nearby or distant areas, such as exposed rock and sediment within the immediate vicinity of the lakes, including dry lakebeds, glacial outwash plains, or exposed moraines. Based on multiproxy element analyses, including REEs, high field strength elements, and lithophile elements, the geochemistry of the studied sediments, the overall geochemical characteristics cannot be fully explained by the local sources, suggesting that weathering processes and minor contributions from dust materials have played a nonnegligible role in shaping their chemistry. [ABSTRACT FROM AUTHOR]

This study assesses the spatial distribution and contamination level of heavy metals in Safi Bay surface sediments. In this order, 28 surface sediment samples were retrieved from the study area and analyzed using the x-fluorescence method. To assess the contamination of the examined sediment, we used geo-ecological indices such as contamination factor (CF), degree of contamination (DC), geo accumulation index, and pollution load index (PLI). The results show that only Pb and Cd present moderate and considerable contamination in some sampling sites, while other elements (Cr, Cu, Zn, and Ni) indicate no contamination and low contamination by these elements. The inhomogeneous distribution of metal concentrations along the bay suggests different heavy metal sources. Given the ecological and socioeconomic importance of the study area, there is a need for a further analysis of both sediments and biological samples for a better understanding of the contamination levels and origin of metals, in addition to the sustainability of Safi Bay. [ABSTRACT FROM AUTHOR]

The analysis of exceptionally well-preserved visible clastic laminations in deep alluvial sediments at Kempsey, Worcestershire (UK), allows a new high-resolution analysis of late-Holocene flood-history in the largest UK catchment, as well as local human response. At the sample site over 4.5 m of sandy-silt overbank-alluvium accumulated on the floodplain and optically stimulated luminescence (OSL) dating of the upper 2.25 m demonstrates accretion from the late 14th century CE onwards. Sub-centimetre to centimetre resolution multi-proxy sediment analysis (loss on ignition, magnetic susceptibility, particle size, ITRAX and portable XRF) demonstrate clear variations in depositional history over the last millennium due to channel stability. Between c. 1380 and 1550 CE overbank sedimentation was driven by lower energy flood events, with negligible effect from climatic conditions during the Spörer Minimum (1460–1550 CE). After c. 1550 CE the magnitude of flooding events increased and by c. 1610 CE, the start of the visible sub-centimetre laminations, the accumulation rate regularly exceeded 3 mm year−1, which increased to 4.5 mm year−1 between c. 1690 and 1710 CE, and 3 and 3.5 mm year−1 between c. 1790 and 1840 CE before alluviation was altered by an embankment. The greatest extent of coarse overbank deposition and increased accumulation rate occur concurrently with periods of climatic instability associated with the Maunder (1645–1715 CE) and Dalton (1790–1820 CE) Minima, the periods of largest historical floods and during the intensification of arable cultivation across the middle Severn catchment. This data correlates well with other sites in the catchment suggesting that these are basin-wide forcing-responses. We also present evidence that this catchment-wide hydro-geomorphological history had local effects in shifting the geographical focus of an important settlement away from its historic floodplain edge location – which can be viewed as an adaptation to the flood risk. [ABSTRACT FROM AUTHOR]

Nonstationary calculation of sediment load is an important basis for reservoir operation and management. The Jinsha River Basin (JRB) is the most important sediment-producing section of the Yangtze River, and the main source of sediment into the Three Gorges Reservoir (TGR). In this study, three sediment transport nonstationary analysis models were constructed through the Generalized Additive Models for Location, Scale and Shape (GAMLSS) model, namely Mode0, Mode1 and Mode2. The study found that the correlation coefficients between sediment load with runoff and rainfall are 0.78 and 0.73, respectively. Runoff and precipitation can be used as covariates for the nonstationary analysis of sediment transport. The optimal edge distribution of Mode0, Mode1, and Mode2 is Gumbel, Weibull, and Logistic, respectively. Mode2 can accurately describe the nonstationary change of sediment load, and Mode1 can basically reflect the nonstationary change of sediment load. While Mode0 is a consistent model, which cannot reflect the nonstationary change of sediment load over time. Mode2 has a good ability to simulate the quantile changes of sediment load during the training period and the test period, while Mode1 has a weak generalization ability. Mode0 cannot reflect inconsistent changes, and the simulation result is a fixed value. This study provides an important reference for the nonstationary analysis of sediment load under inconsistency conditions in the JRB. [ABSTRACT FROM AUTHOR]

The work by Raposeiro et al. ([6]) is very useful in that, contrary to the opinion of Elias et al. ([4]), it provides strong and widespread support for pre-Portuguese human colonization of the Azores archipelago and the ensuing landscape impact (Rull, [8]). Coring localities after Connor et al. ([2], [1]); Rull, Lara, et al. ([10]) and Raposeiro et al. ([6]). gl Raposeiro et al. ([6]) contended that the Azorean archipelago was settled by the early Middle Ages (700-850 CE), much earlier than the Portuguese occupation in the 15th century. Simplified from Rull, Lara, et al. ([10]). gl Another issue is the inaccuracy of some representations, including the cereal - Cerealia, not "Cerealea", as repeatedly stated by Raposeiro et al. ([6]) - pollen, one of the most important proxies for anthropogenic impact. [Extracted from the article]

The studied crevasse-splay complex, situated within the 1st Mid-Polish lignite seam (MPLS-1), ranks amongst the best-developed and most readily accessible for direct research of all hard coal and lignite occurrences worldwide. The sandy-coaly sediments constituting it required a number of field and laboratory tests. However, the present article focuses solely on sedimentological and statistical analyses of sediments along a selected key section, the most important results of which are presented below. First of all, data obtained in previous sedimentological studies have been confirmed, in that individual segments of this complex represent both subaerial and subaqueous types of crevasse splays. On the one hand, their sediments are characterised by an extremely high content of coalified organic matter, reaching 20–40 wt.% in some samples; on the other, these crevasse splays are composed of fine sands with a median and mean grain size of 0.15 mm. In addition, the remaining statistical parameters (standard deviation, skewness and kurtosis) indicate a very good sorting of these sands, no significant so-called 'tails' and a better sorting close to the sediment mean grain size value, respectively. [ABSTRACT FROM AUTHOR]

Subsurface stratigraphic modeling is crucial for a variety of environmental, societal, and economic challenges. However, the need for specific sedimentological skills in sediment core analysis may constitute a limitation. Methods based on Machine Learning and Deep Learning can play a central role in automatizing this time-consuming procedure. In this work, using a robust dataset of high-resolution digital images from continuous sediment cores of Holocene age that reflect a wide spectrum of continental to shallow-marine depositional environments, we outline a novel deep-learning-based approach to perform automatic semantic segmentation directly on core images, leveraging the power of convolutional neural networks. To optimize the interpretation process and maximize scientific value, we use six sedimentary facies associations as target classes in lieu of ineffective classification methods based uniquely on lithology. We propose an automated model that can rapidly characterize sediment cores, allowing immediate guidance for stratigraphic correlation and subsurface reconstructions. [ABSTRACT FROM AUTHOR]

Cyanobacterial blooms in aquatic environments have impacted ecosystem health, altered food webs and contributed to substantial regional economic losses. The relative impacts of climate change, eutrophication and other environmental stressors on the formation of cyanobacterial blooms remain unclear as a consequence of the lack of long‐term data. The analysis of lake sediment archives can help address such questions.The abundance of target cyanobacterial genes was quantified using droplet digital PCR from two experimental and two reference lakes at the IISD ‐ Experimental Lakes Area, Northwestern Ontario, Canada where various anthropogenic drivers have been manipulated and phytoplankton biomass and taxonomy (via microscopy) tracked over the past 50 years.Based on sediment DNA (sedDNA) records, Lake 227 has seen more than two full orders of magnitude rise in cyanobacterial abundance in response to experimental nutrient (nitrogen and phosphorus) loading since 1969. Lake 223 also experienced a small increase in cyanobacterial abundance during a period of experimental acidification. The sedDNA archives also identified an increase in abundance of mcyE, a gene involved in microcystin synthesis, in Lake 227 after 1990 when experimental nitrogen loading ceased and only phosphorus loading continued. Sequencing of the cyanobacterial 16S rRNA gene from sedDNA revealed a shift towards Nostocales dominance in response to eutrophication in Lake 227; this was also seen in the more recent sediments of the other lakes but to a much lesser extent.When comparing the sedDNA data with historical phytoplankton records of the past ~50 years, moderate‐to‐strong correlations were found between the two. This research validated the use of sedDNA for the analysis of long‐term trends in lakes and the results revealed additional changes that were not recorded from the surface‐water records.Experimental nutrient loading had the greatest influence on the cyanobacterial community in Lake 227. However, climate change, via declines in heating degree days, was also significant in explaining variation in the cyanobacterial communities in the experimental lakes as well as the reference lakes. [ABSTRACT FROM AUTHOR]

The middle and lower reaches of the Yangtze River and its adjacent areas contain abundant mineral resources, especially porphyry–skarn–stratabound Cu–Au–Mo–Fe deposits, and still have great potential for mineral prospecting. In this paper, geochemical blocks and local singularity mapping methods were used to delineate the spatial distribution pattern of Cu and identify the geochemical anomalies related to Cu deposits. Six copper geochemical blocks, each with an area of more than 1000 km2, were all spatially consistent with the locations of the five Cu ore districts (Edongnan, Jiurui, Anqing-Guichi, Tongling, and Ningzhen) and one ore field (Dexing) in the study area. Thus, geochemical blocks delineated with low-density geochemical data can effectively track the locations of ore districts or large ore deposits. Most of the known Cu deposits in the study area were located in anomalous areas with singularity indices less than 1.741 in the Cu singularity map. The singularity analysis could reduce the anomalous areas and identify the geochemical anomalies related to Cu deposits effectively. Geochemical blocks combining a local singularity mapping method is an effective tool for identifying prospecting targets. [ABSTRACT FROM AUTHOR]

A comparative analysis between water and sediment can provide better information to understand the dynamics of the inhabitant microbiome and their respective antibiotic resistance genes of a river. Therefore, the present investigation was carried to explore the limited information available on bacterial microbiome and their predictive antibiotic resistance genes (ARGs) from water and sediment of the Ganga River. The study utilized the NGS-based sequences previously submitted under the accession number (PRJNA847424 and PRJNA892876). Overall analysis revealed that twenty phyla and fifty-four genera were shared between the water and sediment of the Ganga River. Of them, nine phyla and nineteen genera were observed as significantly different (p-value < 0.05). Where the majority of the genera were associated with the sediment samples over the water that identify the sediment samples as more diverse for species richness. Similarly, seventy-six ARGs were shared between water and sediment samples. Of the ten abundant antibiotic resistance pathways, seven were relatively abundant in sediment samples as compared to the water. Vancomycin resistance genes were significantly more abundant among sediment samples, whereas β-lactam resistance genes were equally distributed in water and sediment samples. The network analysis further revealed that five genera (Flavobacterium, Pseudomonas, Acinetobacter, Candidatus_divison CL5003, and Candidatus_division SWB02) showed a significantly positive correlation with six antibiotic resistance pathways (β-lactam, vancomycin, multidrug resistance, tetracycline, aminoglycoside, and macrolide resistance pathways). The study comes out with several findings where sediment may be considered as a more atrocious habitat for evolving the resistance mechanisms against threatful antibiotics over the water samples of the Ganga River. [ABSTRACT FROM AUTHOR]

Background: Urine sediment examination provides numerous information about patient's kidney condition. Flowcytometry and digital imaging system could conduct automatic urine sediment analysis. Therefore, determining the diagnostic performance of the examination is very important in the management carried out by the clinician. This study aims to determine the diagnostic performance of urine flowcytometry and digital imaging sediment examination tools compared to manual microscopes that are standardized as gold standards. Methods: This study is an analytical observational study with a cross-sectional approach on 92 urine samples of patients who attended the Internal Medicine Nephrology Polyclinic of Dr. Soetomo Academic Hospital Surabaya. The performance of flowcytometry and digital imaging methods is assessed by calculating sensitivity and specificity. Analysis of the suitability of each urine sediment parameter used Cohen's kappa. Urine sediment analysis with a light microscope was conducted with the Shih-Yung method as a gold standard. Results: The erythrocyte parameters revealed a very favorable result with the concordance of the flowcytometry with the Shih-Yung method (κ=0.82) and fair results for WBC (κ=0.25), Epithelium (κ=0.57) and Cast (κ=0.27). At the same time, yeast had substantial conformity (κ=0.63). The digital imaging method showed substantive fit for WBC (κ=0.676), RBC (κ=0.621), fair for SEC (κ=0.42) and NSE (κ=0.24), moderate for Yeast (κ=0.45), and slight for Hyaline Cast (κ=0.074) and Path Cast (κ= 0.134) Conclusion: The urine flowcytometry demonstrates better performance compatibility with a standardized manual microscope compared to urine digital imaging. However, pathological samples should still be verified with a manual microscope. [ABSTRACT FROM AUTHOR]

Abandoned rookeries belonging to any of the Pygoscelis species are very particular taphocoenosis, usually preserved due to the accumulations of bones, pebbles, and guano year after year in the same nesting area, that condense together with other biogenic material and form ornithogenic sediments. The results of the excavation, sieved and analyses of sediment and materials found in two rookeries formed during the last 8000 years, named Pingfo I and Pingfo II and found in the 25 de Mayo/King George Island (South Shetland Islands, West Antarctica) are presented here. The analyses of the bones and eggshells, taxonomic and ontogenetic composition, elements representation, transport degree, predation, and scavenging marks, together with the micropalaeontological content provided informative tools for the reconstruction of the nesting areas, suggesting that bones were transported and accumulated in Pingfo I that would represent high energy beach, whereas a breeding colony was settled in Pingfo II. The preservation of hexactinellid spicules and several arthropod remains are particularly informative for the levels at Pingfo I. The preservation of a Culicidae (Diptera) wing could be the first middle Holocene record of the group in Antarctica, the only continent without extant mosquitoes. [ABSTRACT FROM AUTHOR]

Fundamental understanding of paleoecological proxies is necessary when attempting to compare, complement, or contrast two or more methods, and lack thereof may lead to erroneous conclusions. This comment addresses three such misunderstandings found in a recently published paper by Paillard et al. regarding soil macrofossil charcoal analysis (SMCA) and its relationship to lacustrine sediment analysis. The aim is to correct some misinformation associated with the following three assertions: (1) Broadleaved tree species produce fewer charcoal fragments than coniferous species. Although coniferous stands are more fire-prone, experimental burning shows that species with denser wood, that is, broadleaves, produce greater amounts of charcoal under similar fire conditions. (2) Preservation of charcoal particles is poor at the referenced study site. Once buried in the mineral soil compartment, charcoal particles remain quite stable. As such, SMCA has revealed Late Pleistocene marginal stands of broadleaved species. (3) Underestimating the importance of range-edge dynamics on the results of SMCA reconstructions. SMCA offers a stand-scale historical reconstruction that has proven well-suited to study peripheral stands and to reflect the heterogeneity of a landscape mosaic. By attempting to reconcile the SMCA (in situ) and lake sediments (ex situ) narratives, Paillard et al. missed one key aspect of comparing complementary proxies: they show different aspects of the past. [ABSTRACT FROM AUTHOR]

Automated urine sediment analysis has become an essential part of diagnosing, monitoring, and treating various diseases that affect the urinary tract and kidneys. However, manual analysis of urine sediment is time-consuming and prone to human bias, and hence there is a need for an automated urine sediment analysis systems using machine learning algorithms. In this work, we propose Swin-LBP, a handcrafted urine sediment classification model using the Swin transformer architecture and local binary pattern (LBP) technique to achieve high classification performance. The Swin-LBP model comprises five phases: preprocessing of input images using shifted windows-based patch division, six-layered LBP-based feature extraction, neighborhood component analysis-based feature selection, support vector machine-based calculation of six predicted vectors, and mode function-based majority voting of the six predicted vectors to generate four additional voted vectors. Our newly reconstructed urine sediment image dataset, consisting of 7 distinct classes, was utilized for training and testing our model. Our proposed model has several advantages over existing automated urinalysis systems. Firstly, we used a feature engineering model that enables high classification performance with linear complexity. This means that it can provide accurate results quickly and efficiently, making it an attractive alternative to time-consuming and biased manual urine sediment analysis. Additionally, our model outperformed existing deep learning models developed on the same source urine sediment image dataset, indicating its superiority in urine sediment classification. Our model achieved 92.60% accuracy for 7-class urine sediment classification, with an average precision of 92.05%. These results demonstrate that the proposed Swin-LBP model can provide a reliable and efficient solution for the diagnosis, surveillance, and therapeutic monitoring of various diseases affecting the kidneys and urinary tract. The proposed model's accuracy, speed, and efficiency make it an attractive option for clinical laboratories and healthcare facilities. In conclusion, the Swin-LBP model has the potential to revolutionize urine sediment analysis and improve patient outcomes in the diagnosis and treatment of urinary tract and kidney diseases. [ABSTRACT FROM AUTHOR]

The arid region of Mongolia is sensitive to climate change. Understanding of climate variations in the past plays an important role in predicting further climate changes. In this study, we aim to investigate the relationship between the climatic factor and sedimentation history in the late Holocene. We analyzed the 18TS1 core sample (136 cm in length) from the Tsagaan lake in the Valley of the Gobi Lakes, Mongolia. The sediment core mainly consists of clay and silt sediments, occasionally interrupted by the sand-dominated layers. 210Pb dating method is applied and indicates that the upper 24 cm sediment spans the sedimentation history of the last 87 years. Along-core variations in sediment characteristics such as organic matter, carbonate, and amorphous silica abundance are indicative of the drought -inducing period based on the significant correlations between sediment characteristics and Self-calibrated Palmer Drought Severity Index. Moreover, the enrichment of carbonates is a great indicator of shallow lake conditions prior to the lake disappearance during the dry period. The chemical composition of sand-dominated units in the sediment core well agrees with that of sand sheets and sand dunes in the catchment. Modern expansion and migration of sand sheets are identified by aerial photo imagery. The insufficient sediment chronology is limiting our interpretation, though; the comparison with the other paleoclimate records helps the establishment of environmental changes in the last millennium. [ABSTRACT FROM AUTHOR]

The Paisley Cave archeological site in the Northern Great Basin has provided a rich archaeological record from 13,000 to 6000 cal yr BP, including abundant mammalian coprolites preserved in a well-dated stratigraphy. Here we analyze and contrast pollen from within coprolites and pollen in associated sediments to examine vegetation history and assess whether coprolite pollen provides unique information with respect to the coprolite producer, such as the use of specific habitats, foods, or water sources. We found that the dissimilarity of pollen assemblages between coprolites and associated sediments was greater than the serial dissimilarity between stratigraphically adjacent samples within either group. Serial dissimilarity within types was not greater for coprolites than sediments, as would be expected if there were unique pollen signatures derived from the short period (1–2 days) represented by each coprolite. Compared with sediment pollen assemblages, the coprolites had higher abundances of lighter pollen types, and some individual samples were high in wetland taxa (especially Typha). Our results are consistent with coprolite pollen representing short time periods collected as a mammal moves on the landscape, whereas sediment pollen reflects longer time periods and more regional vegetation indicators. [ABSTRACT FROM AUTHOR]

Sedimentary records from the Kumtag (also known as Kumtagh) Desert (KMD) in northwestern China are investigated to better understand Late Quaternary paleoenvironmental changes in this hyper-arid region. Presented here are the results of probably the first systematic survey of sedimentary sequences from the KMD, with the chronology determined by the optically stimulated luminescence dating. The variation of sedimentary facies, supported by granular and geochemical paleoenvironmental proxies, is used to decipher the history of Late Quaternary environment changes. The results demonstrate that a constantly dry condition characterized the eastern KMD since the last glacial maximum, but with occurrences of wetter periods. From ca. 17 to 15 ka, fluvial activity was probably triggered by melting of glaciers in mountains located south of the KMD. A distinctly drier stage (ca. 13–7 ka) was recognized due to the prominent occurrence of aeolian sands. A wetter environment likely persisted between ca. 4.4 and 2.2 ka, consistent with evidence of human activities. While the causes of paleoenvironmental changes in the eastern KMD are still a matter of debate, the melting of glaciers in the Altyn-Tagh Mountains in the south must be considered as an important factor. [ABSTRACT FROM AUTHOR]

Coastal evolution is influenced by past sea-level changes and resultant shifts from fluvial- to marine-dominant environments and the accompanying significant geochemical and isotopic changes in the water mass and sediments. We investigated the elemental and isotopic features of coastal sedimentary cores (27 m in length) from a small paleo-bay located on the southern coast of Korea to determine such geochemical variability and specify past changes in the bay environment and anoxic conditions and possible links to past climate changes. We analyzed total organic carbon (TOC), total sulfur (TS), their isotopes (δ13CTOC and δ34STS), and pyrite. The δ13CTOC values ranging from −25 to −19‰ (a proxy for terrestrial influence) were lower than average (−22.5‰) before 8300 cal yr BP and since 500 cal yr BP, while the intervening Early to Late Holocene showed higher δ13CTOC values, indicating a shallow coastal environment. The δ34STS values fluctuating between −35 and +5‰ resembled sedimentation rate change. Based on the changes in the ratios of TOC to TS (C/S ratios), sedimentation rate, and δ34STS, we found five possible periods with higher salinity and intensified anoxic conditions at millennial timescales: 8900–8200, 7950–6500, 5200–4300, 3500–2600, and 2000–1100 cal yr BP. These intensified anoxic conditions seem to have been influenced by increased air temperature and sea-surface temperature conditions, which could have intensified the intensity of thermal stratification (less ventilation and mixing) between surface and bottom waters and resultant anoxic conditions. [ABSTRACT FROM AUTHOR]

A 13.0 cal ka BP pollen record from Twin Ponds, Vermont, provides new insights into the climate history of the northeastern United States. Modern analogs were used to produce qualitative and quantitative climate reconstructions for Twin Ponds. The Twin Ponds record was compared with nearby Knob Hill Pond to develop a Vermont reconstruction that was compared with reconstructions from two sites at a similar latitude. Postglacial warming at 11.5 cal ka BP followed a cool, wet Younger Dryas and was the largest temperature change of the record. The warmest, driest conditions occurred at ca. 9.0 cal ka BP, followed by an increase in moisture. Latitudinal and elevational shifts in the location of modern analogs from 5.7 to 4.0 cal ka BP were used to infer cooling and increased moisture during the Tsuga canadensis decline. Analysis of the timing of pollen events between the two Vermont sites suggests a more rapid decline in T. canadensis at the more northern Knob Hill Pond and further supports the possibility that colder temperatures contributed to this event. The other northern sites show similar trends until 2.5 cal ka BP, when precipitation in the easternmost site diverges, indicating the establishment of modern climatic gradients. [ABSTRACT FROM AUTHOR]

Mechanisms related to sub‐seabed fluid flow processes are complex and inadequately understood. Petrophysical properties, availability of gases, topography, stress directions, and various geological parameters determine the location and intensity of leakage which change over time. From tens of seafloor pockmarks mapped along Vestnesa Ridge on the west‐Svalbard margin, only six show persistent present‐day seepage activity in sonar data. To investigate the causes of such restricted gas seepage, we conducted a study of anisotropy within the conduit feeding one of these active pockmarks (i.e., Lunde Pockmark). Lunde is ∼400–500 m in diameter, and atop a ∼300–400 m wide seismic chimney structure. We study seismic anisotropy using converted S‐wave data from 22 ocean‐bottom seismometers (OBSs) located in and around the pockmark. We investigate differences in symmetry plane directions in anisotropic media using null energy symmetries in transverse components. Subsurface stress distribution affects fault/fracture orientations and seismic anisotropy, and we use S‐wave and high‐resolution 3D seismic data to infer stress regimes in and around the active seep site and study the effect of stresses on seepage. We observe the occurrence of changes in dominant fault/fracture and horizontal stress orientations in and around Lunde Pockmark and conclude minimum (NE‐SW) and maximum (SE‐NW) horizontal stress directions. Our analysis indicates a potential correlation between hydrofractures and horizontal stresses, with up to a ∼32% higher probability of alignment of hydrofractures and faults perpendicular to the inferred minimum horizontal stress direction beneath the Lunde Pockmark area. Plain Language Summary: Hydrocarbon gases, mostly methane, leak from the seabed into the ocean at different locations worldwide. Methane is a potent greenhouse gas, therefore understanding the natural processes of methane release has important implications for climate research. We investigate the role of regional and local stresses in controlling an ongoing gas leakage at Vestnesa Ridge, offshore west‐Svalbard. For this, we study the behavior of shear (S)‐waves, recorded by 22 sensors on the seabed, around a geological feature (pockmark) that releases methane at the present day. S‐waves propagate in relation to the orientation of subsurface faults, fractures and stresses. S‐wave data analysis indicates a change of stress in shallow (<150–200 m below the seafloor) sediments across the pockmark. We observe that the preferred orientation of fractures releasing methane into the ocean, matches the orientation of the stresses predicted from the wave analysis. This study advances our understanding of the influence of local and regional geological processes on the release of methane from the seabed. Key Points: The S‐wave analysis using ocean‐bottom seismic (OBS) data indicates seismic anisotropy around a seeping pockmark on the W‐Svalbard MarginThe occurrence and orientation of symmetry planes in shallow anisotropic sediments vary across the pockmarkCombined analyses using S‐wave and 3‐D seismic data suggest that preferred fault and fracture orientations follow local stress conditions [ABSTRACT FROM AUTHOR]

A geochemical review of Pleistocene sediments in the Indian Ocean has been accomplished based on the deep-sea drilling cruise reports and other literature references. We compiled the database including more than 2000 chemical analyses of sediment samples and tables showing the mean arithmetic composition of lithogenic and biogenic sediments. All data were PAAS-normalized. The dominant role of terrigenous clastics is revealed in the formation of the chemical composition of noncarbonate sediments and noncarbonate matter in planktonic carbonates. The results made it possible to establish the main geochemical associations together with three main (terrigenous, carbonate, and hydrogenous) factors determinating the sediment composition. We calculated the weighted mean chemical composition, as well as the element accumulation rate in the sediments and their mass accumulation rates. All these parameters of the chemical composition can be used for the comparative analysis, with analogous parameters in other ocean sediments within Pleistocene straton in the World Ocean. [ABSTRACT FROM AUTHOR]

Introduction: in spite of the introduction of automated systems for urine sediment analysis, microscopy examination remains the gold standard. External Quality Assessment (EQA) programs on urine sediment are rare. This paper provides an analysis of results from 2012 to date of the EQA Italian program (Centro di Ricerca Biomedica, Regione Veneto) which involves today 255 laboratories. Methods: the EQA program includes four surveys/year. Participants are asked to identify and provide the clinical association of the presence of specific particles (2 surveys) and formulate the diagnosis of clinical cases presented (2 surveys). In 11 years, 202 images were proposed: 64 cells (9 types), 10 lipids (4 types), 59 casts (16 types), 36 crystals (13 types), 14 microorganisms (5 types), 19 contaminants (8 types) and 22 clinical cases were presented. Results: the correct identification rate (median; interquartiles) was very high for micro organisms (96.4; 91.9-99.9); high for crystals (92.2; 80.2-96.3) and lipids (91.1; 90.5-93.6); followed by casts (87.7; 80.1-91.8); contaminants (87.3; 77.2-96.0) and cells (82.8; 74.4-91.3). For clinical associations, the rate of correct answers was 96.5 (range 48.7- 100%). For clinical cases, due to the overall rate of particle misidentification throughout surveys, only 58.6% (44.9- 68.8%) of participants achieved access to clinical diagnosis. Of these, 92,0% (78.1-95.5%) were able to indicate the correct diagnosis. Conclusions: the program can be used as a tool to improve the identification of urine particles and the knowledge of their clinical significance and to encourage specialists of laboratory medicine to correlate urine findings with other laboratory data and the clinical history of the patient, an aspect that improves the value of the day by day work. [ABSTRACT FROM AUTHOR]

Cystinuria is one of the unrecognized causes of nephrolithiasis. As other stones, cystine stones can present with flank pain, haematuria, dysuria, as well as systemic symptoms such as nausea and vomiting. This report describes the case of a 36-years-old pregnant woman, admitted at Emergency Department for severe vomiting and weight loss (6 kilograms in one month), soon after being treated for hyperemesis gravidarum. Failure of response to conventional management prompted further clinical and laboratory investigations. Urinary sediment analysis by automated analyser and intelligent verification rules, allowed to highlight cysteine casts, recognized by well trained staff. Cooperation between laboratory staff and clinicians allowed diagnosing cystinuria and starting therapy with vomiting remission. [ABSTRACT FROM AUTHOR]

Rivers discharge significant quantities of dissolved organic carbon (DOC) to the ocean, yet biomarker and isotope studies suggest that terrigenous DOC makes up only a small amount DOC in the ocean. One of the removal pathways proposed for riverine DOC is sorption to marine sediments. This process is chemically selective, but whether sorption alters the isotopic composition of riverine DOC is unknown. Because there is isotopic variability across different organic compound classes, sorptive removal of DOC could also alter the isotopic composition of DOC. As a first step in addressing this question, we examined phase partitioning and isotopic composition of a riverine DOC standard in the presence of marine sediment particles. In a series of controlled experiments, the standard was mixed with marine sediment in 35‰ NaCl solution, then separated into particulate and dissolved phases for analyses of mass, δ13C, and ∆14C of organic carbon (OC). Across a range of sediment OC to DOC mass ratios (from < 0.1 to ~ 3), we found that: (1) sediment sorbed 0.8 μg OC per mg of sediment; and (2) DOC compounds with higher ∆14C and lower δ13C values relative to the bulk DOC was preferentially removed from solution. In effect, mixing a riverine DOC standard with marine sediment resulted in increased ∆14C and decreased δ13C of the DOC that remained in solution. These results show that sorption of DOC to sediment can alter the isotopic content of riverine DOC. [ABSTRACT FROM AUTHOR]