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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]

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]

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 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]

Several techniques, such as chemical methods and inductively coupled plasma mass spectrometry (ICP-MS), are available to accurately determine element content. However, they are time-consuming, labor-intensive, or expensive. Portable X-ray fluorescence spectrometry (pXRF) can be applied in various scenarios, with significantly higher efficiency and cost-effectiveness than laboratory methods. However, it also has limitations such as lower detection capability, relatively high detection limits, and lower accuracy than laboratory methods. In this study, we focused on applying pXRF to determine the elemental content of sediment samples and investigate its use in mineral exploration. A variety of factors influencing the results of pXRF analysis were analyzed. Our results showed that pXRF could detect more than 30 elements in stream sediments. The reliability of pXRF's measurements was affected by factors such as the kind of element, sediment particle size, sample grinding treatment, count time, averaged element content, standard deviation of content, and range of content variation. The combination of pXRF analysis and laboratory analysis of partial samples is adequate for establishing a multi-element content inference equation. With this equation, it is possible to effectively infer the content gradient of elements, which will provide valuable support for mineral resource exploration. [ABSTRACT FROM AUTHOR]

Of the different renewable sources of energy, photovoltaic energy has one of the highest potentials. In recent decades, several technological and research advances have contributed to the consolidation of its potential. One current photovoltaic energy research topic is the analysis of the impact of sediments on the panels' performance. The development of models to predict the performance of panels in the presence of sediments may allow for better decision-making when considering maintenance operations. This work contributed to the investigation of the influence of sand on the production of photovoltaic energy in cadmium telluride (CdTe) panels. Six panels of this type with different colors and transparencies were experimentally tested with and without the presence of sand. The impact of the sand on the cells' performance was evaluated by analyzing the change in the 1M5P model's parameters and in the power, efficiency, and fill factors. The experimental results show different negative impacts on the output power of the CdTe panels, from −14% in the orange panel to −36% in the green panel. Based on this study, the development of a model capable of predicting the effect of the sand on these panels was introduced. The developed model was validated experimentally, with a maximum deviation of 4.6%. These results can provide support for the decision-making around maintenance activities and for the development of new techniques to avoid sediment deposition on CdTe panels. [ABSTRACT FROM AUTHOR]

Estuaries are productive systems with rapid changes in natural stressors, such as salinity, that make perturbation detection challenging. Amphipods are vital to estuarine assemblages and may serve as anthropogenic stress indicators. However, practical methods of monitoring species composition and abundance are lacking. This study aims to describe the spatial patterns of four Gammarus spp. in northwest Atlantic estuaries and to compare their compositions and abundances between collection methods using artificial substrates, macrophyte raking, light-baited traps, and species-specific quantitative PCR analyses from sediment environmental DNA (eDNA). Sampling occurred in upper, mid, and lower estuary zones within three estuaries of Prince Edward Island (Canada). G. tigrinus was rarely found in the upper zones with any method. G. mucronatus was predominant in the upper–mid zones across the physical methods, and its abundance declined with increasing salinity. G. lawrencianus was a dominant species across zones, but its abundance did not change with salinity. G. oceanicus was predominant in lower-zone artificial substrates. Species abundances generally correlated with physical collection methods. Sediment eDNA did not detect the spatial effects observed via the physical methods but was correlated with the mean counts of G. mucronatus. The Gammarus spp. assemblages are spatially partitioned in short estuaries, though the sampling method is critical when interpreting estuary patterns. Though multiple methods are ideal for compositional comparisons, abundance monitoring should employ light traps. [ABSTRACT FROM AUTHOR]

The upper part of the Krka River estuary and Prokljan Lake are a specific example of a well-stratified estuarine environment in a submerged river canyon. Here, we reconstructed the geomorphological evolution of the area and classified the data gathered in the study, integrating multibeam echosounder data, backscatter echosounder data, side-scan sonar morpho-bathymetric surveys, and acoustic sub-bottom profiling, with the addition of ground-truthing and sediment analyses. This led to the successful classification of the bottom sediments using the object-based image analysis method. Additional inputs to the multibeam echosounder data improved the segmentation of the seafloor classification, geology, and morphology of the surveyed area. This study uncovered and precisely defined distinct geomorphological features, specifically submerged tufa barriers and carbonate mounds active during the Holocene warm periods, analogous to recent tufa barriers that still exist and grow in the upstream part of the Krka River. Fine-grained sediments, classified as estuarine sediments, hold more organic carbon than coarse-grained sediments sampled on barriers. A good correlation of organic carbon with silt sediments allowed the construction of a prediction map for marine sedimentary carbon in this estuarine/lake environment using multibeam echosounder data. Our findings highlight the importance of additional inputs to multibeam echosounder data to achieve the most accurate results. [ABSTRACT FROM AUTHOR]

X-ray diffraction (XRD) analysis, as one of the most powerful methods, has been widely used to identify and quantify minerals in earth science. How to improve the precision of mineral quantitative analysis is still a hot topic. To date, several quantitative methods have been proposed for different purposes and accompanied by diverse software. In this study, three quantitative mineral analysis methods, including the reference intensity ratio (RIR), Rietveld, and full pattern summation (FPS) methods, are compared and evaluated to systematically investigate their accuracy and applicability. The results show that the analytical accuracy of these methods is basically consistent for mixtures free from clay minerals. However, there are significant differences in accuracy for clay-mineral-containing samples. In comparison, it seems that the FPS method has wide applicability, which is more appropriate for sediments. The Rietveld method has been shown to be capable of quantifying complicated non-clay samples with a high analytical accuracy; nevertheless, most conventional Rietveld software fails to accurately quantify phases with a disordered or unknown structure. The RIR method represents a handy approach but with lower analytical accuracy. Overall, the present results are expected to provide a potentially important reference for the quantitative analysis of minerals in sediments. [ABSTRACT FROM AUTHOR]

Climate fluctuations and landscape evolution, with their associated impacts on northern coastal ecosystems, likely influenced human populations of Nunatsiavut who have inhabited the region for nearly 7000 years. As part of an interdisciplinary research initiative within the Nain Archipelago on the subarctic coast of Labrador, this project sought to reconstruct the postglacial palaeoclimatic and palaeoenvironmental variability of Dog Island and document its impacts on the evolution of lakes located in the vicinity of significant archaeological sites. To address these questions, we analysed physical, geochemical, and biological indicators preserved in sediment cores of two lakes. Results from Oakes Bay West Lake revealed gradual acidification since ca. 4900 cal. yr BP, coherent with terrestrial vegetation development and/or neoglacial cooling, interrupted by periods of milder climatic conditions (ca. 4900–3640 cal. yr BP and ca. 1520 cal. yr BP—present) that favoured large sediment inputs. Evilik Lake revealed the classic sequence of isolation of the basin in three major phases in response to glacio-isostatic rebound. These complementary results allowed for the development of a local palaeoenvironmental framework that contributes to a better understanding of how landscape evolution and climate have influenced human societies through site availability and proximity to marine resources, and how, in turn, they impacted their immediate environment through activities, such as wood harvesting and its associated effects on nutrients and lake sediment inputs. [ABSTRACT FROM AUTHOR]

This study examined the effects of commonly used oxidants in sedimentary macroscopic charcoal analysis on two sediment cores from Thirlmere Lakes National Park, Southeast Australia. The cores, from Lake Werri Berri (WB3) and Lake Couridjah (LC2), span ~900 years and 135,000 years, respectively. The Charcoal Accumulation Rate (CHAR) for both charcoal area and count was quantified using four different chemical treatments and compared to a control using only water. We also quantified the Charring Intensity (CI) of isolated charcoal fragments, a proxy for the severity/intensity of fire, determined using the FTIR spectral characteristics of the remaining charcoal after each treatment. We found significant differences in both the area and number of particles across all treatments in both cores. Significantly, we found substantial differences in CI between treatments, with few charcoal particles formed in low-severity fire (e.g., below ~400 °C or 3.0 °C.s.106) in groups treated with an oxidant. In contrast, the control group displayed a wider range of CI values and contained lightly pyrolyzed particles. This suggests that methods using an oxidant to concentrate sedimentary charcoal are potentially biasing records towards high-intensity or -severity fires. We suggest that consideration should be used when choosing laboratory methods based on the hypotheses being tested. [ABSTRACT FROM AUTHOR]

Lake sediments accumulate various pollutants and act as efficient natural archives suitable for reconstruction the environmental conditions of the past. In contrast to fairly good knowledge of mineral sediments in lakes of European and North America boreal lakes, Siberian lakes of the boreal zone remain quite poorly studied. In this work, two cores of lake sediments of the Ob River valley were investigated. Elemental analyses were carried out on the sediments, losses on ignition were determined, and the rate of sedimentation was measured from the activity of Pb-210 and Cs-137. According to the content of organic matter, bottom sediments belong to different types: clastic (Lake Inkino, located in the Ob River floodplain) and organogenic (Lake Shchuchie on the second terrace). The rate of sedimentation in Lake Shchuchie is several times higher than that in Lake Inkino. The sediments of Lake Inkino are similar in composition (including the pattern of rare earth elements) to the suspended particulate matter of the Ob River as well as to average detrital matter of the upper continental crust. Sediments of Lake Shchuchie (sapropels) are enriched in a number of heavy metals. Based on the elemental composition, signs of diagenetic processes and authigenic mineral formation were determined, such as accumulation of carbonates and the formation of manganese oxides and hydroxides. There is an enhanced recent input of Cr, Co, Cu, Zn, Cd, Sb, Pb, and Bi in the upper layers of sediments as a result of atmospheric anthropogenic pollutant deposition. [ABSTRACT FROM AUTHOR]

The Cd, Hg, Zn, Pb and U contents in sapropel lakes depend on the amount of organic matter in the bottom sediments. Ignatovicîus and coauthors [[2]] show that anthropogenic factors and paleoenvironmental conditions are reflected in the heavy metal distribution in cores from sapropel lake sediments from suburban territories of Vilnius, Lithuania. These main factors cause the different contents and patterns of heavy metal accumulation, as well as diagenetic transformation in sediments of the two studied lakes. [Extracted from the article]

(1) Background: As the chemical and physicochemical properties of marine sediments are closely related to natural and anthropogenic events, it is a real challenge to use their specific assessment as an indicator of environmental pollution discharges. (2) Methods: It is addressed in this study that collection with intelligent data analysis methods, such as cluster analysis, principal component analysis, and source apportionment modeling, are applied for the assessment of the quality of marine sediment and for the identification of the contribution of pollution sources to the formation of the total concentration of polluting species. A study of sediment samples was carried out on 174 samples from three different areas along the coast of the Varna Gulf, Bulgaria. This was performed to determine the effects of pollution. As chemical descriptors, 34 indicators (toxic metals, polyaromatic hydrocarbons, polychlorinated biphenyls, nutrient components, humidity, and ignition loss) were used. The major goal of the present study was to assess the sediment quality in three different areas along the Gulf of Varna, Bulgaria by the source apportionment method. (3) Results: There is a general pattern for identifying three types of pollution sources in each area of the coastline with varying degrees of variation between zone A (industrially impacted zones), zone B (recreational areas), and zone C (anthropogenic and industrial wastes). (4) Conclusions: The quantitative apportionment procedure made it possible to determine the contribution of each identified pollution source for each zone in forming the total pollutant concentrations. [ABSTRACT FROM AUTHOR]

Alluvial placer gold deposits that accumulate in streams across the globe are essentially allochthonous sedimentary deposits that are transported from their source to their location of deposition. The purpose of this study was to find placer gold deposits in alluvial sediments along the Indus River in the NW Himalaya of Pakistan. The investigated region was divided into five clusters based on river morphology. The research focused on mineralogical distribution, sediment source, gold transport distance, elemental composition, and gold concentration in river sediments. Throughout, during the deposition at point and channel bars, the mixed source of alluvial sediments was revealed by its mineralogical composition. However, the SEM analysis demonstrated that the gold grains had a high flatness index, indicating that they had been transported a significant distance. The elemental composition of several samples revealed a significant concentration of silicon dioxide, iron oxide, and alumina oxide transported from the Himalaya. The study of the trace elements indicated gold and related base metals with granitic provenance were transported from an acidic/granitic source. Based on gold concentration, it is demonstrated that the left riverbank (clusters C1, C2, and C3) has a higher concentration of gold deposits and higher potential for economic gold exploration than the right bank (clusters C4 and C5) due to the lower velocity of running water in the study area. The findings revealed that the studied area has good potential for commercial exploration of gold resources, and the workflow can be adopted in any region with a similar geological setting and morphology. [ABSTRACT FROM AUTHOR]

Trace element analysis of sediments from archaeological sites is a valuable method to investigate the anthropic impact and obtain information on the functions of different areas and changes in human activities. One of the most used and effective techniques to carry out this kind of analysis is inductively coupled plasma–mass spectrometry. This technique needs a previous dissolution of the sample by acid attack, but the development of the best method is still a discussed issue. In the present work, total and partial digestion methods were carried out in sediment samples of Cueva de la Cocina (Dos Aguas, Spain), and trace elements were measured and statistically compared. Major elements, soil organic matter amount, and pH data were used to evaluate the main drivers of trace element contents. The differences between the results from the two methods were highlighted. Total digestion is more effective for aluminosilicates and heavy minerals, although the partial digestion results suggested that, in most cases, the difference between the two methods is irrelevant for archaeological interpretations. Furthermore, in some cases, the total digestion of the mineral phases related to the geological contribution could mask the anthropic elemental signals. [ABSTRACT FROM AUTHOR]

Provenance analysis of sediments provides important constraints on basin formation and orogenic processes. With the aim to define the sedimentary provenance and tectonic evolution of the southern margin of the North China Craton, this paper presents new detrital zircon U-Pb data from Early Triassic sediments in the Yiyang area. The results showed major peaks at 1848, 458, 425, and 268 Ma and subordinate peaks at ca. 2500, 872, and 957 Ma on age spectra from the Liujiagou Formation. The Heshanggou Formation exhibited a major age peak at 445 Ma and subordinate peaks at 755 and 947 Ma. Integrated with the analysis of sandstone detrital compositions, we suggest that the sources of the Liujiagou Formation were mainly a mixture of the southern margin of the North China Craton and the North Qinling Orogenic Belt, whereas the Heshanggou Formation was derived primarily from the North Qinling Orogenic Belt. Age comparisons of detrital zircon geochronology collected from different basins in the North China Craton indicated that the paleogeography of the North China Craton during the Early Triassic was strongly asymmetric, wherein the uplifted highland along the southern margin of the North China Craton was relatively lower than the northern margin. Meanwhile, the marked shift in source region from the Liujiagou to the Heshanggou formations provides a constraint regarding the conversion from denuded zone to deposited zone along the southern margin of the North China Craton in the Early Triassic, which controlled the evolution of the provenance and sedimentary system. [ABSTRACT FROM AUTHOR]

River islands are sandbars formed by scouring and silting. Their evolution is affected by several factors, among which are runoff and sediment discharge. The spatial-temporal evolution of seven river islands in the Nanjing Section of the Yangtze River of China was examined using TM (Thematic Mapper) and ETM (Enhanced Thematic Mapper)+ images from 1985 to 2015 at five year intervals. The following approaches were applied in this study: the threshold value method, binarization model, image registration, image cropping, convolution and cluster analysis. Annual runoff and sediment discharge data as measured at the Datong hydrological station upstream of Nanjing section were also used to determine the roles and impacts of various factors. The results indicated that: (1) TM/ETM+ images met the criteria of information extraction of river islands; (2) generally, the total area of these islands in this section and their changing rate decreased over time; (3) sediment and river discharge were the most significant factors in island evolution. They directly affect river islands through silting or erosion. Additionally, anthropocentric influences could play increasingly important roles. [ABSTRACT FROM AUTHOR]

A detailed study had been conducted on the sediment of Mount Samalas' volcanic eruption in 1257 AD. Using the framework of the reconstruction of the ancient eruption of Mount Samalas, the first step was to map and analyze the deposits of volcanic sediment. Secondly, we analyzed the effect of geomorphology and the distance function to the isopach thickness. The results show that a combination of methods allowed to provide a high resolution map of the distribution of the thickness of the volcanic deposits, both on the slope and in alluvial areas. Geo-electric survey results (both Vertical Electric Sound (VES) and 2D mapping) show consistent changes in the pattern of contrast resistivity layer interface, for all areas. The pattern changes in a row of the top layer, the high resistivity turned into the low. Furthermore, the second and third layer interface changes from low to the high resistivity. High resistivity on the top layer is interpreted as a layer of unconsolidated volcanic sediment. High resistivity values are range from 736 to 2000 Ohm.m on the top layer in the area of the slopes while in the area of alluvial, the resistivity values range from 20 to 958 Ohm.m. Generally, the volcanic deposits in the area of the slopes have a higher value of isopach (>17 m) than in areas of alluvial (<25 m). The geomorphology seemed to have no significant effect on the isopach value, particularly pyroclastic fallout. Such is the case with distance from the source to the site, which is not linear. The value of isopach increases westward from 21 to 31 km, in contrast to the East, which began to occur at a distance of 14 km to 21 km. [ABSTRACT FROM AUTHOR]

This research applied terrestrial LiDAR for laboratory beach evolution experiments to quantify the impact of resolution on topographic mapping and change analyses. The multi-site registration and multi-temporal scanning processes produced high accuracy (-0.002 u 0.003 m) topographic models in a wave tank environment. Morphological analyses based on surface change and profiles showed that models of all resolutions were capable of capturing major sediment changes in relatively smooth areas. However, higher resolution models were necessary in areas with rough surfaces and sudden elevation changes, while coarser resolution models smoothed the roughness and underestimated feature height (e.g., peaks and troughs). Decreasing resolutions from 1 to 10 cm resulted in a 2% underestimation of erosional volumes with a linear regression of y = -0.0964x + 0.4185 (R2 = 0.9651) and 3.5% overestimation of depositional volumes with a linear regression of y = 0.0664x + 0.3308 (R2 = 0.3645). However, its impact on erosion and deposition volume assessment based on object-oriented beach evolution analysis is less significant, except when fragment objects dominate the sediment changes. For Coastal Morphology Analyst (CMA), the impact of resolution is more observable through 2D object mapping in terms of object size, number and spatial distribution. Finally, wave modeling experiments proved that resolutions caused significant changes on the behavior of the maximum wave height the shape of the wave fronts and magnitudes of the currents. [ABSTRACT FROM AUTHOR]

Seafloor sediments of different geographical areas in the southern South China Sea (continental shelf, continental slope, and Okinawa Trough) were gravity cored at 21 locations. Sound velocities (V) of the samples were measured at 15-cm increments immediately upon retrieval, and porosity, wet bulk density, and mean grain size were measured later in the laboratory. Empirical equations from previous studies were applied to predict V of sediment samples from the measured physical properties and it was found that the sound velocities derived from the existing equations did not closely match the measured sound velocities. Therefore empirical equations were reconstructed based on the measured data that represent the relationships between physical and acoustic properties of the different geographical area in the study area. Possible explanations for the discrepancies between the measured data and those of previous studies were investigated and found that physical properties, sediment types, geographical area, etc. are important factors that influence sound velocity. The empirical equations of this report should be preferred for prediction of sediment sound velocity for high-frequency acoustic experiments. [ABSTRACT FROM AUTHOR]

Microcystins are toxins produced by cyanobacteria. They occur in aquatic systems across the world and their occurrence is expected to increase in frequency and magnitude. As microcystins are hazardous to humans and animals, it is essential to understand their fate in aquatic systems in order to control health risks. While the occurrence of microcystins in sediments has been widely reported, the factors influencing their occurrence, variability, and spatial distribution are not yet well understood. Especially in shallow lakes, which often develop large cyanobacterial blooms, the spatial variability of toxins in the sediments is a complex interplay between the spatial distribution of toxin producing cyanobacteria, local biological, physical and chemical processes, and the re-distribution of toxins in sediments through wind mixing. In this study, microcystin occurrence in lake sediment, and their relationship with biological and physicochemical variables were investigated in a shallow, eutrophic lake over five months. We found no significant difference in cyanobacterial biomass, temperature, pH, and salinity between the surface water and the water directly overlying the sediment (hereafter 'overlying water'), indicating that the water column was well mixed. Microcystins were detected in all sediment samples, with concentrations ranging from 0.06 to 0.78 µg equivalent microcystin-LR/g sediments (dry mass). Microcystin concentration and cyanobacterial biomass in the sediment was different between sites in three out of five months, indicating that the spatial distribution was a complex interaction between local and mixing processes. A combination of total microcystins in the water, depth integrated cyanobacterial biomass in the water, cyanobacterial biomass in the sediment, and pH explained only 21.1% of the spatial variability of microcystins in the sediments. A more in-depth analysis that included variables representative of processes on smaller vertical or local scales, such as cyanobacterial biomass in the different layers and the two fractions of microcystins, increased the explained variability to 51.7%. This highlights that even in a well-mixed lake, local processes are important drivers of toxin variability. The present study emphasises the role of the interaction between water and sediments in the distribution of microcystins in aquatic systems as an important pathway which deserves further consideration. [ABSTRACT FROM AUTHOR]

Construction of the Włocławek Barrage on the Vistula River in 1970 became an important source of energy; however, it discontinued sediment transport in the Vistula River. This phenomenon resulted in accumulation before and erosion below the barrage; a similar problem can be expected due to the planned construction of the Lower Vistula Cascade. This study is dedicated to finding an effective and feasible solution to sediment transport management, acceptable to a wide group of users (e.g., navigation, energy producers, and ecologists). A numerical 1D model was applied to carry out analysis of hydrodynamics and sediment transport in the river section from Włocławek Barrage to the Vistula River mouth in the Baltic Sea. For calibration, historical data describing the accumulation and erosion created by the Włocławek Barrage were used. The proposed model allowed incorporation of new barrages chronologically, in accordance with the proposed time schedules. Analysis was carried out in a 50-year horizon, using a set of historical flow data. For sediment flushing, it was proposed to use natural flooding events exceeding Q10% discharge and to control sediment management of the adjacent barrages. To use this method in practice requires verification. [ABSTRACT FROM AUTHOR]

This paper presents the easternmost mineralogical and geochemical evidence of the 1755 Lisbon tsunami found in the Western Mediterranean. This multidisciplinary analysis of a sediment core obtained in Gibraltar (southern Iberian Peninsula) has allowed us to differentiate a tsunamiite from an old lagoon (The Inundation). This tsunamigenic layer has increased levels of calcite and aragonite and higher concentrations of Ba and ferromagnesian elements in comparison with the underlying lagoonal sediments of this core. This layer is also differentiated by its paleontological record, with the introduction of marine species within this lagoon. The uppermost part of the core includes a transition from swampy/marsh paleoenvironments to terrestrial scenarios, with a final anthropogenic filling occurring during the last century. [ABSTRACT FROM AUTHOR]

In the aftermath of pyroclastic density current-dominated eruptions, lahars are the main geomorphic agent, but at the decadal scale, different sets of processes take place in the volcanic sediment cascade. At Unzen volcano, in the Gokurakudani gully, we investigated the geomorphologic evolution and how the topographic change and the sediment change over time is controlling this transition. For this purpose, a combination of LiDAR data, aerial photography and photogrammetry, ground penetrating radar and sediment grain size analysis was done. The results show choking zones and zones of enlargement of the gully, partly controlled by pre-eruption topography, but also by the overlapping patterns of the pyroclastic flow deposits of 1990–1995. The ground penetrating radar revealed that on top of the typical lahar structure at the bottom of the gully, side wall collapses were trapping finer sandy sediments formed in a relatively low-energy deposition environment. This shows that secondary processes are taking place in the sediment transport process, on top of lahar activity, but also that these temporary dams may be a source of sudden sediment and water release, leading to lahars. Finally, the sediments from the gully walls are being preferentially oozed out of the pyroclastic flow deposit, meaning that over longer period of time, there may be a lack of fines, increasing permeability and reducing internal pore pressure needed for lahar triggering. It also poses the important question of how much of a past event one can understand from outcrops in coarse heterometric material, as the deposit structure can remain, even after losing part of its fine material. [ABSTRACT FROM AUTHOR]

Geochemical analysis of the 23 sediment samples collected from a short (0.6 m long) core retrieved from the coastal creek that was previously connecting the northern and southern Al-Shuaiba Lagoons, Red Sea, Saudi Arabia, was accomplished to assess the elemental enrichment levels and the natural and anthropogenic driving forces for this enrichment. Statistical analysis and upcore variation in elemental concentrations enabled subdivision of the core formally into three units, lower, middle, and upper. The enriched elements in the lower and middle units display poor to negative correlations with the enriched elements in the upper unit. The lower unit is enriched in elements (Mo, As, U, and Re) suggesting deposition under anoxic conditions, possibly related to the Medieval Climate Anomaly. The middle unit is enriched in the carbonate-related constituents (CaCO3, Ca, and Sr). The upper unit is enriched in elements that co-vary significantly with Al suggesting increased terrigenous supply associated with the construction of the road between the two lagoons. The enrichment of elements in the lower and middle units is naturally driven, whereas the enrichment of lithogenic elements in the upper unit, though of geogenic origin, is induced after the road construction. [ABSTRACT FROM AUTHOR]

We used concentrations of in situ cosmogenic 10Be from riverine sediment to quantify the basin-averaged denudation rates and sediment fluxes in the Plessur Basin, Eastern Swiss Alps, which is a tributary stream to the Alpine Rhine, one of the largest streams in Europe. We complement the cosmogenic dataset with the results of morphometric analyses, geomorphic mapping, and sediment fingerprinting techniques. The results reveal that the Plessur Basin is still adjusting to the landscape perturbation caused by the glacial carving during the Last Glacial Maximum c. 20,000 years ago. This adjustment has been most efficient in the downstream part where the bedrock comprises high erodibility North Penninic flysch and Bündnerschist, whereas glacial landforms are still prominently preserved in the upstream region, comprising low erodibility South Penninic and Austroalpine bedrock. This geomorphic observation is supported by the 10Be based denudation rate and sediment provenance analysis, which indicate a much faster sediment production in the flysch and schist lithologies. Interestingly, the reach of fast denudation has experienced the highest exhumation and rock uplift rates. This suggests that lithologic and glacial conditioning have substantially contributed to the local uplift and denudation as some of the driving forces of a positive feedback system. [ABSTRACT FROM AUTHOR]

Simple Summary: Some main drains in the Nile Delta of Egypt are subjected to heavy pollution loads and used to irrigate crops and vegetables. Here, we assessed the pollution level and the ability of some wild aquatic macrophytes (Cyperus alopecuroides, Echinochloa stagnina, Eichhornia crassipes, Ludwigia stolonifera, Phragmites australis, Ranunculus sceleratus, and Typha domingensis) to accumulate eight heavy metals (Fe, Cu, Zn, Mn, Co, Cd, Ni, and Pb) in three of the polluted drains (Amar, El-Westany, and Omar-Beck). The sediment in the three drains exceeded the worldwide permissible ranges of Cu, Zn, and Pb, but it ranged within safe limits for Mn, Cd, Ni, and Co. P. australis accumulated the highest levels of Fe, Co, Cd, and Ni, while E. crassipes contained the highest concentrations of Cu, Zn, Mn and Pb. The bioaccumulation factor was > 1 for the investigated heavy metals (except Cu) in all species, except C. alopecuroides. Accordingly, these species could be applied for the accumulation and phytostabilization of these metals. The current study addressed the heavy metals accumulation potentials of seven perennial aquatic macrophytes (Cyperus alopecuroides, Echinochloa stagnina, Eichhornia crassipes, Ludwigia stolonifera, Phragmites australis, Ranunculus sceleratus and Typha domingensis) and the pollution status of three drains (Amar, El-Westany and Omar-Beck) in the Nile Delta of Egypt. Nine sites at each drain were sampled for sediment and plant analyses. Concentrations of eight metals (Fe, Cu, Zn, Mn, Co, Cd, Ni, and Pb) were determined in the sediment and the aboveground and belowground tissues of the selected macrophytes. Bioaccumulation factor (BF) and translocation factor (TF) were computed for each species. The sediment heavy metals concentrations of the three drains occurred in the following order: El-Westany > Amar > Omar-Beck. The concentrations of sediment heavy metals in the three drains were ordered as follows: Fe (438.45–615.17 mg kg−1) > Mn (341.22–481.09 mg kg−1) > Zn (245.08–383.19 mg kg−1) > Cu (205.41–289.56 mg kg−1) > Pb (31.49–97.73 mg kg−1) > Cd (13.97–55.99 mg kg−1) > Ni (14.36–39.34 mg kg−1) > Co (1.25–3.51 mg kg−1). The sediment exceeded the worldwide permissible ranges of Cu, Zn and Pb, but ranged within safe limits for Mn, Cd, Ni and Co. P. australis accumulated the highest concentrations of Fe, Co, Cd and Ni, while E. crassipes contained the highest concentrations of Cu, Zn, Mn, and Pb. Except for C. alopecuroides and Cu metal, the studied species had BF values greater than one for the investigated heavy metals. Nevertheless, the TFs of all species (except Cd in L. stolonifera) were less than one. Hence, the studied species are appropriate for accumulation, biomonitoring, and phytostabilization of the investigated metals. [ABSTRACT FROM AUTHOR]

Age gelation is a major quality defect in ultra-high-temperature (UHT) pasteurized milk during extended storage. Changes in plasmin (PL)-induced sedimentation were investigated during storage (23 °C and 37 °C, four weeks) of UHT skim milk treated with PL (2.5, 10, and 15 U/L). The increase in particle size and broadening of the particle size distribution of samples during storage were dependent on the PL concentration, storage period, and storage temperature. Sediment analysis indicated that elevated storage temperature accelerated protein sedimentation. The initial PL concentration was positively correlated with the amount of protein sediment in samples stored at 23 °C for four weeks (r = 0.615; p < 0.01), whereas this correlation was negative in samples stored at 37 °C for the same time (r = −0.358; p < 0.01) due to extensive proteolysis. SDS-PAGE revealed that whey proteins remained soluble over storage at 23 °C for four weeks, but they mostly disappeared from the soluble phase of PL-added samples after two weeks' storage at 37 °C. Transmission electron micrographs of PL-containing UHT skim milk during storage at different temperatures supported the trend of sediment analysis well. Based on the Fourier transform infrared spectra of UHT skim milk stored at 23 °C for three weeks, PL-induced particle size enlargement was due to protein aggregation and the formation of intermolecular β-sheet structures, which contributed to casein destabilization, leading to sediment formation. [ABSTRACT FROM AUTHOR]

Methane hydrate has attracted attention as a next-generation resource, and many researchers have conducted various studies to estimate its productivity. Numerical simulation is the optimal method for estimating methane gas productivity. Meanwhile, using a reasonable input parameter is essential for obtaining accurate numerical modeling results. Permeability is a geotechnical property that exhibits the greatest impact on productivity. The permeability of hydrate-bearing sediment varies based on the sediment pore structure and hydrate saturation. In this study, an empirical permeability model was derived from experimental data using soil specimens from the Ulleung Basin, and the model was applied in numerical analysis to evaluate the sediment gas productivity and ground stability. The gas productivity and stability of hydrate-bearing sediments were compared by applying a widely used permeability model and the proposed model to a numerical model. Additionally, a parametric study was performed to examine the effects of initial hydrate saturation on the sediment gas productivity and stability. There were significant differences in the productivity and stability analysis results according to the proposed permeability model. Therefore, it was found that for accurate numerical analysis, a regional permeability model should be applied. [ABSTRACT FROM AUTHOR]

During the production of beer, and especially beer wort, the main wastes are spent grain and hot trub, i.e., the so-called "hot break." Combined with yeast after fermentation, they represent the most valuable wastes. Hot trub is also one of the most valuable by-products. Studies on the chemical composition of these sediments and their rheological properties as waste products will contribute to their effective disposal and even further use as valuable pharmaceutical and cosmetic raw materials. So far, hot trub has been studied for morphology and particle distribution depending on the raw material composition and beer wort extract. However, there are no preliminary studies on the rheological properties of hot trub and hops. In particular, no attention has yet been paid to the dependence of these properties on the hop variety or different protein sources used. The aim of this study was to examine the effect of different hopping methods on hot trub viscosity and beer wort physicochemical parameters. Additionally, the hop solutions were measured at different temperatures. A microbiological analysis of hop sediments was also performed to determine the post-process survival of selected microorganisms in these wastes. For manufacturers of pumps used in the brewing industry, the most convenient material is that of the lowest viscosity. Low viscosity hot trub can be removed at lower velocities, which reduces costs and simplifies washing and transport. The sediments also had similar equilibrium viscosity values at high shear rates. [ABSTRACT FROM AUTHOR]

Hyperspectral imaging has recently emerged in the geosciences as a technology that provides rapid, accurate, and high-resolution information from lake sediment cores. Here we introduce a new methodology to infer particle size distribution, an insightful proxy that tracks past changes in aquatic ecosystems and their catchments, from laboratory hyperspectral images of lake sediment cores. The proposed methodology includes data preparation, spectral preprocessing and transformation, variable selection, and model fitting. We evaluated random forest regression and other commonly used statistical methods to find the best model for particle size determination. We tested the performance of combinations of spectral transformation techniques, including absorbance, continuum removal, and first and second derivatives of the reflectance and absorbance, along with different regression models including partial least squares, multiple linear regression, principal component regression, and support vector regression, and evaluated the resulting root mean square error (RMSE), R-squared, and mean relative error (MRE). Our results show that a random forest regression model built on spectra absorbance significantly outperforms all other models. The new workflow demonstrated herein represents a much-improved method for generating inferences from hyperspectral imagery, which opens many new opportunities for advancing the study of sediment archives. [ABSTRACT FROM AUTHOR]

The theoretical analysis of sediment scour in vertical direction caused by a vertical suction inlet is presented here. The predictive formulas of the critical inlet height of particle initial motion and scour depth in equilibrium state are expressed as Froude type relations based on the phenomenological theory of turbulence and the momentum transfer hypothesis between fluid and grain. The experimental data of the literature shows good consistency with the theoretical relationship, and the physical mechanism is clear. In addition, the discussion for the applicability of the predictive formula in an extensive range of Reynolds numbers reveals that the sediment incipient motion can be excellently explained by the energy spectrum of the phenomenological theory. Then the theoretical errors in different flow regions are investigated. The research presents universal relevance and reference value for similar research and application. [ABSTRACT FROM AUTHOR]

An intraocular lens (IOL) is a synthetic, artificial lens placed inside the eye that replaces a natural lens that is surgically removed, usually as part of cataract surgery. The opacification of the artificial lens can be related to the formation of the sediments on its surface and could seriously impair vision. The physicochemical analysis was performed on an explanted hydrophilic IOL and compared to the unused one, considered as a reference IOL. The studies were carried out using surface sensitive techniques, which can contribute to a better understanding of the sedimentation process on hydrophilic IOLs' surfaces. The microscopic studies allowed us to determine the morphology of sediments observed on explanted IOL. The photoelectron spectroscopy measurements revealed the presence of organic and inorganic compounds at the lens surface. Mass spectroscopy measurements confirmed the chemical composition of deposits and allowed for chemical imaging of the IOL surface. Applied techniques allowed to obtain a new set of information approximating the origin of the sediments' formation on the surface of the hydrophilic IOLs after Descemet's stripping endothelial keratoplasty. [ABSTRACT FROM AUTHOR]

Sediment provenance studies have become a major theme for source-to-sink systems and provide an important tool for assessing paleogeographic reconstruction, characterizing the depositional system, and predicting reservoir quality. The lower Miocene is an important stratigraphic unit for deciphering sediment evolution in the continental shelf of the northwestern South China Sea, but the provenance characteristics of this strata remain unclear. In this study, detrital zircon U-Pb geochronology and Lu-Hf isotopes from the lower Miocene Sanya Formation in the Yinggehai-Song Hong Basin were examined to study the provenance and its variation in the early Miocene. U-Pb dating of detrital zircons yielded ages ranging from Archean to Cenozoic (3313 to 39 Ma) and displayed age distributions with multiple peaks and a wide range of εHf(t) values (from −27.2 to +8.5). Multi-proxy sediment provenance analysis indicates that the Red River system was the major source for the sediments in the northern basin, with additional contribution from central Vietnam, and the Hainan played the most important role in contributing detritus to the eastern margin of the basin in the middle Miocene. This paper highlights the provenance of early Miocene sediments and contributes to paleogeographic reconstruction and reservoir evaluation. [ABSTRACT FROM AUTHOR]

Linking marine sinks to potential terrestrial sources is one of most intriguing but challenging aspects of sediment source-to-sink studies. In this study, we analyzed 23 zircon samples (3271 filtered best ages) from surface sediments of the east China seas (ECSs) that cover a large portion of the Bohai Sea, Yellow Sea, East China Sea to part of the northeastern South China Sea. The results of U-Pb age distributions exhibit variable signatures in different seas. The Bohai Sea is characterized by 4 age populations at 203–286 Ma, 383–481 Ma, 1830–1940 Ma and 2480–2548 Ma, whereas the southern Yellow Sea and the East China Sea are featured by 5 age populations at 176–223 Ma, 383–481 Ma, 732–830 Ma, 1830–1940 Ma and 2480–2548 Ma. We propose that the presence or absence of the population of 732–830 Ma in the Yangtze Craton (YC) and the North China Craton (NCC) is a possible geochronological signature to distinguish zircon grains derived from the two source regions. Furthermore, on the basis of multidimensional scaling (MDS), U-Pb ages in the sediments of the Bohai Sea, East China Sea and the Taiwan Strait could be correspondently linked to those of the Yellow River, the Yangtze River and Taiwan rivers. The good linkages support the view that U-Pb age distributions of detrital zircons in the margin seas are mainly controlled by fluvial discharges, and ultimately, by the tectonic history of the corresponding source regions. Using a sediment forward mixing model, we obtained the relative sediment contributions and spatial variations of five most important river discharges in the region. The mixing results suggest that the major rivers in the region, i.e., the Yangtze and the Yellow Rivers, are the dominant sediment contributors to the continental margin, and their mixing coefficients could be used to infer relative sediment budgeting. In addition, spatial variations in mixing coefficient in the East China Sea indicate that sediment mixing and partitioning processes in the marine depositional environment have played a part role in propagating the provenance signals as a result of interaction of oceanic currents and tides. The combined method between provenance analysis and mixing modeling provides a feasible way to appreciate sediment budgeting in the geological past. [ABSTRACT FROM AUTHOR]

Gas hydrates have great potential as future energy resources. Several productivity and stability analyses have been conducted for the Ulleung Basin, and the depressurization method is being considered for production. Under depressurization, ground settlement occurs near the wellbore and axial stress develops. For a safe production test, it is essential to perform a stability analysis for the wellbore and hydrate-bearing sediments. In this study, the development of axial stress on the wellbore was investigated considering the coupling stiffness of the interface between the wellbore and sediment. A coupling stiffness model, which can consider both confining stress and slippage phenomena, was suggested and applied in a numerical simulation. Parametric analyses were conducted to investigate the effects of coupling stiffness and slippage on axial stress development. The results show that shear coupling stiffness has a significant effect on wellbore stability, while normal coupling stiffness has a minor effect. In addition, the maximum axial stress of the well bore has an upper limit depending on the magnitude of the confining stress, and the axial stress converges to this upper limit due to slipping at the interface. The results can be used as fundamental data for the design of wellbore under depressurization-based gas production. [ABSTRACT FROM AUTHOR]

Fe and Mn oxides and (oxy)-hydroxides are the most abundant solid-phase electron acceptors in marine sediments, and dissimilatory Fe/Mn reduction usually links with the anaerobic oxidation of methane (AOM) and organic matter oxidation (OMO) in sediments. In this study, we report the results from subsurface marine sediments in the Dongsha hydrate-bearing area in the South China Sea. The petrological and geochemical signatures show that the Fe/Mn reduction mediated by AOM and OMO might occur in sediments above the sulfate-methane transition zone. X-ray diffraction and scanning electron microscopy analyses of sediments indicate that Fe(III)/Mn(IV)-oxides and authigenic carbonate minerals coexisted in the Fe/Mn reduction zone. The lower δ13C values of dissolved inorganic carbon, coupled with an evident increase in total inorganic carbon contents and a decrease in Ca2+ and Mg2+ concentrations indicate the onset of AOM in this zone, and the greater variation of PO43− and NH4+ concentrations in pore water suggests the higher OMO rates in subsurface sediments. Geochemical and mineralogical analyses suggest that the previously buried Fe(III)/Mn(IV) oxides might be activated and lead to the onset of Fe/Mn reduction induced by AOM and OMO. These findings may extend our understanding of the biogeochemical processes involved in Fe/Mn reduction in continental shelves with abundant methane, organic matter, and terrigenous metal oxides. [ABSTRACT FROM AUTHOR]

The exploration of the deep biosphere continues to reveal a great diversity of microorganisms, many of which remain poorly understood. This study provides a first look at the microbial community composition of the Costa Rica Margin sub-seafloor from two sites on the upper plate of the subduction zone, between the Cocos and Caribbean plates. Despite being in close geographical proximity, with similar lithologies, both sites show distinctions in the relative abundance of the archaeal domain and major microbial phyla, assessed using a pair of universal primers and supported by the sequencing of six metagenomes. Elusimicrobia, Chloroflexi, Aerophobetes, Actinobacteria, Lokiarchaeota, and Atribacteria were dominant phyla at Site 1378, and Bathyarchaeota, Chloroflexi, Hadesarchaeota, Aerophobetes, Elusimicrobia, and Lokiarchaeota were dominant at Site 1379. Correlations of microbial taxa with geochemistry were examined and notable relationships were seen with ammonia, sulfate, and depth. With deep sediments, there is always a concern that drilling technologies impact analyses due to contamination of the sediments via drilling fluid. Here, we use analysis of the drilling fluid in conjunction with the sediment analysis, to assess the level of contamination and remove any problematic sequences. In the majority of samples, we find the level of drilling fluid contamination, negligible. [ABSTRACT FROM AUTHOR]

The presence of a gas hydrate reservoir and free gas layer along the South Shetland margin (offshore Antarctic Peninsula) has been well documented in recent years. In order to better characterize gas hydrate reservoirs, with a particular focus on the quantification of gas hydrate and free gas and the petrophysical properties of the subsurface, we performed travel time inversion of ocean-bottom seismometer data in order to obtain detailed P- and S-wave velocity estimates of the sediments. The P-wave velocity field is determined by the inversion of P-wave refractions and reflections, while the S-wave velocity field is obtained from converted-wave reflections received on the horizontal components of ocean-bottom seismometer data. The resulting velocity fields are used to estimate gas hydrate and free gas concentrations using a modified Biot-Geertsma-Smit theory. The results show that hydrate concentration ranges from 10% to 15% of total volume and free gas concentration is approximately 0.3% to 0.8% of total volume. The comparison of Poisson's ratio with previous studies in this area indicates that the gas hydrate reservoir shows no significant regional variations. [ABSTRACT FROM AUTHOR]

Lake Limboto is one of the major lakes in Sulawesi, Indonesia. It is currently undergoing serious degradation due to population pressure. As more residential areas have been established around the lake, the sedimentation rate has increased because of the contribution of anthropogenic particles. In this study, the lithogenic and anthropogenic components in surface sediments from 17 points in the lake were studied and identified using a combination of magnetic and geochemical analyses. The results showed that although the magnetic susceptibility values in R (residential) and NR (non-residential) areas were relatively similar, the values of saturation isothermal remanent magnetization (SIRM) as well as those of SIRM/χLF differed significantly, implying that the magnetic characteristics of the lithogenic component (in the NR area) differ from those of the anthropogenic component (in the R area). The discrepancy between the anthropogenic and lithogenic contributions was further supported by trace metals and rare earth element (REE) contents. Sediment samples in the R area contained higher levels of Mn, La, Pr, and Gd, while in the NR area they contained higher levels of Fe, Sc, Nd, and Ce. The magnetic susceptibility also correlated strongly with Fe, Cu, Zn, and Mn contents in the NR area. A similar correlation was not observed in the R area. The results above imply that a combination of magnetic and geochemical analyses can successfully differentiate lithogenic and anthropogenic components or contributions in lake sediments. [ABSTRACT FROM AUTHOR]