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Determining the type and properties of saturated groundwater for complex sedimentary facies, as well as the various properties of these sedimentary facies, requires extensive geological, hydrogeological, and geophysical studies. Therefore, identifying the different types of subsurface deposits and their physical properties as well as their geological, hydrogeological, and structural settings are the interesting features in this study which play an important role in achieving its objectives. To achieve these objectives, the Direct Current (DC) resistivity method and the Direct Current Time-Domain Induced Polarization (DC-TDIP) method were used. These two methods were applied because they are complementary methods, one of which is more accurate in sediments saturated with fresh water (the DC resistivity method) and the other in sediments saturated with salt water (DC-TDIP method). Also, the DC-TDIP method was applied to avoid ambiguity in the resistivity results, as well as their results were compared with the available geological and hydrogeological field data. Accordingly, 2D and 3D resistivity values were designed to describe the hydro-lithological environment of the recorded sediments, and their hydrogeoelectric properties and groundwater zones were also identified and divided. Also, 2D and 3D chargeability values were designed to distinguish between sediments, their depositional facies, and their saturated water properties. These values also succeeded in separating clay from non-clay layers, and clay layers from layers containing salt water. Therefore, it was found that the integration between the two methods helped in identifying and visualizing the characteristics of the sediments and determining their facies and their water content, which helped in understanding the complex sedimentary facies recorded in the study area as well as identifying the types and characteristics of groundwater contained in these facies. Therefore, it can be recommended to apply the previous methodology and include the two geophysical methods and their results to study complex facies deposits and determine their water content and type, especially in similar depositional environments that are located next to a source of salt water mixed with other types of water. [ABSTRACT FROM AUTHOR]

The blue carbon ecosystems possess the potential to mitigate climate change impacts, support adaptation, assist in reaching the national and global net-zero goals, and secure social, economic, and environmental outcomes through sequestering and storing carbon in sediments. The marine environment along the Red Sea coast of Egypt is distinguished by a high biodiversity with key marine ecosystems such as seagrasses meadows, coral reefs, and mangroves that can play a role in blue carbon ecosystems. To understand the capacity of the seagrasses to store carbon, this study aims at quantifying the vertical distribution of the organic carbon density (OCD) and the carbon sequestration potential (CSR) and evaluate the economic feasibility of seagrasses vegetation as a tool for mitigating climate change. Two sediment cores were sampled from vegetated areas (inhabited with seagrasses species: Thalassia hemprichii) and one core from a non-vegetated area (for comparison) from three nearshore locations within Wadi El Gemal Protected Area, Red Sea Egypt. The OCD in the vegetated areas increased with depth and showed higher capacities of carbon storage compared to the non-vegetated area. The overall calculated CSR for seagrasses in Wadi El-Gemal is 341.65 g C m−2 yr−1. These findings support the key role of seagrasses to mitigate climate change through CO2 sequestration and return an equivalent of 6,000 to 11,000 USD per year for every 100 hectares in monetary value. This highlights the importance of the conservation and restoration of seagrasses along the Red Sea coast and the potential of blue carbon finance that can be leveraged to meet national-level climate mitigation strategies and policies in Egypt. [ABSTRACT FROM AUTHOR]

In hydrocarbon exploration, total organic carbon (TOC) content and Rock-Eval pyrolysis are commonly employed geochemical techniques that offer concise insights into kerogen type, effective source-rock identification and thermal maturity. In the current study, the data obtained from Rock-Eval pyrolysis has been used to define the source-rock quality, generative potential, kerogen type, maturity of the source sediments and kerogen kinetics of the Baisakhi–Bhadesar Formation of Kimmeridgian–Tithonian (154.7–145.6 Ma) age. Basinal level hydrogen index (HI), TOC content, source-rock maturity, transformation ratio and heat-flow maps have been generated by integrating the data from pyrolysis with previously available data from wells drilled in the basin. The TOC content of the Kimmeridgian–Tithonian sequence ranges from 0.03 to 12.71% in the studied samples, with an average TOC content of 1.28%, indicating good source-rock quality. The HI, in collaboration with Tmax and vitrinite reflectance (VRo) data, demonstrates that the Baisakhi–Bhadesar Formation is characterized by type II, a mixture of type II/III and type III kerogen facies and exhibits good source-rock quality and poor to good generative potential in the basin. The studied samples are marginally mature to mature in nature (Tmax, 430–450°C; VRo, 0.52–0.72%). A maturity analysis of the basin suggests that during the Late Jurassic most areas were under the oil window zone, except for the Bhakhari Tibba and Miajlar areas. The transformation ratio overlay for the Kimmeridgian–Tithonian source sequences shows better transformations of the source rock in the area of the Shagarh Sub-basin. Kerogen kinetics of the studied Baisakhi–Bhadesar Formation demonstrate that the activation energy ranges between 46 and 74 kcal mol−1 with the significant distribution of activation energy being 54 kcal mol−1 (42.07%), representing a strong heterogeneous type of organic matter in the sediments. Based on lithological, palaeontological and electrolog studies, a shallow-marine to nearshore environment of deposition with a sediment-input direction from the SE has been inferred for the Kimmeridgian–Tithonian sequences. The results of this study quantitatively establish the role of the Kimmeridgian–Tithonian sequence as a source rock, ultimately contributing to the generation of hydrocarbons in the basin along with spatial changes in the quality of source sediments in different parts of the basin. [ABSTRACT FROM AUTHOR]

Spatial analysis was used to analyze the environmental quality of soil in the Al-Zarqa region in order to identify sources and estimate heavy metal concentrations, which aided in the assessment of soil quality and heavy metal pollution. The primary goal of this study was to assess the environmental impact of heavy metal pollutants in the Al-Zarqa region. To assess pollution levels, the concentrations of Cu, Mn, Cd, and Pb were measured in surface soil (sediment) samples collected from Khirbet al-Samra. A total of sixteen samples were analyzed. The elevated levels of Cu and Cd are primarily attributed to various sources such as the weathering of nearby rock formations and the release of agricultural waste materials. An evaluation of sediment contamination was conducted using pollution indicators including Geo-accumulation index (Igeo), enrichment factor (EF), and pollution load index (PLI). Spatial distribution analysis was used to determine the distribution pattern of each metal. The results revealed that metal concentrations (Cu, Pb, and Mn) are higher, while Cd concentrations are lower than the maximum allowed limits. The results from the EF analysis indicated elevated concentrations of Cu and Cd in the sampled area. In terms of the Igeo analysis of Khirbet al-Samra sediments, it was found that the concentrations of Pb, Cu, and Mn are within safe levels and relatively unaffected by human activities, whereas the concentrations of Cd exceed the mean values, suggesting a higher level of contamination specifically for cadmium. The potential sources of heavy metals in the investigated area were identified using factor analysis, and the geographical distribution of heavy metals was shown using spatial distribution. The examination of correlation coefficients revealed diverse relationships between the different parameters, depending on the source of input for each metal. [ABSTRACT FROM AUTHOR]

The article explores the Soil and Water Assessment Tool (SWAT), its features, applications and advancements that propelled the use of this hydrological modelling tool. Topics discussed include runoff modelling using SWAT, sediment yield modelling, nutrient cycle modelling, and limitations such as the need for extensive input data, simulation of runoff and sediment in certain months, and performance depending on the specific characteristics of the watershed being studied.

Urban tropical lagoons are commonly impacted by silting, domestic sewage and industrial wastes and the dredging of their sediments is often required to minimize environmental impacts. However, the ecological implications of land disposal of dredged sediments are still poorly investigated in the tropics. Aiming to contribute to filling this gap, an ecotoxicological evaluation was conducted with dredged sediments from Tijuca Lagoon (Rio de Janeiro, Brazil) using different lines of evidence, including soil and sediment characterization, metal determination, and acute and avoidance bioassays with Eisenia andrei. Two different dredged sediment samples, a sandy sediment and another muddy one, were obtained in two distinct and spatially representative sectors of the Tijuca Lagoon. The sediments were mixed with an artificial soil, Ferralsol and Spodosol to obtain doses between 0 (pure soil) and 12%. The sediment dose that caused mortality (LC50) or avoidance responses (EC50) to 50% of the organisms was estimated through PriProbit analysis. Metal concentrations and toxicity levels were higher in the muddy sediment (artificial soil LC50 = 3.84%; Ferralsol LC50 = 4.58%; Spodosol LC50 = 2.85%) compared to the sandy one (artificial soil LC50 = 10.94%; Ferralsol LC50 = 14.36%; Spodosol LC50 = 10.38%), since fine grains tend to adsorb more organic matter and contaminants. Mortality and avoidance responses were the highest in Spodosol due to its extremely sandy texture (98% of sand). Metal concentrations in surviving earthworms were generally low, except sodium whose bioaccumulation was high. Finally, the toxicity is probably linked to marine salts, and the earthworms seem to accumulate water in excess to maintain osmotic equilibrium, increasing their biomass. [ABSTRACT FROM AUTHOR]

Sediment connectivity at the catchment scale includes the processes linking sediment sources, sinks and the river outlet. Soil erosion models usually estimate yields without considering riverine processes or human infrastructure that may affect sediment connectivity. Quantifying these processes at a large scale is a determinant of understanding sediment transfers from continental lands to marine ecosystems. This study tries to fill this gap by coupling the soil erosion model WaTEM/SEDEM (WS) with the riverine connectivity tool CASCADE to quantify sediment fluxes in the Rhône watershed. The coupling returned a good fit, with deviations of −51.7%. WS alone predicts the exported fluxes better with a deviation of −34.9%. Nevertheless, this paper shows the importance of considering connectivity and transport capacity to develop a more realistic representation of fine sediment dynamics at a large scale. However, connectivity tools depend on the quality of the models (soil erosion and hydrology) and the geomorphological data on which they depend, which is a limiting factor in large‐scale studies. [ABSTRACT FROM AUTHOR]

Three extremophile bacterial strains (BBCOL-009, BBCOL-014 and BBCOL-015), capable of degrading high concentrations of perchlorate at a range of pH (6.5 to 10.0), were isolated from Colombian Caribbean Coast sediments. Morphological features included Gram negative strain bacilli with sizes averaged of 1.75 × 0.95, 2.32 × 0.65 and 3.08 × 0.70 μm, respectively. The reported strains tolerate a wide range of pH (6.5 to 10.0); concentrations of NaCl (3.5 to 7.5% w/v) and KClO4− (250 to 10000 mg/L), reduction of KClO4− from 10 to 25%. LB broth with NaCl (3.5–30% w/v) and KClO4ˉ (250-10000 mg/L) were used in independent trials to evaluate susceptibility to salinity and perchlorate, respectively. Isolates increased their biomass at 7.5 % (w/v) NaCl with optimal development at 3.5 % NaCl. Subsequently, ClO4ˉ reduction was assessed using LB medium with 3.5% NaCl and 10000 mg/L ClO4ˉ. BBCOL-009, BBCOL-014 and BBCOL-015 achieved 10%, 17%, and 25% reduction of ClO4ˉ, respectively. The 16 S rRNA gene sequence grouped them as Bacillus flexus T6186-2, Bacillus marisflavi TF-11 (T), and Bacillus vietnamensis 15 − 1 (T) respectively, with < 97.5% homology. In addition, antimicrobial resistance to ertapenem, vancomycine, amoxicillin clavulanate, penicillin, and erythromycin was present in all the isolates, indicating their high adaptability to stressful environments. The isolated strains from marine sediments in Cartagena Bay, Colombia are suitable candidates to reduce perchlorate contamination in different environments. Although the primary focus of the study of perchlorate-reducing and resistant bacteria is in the ecological and agricultural realms, from an astrobiological perspective, perchlorate-resistant bacteria serve as models for astrobiological investigations. [ABSTRACT FROM AUTHOR]

Sets of marine terraces, sediments, and paleoshorelines are commonly found in forearc regions worldwide. A common assumption holds that crustal uplift prevents these features from littoral erosion. Here, we study the vertical deformation of Karpathos, a forearc island in the eastern Mediterranean, whose long axis extends at a high angle to the strike of the Hellenic Subduction System (HSS). We target three key coastal localities along the island to discuss spatial and temporal variability of vertical motion. We mapped sets of up to 19 marine terraces per locality, with elevations ranging from 1.5 to ∼350 masl. Ages for terraces and sediments are constrained by radiocarbon (<31 masl) and Sr‐isotope (2–310 masl) dating, and range from 2.4 ka to ∼4.3 Ma. Data analysis shows that average uplift rates are up to two orders of magnitude faster over shorter (⪅100 ka) than longer (⪆100 ka) timescales, in agreement with other local and global data sets. Further, we find evidence for multiple marine reoccupations of late Pleistocene terraces, indicating that carbonate beachrock is often resistant to multiple interactions with sea‐level. Neogene marine sequences that witness longer periods (∼4 Ma) show signs of alternating vertical motion. Using this novel data set, we explore the effects of various mechanisms (i.e., upper‐plate normal faulting, splay‐thrust faulting, basal underplating) on the spatial and temporal patterns of vertical deformation. Although the contribution of each mechanism to the net vertical deformation cannot be isolated with certainty, our results show that none alone could account for the observations. Plain Language Summary: In this study, we focus on understanding how the landmass of Karpathos Island, in the Hellenic Subduction System in the Mediterranean Sea, moved vertically over time. We focus mainly on marine terraces, which are wave‐cut platforms near the sea forming staircase‐like topography. The age of these platforms has been constrained by dating fossil shells, shell fragments, and soils that mantle the terraces: for young (closer to the sea‐level) markers we used the isotope Carbon‐14, while for older terraces (further inland) Strontium‐87. We found that the island of Karpathos subsided prior to ∼4.3 Ma, but since then it experiences uplift. From our analysis, we find that the vertical motion of the island is the result of, at least, three interrelated processes: (a) sediment underplating, that scrapes sediments from the down‐going plate during subduction and attaches them to the base of the upper plate, pushing it upwards; (b) large earthquakes that occur either at the interface of two converging plates or on large faults that splay from this interface; and (c) smaller earthquakes produced by the horizontal stretching of the Aegean crust. Key Points: Karpathos provides a natural transect across the Hellenic forearc for exploring vertical deformationNo single mechanism of vertical movement alone can explain the full range of observations and dataUnderplating, splay faulting, and normal faulting interact in space and time to produce overall uplift on Karpathos since ∼4.3 Ma [ABSTRACT FROM AUTHOR]

Information about estuarine mixing and its control of sediment transport is crucial to elucidating the dynamics and evolution of estuaries. Here, the microtidal and funnel-shaped Zhenhai Estuary, located in the southwestern Pearl River Delta of China, is used to investigate the characteristics and mechanisms of water mixing and sediment transport based on observations from three spring tides. The results reveal that the studied estuary remains well mixed during spring tides from 2013–2022 despite its microtidal regime. Tidal stirring, which is enhanced by tidal energy convergence and benefits from the funnel-shaped geometry and shallow bathymetry, favors vertical mixing, contributing to the formation of strong mixing in the estuary. Due to the well-mixed regime, sediment transport in the estuary is dominated by the advective term, followed by a moderate tidal pumping term and minor estuarine circulation term. Accordingly, sediments within the estuary tend to be transported landward owing to the regulation of the funnel-shaped geometry, and a gradual but slow infilling trend is predictable. This paper deepens our understanding of hydrodynamics and sediment transport in microtidal estuaries. [ABSTRACT FROM AUTHOR]

This paper investigated the relationships of some physical and mechanical parameters of sediments and a typical clay during a natural dewatering process. Four sediments from different French river dams sampled by the Électricité De France group (EDF group) and a commercial kaolin clay used for comparative purposes were the focus of this study. Continuous dewatering was monitored in a laboratory by quantifying the percentage of water remaining in sediments or clay, drained and evaporated. Undrained shear strength was also assessed during the sediment or clay dewatering process, using the laboratory vane shear test. The samples were controlled along different dimensions during the dewatering process throughout the whole experiment. The results showed a certain interdependence between the physical parameters and the water content (ω), which was normalized by the liquidity limit (ω/LL) over time. This led to sigmoidal and exponential correlations when considering the percentage of water drained. The percentage of water remaining in the sediments or clay was characterized using the normalized water content, leading to exponential and power correlations. Both exponential and linear correlations were perfect for describing the evolution of the percentage of water evaporated. Other correlations were established for variations in void index, dry unit weight/solid unit weight ratio and undrained shear strength during the dewatering process. [ABSTRACT FROM AUTHOR]

This study aims to investigate the stratigraphic features and rare earth element (REE) mechanisms of deep-sea REE-rich sediments in the West Pacific Pigafetta Basin using acoustic rapid detection technology. Through an analysis of sub-bottom profile data and synthesis of existing studies, this study reveals the acoustic properties and thickness distribution of the REE-rich sediments. Acoustic spectral records identify three distinct acoustic facies: opaque (O), transparent (T), and laminated (L). This study maps the thickness and spatial distribution of the REE-rich sediment layer in the research area, ranging from approximately 6 to 36 m in thickness. Regions with REE-rich sediments exceeding 30 m in depth are identified, showing concentrated distribution along the northwest–southeast axis and a contiguous zone in the southwest corner of the study area. The method employed in this study can determine the potential bottom boundary of the REE-rich layer by assessing the thickness range of the sedimentary layer, overcoming limitations of traditional sampling methods. Furthermore, the thickness distribution characteristics of the REE-rich sedimentary layer in the study area provide valuable insights for future research on resource evaluation and estimation. [ABSTRACT FROM AUTHOR]

Change in land use and land cover (LULC) is crucial to freshwater ecosystems as it affects surface runoff, groundwater storage, and sediment and nutrient transport within watershed areas. Ecosystem components such as wetlands, which can contribute to the reduction of water pollution and the enhancement of groundwater recharge, are altered by LULC modifications. This study evaluates how wetlands in the Big Sunflower River Watershed (BSRW) have changed in recent years and quantified their impacts on streamflow, water quality, and groundwater storage using the Soil and Water Assessment Tool (SWAT). The model was well calibrated and validated prior to its application. Our study showed that the maximum increase in wetland areas within the sub-watersheds of interest was 26% from 2008 to 2020. The maximum changes in reduction due to the increase in wetland areas were determined by 2% for streamflow, 37% for total suspended solids, 13% for total phosphorus (TP), 4% for total nitrogen (TN), and the maximum increase in shallow groundwater storage by 90 mm from 2008 to 2020 only in the selected sub-basins. However, the central part of the watershed experienced average declines of groundwater levels up to 176 mm per year due to water withdrawal for irrigation or other uses. This study also found that restoration of 460 to 550 ha of wetlands could increase the reduction of discharge by 20%, sediment by 25%, TN by 18%, and TP by 12%. This study highlights the importance of wetland conservation for water quality improvement and management of groundwater resources. [ABSTRACT FROM AUTHOR]

Lake sediments are ideal archives to evaluate the interactions between climatically driven environmental responses and human activity on seasonal to multi‐decadal timescales. This study focuses on the unique sediments of Diss Mere, the only lake in England providing an annually laminated (varved) record for most of the Holocene. We combine microfacies analysis with X‐ray core scanning data to explore the influence of natural and human‐led changes on sediment deposition over the past 10 200 years and evaluate the sensitivity of the lake sediments to climate variability through time. Variability of titanium (Ti), calcium (Ca) and silica (Si) explain most of the lithological changes observed in the sediment and we identify three stages with low (10 290–2070 cal a bp), intermediate (2070–1040 cal a bp) and intensified (1040 cal a bp – present) human influence. During the first stage, where varved sediments are preserved, Ti is low due to the minimal detrital input into the lake. Ca and Si during this stage reveal high‐amplitude variability responding to seasonal changes in sediment deposition. The termination of varved sediment preservation and increases in sedimentation rates coincide with a major rise in Ti after this first stage, marking the intensification of human activity around the lake. Ca is used here as an indicator of temperature‐included calcite precipitation, and the long‐term variability of the Ca profile resembles Holocene temperature evolution. This continues during periods of intensified human activity, suggesting that the Diss Mere sediments remain sensitive to climate through time. [ABSTRACT FROM AUTHOR]

The coastal zone of the Red Sea had been seriously subjected to enduring impacts including; petroleum exploration and production, overpopulation, and severe land-based enterprises. Heavy metal (HM) pollution in the marine ecosystem has become a severe ecological problem due to its damaging effects and persistence in the environment. Therefore, 41 surface sediment samples were collected from the frontal marine areas off the megacities of the Egyptian Red Sea to investigate the HMs contamination using Atomic Absorption Spectrophotometer. The recorded HM averages (μg/g) were follow the order of; Fe (6545.72) > Mn (177.76) > Zn (48.61) > Ni (20.96) ≥ Pb (20.84) > Cu (11.31) > Cd (1.38). Except for Cu, Ni, and Pb, the mean values of HMs in the examined samples surpassed the low reference values observed in the different sediment quality guidelines (SQGs), demonstrating these HMs have a rare risk to the aquatic population. The results of single pollution indices revealed that all investigated areas were unpolluted by Fe, Mn, Cu, Zn, and Ni, and minimal to mildly contaminated by Pb and Cd. However, the pollution load index (PLI) indicated that the seafloor sediments of all studied cities were clearly unpolluted by HMs (PLI < 1). Additionally, correlations revealed that the observed HMs originated from comparable (terrigenous) origins, except for Ni, which could have accumulated from another anthropogenic source. In addition to providing global insights, this study will give Egypt a road map for working together to protect the northern Red Sea's coastal ecology. [ABSTRACT FROM AUTHOR]

In the riparian zone of the Yangtze River, using polders to impound flood water with high sediment content probably brings eutrophication. A nutrient (nitrogen and phosphorus) release experiment was conducted to reveal the risk. Bare soil and arable soil were used as underlying soils. Overlying water with two sediment concentrations (formed 1 cm and 4 cm thickness layer after deposited, respectively) was used to simulate reserved floods. Higher nutrient content in arable soil led to faster nutrient release into overlying water (16–21 and 0.32–1.32 mg/d·cm2 for TN and TP, respectively) relative to bare soil (5–13.5 and 0.25–1.26 mg/d·cm2 for TN and TP, respectively), suggesting that bare land with lower nutrient content is better than arable land for storing flood water. Nutrient content in sediment deposit layer relative to in original underlying soil determined whether deposited sediment accelerated or mitigated the release of nutrients into overlying water. Because sediment has higher nutrient content than bare soil, the preferred time to impound flood is at the end of flood seasons when sediment load steeply decreases. It is more likely to suffer eutrophication in the initial stage of flood impounding, when overlying water was abundant in both nitrogen and phosphorus and N/P ratio (10–23) was fit for phytoplankton growth. This study helps to identify the risk of eutrophication due to reserving turbid flood water in polders. [ABSTRACT FROM AUTHOR]

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The study evaluated the thermal stability of sterilized camel milk. The sterilized product was obtained from raw milk containing 9.11 ± 0.57% nonfat solids and 2.83 ± 0.45% fat. Disodium/dipotassium hydrogen phosphate (Na2HPO4 or K2HPO4), sodium citrate (SC), ethylenediaminetetraacetic acid (EDTA, disodium), sodium chloride (NaCl), and gum arabic (GA) were evaluated for their effects as thermal stabilizers of camel milk (CAM). Stabilizers were separately added to pasteurized camel milk (pH 6.67) followed by the in‐container sterilization (115°C, 20 min). Phosphate salts afforded thermal stability (sediment test) when added to camel milk at 13 mM final concentration. During storage for four weeks at 21°C, the pH values of stabilized camel milk were 6.40−5.67, depending on the type and concentration of stabilizers. While nonstabilized (control) CAM showed substantial sediments during storage periods at ambient conditions (21°C), stabilized and sterilized CAM had no sediments reflecting one of the good quality characteristics (no sediments) of CAM. Color changes (ΔE∗) in stored sterilized camel milk were below 2.3. It could be concluded that nonevaporated CAM could be made from CAM stabilized with Na2HPO4 or K2HPO4. This is the first study on the thermal stability of nonevaporated camel milk. [ABSTRACT FROM AUTHOR]

Reactive iron (FeR) serves as an important sink of organic carbon (OC) in marine surface sediments, which preserves approximately 20% of total OC (TOC) as reactive iron-bound OC (FeR-OC). However, the fate of FeR-OC in subseafloor sediments and its availability to microorganisms, remain undetermined. Here, we reconstructed continuous FeR-OC records in two sediment cores of the northern South China Sea encompassing the suboxic to methanic biogeochemical zones and reaching a maximum age of ~100 kyr. The downcore FeR-OC contributes a relatively stable proportion of 13.3 ± 3.2% to TOC. However, distinctly lower values of less than 5% of TOC, accompanied by notable 13C depletion of FeR-OC, are observed in the sulfate-methane transition zone (SMTZ). FeR-OC is suggested to be remobilized by microbially mediated reductive dissolution of FeR and subsequently remineralized, the flux of which is 18–30% of the methane consumption in the SMTZ. The global reservoir of FeR-OC in microbially active Quaternary marine sediments could be 19-46 times the size of the atmospheric carbon pool. Thus, the FeR-OC pool may support subseafloor microorganisms and contribute to regulating Earth's carbon cycle. This study shows that iron-bound organic carbon (FeR-OC) is generally persistent but can be remobilized during iron reduction and utilized by microbes in subseafloor sediments. This sedimentary FeR-OC pool may contribute to regulating Earth's carbon cycle. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that vegetation‐generated turbulence can enhance erosion rate and reduce the velocity threshold for erosion of non‐cohesive sediment. This study considered whether vegetation‐generated turbulence had a similar influence on natural cohesive sediment. Cores were collected from a black mangrove forest with aboveground biomass and exposed to stepwise increases in velocity. Erosion was recorded through suspended sediment concentration. For the same velocity, cores with pneumatophores had elevated turbulent kinetic energy compared to bare cores without pneumatophores. However, the vegetation‐generated turbulence did not increase bed stress or the rate of resuspension, relative to bare cores. It was hypothesized that the short time‐scale fluctuations associated with vegetation‐generated turbulence were not of sufficient duration to break cohesion between grains, explaining why elevated levels of turbulence associated with the pneumatophores had no impact on the erosion threshold or rate. Plain Language Summary: Mangrove habitat grows by retaining sediment. To restore these systems, it is necessary to understand how vegetation influences the transport and retention of sediment. This study used sediment cores collected from the interior of a mangrove forest to study how the aboveground roots, called pneumatophores, influence hydrodynamic conditions and sediment transport, and in particular the onset and rate of sediment erosion. Individual pneumatophores generate eddies that enhance turbulence, compared to conditions without pneumatophores. In sandy soil, vegetation‐generated turbulence can enhance erosion. However, in this study, vegetation‐generated turbulence did not increase the rate of erosion for natural cohesive (muddy) sediment, suggesting that the mangrove forest interior has naturally greater resistance to erosion and sediment loss. Key Points: For the same velocity, cores with pneumatophores had higher turbulent kinetic energy (TKE) compared to cores without pneumatophoresUnlike sands, the inception of erosion and erosion rates for cohesive sediment were better predicted by bed shear stress than by TKEModelers should parameterize erosion within vegetation differently for cohesive and non‐cohesive sediment [ABSTRACT FROM AUTHOR]

Mediterranean high-mountain lakes are being increasingly affected by strong Saharan dust deposition events. However, the ecological impacts of these severe atmospheric episodes remain largely unknown. We examined the effects of a strong Saharan dust intrusion to the Iberian Peninsula in 2022 on the physicochemical parameters and prokaryotic communities in sediments of nine high-mountain lakes of Sierra Nevada (Spain) located above 2800 m.a.s.l and in different orientations (north vs. south). A previous year (2021), with lower Saharan dust deposition with respect to 2022, was used for interannual comparisons. The strong dust deposition to the high-mountain lakes resulted in a significant increase in sediment nutrient availability which was linked to changes in the composition of prokaryotic communities. Decreases in alpha diversity and changes in beta diversity of prokaryotic communities were mainly observed in lakes located in the south compared to the north orientation likely because the former was more affected by the atmospheric dust deposition episode. Dust intrusion to the high-mountain lakes resulted in significant changes in the relative abundance of specific genera involved in important nutrient cycling processes such as phosphate solubilization, nitrogen fixation, nitrification, and denitrification. Saharan dust deposition also increased predicted microbial functionality in all lakes. Our findings show that severe atmospheric dust inputs to remote high-mountain lakes of Sierra Nevada can have significant biogeochemical and biodiversity consequences through changes in nutrient availability and prokaryotic communities in sediments of these freshwater ecosystems. This information contributes to understanding how Mediterranean high-mountain lakes of Sierra Nevada face strong intrusions of Saharan dust and their ecological consequences. [ABSTRACT FROM AUTHOR]

Invasive Spartina alterniflora (S. alterniflora) has significant impacts on sediment biogeochemical cycling in the tidal wetlands of estuaries and coasts. However, the impact of exotic Spartina alterniflora invasion on greenhouse gases (GHGs) production dynamics in sediments remain limited. Here, we investigated the dynamics of sediment physicochemical properties, GHGs production rates, and microbial gene abundances in a native Cyperus malacensis habitat and three invasive S. alterniflora habitats (6-, 10-, and 14-year) in the Minjiang River Estuary, China. The methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) production rates varied both spatially and seasonally, while microbial gene abundances (bacterial and fungal gene abundances) and organic matter (TOC and TN) only varied spatially. GHGs production rates were also characterized by higher values in surface sediment (0-10 cm) compared to subsurface sediment (10-20 cm) and by seasonal variations with higher values in summer than in winter. S. alterniflora invasion can significantly increase CH4 and CO2 production rates, organic matter, and microbial gene abundances (p < 0.05). Temperature, organic matter and microbial gene abundances were the most dominating factor controlling the spatio-temporal variations of CH4 and CO2 production rates. Overall, our findings highlighted the significant role of S. alterniflora invasion in regulating GHGs production rates in coastal wetland sediments and provided fundamental data for estimating GHGs emissions and carbon sequestration in the complex tidal wetlands. [ABSTRACT FROM AUTHOR]

The Qicheng city wall is located in Puyang, Henan Province, China, and it is an important archaeological site from the Neolithic period in the North China Plain region. A trench across the northwest corner of the city wall revealed an 11 m thick sediment sequence, closely associated with human activities, which provides valuable records for the dating and environmental evolution of the site. In this study, we have applied field geological investigation, grain size analysis, optically stimulated luminescence (OSL) dating, and radiocarbon (14C) dating to reveal the history and changes in the site. The ancient city wall was built on the sedimentary sequence (U1) of the high terrace of the Ancient Yellow River. The upper 11 m thick sedimentary sequence (U2) recorded early moat sedimentation (U2 L) and was followed by three cycles of paleosol-flooding deposits (U2 U). The quartz OSL signals of the U2 silts are extremely bright, indicating high sensitivity. Partial bleaching was observed as well. The quartz OSL single-grain SAR dating results are consistent with that of charcoal 14C dating and are closer to the 'true' burial ages of the sediments than those obtained with multiple grains. By using a Bayesian statistical model, a chronological framework for the U2 sedimentary sequence was established. The earliest construction date of the Qicheng city wall is dating to 2100–1300 BC, during the late Longshan period, which is consistent with archaeological evidence (Li et al., 2015). The Qicheng city was not significantly affected by paleo-flooding prior to 870–960 AD, but experiences frequent flooding thereafter. [ABSTRACT FROM AUTHOR]

The post-Infrared Infrared Stimulated Luminescence (pIRIR) protocol has been successfully applied to date Quaternary sediments using the K-rich feldspar fraction (density ＜2.58 g/cm3). However, during the extraction of K-feldspar grains, Na-feldspar particles (density 2.58–2.62 g/cm3) may be included, especially within the medium grained fraction. However, the possible influence of Na-feldspar contamination on K-feldspar IRSL dating results has not been investigated in detail. In this study, we applied the pIRIR dating protocol to measure the coarse- and medium-grained K-and Na-feldspar fractions of eight aeolian samples from various regions. Blue-violet and yellow-green detection windows were used for derived the signals of K- and Na-feldspar, respectively, and we attempted to evaluate the influence of the contamination by Na-feldspar grains on feldspar pIRIR dating. Comparison of the three signals (K-feldspar blue, Na-feldspar blue, Na-feldspar yellow) from each sample showed that the influence of the IRSL blue signal from Na-feldspar grains on the signal of the K-feldspar fraction was < 1–3%. Because of high fading rates, the D e s or pIRIR ages obtained from the Na-feldspar yellow signal were underestimated. The Na-feldspar blue pIRIR D e s and ages were nevertheless consistent with their corresponding K-feldspar blue D e values and ages. This is because the few K-feldspar grains included within the Na-feldspar fraction emitted the greater part of the blue signals. From these observations, we conclude that the influence of Na-feldspar grains within the K-feldspar fraction on K-feldspar IRSL dating results can be ignored. [ABSTRACT FROM AUTHOR]

The object of this research is the polychlorinated biphenyls (PCBs) in sediments along Shatt Al-Arab estuary, Iraq. The study examines the problem of river PCB pollution. PCB effects on humans include cancer, impaired reproduction, neuro-developmental effects in infants, immunotoxicity and endocrine disruption. PCBs lead to liver damage and stimulate changes in the DNA sequence. The Shatt Al-Arab Estuary is formed in southern Iraq near Al-Qurna city after the confluence of the Tigris and Euphrates Rivers. The Shatt Al-Arab Estuary region is shared between Iraq and Iran. The Estuary receives pollutants when it is passing during Basrah City regions, due to industrial, agricultural and human activities which discharge the pollutants to the Estuary without treatment. The concentrations of Σ13 PCBs compound in sediment samples were determined and analyzed at each site by using gas chromatography-mass spectrometry (GC-MS, Agilent). Six sites were chosen along Shatt Al-Arab Estuary. They are Al-Qurna (S1), Al-Deer (S2), Al-Qarma (S3), Al-Ashar (S4), Abi Al-Khasib (S5) and Al-Fao (S6), at Basrah city, south of Iraq. Sediment samples were collected seasonally, starting from Autumn season on September 2019 to summer season on July 2020. The Σ13 (PCB-18, PCB-29, PCB-31, PCB-28, PCB-44, PCB-52, PCB-101, PCB-141, PCB-149, PCB-138, PCB-153, PCB-189, and PCB-194) concentrations at the sediment samples ranged from 4.48 ng/g in Al-Deer site during summer season to 27.75 ng/g in Al-Ashar site during winter season for all selected sites. The Al-Deer site were found to have the lowest mean of PCBs its 0.345 ng/g and Al-Ashar site were found to have the highest mean of PCBs its 2.135 ng/g. PCBs concentrations in sediment samples during autumn, winter, spring and summer seasons ranged from 7.75 to 21.68 ng/g, 16.25 to 27.75 ng/g, 7.28 to 22.01 ng/g and 4.48 to 14.41 ng/g, respectively. The congener distribution patterns in these samples indicate the dominance highly chlorinated congeners (tri- and hexa-PCBs) in comparison with remaining others PCBs congeners. This project is the first of its kind in Basrah and all Iraq that reports PCB concentrations in the region and is considered a baseline study and can be used for subsequent studies. [ABSTRACT FROM AUTHOR]

This study aims to classify seafloor sediments using physics‐inspired and data‐driven soil models combined with machine learning algorithms and oversampling techniques. The field data used for the input variables include porosity, S‐ and P‐wave velocities and depth. The soil information reported in the original literature and the "six reference sediments" and effective stress‐versus‐depth models proposed by the previous study confirm the sediment type across all of the input variables. We use three machine learning algorithms and four oversampling methods to enhance the performance accuracy and overcome data imbalance in the minority class. The results show that the averaged accuracy of sediment classification with original data corresponds to 0.88 for porosity, 0.61 for S‐wave velocity, and 0.97 for P‐wave velocity. In particular, the enhanced accuracy with oversampled input variables becomes more pronounced when the depth data are considered in a dataset. The class‐oriented grouping method newly proposed in this study appears to be a robust approach to enhancing performance. Surprisingly, model‐based input variables lead to the best performance in all cases. The proposed analyses conducted using machine learning algorithms and oversampling techniques within the physics‐inspired models could be extended to obtain a first‐order assessment of marine sediment properties. [ABSTRACT FROM AUTHOR]

As a response of the coastal oceans to more severe anthropogenic disturbance, increasing coastal primary production has been more frequently observed in recent years. This raises the question of howthis progressive change reshapes the long-term carbonsequestration in thecoastal oceans. With this question inmind, we investigated the sediment organic matter (OM) preserved on the shelf of the northern SouthChina Sea (NSCS) where high primary production has been observed. Across this sediment core, relatively lowtotal organic carbon content of around 0.60%was observed. Fatty acids with less carbon numbers exhibit exponential decreases downward with degradation rate constants ranging from 0.10 to 0.17 y-1, no matter they were from single sources (14:0 presumably from marine OM and ai-15:0, i-15:0, 15:0 from bacterial OM) or mixed sources (16:0). Meanwhile fatty acids with more carbon numbers, either 18:0 and 24:0 from mixed sources, or 26:0 and 28:0 presumably fromterrestrial input, were less varied inconcentrationswithdepth. Thisdemonstrates a preferential decomposition of labile fatty acids during the early diagenesis of coastal sediment organicmatter. A decrease of labile fatty acids δ13Cvalueswas observed with the decomposition, from which kinetic isotope fractionations were predicted ranging from 0.7 to 1.5‰. This provides an isotopic constraint of the mixing model to quantify labile organicmatter from terrestrial input and local phytoplankton production, from which declined contribution of local phytoplankton production to labile fatty acids was identified in more recent sediment. This finding together with the low organic carbon content and rapid removal of fatty acids in the top sediment, demonstrates the poor preservation of labile organic matter on the shelf of NSCS, implying that the increasing primary production has not enhanced the coastal carbon sequest ration yet, but rather leads tomore intensified respiration with a potential risk toincrease the CO2 outgassing fromthe coastal oceans. [ABSTRACT FROM AUTHOR]

Sediment grain size characterization is one of the main components of aeolian geomorphology research. Sand particle size can determine the basic form of sand movement. The distribution and form of grain size parameters of different types of sediments were calculated using six surface types of sediments around Qixing Lake in the Kubuqi Desert: Mobile dune Semi-fixed dune Fixed dune Lakeshore terrace Wetland and Grassy flat wetland The results showed that the surface sediments were mainly composed of medium sand and fine sand, and all types were negatively skewed. The differentiation pattern of the saltation component and suspended component of the surface sediment is characterized by a twostage pattern. The percentage contribution of suspended components in lakeshore terraces, wetlands, and Grassy flat wetlands (total average 21.07%) is more than twice that of mobile dunes, semifixed dunes, and fixed dunes (total average 9.47%). This suggests that mobile dunes, semi-fixed dunes, and fixed dunes are not the main contributing surface type of suspended material in the Qixing Lake area. [ABSTRACT FROM AUTHOR]

The Skagerrak basin represents the main sink area for fine-grained sediment in the North Sea region and constitutes a natural deposition center for sediments that are supplied from the Atlantic, the Baltic Sea and the surrounding continental margins and coasts. However, the exact sources and their proportional contributions to the North Sea sediments and to the Skagerrak deposits are not well understood. To trace the predominant sources of the sediment and to gain a better understanding of the sedimentary processes in the North Sea and the Skagerrak basin, radiogenic Sr, Nd, and Hf isotope signatures and clay mineral compositions of the detrital clay fraction of surface sediment samples from the North Sea, the Scandinavian margins and the Baltic Sea were measured. The results indicate that the major source for Skagerrak clay-size sediments is the northern North Sea but Scandinavia as well as the southern North Sea including the southern England coast also contribute material. Seabed and coastal erosion in the northern North Sea are enhanced by the inflowing Atlantic Currents, which provide the Skagerrak with high amounts of clay size sediments. In contrast, the southern North Sea, the Baltic Sea and mid-European rivers such as Weser, Elbe and Ems are only minor contributors. As Skagerrak deposits are dominated by clay sized material (up to 60%), the reconstructed sediment processes in this study deviate from findings in previous sediment budget studies, which were based on both clay and silt fraction and indicated predominant influences from the southern North Sea. These results highlight that coastal and seabed erosion in the North Sea is a previously underestimated source of fine-grained sediments for depocenters in the entire North Sea. With regard to climate change, the global sea-level rise will likely enhance erosional processes and can therefore significantly influence the sediment budget of the entire North Sea. [ABSTRACT FROM AUTHOR]

The polar regions are the fastest warming places on earth. Accelerated glacial melting causes increased supply of nutrients such as metal oxides (i.e., iron and manganese oxides) into the surrounding environment, such as the marine sediments of Potter Cove, King George Island/Isla 25 de Mayo (West Antarctic Peninsula). Microbial manganese oxide reduction and the associated microbial communities are poorly understood in Antarctic sediments. Here, we investigated this process by geochemical measurements of in situ sediment pore water and by slurry incubation experiments which were accompanied by 16S rRNA sequencing. Members of the genus Desulfuromusa were the main responder to manganese oxide and acetate amendment in the incubations. Other organisms identified in relation to manganese and/or acetate utilization included Desulfuromonas, Sva1033 (family of Desulfuromonadales) and unclassified Arcobacteraceae. Our data show that distinct members of Desulfuromonadales are most active in organotrophic manganese reduction, thus providing strong evidence of their relevance in manganese reduction in permanently cold Antarctic sediments. [ABSTRACT FROM AUTHOR]

The efficiency of beach recovery during a time of moderate waves following storm waves is closely related to the interaction between dynamics, sediment, and the landform. The existing studies mainly focus on the description of erosion and accretion characteristics, while the response and feedback mechanism of beach berm sediment have not been elucidated. The main controlling factors of recovery efficiency are not clear. In this paper, field observation and the XBeach numerical model are utilized on the sandy beach in Puqian Bay, China, to capture high-frequency cross-shore data during the post-storm recovery period. The variation characteristics and rules of berm elements, including berm ridge height and slope on two sides of the berm ridge, are analyzed. It is observed that the berm constantly changes to adapt to dynamic conditions. Additionally, a correlation between volume change and certain landform parameters is proposed, leading to the identification of a new relationship in wave run-up. The new forum reflects berm influence and considers the berm ridge and berm width. [ABSTRACT FROM AUTHOR]

Fine sediment infiltration and subsequent clogging in a gravel bed affect several fluvial, ecological, and biological processes, resulting in the degradation of the river ecosystem. Despite many experimental and a few numerical studies, the process is yet to be entirely understood. We employed a pure Lagrangian framework, called the Discrete Element Method (DEM), to numerically investigate the infiltration process. Special attention is given to tackling the issue of non-spherical and irregular particle shapes and particle size distributions (PSDs) in numerical simulations. Due to computational limitations, these aspects were either not considered or simplified in previous numerical studies. We implicitly included non-spherical and irregular shape effects through rolling resistance models, which do not cause excessive computational overhead. Our study shows that rolling resistance models greatly influence packing and fine sediment infiltration. However, they may also lead to unphysical particle behavior; thus, they should be carefully used in numerical simulations. Oversimplified PSDs do not mirror natural systems, and full PSDs pose computational challenges. Sufficient grain classes are needed to mimic the non-homogeneity and poly-dispersity found in natural fluvial sediments. The infiltrating characteristics of sand concerning PSD and shape effects are linked to size ratio D15,Gravel/D85,Sand, assuring physical and realistic modeling of the infiltration process. [ABSTRACT FROM AUTHOR]

Background: Myxococcota, characterized by their distinct social lifestyles, are widely distributed micro-predators in global sediments. They can feed on a wide range of bacterial, archaeal, and fungal prey. Myxococcota are capable of producing diverse secondary metabolites, playing key roles in microbial food webs, and regulating the microbial community structures in different ecosystems. However, Myxococcota are rarely pure cultured due to the challenging and stringent culturing conditions. Their natural distribution, niche differentiation, and predator–prey relationships in a specific habitat are poorly understood. Results: In this study, we conducted a comprehensive analysis of the 16S rRNA gene sequence data from public databases and our collection. We compared the abundance, diversity, and distribution patterns of Myxococcota in various habitats, with a specific focus on mangroves. We found that Myxococcota accounted for 1.45% of the total prokaryotes in global sediments based on the abundance of 16S rRNA genes. Myxococcota are abundant and diverse in mangrove sediments. They tend to be more generalistic in mangroves than in other habitats due to their wide niche breadth. Besides, the deterministic processes (variable selection) influenced the assembly of mangrove Myxococcota communities significantly more than stochastic processes. Further, we determined that environmental factors explained a greater amount of total community variation in mangrove Myxococcota than geographical variables (latitude and sediment depth). In the end, through the analysis of microbial co-occurrence networks, Myxococcota emerges as a key component and functions as a connector in the mangrove microbial community. Conclusions: Our study enhances comprehension of mangrove Myxococcota's biogeography, assembly patterns, driving factors, and co-occurrence relationships, as well as highlights their unique niche and ecological importance in mangrove sediments. [ABSTRACT FROM AUTHOR]

This study aimed to measure spatial and temporal distributions of total phenolic compounds and their ecological and health hazards using UV-vis spectrophotometers as a low-cost, fast, simple method in water and sediments collected from Timsah Lake, Suez Canal, Egypt, 2022. Also, assessing highly adaptive fungal species associated with contamination is designed. Due to human and environmental activities and industrial waste discharges, Timsah Lake is increasingly threatened by all kinds of pollutants. The results indicated that the seasonal concentration means of the phenolic compounds were winter (0.229) > spring (0.161) > summer (0.124) > autumn (0.131) mg/l and winter (3.08) > summer (2.66) mg/g in water and sediment samples, respectively. The result has shown that the phenol concentrations in all stations were more than 0.005 and 0.1 mg/l for Egyptian National Standards and World Health Organization (WHO) for drinking water but less than the limits of 1 mg/l for wastewater. Notably, the fungi recorded the highest counts during spring, totaling 397 colonies/100 ml of water and 842 colonies/gram of sediment. Four isolates of fungi were identified and deposited in the GenBank database by Aspergillus terreus, Aspergillus terreus, Penicillium roqueforti, and Penicillium rubens under accession numbers OR401933, OR402837, OR402878, and OR424729, respectively. Moreover, ecological risk (RQ) for the total phenolic compounds was > 1 in all investigated stations for water and sediments. The hazard quotient is HQ < 1 in all seasons in water and sediments except winter. The hazard index (HI) in water and sediments for children is higher than for adults. It can be concluded that the low-cost, fast, simple method for determining phenolic content in water and sediment samples, using UV-vis spectrophotometry, was useful for predicting the reactivates of a wide variety of phenol and their derivatives. Furthermore, it can be concluded that Periodic assessments of water quality and strict regulations are necessary to safeguard this vital resource from pollution and ensure the well-being of future generations. Finally, policymakers and water treatment specialists might use the information from this research to reduce these chemical pollutants in Egypt. [ABSTRACT FROM AUTHOR]

Ice sheet models must be able to accurately simulate palaeo ice sheets to have confidence in their projections of future polar ice sheet mass loss and resulting global sea-level rise, particularly over longer timescales. This requires accurate reconstructions of the extent and flow patterns of palaeo ice sheets using real-world data. Such reconstructions can be achieved by tracing the detrital components of offshore sedimentary records back to their source areas on land. For Antarctica, however, sediment provenance data and ice sheet model results have not been directly linked, despite the complimentary information each can provide on the other. Here, we present a computational framework (Tracing Antarctic Sediment Provenance, TASP) that predicts marine geochemical sediment provenance data using the output of numerical ice sheet modelling. The ice sheet model is used to estimate the spatial pattern of erosion rates and to trace ice flow pathways. Beyond the ice sheet margin, approximations of modern detrital particle transport mechanisms using ocean reanalysis data produce a good agreement between our predictions for the modern ice sheet/ocean system and seabed surface sediments. These results show that the algorithm could be used to predict the provenance signature of past ice sheet configurations. TASP currently predicts neodymium isotope compositions using the PSUICE3D ice sheet model, but thanks to its design it could be adapted to predict other provenance indicators or use the outputs of other ice sheet models. [ABSTRACT FROM AUTHOR]

Riverbed sediments have been identified as temporary and long-term accumulation sites for microplastic particles (MPs), but the relocation and retention mechanisms in riverbeds still need to be better understood. In this study, we investigated the depth-specific occurrence and distribution (abundance, type, and size) of MPs in river sediments down to a depth of 100 cm, which had not been previously investigated in riverbeds. In four sediment freeze cores taken for the Main River (Germany), MPs (≥ 100 µm) were detected using two complementary analytical approaches (spectroscopy and thermoanalytical) over the entire depth with an average of 21.7 ± 21.4 MP/kg or 31.5 ± 28.0 mg/kg. Three vertical trends for MP abundance could be derived, fairly constant in top layers (0–‍30 cm), a decrease in middle layers (30–60 cm), and a strong increase in deep layers (60–100 cm). The dominant polymer types were polyethylene (PE), polypropylene (PP), and polystyrene (PS). Polyethylene terephthalate (PET) and PP were also found in deep layers, albeit with the youngest age of earliest possible occurrence (EPO age of 1973 and 1954). The fraction of smaller-sized MPs (100–500 µm) increased with depth in shallow layers, but the largest MPs (> 1 mm) were detected in deep layers. Based on these findings, we elucidate the relationship between the depth-specific MP distribution and the prevailing processes of MP retention and sediment dynamics in the riverbed. We propose some implications and offer an initial conceptual approach, suggesting the use of microplastics as a potential environmental process tracer for driving riverbed sediment dynamics. [ABSTRACT FROM AUTHOR]

Ivermectin (IVM) is a widely used antiparasitic. Concerns have been raised about its environmental effects in the wetlands of Río de la Plata basin where cattle have been treated with IVM for years. This study investigated the sublethal effects of environmentally relevant IVM concentrations in sediments on the Neotropical fish Prochilodus lineatus. Juvenile P. lineatus were exposed to IVM-spiked sediments (2 and 20 µg/Kg) for 14 days, alongside a control sediment treatment without IVM. Biochemical and oxidative stress responses were assessed in brain, gills, and liver tissues, including lipid damage, glutathione levels, enzyme activities, and antioxidant competence. Muscle and brain acetylcholinesterase activity (AChE) and stable isotopes of 13C and 15N in muscle were also measured. The lowest IVM treatment resulted in an increase in brain lipid peroxidation, as measured by thiobarbituric acid reactive substances (TBARs), decreased levels of reduced glutathione (GSH) in gills and liver, increased catalase activity (CAT) in the liver, and decreased antioxidant capacity against peroxyl radicals (ACAP) in gills and liver. The highest IVM treatment significantly reduced GSH in the liver. Muscle (AChE) was decreased in both treatments. Multivariate analysis showed significant overall effects in the liver tissue, followed by gills and brain. These findings demonstrate the sublethal effects of IVM in P. lineatus, emphasizing the importance of considering sediment contamination and trophic habits in realistic exposure scenarios. [ABSTRACT FROM AUTHOR]

This study aimed at assessing the long term impacts of watershed management interventions and scenarios on sediment export reduction in the data-scarce region of the Yezat watershed in north-west Ethiopia. The modified ecosystem services valuation model (InVEST) was employed to evaluate the amount of sediment export in the watershed. Different watershed management intervention scenarios were applied to evaluate the effectiveness of watershed management interventions on sediment export reduction. The results of the study showed that the mean annual sediment yield was 35 tons ha yr in 20000, due to the expansion of cultivated land and built-up area. Conversely, it decreased from 35 ton ha yr in 2000 -18.4 ton ha yr in 2021 due to watershed management interventions. On the contrary, moderate, severe, and very severe categories of sediment export intensity were high in 2000. But it decreased in 2021 due to watershed management interventions. The mean annual sediment export in the baseline scenario (BS) was 35 tons per year, which was reduced to 13.39 tons per year, 3.46 tons per year, and 1.17 tons per year in the reforestation scenario, soil/stone bund, and integrated scenarios, respectively. The result revealed that areas covered by high sediment severity classes were reduced. [ABSTRACT FROM AUTHOR]

Since the 1980s, the flow- sediment regime entering the Lower Yellow River (LYR) has altered significantly. The channel in the LYR continuously experienced aggradation under the heavy sediment load and degradation by the operation of the Xiaolangdi (XLD) Reservoir. Based on the measured flow-sediment data and the topography at fixed sections from 1986 to 2020, the reach- scale bankfull discharges were calculated, and the contributions were quantified of flow-sediment regime during the flood and non- flood seasons to the flood discharge capacities in different reaches. Results show that: ① In the pre-dam period, the fluvial erosion intensity decreased temporally, leading to a predominance of channel aggradation with deposition in flood seasons and erosion in non-flood seasons. Consequently, the bankfull discharge decreased continuously with the minimum value less than 2 000 m³ / s. ② In the post- dam period, the fluvial erosion intensity increased significantly especially in the non- flood seasons, contributing greatly to the channel degradation. The flood discharge capacity recovered remarkably, with the most rapid recovery occurring in the braided reach. ③ There was a close power law relationship between the bankfull discharge and the 5- year average fluvial erosion intensity during the flood and non- flood seasons, reflecting the cumulative impact of flow- sediment regimes in the flood and non- flood seasons on the flood discharge capacity. ④ Owning to the upstream damming, the contribution of the flow-sediment regime in non-flood seasons to the flood discharge capacity increased especially in the braided reach (53%), while it was lower in the transitional and the meandering reaches (less than 20%). [ABSTRACT FROM AUTHOR]

In order to scientifically guide the practice of water and sediment regulation of the Yellow River, an optimization was necessary for water and sediment regulation indicators according to the law of scouring and silting in the Lower Yellow River after water and sediment regulation of the Xiaolangdi Reservoir. For this purpose, 121 water and sediment processes at different sediment concentrations measured in the Lower Yellow River from 2011 to 2022 were selected to analyze the water and sediment characteristics, and the relationship between the efficiency of scouring and silting and the water and sediment conditions. On this basis, water and sediment regulation indicators were proposed to ensure generally no siltation in the Lower Yellow River and no reduction of the discharge capacity of main channel. The results showed that: ① The Xiaolangdi Reservoir has a polarized regulation effect on the water and sediment process in the Lower Yellow River, that is, the sediment in the high sediment concentration flow (average sediment concentration Sav > 10 kg / m³) accounts for 94% in the whole year, and the water in the clear water flow (Sav < 1 kg / m³) accounts for 85% in the whole year. ② The silting efficiency of high sediment concentration flow has a positive linear correlation relationship with the average sediment concentration. ③ The scouring efficiency of clear water flow has a positive logarithmic correlation relationship with the average discharge. ④ For high sediment concentration flow, in a high flow year, the water volume regulated is 8 billion m³, the average discharge is 2 000— 4 600 m³ / s and the average sediment concentration is 50 kg / m³; in a normal flow year, the water volume regulated is 1 billion m³, the average discharge is 2 000—4 600 m³ / s and the average sediment concentration is 150 kg / m³; and in a low flow year, no sediment is discharged from the reservoir. For clear water flow, it is necessary to avoid water flow process with an average discharge of 800—1 800 m³ / s. [ABSTRACT FROM AUTHOR]

To investigate the suspension and diffusion mechanisms of sediment particles under the action of fluids from both particle and flow field scales, a Gaussian curvature model is introduced in the discrete element method to characterize the nonlinear contact properties of non-spherical particles. Additionally, improvements are made to the drag force model and porosity models for non- spherical particles. By doing so, the polydispersed non-spherical particle CFD-DEM coupling numerical method is established. The accuracy and superiority of this model are validated through comparisons with physical experimental results. Subsequently, the suspension and diffusion processes of sediment under fluids are simulated. Results show that the sediment settling rate is positively correlated with the initial discharge quantity of particles and negatively correlated with flow velocity, while the escape rate shows an opposite trend. At high initial discharge, particle clustering effects promote fluid kinetic energy dissipation, causing gravity to surpass inertial forces and leading to rapid particle settling. At low initial discharge, higher fluid kinetic energy enhances horizontal particle transport. At lower flow velocities, particle shape significantly affects the spatial distribution of sediment particles. [ABSTRACT FROM AUTHOR]

The construction of large reservoirs causes shoal- channel adjustments downstream of dams, which significantly affects river regimes, navigation, flood control and ecology. To explore the characteristics and mechanism of shoal- channel adjustment in the Wuhan reach, water and sediment observation data from 1952 to 2022 and topographic observation data from 1959 to 2021 were used to analyse the effects of the bed sediment composition, runoff and sediment load and regulation projects. The results revealed the following: ① After the operation of the Three Gorges Dam (TGD), the flushing volume in the low-water channel in the Wuhan reach accounted for 90. 4% of the total flushing volume in the channel, the channel section became increasingly narrow, and the river phase coefficient decreased. Different adjustments occurred based on scouring and silting in different central bars and branches. From 2001 to 2021, the continental areas of the Tieban bar and Baisha bar decreased by 63. 1% and 61. 5%, respectively, whereas the continental areas of the Qian bar and Tianxing bar increased by 212. 3% and 14. 5%, respectively. After 2013, the left and right branches of the Tieban bar were scoured, the left branch of the Tianxing bar was silted, and the right branch was scoured. ② When the amount of incoming sand decreased sharply, the riverbed was mostly fine sand, with grain sizes of 0. 125 mm≤d < 0. 25 mm, and the antiscourability was weakened, which is a prerequisite for increased erosion. The peak of erosion and dry replenishment of the TGD intensified the amplitude of erosion of the low-flow branch. Regulation projects has changed the transverse distribution of erosion and deposition in the shoal channel, which is the dominant factor influencing the adjustment of central bars and significantly explains why the left branch of the Tianxing bar was silted and the right branch was scoured. Before the operation of the TGD, the evolutionary linkages between shoals were strong. After the operation of the TGD, the decrease in sediment inflow and the prolongation of the period of moderate water led to erosion of the shoal, and the evolutionary linkage between the shoals weakened. After the implementation of regulation projects, the stability of the central bar was maintained, and the slow flow and sediment retention effect improved erosion resistance. The sedimentation of the central bar limited the development of the side beach. The sand source was also reduced by the operation of the TGD. The evolutionary linkage between the side beaches was further weakened, and the evolutionary linkage between the central bars was also further weakened. In contrast, the evolutionary linkage between the side beach and the central bar was strengthened again. [ABSTRACT FROM AUTHOR]

A palynological study of 84 cutting samples from Cape Three Points 1 (CTP-1) well in the Tano basin allows the identification of three biozones based on the First Appearance Datum (FAD) and Last Appearance Datum (LAD) of stratigraphically significant sporomorphs taxa recovery. These are Elateropollenites jardinei - Reyrea polymorphus Zone, Elaterocolpites castelainii - Afropollis jardinus Zone, and Cretacaeiporites polygonalis - Classopollis classoides Zone, which permit an age assignment of early - middle Albian, late Albian - early Cenomanian and late Cenomanian respectively. The diagnostic miospores from the samples are characteristic of the Albian-Cenomanian Elaterate paleofloral Province in a semi-arid to arid climate, with sediments yielding mixed kerogen assemblage which reflects a marginal marine or nearshore environment. Four palynofacies assemblages (P-1 to P-4) and kerogen types identified indicate deposition under marginal dysoxic-anoxic basin (kerogen type III), shelf to basin transition (kerogen type III/II), a distal suboxic-anoxic basin (kerogen type II>I) and distal dysoxic-anoxic shelf (kerogen type II) conditions respectively. Thermal maturity values obtained from colour changes of psilate spore (Deltoidspora, Cyathidites) reveal that samples from P-1 and P-2 are within immature phase and P-3 and P-4 are mature. [ABSTRACT FROM AUTHOR]

The paper presents research results obtained during the exploration of copper and silver deposits on the southern rim of the Wolsztyn–Pogorzela High in terms of identification of the regional geological structure of Permian and Mesozoic sediments, with particular focus on tectonic zones. It discusses a new methodology of developing seismic and gravimetric data in the form of sections of effective reflection coefficients (ERC) and vertical gravimetric cross-sections, which in combination with borehole logging allowed for the identification or an update of the knowledge about regional tectonic zones which are missing from the maps of the sub-Zechstein substrate prepared to date. The discussion of the methodology uses the example of two tectonic zones: the Rawicz and Oleśnica grabens. Conversion of seismic sections into ERC cross-sections made it possible to trace strata of smaller thickness and facilitated the identification of low-amplitude dislocations. Vertical gravimetric cross-sections confirm the credibility of the interpreted faults and grabens, also showing whether the faults are deeply rooted. Historical geophysical materials developed in this manner constitute an important supplement to the identification of the geological structure of the Lower Silesian Basin and in particular, the tectonic zones which may provide ways of migration and circulation of solutions, as well as the ore generation zones. The collected materials may be used to supplement the structural and tectonic maps of the sub-Zechstein substrate in the Lower Silesian Basin, and the applied methodology and data analysis may be used in other regions of Poland. [ABSTRACT FROM AUTHOR]

Landslides influence fluvial suspended sediment transport by changing sediment supply and grain size, which alter suspended sediment concentrations and fluxes for a period of time after landsliding. To investigate the duration and scale of altered suspended sediment transport due to landsliding, we analyzed suspended sediment concentration and water discharge measurements at 87 gauging stations across Taiwan over an 11-year period after Typhoon Morakot, which generated nearly 20 000 landslides in 2009. At each gauging station, we computed annual rating curves to quantify changes over time in the sensitivity of suspended sediment concentrations to water discharge. Among the 40 stations in basins that were impacted by landsliding, the discharge-normalized rating curve coefficient ã was higher than that before Morakot by a factor of 5.1±1.1 (mean ± standard error) in 2010, the first year after Morakot. The rating curve exponent b did not decrease at most stations until a year later (2011), when the average b value was lower than that before Morakot by 0.25±0.05. Across the compilation of gauging stations, post-Morakot changes in discharge-normalized sediment concentration (ã) were positively correlated with landslide intensity for 7 years after Morakot, while post-Morakot changes in the exponent of the discharge–concentration relationship (b) were negatively correlated with landslide intensity from 2011 to 2014. This reflects a tendency for larger changes in ã and b to occur in basins with more intense landsliding. At 26 of these 40 stations, elevated values of ã declined after the initial post-Morakot peak, consistent with a gradual return to pre-Morakot suspended sediment transport conditions. Exponential regressions to these ã values reveal a median characteristic decay time of 8.8 years (interquartile range: 5.7–14.8 years). Values of ã increased more and declined faster in basins with more intense landsliding, with a mean characteristic decay time of 6 years in the basins hit hardest by landsliding. Furthermore, changes in ã and b tended to be larger in basins with more intense landsliding. At stations that were not impacted or only minimally impacted by landsliding, neither ã nor b exhibited systematic responses to Morakot. To quantify the effect of landsliding on sediment discharge, we compared the measured sediment discharges after Morakot to the hypothetical sediment discharges that would have occurred if Morakot had induced no landslides, calculated by applying each station's pre-Morakot rating curve to its post-Morakot water discharge history. This analysis suggests that Morakot-induced landsliding increased sediment discharge by as much as > 10-fold in some basins in the 1–2 years after Morakot. Together, these results indicate that the influence of Morakot-induced landsliding on rating curves was large shortly after Morakot but diminished in less than a decade in most of the study rivers and will be imperceptible in another few decades in all of the study rivers. To the extent that these results are applicable to other landscapes, this suggests that periods of elevated sediment transport efficiency after landsliding should persist for years to decades, even if the landslide deposits persist for centuries to millennia. [ABSTRACT FROM AUTHOR]

This study assessed the impacts of the land use/cover (LULC) and climate changes on the runoff and sediment flows in the Megech watershed. The Geospatial Water Erosion Prediction Project (GeoWEPP) was used to assess LULC and climate changes' impact on runoff, soil loss, and sediment yield. The QGIS 2.16.3 plugin module for land use change evaluation (MOLUSCE) tool with the cellular automata artificial neural network (CA-ANN) was used for LULC prediction based on historical data and exploratory maps. Two commonly used representative concentration pathways (RCPs)—4.5 and 8.5—were used for climate projection in the 2030s, 2050s, and 2070s. The LULC prediction analysis showed an expansion of cropland and settlement areas, with the reduction in the forest and rangelands. The climate projections indicated an increase in maximum temperatures and altered precipitation patterns, particularly with increased wet months and reduced dry periods. The average annual soil loss and sediment yield rates were estimated to increase under both the RCP4.5 and RCP8.5 climate scenarios, with a more noticeable increase under RCP8.5. By integrating DEM, soil, land use, and climate data, we evaluated runoff, soil loss, and sediment yield changes on only land use/cover, only climate, and the combined impacts in the watershed. The results revealed that, under all combined scenarios, the sediment yield in the Megech Reservoir was projected to substantially increase by 23.28–41.01%, showing a potential loss of reservoir capacity. This study recommends strong climate adaptation and mitigation measures to alleviate the impact on land and water resources. It is possible to lessen the combined impacts of climate and LULC change through implementing best-management practices and adaptation strategies for the identified scenarios. [ABSTRACT FROM AUTHOR]

The composition of the trilobite fauna from the Devonian Paraná Basin in Brazil is still not fully elucidated. Although rich literature on the southern portion of this basin, the northwestern part has been poorly explored. In this study, we reveal new taxa and provide a comprehensive taxonomic composition of malvinoxhosan trilobites collected from the PragianEmsian sediments of Alto Garças Subbasin, Brazil. We report Burmeisteria notica, Metacryphaeus australis, Pennaia pauliana, Calmonia signifer and Kozlowskiaspis subseciva, well known elements from the southern portion of the Paraná Basin. Metacryphaeus meloi, unprecedented in the Paraná Basin, reveals itself here in the oldest biostratigraphic position in relation to other specimens reported from the Cabeças Formation (Frasnian-Famennian, Parnaíba Basin). We reveal a new species of Bainella, here described as Bainella (Belenops) sulmatogrossensis sp. nov. We discuss the biostratigraphic position of components of this fauna and their correlation with other Devonian units. Taking all together, our work provides a new picture about the trilobite taxonomic composition in the northwestern portion of the Paraná Basin, and can help our understanding of speciation pulses and dispersion patterns among the different Devonian basins in Gondwana. [ABSTRACT FROM AUTHOR]

The study records the extent of microplastics distribution in the surficial sediments of the Southern Ocean. This represents the first study of microplastics in the sediments of Prydz Bay, Southern Ocean. Prydz Bay is the largest embayment located in the Indian Ocean Sector of the Southern Ocean and receives sediments supplied by the Lambert Glacier/Amery Ice Shelf, draining approximately 10% of the total ice volume of Antarctica. It is an important site of circumpolar deep water (CDW) and Antarctic bottom water (AABW) formation. This study focuses on the distribution of microplastics in the sediments of the Prydz Bay, Southern Ocean with special reference to the ecological risk factor of these microplastics. The type distribution of microplastics revealed percent content as bead > fiber > fragment. Ecological risk factors (CF and PLI) of microplastics in sediment samples revealed a minor to major risk of these pollutants in the analyzed environment. Statistical analyses such as principal component analysis (PCA), ANOVA, Tukey's HSD test, and correlation analysis were performed to highlight the interrelationship of MPN with CF, PLI, pH, TOC, and sediment texture. The levels of microplastic pollution in the Prydz Bay are significant on a local scale, particularly around research stations. This report underlines the immediacy of microplastic pollution management in the Southern Ocean to maintain the serenity of this pristine marine habitat. So further research on the information of microplastics policy discussions to develop appropriate management responses. [ABSTRACT FROM AUTHOR]

The seabed of the Gunneklev Fjord in south-eastern Norway is covered with exceptionally soft contaminated sediment containing mercury and dioxins. The sediments have an undrained shear strength less than 1 kPa and a variable thickness of up to 2.5 m. To reduce the potential for leaching of contaminants from these sediments, Hydro Energy AS developed a remediation plan involving capping of the sediment. Significant uncertainties are associated with the sediment's undrained shear strength and the cap thickness. An unfortunate combination of low shear strength and thick cap could cause slope failure (e.g. translational sliding of the sediment and/or bearing capacity failure (e.g. punching through). Failure, particularly slope failure, can cause spreading of the contaminants in the fjord causing serious consequences. This paper presents an assessment of the probability of slope failure associated with the contaminated sediment before and after the cap placement. Probability of bearing capacity failure is considered to have more local effect and is also discussed briefly. The study used the Monte Carlo method with random undrained shear strength and sediment thickness. The simulations show high slope failure probability when the seabed inclination was ≥ 1:50 combined with an average undrained shear strength ≤ 0.4 kPa. Based on the probabilistic analyses, a pilot field testing campaign was carried out (after this study) with 20-cm thickness cap in the "gentle" sloping area and 5-cm thickness in the "steep" areas to avoid causing a failure. The analyses were used to support evidence-based decision-making on the cap design and implementation for further field testing. [ABSTRACT FROM AUTHOR]

In order to investigate the impact of marine propeller wake fields on sediment siltation in shallow water channels, this study employs the unsteady RANS approach and the Volume of Fluid model. A full-scale numerical self-propulsion test was conducted on a 50,000 DWT oil tanker under the influence of a free surface. The research includes forecasting the effect of propeller wakes on sediment redeposition following the dredging of the approach channel to Jiaxing Port in the China Sea. Initially, uncertainty research was carried out on the full-scale ship and propeller system, and the credibility of the computational results was quantified. The simulated results based on the sediment transport numerical model were then compared and validated against actual data from monitoring stations. The self-propulsion performance and the velocity distribution of the propeller wake were examined under three different propeller speeds. Scenarios simulated included no ship navigation, daily single-ship navigation, and daily two-ship navigation, evaluating the siltation distribution within the channel over one month. The results demonstrate that ship propeller wakes positively influence the reduction of channel sedimentation, with the maximum monthly siltation reduction reaching 0.108 m during single-ship tidal navigation and 0.11 m during two-ship tidal navigation. [ABSTRACT FROM AUTHOR]