Sediment Characteristics Research Articles

Factors Diversifying the Characteristics of Fluvial Sediments Accumulated in Mountain Stream Channels—A Case Study from the Polish Carpathians

This paper presents the diversification of fluvial sediments caused by the occurrence of coarse woody debris (CWD), boulder steps (BSs), and mixed structures (MSs), understood as a combination of CWD and BSs in a stream channel in a small forested catchment in the Polish Carpathians. This research is crucial for understanding the role of this kind of threshold present in a stream channel in shaping fluvial sediment characteristics in small forested mountain catchments. Our hypothesis is that the threshold type in a stream channel determines fluvial sediment diversification. This was verified in field research, including identification of the channel’s morphodynamic structure and the morphometric characteristics of CWD, BSs, and MSs as well as the collection of fluvial sediments upstream and downstream of them. In order to preserve research objectivity, tests were performed during comparable flow conditions in the summer (EX1) and autumn (EX2) periods. The statistical analysis showed that the type of threshold significantly affects the processing, size, and shape diversification of mineral material. This diversity is particularly noticeable in fluvial sediments within CWD and MSs, which retain material of more diverse sizes and shapes.

Spatiotemporal Changes and Recovery of Benthic Macroinvertebrate Communities after the Hebei Spirit Oil Spill in the Subtidal Area around the Taean Peninsula in South Korea

Marine oil pollution is a significant environmental issue that significantly threatens ocean ecosystems. It occurs frequently and has devastating consequences for marine life, coastal habitats, and human communities. We examined the recovery of benthic macroinvertebrate communities in shallow subtidal areas following the Hebei Spirit oil spill around the Taean Peninsula, South Korea, in 2007. Benthic macroinvertebrates were collected seasonally from 15 survey sites between 2008 and 2015. Immediately after the spill in 2008, species richness and density of benthic macroinvertebrates decreased by 66.7% and 37.0%, respectively, compared to before the oil spill in 2007. Cluster analysis based on benthic macroinvertebrate communities delineated the communities from 2008 to 2009 as a distinct cluster characterized by markedly low species richness. Communities from other periods exhibited spatiotemporal variability based on the sampling location and sediment characteristics. By 2011, species richness and density had recovered to levels similar to those in 2007, which was particularly pronounced regarding the resurgence of arthropods and mollusks. Notably, populations of amphipods that are particularly sensitive to oil, such as Urothoe sp. and Byblis spp., showed signs of recovery in 2011; however, recovery of the benthic community at the site nearest to the oil spill area, was not evident until July 2013, as indicated by the benthic opportunistic polychaete amphipod index. This underscores that prolonged time periods are required for communities to fully recuperate after oil spills.

Provenance and sediment dispersal in Pearl River Estuary, southern China unraveled by magnetic properties

The Pearl River Estuary (PRE), with eight outlets supplied by multiple tributaries, is an excellent study area for reconstructing sediment provenance and transport pathways of a multi-sourced sediment-routing system. However, it less known the sediment source to sink dispersal model. This study aimed to estimate the PRE sediment budget by comparing the magnetic characteristics of estuarine surface sediments with those of all potential sources. In the bottom sediments of PRE and adjacent region, magnetic minerals, mainly magnetite and hematite, have a characteristic terrigenous signature. Source and sink comparison for magnetic parameters shows that the possible input of southwestern Taiwan rivers can be excluded, whereas the possibility of sediment contribution from nearby rivers, including Han, Rong, and Jiulong rivers, to the estuary could not be ruled out. Quantitative provenance analysis indicates that West River-sourced sediment dominates the western side of the estuary, the East River-sourced sediment is most important in the eastern side of the estuary, whereas sediment supplied by the North River is high only close to the outlets. A mixed-sediment contribution to the estuary is suggested, with a fluvial-dominated sediment input around the west river outlets and a tide-dominated sediment dispersal in the eastern side of the estuary. Overall, our study demonstrates the importance of fingerprinting changes in sediment supply using sediment magnetic properties and provides new insights into the PRE sediment-routing system.

Paleoenvironmental evolution and East Asian monsoon records through three stages of paleochannels since the mid-pleistocene in the Western Bohai Sea, North China

Three stages of paleochannels development, dating back to the Mid-Pleistocene, have been identified in the western Bohai Sea (BS) region. However, the factors controlling their sedimentary formation remain unclear. This study analyzed samples from DZQ01 and adjacent boreholes to establish a chronological framework through AMS 14C and OSL dating, complemented by grain size and geochemical analyses. End-member analysis using the Generalized Weibull method successfully separated three components: EM1, EM2, and EM3. EM3 (<26.28 μm) reflects the influence of the East Asian Summer Monsoon (EASM), while EM2 (26.28–105.1 μm) is indicative of the East Asian Winter Monsoon (EAWM). Geochemical indicators, such as the Rb/Sr ratio, reflect the impact of paleoclimatic changes. This study identified five major glaciation events since the Mid-Pleistocene. The DU6 unit recorded two glacial stages (300–272 cal. ka B.P.), characterized by a weakened EASM and a stronger EAWM. Similarly, the DU4 unit recorded two glacial stages (165–127 cal. ka B.P.), also marked by a subdued EASM and an enhanced EAWM. The DU2 unit reflects a prolonged glacial stages (71–14 cal. ka B.P.), dominated by the EAWM, resulting in cold and dry conditions. Overall, the uplift of the Tibetan Plateau and sea-level fluctuation significantly influenced the formation and evolution of paleochannels, with the sedimentary characteristics closely tied to the intensities of the East Asian Monsoon (EAM).

Bayesian statistical analysis reveals spatial heterogeneity in Cyclone Thane deposits from Southeast India

Modern and geological records of storm sedimentary deposits preserved on siliciclastic coastlines are important archives to evaluate the past and current magnitude and impacts of.storms. Examination of modern storm deposits also offers the opportunity to evaluate the similarities and differences between storm and other coastal overwash processes and hazards.We examined the stratigraphy and sedimentary characteristics of the 31st December 2012 Cyclone Thane and underlying coastal units from 14 pits from six sites from the coastal zone of Tamil Nadu Province, southeast India. We analysed the grain size parameters, grain shape, and heavy mineral proportions of each deposit in high resolution and examined the sedimentary structures of each unit. For the first time, we use Bayesian factors to quantitatively evaluate the similarities and differences between the storm sedimentary deposits and other co-located coastal sedimentary deposits. At several sites, the storm deposits differ in several parameters from the underlying coastal deposits, but at some locations, distinguishing between different depositional units cannot be achieved. In comparing the storm deposits from the different sites, mean grain size results in the most coherent pattern with closely located sites having similar mean grain size, and more southerly sites being finer grained. The other measured parameters show a far less coherent pattern with adjacent sites often preserving larger differences than more distal sites attesting to very local hydrodynamic variations during sediment deposition. As with the sedimentary parameters, the sedimentary structures formed during sediment deposition preserved at each site are highly variable. To date, the presence of terminal foresets at the landward edge of washover fans remains the only diagnostic feature of storm deposition, but that this feature is not ubiquitous across all storm deposits. Our findings demonstrate the spatially heterogeneous nature of storm sediment deposition and the challenges of identifying storm deposits in coastal siliciclastic sequences. The use of Bayesian statistical approaches also offers a robust method for evaluating and discriminating between coastal sediment deposits that has many advantages over traditional frequentist approaches. This method can easily be applied to other sedimentary depositional environments.

Geomorphological management strategies for cyclone-impacted sea turtle nesting habitat along the eastern seaboard of India.

Sea turtles are globally vulnerable due to climate change uncertainties and anthropogenic threats. The present study highlights the impacts of a very severe tropical cyclone (VSCS) on a potential sea turtle rookery and suggests management strategy for protection and conservation of rookery habitat under changing spit geomorphology. The results show that VSCS has short-term impact on rookery and spit geomorphology, while long-term precarious impact over the coastal sedimentology due to debris pollution. Study on geomorphology, sedimentology, and debris pollution indicates that plastic pollution and change in sediment characteristics are the most probable cause for failure of arribada events during post-cyclone year. Further, study identified that reduced estuary mouth and elongation of sand spit are the potential cause for coastal flooding and loss of nesting habitat. Therefore, locational stability of estuary cross-section under varying dimension of inlet channel and width are estimated for better management of uncertainties arises from the extreme events. Results of stability analysis show that observed cross Sect.(207-1728 m2) is often fall within unstable regimes compared to the estimated equilibrium cross-sectional area (790-1085 m2) under natural estuary condition. Considering the severity of long-shore transport and fast migration of sand spit, study further recommends cross-sectional area of magnitude (951-965 m2) is highly essential while inlet channel oscillates between 3500 and 7500m. Similarly, for siltation issues, cross-sectional area (769-969 m2) is highly required for the varying dimension of estuary widths (50-600m). In addition, involvement of local community in cleaning coast following cyclonic storm could be best approach instead of mechanical way to unalter the rookery sedimentology. This comprehensive approach addresses immediate cyclone-induced threats while promoting the long-term sustainability of sea turtle nesting habitats, offering actionable management recommendations for maintaining estuary stability and preserving critical nesting environments in face of increasing coastal disasters.

Study on the effects of extreme climate and human activities on the growth mechanisms of Zostera japonica in the Yellow River estuary

Zostera japonica, as one of the major seagrasses in the Yellow River Estuary, plays a critical ecological role, particularly in providing habitat for marine organisms, stabilizing sediment, and contributing significantly to carbon sequestration. In recent years, Zostera japonica seagrass beds have receded extensively due to multiple impacts of natural factors and human activities. This study investigates the complex effects of extreme climate events and human activities on the growth mechanisms of Zostera japonica in the Yellow River Estuary using a combination of field sampling, laboratory analysis, and quantitative calculations. The result shows that there are significant differences in sediment characteristics between the north and south shores, with the south shore having finer sediments and higher nutrient content, which support more robust seagrass growth. The Water and Sediment Regulation Scheme (WSRS) dramatically alters water quality by reducing salinity and increasing turbidity, thus inhibiting photosynthesis and disrupting the physiological functions of Zostera japonica. Additionally, WSRS introduces an increase in heavy metals, which could potentially impact plant health and stress levels. Extreme weather events, particularly Super Typhoon Lekima, further compound these impacts by causing soil erosion, uprooting seagrass beds, and reducing biomass and seed production. The interplay of WSRS, climate change, and anthropogenic activities necessitates integrated management strategies to mitigate adverse effects and enhance habitat resilience. This study underscores the need for specific management strategies, such as controlling heavy metal inflows, implementing sediment stabilization techniques, and regulating freshwater discharge during key growth periods, to mitigate adverse effects and enhance habitat resilience for Zostera japonica in the Yellow River Estuary.

Spatial distribution and transport characteristics of debris flow sediment using high resolution UAV images in the Ohya debris flow fan

Debris flows are significant geomorphic processes that can pose hazards to human settlements and infrastructure, making the understanding of their sediment transfer characteristics and impacts on the surrounding landscape crucial for effective land management and hazard mitigation strategies. This study investigates the distribution patterns of sandstone, vegetation, and shale classes within the Ohya debris flow fan, aiming to gain insights into the sediment characteristics, grain size variations, and vegetation cover trends along the flow path. Using a combination of field surveys and image processing we analyzed sediment characteristics and grain size variations a three study zones: upstream, transfer, and downstream. Statistical parameters such as mean, mode, skewness, and kurtosis were employed to quantify the grain size distribution and identify variations across the study zones. Results reveal distinct spatial variations in the distribution of sandstone, vegetation, and shale classes along the flow path. We observed a decrease in sandstone and vegetation cover from the upstream to the downstream sections, while the area covered by the shale class exhibited an increasing trend in the downstream direction. These findings suggest that debris flows selectively remove smaller particles downstream. The distribution of particle sizes within the sandstone class also exhibited variations, with a higher proportion of smaller pebbles downstream due to more effective removal of finer particles in the upstream zone. This study highlights the complex interplay between debris flow dynamics, sediment transport, and vegetation colonization. The findings contribute to the scientific knowledge of debris flow processes and can be used to inform land management decisions and mitigate the hazards associated with debris flows in similar environments.

A Framework for Understanding the Impacts of Thaw‐Driven Disturbance Regimes on Northern Lakes

ABSTRACTThe impacts of permafrost thaw do not manifest uniformly across the Arctic, and this presents challenges for predicting how permafrost‐affected lakes will respond to climate change. Here, we leveraged long‐term field data collection and studies of a particular permafrost lake type (predisposed to thaw slump disturbance) in the Tuktoyaktuk Coastlands region to develop a conceptual model that can shed light on, and facilitate further testing of, lake ecosystem impacts associated with polycyclic shoreline retrogressive thaw slumps. To inform the development of the model, we compared regional changes in slump activity and lake water quality variables known to be impacted by slumping between 2005 and 2017, and showed that the timeline to recovery in lake dissolved organic carbon (DOC) following slump stabilization was longer than the time between cycles of slump growth, stabilization, and re‐initiation in most lakes. We also analyzed geochemical changes in sediment cores that incorporated the last several hundred years of history in 18 lakes that spanned a gradient in thaw slump disturbance, as well as a core dating back to ca. 1365 CE in a lake with an ancient slump. Results indicate that sediment geochemical changes were most pronounced at the initial onset of slumping, with only muted changes in sediment characteristics upon slump growth or re‐initiation. Our conceptual model can guide future investigations into the extent to which lakes with polycyclic slumps are predisposed to, or buffered against, significant limnological changes under anthropogenic climate warming. While our model is specific to lake systems in ice‐cored morainal terrain impacted by retrogressive thaw slumping, similar approaches would be highly useful for understanding ecosystem response under a range of permafrost disturbance categories.

Seismic geomorphology and reservoir conditions of a Middle Miocene submarine channel system in the Taranaki basin, New Zealand

Deepwater channels function as vital deep-sea hydrocarbon reservoirs and as major routes for moving terrestrial clastic sediment to deepwater environments. A high-resolution sequence stratigraphic framework was built for the deepwater area of the Taranaki Basin using high-resolution three-dimensional (3D) seismic data, and various seismic interpretation techniques, including seismic attribute analysis, were applied. The principal controlling factors and petroleum development potential of the Middle-Miocene channel system were investigated with sequence stratigraphy and seismic geomorphology. Four understandings were primarily attained in this study: (1) depending on the different levels of the channel surfaces, the channel system can be divided into five sedimentary units (SU1-SU5), which correspond to the five stages of channel system evolution. These surfaces include one primary draping surface (PDS), five secondary channel erosion surfaces (SCES), and several tertiary channel erosion surfaces (TCES). (2) with the use of seismic facies analysis, six sedimentary elements were identified in the channel system: pelagic deposits (PDs), mass transport deposits (MTDs), outer levee complex (OLC), inner levee and terrace complex (ILTC), and turbidite channel complexes (TCCs). (3) The sedimentary evolution of the channel system was jointly influenced by multiple factors. The sediment supply and submarine geomorphology can directly affect the internal stacking and migration patterns of the channel. In contrast, tectonic activity and relative sea level fluctuations can indirectly affect the sedimentary characteristics of the channel by regulating the components and scale of clastic sediment. (4) SU1, SU2, and SU3 are primarily filled with coarse-grained sediments, which can serve as high-quality hydrocarbon reservoirs. In contrast, SU4 and SU5 can serve as regional cap rocks because they are filled with fine-grained sediments, and the overall channel system can represent a potential hydrocarbon reservoir-cap combination, which can be viewed as a significant research target for upcoming deepwater exploration. Clarifying the sedimentary properties and primary controlling factors at the various evolutionary stages of deepwater channels is vital for predicting the hydrocarbon development potential of the basin and reducing the drilling risk. This also helps with the development of deepwater basins with similar sedimentary environments in New Zealand and elsewhere in the world.

Model Sensitivity Analysis for Coastal Morphodynamics: Investigating Sediment Parameters and Bed Composition in Delft3D

Numerical simulation of sediment transport and subsequent morphological evolution rely on accurate parameterizations of sediment characteristics. However, these data are often not available or are spatially and/or temporally limited. This study approaches the problem of limited sediment grain-size data with a series of simulations assessing model sensitivity to sediment parameters and initial bed composition configurations in Delft3D, leading to improved modeling practices. A previously validated Delft3D sediment transport and morphology model for Dauphin Island, Alabama, USA, is used as the benchmark case. A method for the generation of representative sediment grain sizes and their spatially varying distributions is presented via end-member analysis of in situ surficial sediment samples. Derived sediment classes and their spatial distributions are applied to two sensitivity case simulations with increasing bed composition complexity. First, multiple sediment classes are applied in a single fully mixed layer, regardless of sediment type. Second, multiple sediment classes are applied in a thin, fully mixed transport layer with underlayers containing only the non-cohesive sediment classes below. Simulations were carried out in a probabilistic, Delft3D MorMerge configuration to capture long-term morphology change for 10 years. We found there is sensitivity to the inclusion of additional sediment classes and sediment distribution made evident in bed level and morphology change. Inclusion of highly mobile fine sediments altered model results in each sensitivity case. The model was also found to be sensitive to initial bed composition in terms of bed level and morphology change, with notable differences between sensitivity cases on decadal timescales, indicating an armoring effect in the second sensitivity case, which used the transport and underlayer bed configuration. The results of this study offer guidance for numerical modelers concerned with sediment behavior in coastal and estuarine environments.

Holocene and Reworked Pleistocene Sediments in Mud Depocenters of the Inner Continental Shelf of Sao Paulo Bight (Southeast Brazil)

Mud depocenters are found across most siliciclastic continental shelves, occurring in various bathymetric ranges and typically dating to the Holocene. This study analyzes the sedimentary characteristics and formation processes of mud depocenters in the central sector of the inner continental shelf of the São Paulo Bight. A total of 1700 km of high-resolution seismic profiles, four gravity cores, and 1346 surface sediment samples were analyzed. The sedimentary analysis involved determining grain size parameters, organic matter content, carbonates content, and radiocarbon dating. Seafloor sedimentary mapping shows the predominance of very fine siliciclastic sand, together with three mud depocenters located shallower than the 30-meter isobath. The northern depocenter comprises one sedimentary unit (SU-NZ-01), while the central depocenter consists of two sedimentary units (SU-CZ-01 and SU-CZ-02) and the southern depocenter is made up of two other sedimentary units (SU-SZ-01 and SU-SZ-02). Units SU-SZ-02, SU-CZ-02, and SU-NZ-01 were deposited on Precambrian rock surfaces during the Holocene transgression and include reworked sediments from nearby Upper Pleistocene coastal plains, characterized by a transparent seismic pattern. Above these, units SU-SZ-01 and SU-CZ-01 developed following the Holocene Transgression Maximum, associated with local mud input from the Peruíbe River mouth and the Santos Estuary, respectively. The paleorelief of Precambrian rocks favored the formation of these depocenters by creating wave shadow zones and trapping mud within the paleovalleys.

Tracking Depositional Architecture and Diagenetic Evolution in the Jurassic Carbonates, Trans Indus Ranges, NW Himalayas

The evolution of Jurassic carbonates is globally significant for understanding the depositional framework, diagenetic phases and sedimentary characteristics of shallow marine shelf deposits. For this purpose, two outcrop sections of the Jurassic carbonates with a road distance of 121 km in the Trans Indus Ranges, NW Himalayas, were included in this study. Geological fieldwork was conducted for sedimentological data, and representative samples were collected for microfacies analysis and diagenetic evolution complemented by carbon and oxygen isotope analysis. Results show that eight microfacies were identified in both sections where mudstone microfacies was only present in the Chichali section, whereas wackestone and packstone facies widely existed in both sections. The diagenetic evolution interpreted that dolomitization and stylolization were pronounced in the Paniala section, while micritization and calcite cementation were prevalent in the Chichali section. The interpreted depositional setting implies the wide range from supratidal to outer ramp shallow marine for the Chichali section, suggesting a wide range and relatively deeper environment, alongside merely intertidal to middle ramp settings for Paniala section. Diagenetic evolution suggests marine to meteoric influence in the Chichali section, while burial and uplift phases were dominant in the Paniala section. The diagenetic events were also validated by the isotopic analysis, where most of the samples with values up to −4‰ VPDB δ18O, corresponding to a carbon isotope range of up to +4‰, were interpreted as the burial phase of diagenesis; meanwhile, a few samples with −2 δ13C and −7‰ VPDB δ18O isotope signatures were marked as meteoric influx in the Paniala section. This study indicates the diversity of the depositional environment and diagenetic heterogeneity by integration of thin sections using isotope data, which are quite applicable to shallow marine carbonates.

Ancient and contemporary shellfish cultivation practices bolster bivalve communities and diversity‐biomass relationships

Abstract Marine ecosystems provide humans with access to nutritious food. The discussion surrounding the cultivation of intertidal resources currently focuses on recent decades, disregarding a robust history of complex social‐ecological interactions and environmental stewardship. Here, we use the co‐occurrence of Indigenous clam gardens, shellfish aquaculture farms, and unmodified beaches along Canada's West Coast to test the hypothesis that two different resource management practices, one engineered over millennia and the other decades, bolster contemporary bivalve communities. We quantified the diversity, density and estimated biomass of the bivalve communities within 24 intertidal sites and evaluated the communities' association with the habitat's substrate composition, sediment characteristics and physical complexity. We examined these data using a combination of diversity indices, structural complexity metrics, non‐parametric multivariate statistics and supervised machine learning algorithms. We show that both cultivation methods create distinct biological communities, with community composition proportional to how each cultivation practice alters the habitats' substrate, sediment and physical complexity. Increases in bivalve biomass were comparable across cultivation methods but varied considerably among taxa. We identify a previously undocumented correlation between bivalve biomass and species richness, which is highly influenced by habitat complexity. Our work contributes to the mounting evidence that shellfish cultivation fosters ecologically diverse communities while enhancing food production. We propose that an ecosystem‐wide management approach that considers multiple bivalve species, ecological processes and socio‐cultural practices will elevate the conservation and cultivation of marine resources. Read the free Plain Language Summary for this article on the Journal blog.

Sedimentary Characteristics and Depositional Model of the upper Paleocene – Eocene Halkapinar Formation in the Southern Ulukişla Basin, Türkiye

Sedimentary Characteristics and Depositional Model of the upper Paleocene – Eocene Halkapinar Formation in the Southern Ulukişla Basin, Türkiye

A Correlation Relating the Residual Strength Parameters to the Proportions of Clay Fractions and Plasticity Characteristics of Overburden Sediments from the Open-Pit Mine Drmno

One of the prerequisites for the safe exploitation of surface mines is the stability of the working and final slopes of the mine. In order to ensure this, it is necessary to carry out detailed field and laboratory geomechanical tests of the soil and, based on the obtained results, make calculations related to stability analyses. The results obtained in this way are used for dimensioning the slope of exploitation slopes (excavation). Landslides occur when the ultimate shear strength is reached, and therefore, the adequate definition of shear strength parameters is one of the essential prerequisites for successfully solving the stability problem. Unlike earlier tests in Serbia, when the residual shear strength parameters were determined based on the usual conventional methods (direct shear apparatus, triaxial apparatus), this time, in addition to the direct shear apparatus, a ring shear apparatus was also chosen for testing. The paper shows the method of determining the residual shear strength parameters of high plasticity gray clays and siltstones of roof sediments from open pit mine Drmno, using direct and ring shear apparatus. The results show that the residual angle of internal friction for gray clays obtained with the ring shear apparatus is 9.9–10.8°, and for the siltstone, it is 11.8–12.9°, both of which are lower than the values obtained with the direct shear apparatus. In addition, correlations between the residual parameters of soil shear resistance and some physical indicators (plasticity index, clay content) are provided, showing high correlation coefficients. The proposed correlations should be used only when time and financial constraints prevent the execution of actual tests to determine residual shear strength, as concrete experimental procedures provide a much more reliable assessment of the residual strength properties of the soil.

Some characteristics of sediments in Cenozoic basins in Northern Vietnam: implication for Oligocene paleoclimate

Oligocene sediments in northern Vietnam have been extensively studied in terms of geology, stratigraphy, paleogeography, formation environments, tectonics, etc. However, relatively little attention has been paid to the paleoclimate. The Oligocene climate interpreted herein is based on features recorded in sediments taken from the Dong Ho (Hoanh Bo basin), Na Duong (Na Duong basin), and Co Phuc (Red River Trough) formations. These sediments were analyzed using thin-section microscopy, X-ray diffraction, and palynology with the Coexistence Approach. The sediments primarily consist of conglomerate, gritstone, sandstone, siltstone, claystone, and coal shale, deposited in continental environments and dated to the Oligocene based on palynomorph assemblages. The Oligocene paleoclimate is generally warm subtropical, with intermittent hot-humid or cold-dry periods and a slight influence of monsoons. An alternation of hot-humid and cold-dry climates was recorded in the Hoanh Bo basin. In the Red River Trough, the Oligocene climate exhibited a Mean Annual Temperature (MAT) of 9.3-22.2°C and a Mean Annual Precipitation (MAP) of 1122 to 1857 mm, based on the majority of palynological samples, indicating more continental, drier and colder conditions than present. In the Na Duong basin, a warm subtropical climate with a MAT of 9.3-21.7°C and MAP of 1122-1724 mm in the majority of samples was occasionally replaced by hot and humid subtropical periods; the variations in temperature and precipitation followed a similar pattern, suggesting an alternation between dry-cold and humid-hot phases.

Frictional loss and permeability estimation of sediment in salt cavern: A combined approach of mathematical model, experimental validation, and numerical simulations

Harnessing gas storage in sediment voids presents a promising trajectory for the future construction of large-scale underground gas reservoirs in low-grade salt mines. This approach not only augments the effective gas volume but also enhances the stability of the cavern. In contrast to traditional gas injection and brine discharge process, where brine is expelled from the upper pure brine space without involving brine seepage in sediment voids, gas storage in sediment voids entails expelling brine from these spaces, thus necessitating an understanding of the brine seepage characteristics in the sediment, which remains unclear. This study presents a comprehensive approach for estimating sediment frictional loss and permeability in interconnected wells, integrating mathematical modeling, experimental validation, and numerical simulation. The mathematical principles governing sediment behavior during in-situ gas/brine injection and brine discharge tests are theoretically elucidated, accompanied by derived formulas. Experimental verification is conducted in the horizontal interconnected wells (Ha4-5) of the Huaian salt mine in Jiangsu, yielding the sediment frictional loss (0.53 MPa) and permeability (6.9 × 10−11 m2). Subsequently, a 2D cross-sectional numerical model is established using the COMSOL software, considering the measured and predicted well morphologies. The model provides insights into the relationship between sediment frictional losses and permeability, yielding an inverse calculation of the average permeability (1.016 × 10−10 m2). Simulation results depict laminar brine flow characteristics in the cavern during gas/brine injection and brine discharge processes, with frictional loss occurring as brine passes through sediment. Examination of the brine seepage and pressure fields in the sediment reveals consistent brine flow velocity after passing through the sediment. This combined approach focuses on investigating the seepage characteristics of sediment at the bottom of salt caverns, offering valuable insights for estimating frictional losses and permeability in similar salt mines.

Typha domingensis (Pers.) Poir. ex Steud. Potential to Restore Contaminated Wetlands in Egypt

AbstractSeveral studies have reported Typha domingensis (Typhaceae) as a heavy metal (HM) hyperaccumulator. This study aims to assess the seasonal variations in the accumulation potential of T. domingensis (TD) for HM in polluted wetlands in Greater Cairo, Egypt. Sampling of fresh wild plants from the TD’s subterranean (Root and stem) and surface components were gathered from different polluted sites distributed in the canal of Ismailia and Nahia drain, as well as from the River Nile as an unpolluted site (control). The findings showed that pollution negatively affected the chemical characteristics of sediment and water. Except for the TD’s leaf area, there were significant seasonal variations in the growth characteristics (density, stem diameter, leaf length, and width, fresh and dry biomass). The subterranean parts stored higher amounts of HM than the aboveground shoots. Manganese (Mn) concentration (413.2 mg kg− 1) was greater in the roots of autumn plants, whereas their shoots recorded the highest Pb (225.8 mg kg− 1). Al, Cd, Cu, Fe, Ni, and Zn concentrations in summer plant roots (1499.9, 74.8,1356.1, 3948.8, 403.8, and 1294.2 mgkg− 1, respectively). The factor of metal bioaccumulation (BF) values, was high in TD plants growing in a polluted Ismailia canal, but translocation factor (TF) values for all measured elements were lower than one, except for Pb. Summer is the best season for TD growth to sequester high HM concentrations. The authors recommended that TD be employed to mitigate HM pollution in wetlands and restore them.

New Rotating Coanda-Type Intake for Sediment-Laden Flows

Tyrolean and Coanda types of water intake structures are the most widely preferred bottom intake structures used to divert water from channels and river systems for various purposes, such as energy production, irrigation, and domestic use. Estimation of withdrawal water and filtered sediment amounts are important to obtain maximum efficiency from an intake structure. The purpose of this study is to numerically analyze a newly patented rotating Coanda-type intake system to achieve the highest Water Capturing Efficiency and Sediment Release Efficiency. The newly patented system (patent no: TR2021011306B) presented here incorporates Coanda screens with variable void ratios, autonomously selected based on the sediment characteristics of the inflowing water. The process of selecting and positioning the appropriate screen is fully automated, requiring no human intervention. The system rotates under motor control to place the suitable screen at the operational point based on the specific requirements of the incoming sediment-laden flow.