Sediment Characteristics Research Articles

Control of paleoclimate and paleoweathering on chromium contents in a non-ultramafic aquifer hosting high chromium groundwater.

Cr(VI) is a carcinogen with proven mutagenic and genotoxic effects. The effects of the depositional environment (e.g., paleoweathering, paleoclimate, and paleoredox condition) on Crenrichment in non-ultramafic aquifer solids are unclear. In this study, we presented the sedimentary characteristics of a borehole from a typical non-ultramafic aquifer with high Cr groundwater in Jingbian, central Ordos Basin, China. Chromium was enriched in the K1h sandstone aquifer, especially at depths of 400-500m, with the highest value of mass transport coefficient (τAl,Cr) up to 92.13% and τAl,Fe up to 33.5%. The provenance of aquifer Cr was predominantly intermediate and felsic igneous rocks with a mafic rock mixture. This mafic source was inferred from Cr-rich granodiorite and mafic/ultramafic rocks in the Yinshan (Daqingshan-Wulashan) Block, northern Ordos Basin. The Cr-rich aquifer in K1h was developed due to a moderate chemical index of alteration (CIA) (mean, 56.7) under relatively warm and humid paleoclimate, as evidenced by high CIA-temperature (CIA-Temp) (mean, 6.79°C) and paleoclimatic index values (mean, 0.40). Fe-Mn redox cycling in the oxic to suboxic environments contributed to aquifer Cr accumulation. Using path analysis, we identified that paleoclimate created favorable weathering conditions and enrichment of Fe contributed to the formation of high-Cr aquifers. The study reveals the formation of positive Cr anomalies in non-ultramafic aquifers, which is the potential source of groundwater Cr, and highlights the effects of depositional factors on Cr accumulation during aquifer deposition or early diagenesis. It can provide new insights into the natural processes of high-Cr sediments occurring in non-ultramafic aquifers.

Can Siphon Hole Morphometrics Be Used for Population Assessments of Intertidal Soft-Shell Clams, Mya arenaria?

Measuring infaunal population dynamics relies on destructive sampling that disturbs sediments and removes animals from their habitat. Establishing effective, non-invasive sampling methods for monitoring infaunal populations can reduce the impact of scientific sampling and facilitate efficient population assessments. Using intertidal soft-shell clams (Mya arenaria L.) in eastern Canada, we explored whether population density and size structure could be estimated from visible siphon holes. Across four sites with varying sediment characteristics and infaunal species assemblages, we predicted the presence of M. arenaria with 78–100% accuracy by visually assessing siphon holes. Smaller holes (< 7.5 mm) were more likely to be misidentified. Siphon hole count was a strong predictor of actual clam count and biomass at most sites, except the site with wet muddy sediment and high densities of other infaunal species. Siphon hole length was positively related to clam shell length and wet weight at all sites; however, relationships typically had low R2 values (< 0.35). Ultimately, visual assessments of intertidal siphon holes can be effective for estimating M. arenaria densities and size structure in some habitats. Testing the application of this method to other habitats and species is warranted.

Biogeography of freshwater plants in four major lakes in Kenya

Freshwater plants play a pivotal role in the health and functioning of freshwater ecosystems, and they also offer a variety of benefits to humans. Despite their importance, there is a significant gap in our understanding of the macroecology of freshwater plants in tropical regions, where biodiversity is typically high, and ecosystems face substantial pressures from human activities. To bridge this knowledge gap, we conducted extensive field surveys and applied statistical methods to understand the patterns of distribution, density, and diversity of freshwater plants and their relationship with abiotic components in four freshwater lakes in Kenya. We aimed to answer four key questions: (1) How many freshwater plant species occur in these lakes? (2) What proportion of these freshwater plant species are native and alien to Kenya? (3) What proportion of these species have a history of being invasive somewhere in the world, including in Kenya? (4) Which water and sediment characteristics are significantly associated with the presence, density, and diversity of freshwater plants in the lakes? We inventoried a total of 163 freshwater plant species, of which 114 were native to Kenya and 49 were alien. Online database searches revealed that 114 species had a history of invasion globally, with 22 species already invasive in Kenya. Our statistical analysis showed that the presence and density of plant species were positively correlated with pH and turbidity, but negatively correlated with soluble reactive phosphorus in both water and sediments, ammonia-nitrogen in sediments, and nitrate-nitrogen in water. Shannon-Wiener diversity of the plant species was positively correlated with ammonia-nitrogen in water and nitrate-nitrogen in sediments but negatively correlated with longitude and electrical conductivity of the water. Pielou’s evenness within the communities showed positive correlations with soluble reactive phosphorus in both water and sediments, ammonia-nitrogen in sediments, and nitrate-nitrogen in water but was negatively correlated with water turbidity and pH. The number of species with a history of invasion was positively correlated with longitude and electrical conductivity but negatively correlated with ammonia-nitrogen and nitrate-nitrogen in water. This extensive inventory not only enriches our understanding of the biodiversity within these freshwater plant communities but also highlights the potential risks posed by species with a history of being invasive. The findings regarding environmental variables linked to the presence, density, diversity, and invasive potential of these species underscore the complexity of freshwater ecosystems and the array of factors influencing the composition of freshwater plant communities.

Textural and mineralogical characteristics of sediments originated from salt domes in the northern part of the Hormuz Strait

Textural and mineralogical characteristics of sediments originated from salt domes in the northern part of the Hormuz Strait

Assessing the strength of deep-sea surface ultrasoft sediments with T-bar penetration: A machine learning approach

With the expansion of marine resource utilization, geological disaster prediction, and ecological protection in deep-sea regions, accurate identification of deep-sea engineering geological environments has become paramount, highlighting the significance of understanding the mechanical characteristics of deep-sea surface ultrasoft sediments (DSUSs). However, DSUSs typically exhibit low strength, high compressibility, and significant fluidity, making sampling for indoor strength testing a challenging task. On-site testing employing a T-bar penetrometer has become increasingly prominent for assessing DSUS strength, but the complexity of influencing parameters limits the application of this valuable method. This study utilizes a validated computational fluid dynamics (CFD) approach to model the complete process of T-bar penetration into a DSUS. The aim is to understand the quantitative effects and corresponding mechanisms of various significant complex parameters, including the undrained shear strength, dimensionless penetration depth, rate effect, and interface contact condition, on the dimensionless penetration resistance coefficient. Additionally, a machine learning model based on the random forest algorithm is introduced to establish a multiparameter evaluation method for the dimensionless penetration resistance coefficient. The findings illuminate the intricate interactions and effective evaluation of these factors when evaluating DSUS strength using a T-bar penetrometer, addressing the above challenges in marine engineering geology and the environment.

Lithological and mineralogical characteristic of the bottom sediments in the areas of ice scouring in the south-western Kara Sea

Lithological and mineralogical characteristic of the bottom sediments in the areas of ice scouring in the south-western Kara Sea

A luminescence-derived cryptostratigraphy from the Lake Suigetsu sedimentary profile, Japan: 45,000–30,200 IntCal20 yr BP

The luminescence characteristics of sediments are affected by a variety of environmental factors, reflecting both local and broader regional influences. If seeking to apply stimulated luminescence as a ‘pure’ dating technique, variability in these external variables needs to be controlled for, involving, inter alia, lengthy pretreatment procedures and complex dose rate corrections. However, in so doing, a lot of potentially valuable palaeoenvironmental information is lost.Instead, in the present study, we explicitly analysed raw, non-pretreated sediment that preserves this wealth of contributory environmental influence. Using a SUERC portable luminescence (POSL) reader, we performed rapid profiling across a 14,800 year interval of the annually laminated (varved) Lake Suigetsu sedimentary profile, central Japan (i.e., 45,000 to 30,200 IntCal20 yr BP), producing 303 contiguous measurements with a mean sampling resolution of 49 years. To further inform our understanding of this dataset, additional follow-up laboratory dosing was performed to provide sensitivity estimates.The ‘cryptostratigraphy’ (‘hidden stratigraphy’) revealed by our data includes the identification of a step-change in luminescence parameters circa 39,200 IntCal20 yr BP, which we attribute to a major earthquake that resulted in re-routing of inflow to the lake. Further variability in the derived luminescence signals is compared with supporting high resolution x-ray fluorescence (μXRF) data and palynological data from Lake Suigetsu. A correlation between the luminescence profile (both net infra-red-stimulated and net blue light-stimulated signals) and mean annual temperature is revealed, mediated through subtle differences in sediment characteristics under warmer or cooler climatic conditions.

Effects of wet-dry alternation on organic phosphorus dynamics and sediment characteristics in the intertidal zone of Nansi Lake

The study of the fractions and distribution characteristics of organic phosphorus in the sediment of the water level fluctuating zone of Nansi Lake is conducive to revealing the transformation of phosphorus in the lake, and has important scientific significance for controlling the eutrophication of Nansi Lake. Based on the sediment of the water level fluctuation zone of Nansi Lake. The improved Hedley continuous grading extraction, ultraviolet-visible spectroscopy and three-dimensional fluorescence spectroscope were used to characterize the structural characteristics and stability of organic molecules in the sediment, and to reflect the differences in the structure and stability of organophosphate in the water level fluctuating zone. Principal component analysis (PCA), Redundancy analysis (RDA) and correlation heat map analysis were used to analyze the correlation between phosphorus and physicochemical index. The results showed that the alternation between wet-dry conditions was more favorable for the release of phosphorus from sediment, compared to continuous inundation conditions. Moreover, the higher the frequency of wet-dry alternations, the greater the release of phosphorus in different forms from the sediment. Wet-dry alternation resulted in a reduction of substituent on the aromatic rings of sediment DOM (dissolved organic matter), and the continuous drying would increase the molecular weight and humidification degree of DOM in the sediment. Correlation analysis showed that NaOH-Po content in sediment was significantly negatively correlated with TP, IP, OP and various organophosphorus forms, indicating a close transformation relationship between phosphorus forms in sediment. The results can provide a scientific basis for controlling the release of endogenous phosphorus and the risk of eutrophication in Nansi Lake.

The Sedimentary Characteristics and V Enrichment Mechanism of the Cambrian Terreneuvian Black Shale in the Eastern Guizhou

The Sedimentary Characteristics and V Enrichment Mechanism of the Cambrian Terreneuvian Black Shale in the Eastern Guizhou

Characteristics of Phosphate Sorption on Surface Sediments: A Study in Kendari Bay

Phosphate adsorption and desorption are significant processes that influence the presence of phosphate in aquatic ecosystems and regulate the concentration of phosphate at the water-sediment interface. This research aims to investigate the characteristics of phosphate adsorption and desorption in Kendari Bay sediments, study the relationship between adsorption capacity and sediment characteristics and its phosphorus fraction, and evaluate its potential contribution to the overlying water column. Physicochemical measurements of the water and sediments were performed in the sampling location and the laboratory. Two types of adsorption-desorption kinetics models and two types of isothermal adsorption models were used to estimate the adsorption rate and capacity of the surface sediments. Adsorption kinetics and desorption kinetics experiments produced pseudo-second-order kinetic model equations with regression coefficients (R2) of 0.865–0.936 and 0.886–0.947, respectively. The isothermal adsorption experiment follows the Langmuir equation model with R2 = 0.964. The maximum adsorption capacity (Qmax) value was 156.3–227.3 mg/kg, and the phosphate concentration value at zero equilibrium (EPC0) was 0.0026–0.0047 mgP/L. Notably, the EPC0 value was higher than the SRP concentration, indicating that the resuspension of phosphate ions from sediment into the water column could occur. Furthermore, there was a correlation between Qmax values with OP, Al-P, Fe-P, clay particles, and organic materials. Potential practical applications may include integrating sediment adsorption capacity data into ecosystem models to inform nutrient management strategies and promote sustainable coastal development in Kendari Bay and beyond.

Characteristics of sediments and regolith alterations in the Plio-Pleistocene succession, coastal cliff sections, St Vincent Basin, South Australia

Syn- and post-depositional alterations are distinguished in a detailed lithological and mineralogical study of the largely unconsolidated Plio-Pleistocene non-marine succession in coastal cliff sections in the St Vincent Basin south of Adelaide. At its base, the sequence interfingers with Late Pliocene estuarine marine sediments in places but mostly unconformably overlies older Cenozoic marine sediments or Neproterozoic bedrock. The fluvial and alluvial siliclastics have bioturbation, blocky-prismatic macro-peds and subtle Fe-mottling indicators of hiatuses in deposition, and imprints of soil and shallow groundwater environments. A relative abundance of kaolinite, illite and randomly interstratified illite-smectite reflects both sediment source and conditions in the local depositional environment. A thick deposit of aeolian calcareous silt with associated pedogenic calcretes blankets the succession. Conspicuous bleached Fe mega-mottled intervals and zones of alunite-halloysite within the sequence record post-depositional, groundwater-related alterations in regolith environments. These formed during incision and erosion of the sedimentary fill in the basin in response to regional falls in base level. Each marks a different time and specific geomorphic environment according to the chemistry of the discharge of local groundwaters from aquifers that were intersected by incision and scarp retreat.

Textural characteristics of fluvial sediments in the Kosi River Basin, Bihar, India

The fluvial sediment samples collected from the Kosi River Basin, Bihar were subjected to textural analysis. The textural parameters were computed using the appropriate phi values. Statistical metrics including mean, standard deviation, skewness, and kurtosis were estimated. From the findings, the mean size of river sand has been observed from medium to fine-grained nature (between 0.97 Φ and 2.72 Φ). Within the range of 0.50 Φ to 0.77 Φ, the standard deviation denotes a moderately well-sorted to moderately sorted nature. The sediment samples exhibit skewness values ranging from -0.344 Φ to 0.267 Φ. The Kurtosis varies between 0.86 Φ and 1.9 Φ, indicating a leptokurtic to mesokurtic nature. Thus, the statistical measures have revealed that sediments are dominant in the medium sand category, moderately well sorted, finely skewed, and fall under leptokurtic character. The bivariate plots constructed between the statistical metrics indicate the unimodal nature of sediments.

Seasonal Dynamics of Chemical and Microbiological Characteristics of Bottom Sediments in the Sea Estuary of a Small River in the Sevastopol Region (by the Example of the Chernaya River, Crimea)

Seasonal Dynamics of Chemical and Microbiological Characteristics of Bottom Sediments in the Sea Estuary of a Small River in the Sevastopol Region (by the Example of the Chernaya River, Crimea)

THE EFFECT OF COASTAL AND CHANNEL MANGROVES SEDIMENT ON BIOTURBATION DISTRIBUTION

Mangroves are a type of tropical tree that thrives and flourishes in harsh conditions where most vegetation struggles. Despite their resilience, mangrove ecosystems face significant threats from deforestation, pollution, and human activities. As an exceptionally efficient habitat for the capture and stabilization of sediment, the mangrove region is also supported by the bioturbation activity where organisms burrow and play an important role in the carbon and nutrient cycle while shaping soil geomorphology within the ecosystem. Many discoveries on the distribution of bioturbation have been carried out in coastal areas regarding grain size, soil density, and others. However, the difference in bioturbation activities on different physical attributes such as coastal, channels, and creeks areas has not yet been well addressed especially in Malaysia. Thus, this study proposes to elucidate the difference in bioturbation distribution between coastal and channel regions in the mangrove areas. The aim is to determine bioturbation distribution within coastal and channel regions by investigating the sediment characteristics and bioturbation frequencies along these two regions. The stratified random quadrat sampling method has been used for bioturbation frequencies, inhabitant species, and population richness. The sediment was characterized with a standard soil dry-sieving method and further analysed by laser diffraction method for fine particle distribution. In examining the effect of physical attribute influence on the bioturbation distribution, a two-way ANOVA assessment was carried out. This study has found that coastal and channel had different sediment distribution and the bioturbation frequencies were influenced by different inhabitants in both regions. Thus, the result of this study supports that coastal and channel regions have significant differences in the bioturbation process. The outcome of this study perhaps will increase awareness among the community members and their involvement in the enrichment and nurturing of ground areas, especially mangrove forests (SDG14).

Interaction between shallow and deep structures: Forward-modeling kinematics sequence of a fold-and-thrust belt with double detachment

It is crucial to determine the sequence of deformation and the interaction between shallow and deep structures within the multiple detachment systems to comprehend geological processes fully in fold-and-thrust belts (FTBs). Here, we implement forward modeling to investigate the geometric, kinematic, and syntectonic sedimentary characteristics of shallow and deep structural interactions. We design four combinative patterns of geometric structures, three kinematic sequence scenarios, and two settings with different ratios of the sedimentation rate to the uplift rate to examine the influence of such settings on growth strata geometry. The most effective results of 24 groups of shallow and deep structural interactions were obtained for various combinations of fault-bend fold, detachment fold, and tectonic wedge. This study provides a sequential kinematic image of FTBs, illustrating the interaction of two sets of detachments and demonstrating how different styles of pre- and growth strata can be utilized to identify shallow and deep structure deformation processes. The geometry of pre- and growth strata observed in the models is similar to that observed in natural structures. These forward models facilitate a better understanding of the complex geometry and kinematics of the interaction between shallow and deep fault-related folds.

Sediment Characteristics and Hydrocarbon Composition of Makukwa Seep in Southern Tanzania: Potential Implications for Subterranean Hydrocarbon Accumulation

Sediment Characteristics and Hydrocarbon Composition of Makukwa Seep in Southern Tanzania: Potential Implications for Subterranean Hydrocarbon Accumulation

Impacts of sedimentary characteristics and diagenesis on reservoir quality of the 4th member of the Upper Triassic Xujiahe formation in the western Sichuan basin, southwest China

The 4th member of Xujiahe Formation (Xu4) in the western Sichuan Depression is a typical porous tight sandstone reservoir. Finding reservoirs with relatively high porosity controlled by sedimentation and diagenesis is crucial for successful tight gas exploration. In this study, the Xu4 sandstone was studied by diverse methods, including outcrop and core observation, logging data interpretation, thin section and cathodoluminescence examination, scanning electron microscopy analysis, and X-ray diffraction, to determine sedimentary and diagenetic characteristics and to discuss their impact on the sandstone reservoir quality. During the depositional period of Xu4, subaqueous distributary channel sandstone of braided river delta front developed extensively under controls of bidirectional provenance (LASP and SASP), mainly consisting of litharenite and sublitharenite, with low feldspar and high rock fragments volume, respectively. Strong compaction and carbonate cementation have largely destroyed primary porosity, while secondary pores constitute the main pore space in the Xu4 sandstone. The sediment provenance, sedimentary microfacies and A/S determine the clastic composition of sandstone, genetic type and thickness of sand bodies, furthermore affect the subsequent diagenetic variations. The larger the thickness of the sand body indicates a higher-energy depositional environment, coarser grain size, better sorting, and lower shaliness content of the sandstone during deposition period. This results in stronger resistance to compaction of the sandstone, which is conducive to the preservation of primary pores and dissolution of organic acids, resulting in better physical properties of sandstone. Among them, the physical properties of the sandstones of the Xu4s and Xu4x are better than those of the Xu4z; moreover, LASP's sandstone is superior to SASP. It is worth noting that subaqueous distributary channel sandstones with thickness exceeding 13 m in Xu4s and Xu4x from LASP represent favorable areas for high-quality reservoirs. The work can be used as a reference for the exploration and evaluation of similar tight sandstone gas in the world.

Effect of Gastrodia elata Bl Cultivation under Forest Stands on Runoff, Erosion, and Nutrient Loss

(1) Background: The understory planting of Chinese herbal medicine is a common soil and water conservation farming measure, and this approach makes full use of the natural conditions of the understory. However, a large number of studies on soil erosion have focused on the simulation of natural indoor conditions, and there are very few investigations on soil erosion caused by understory planting in the field. This study aims to investigate the effects of different slopes on soil and water and nitrogen–phosphorus nutrient loss from understory planting of Gastrodia elata Bl by changing the vegetation structure and soil structure of forest land. (2) Methods: To reveal the nitrogen and phosphorus loss and flow and sediment characteristics of the understory planting of Gastrodia elata Bl, runoff plots were set up in a field, and three surface slopes (5°, 15°, and 20°) were designed to collect runoff sediments and compare the soil and water loss between the natural slopes and those with Gastrodia elata Bl. This provides a basis for the restoration of vegetation cover and the enhancement of soil fertility. (3) Results: The total loss of soil, water, nitrogen, and phosphorus in the forested land with Gastrodia elata Bl increased significantly compared with that in the natural forested land, and the greater the slope was, the greater the loss was. (4) Conclusions: Planting Gastrodia elata Bl should be avoided in areas with steep slopes and serious soil erosion. However, some soil and water conservation engineering measures can be taken, such as the construction of retaining walls, drainage ditches, etc., to minimize the scouring and erosion of soil by rainwater.

The Characteristics of Adsorption of Di-n-Butyl Phthalate by Surface Sediment from the Three Gorges Reservoir.

Phthalic acid esters (PAEs), recognized as endocrine disruptors, are identified as predominant organic pollutants in the Three Gorges Reservoir (TGR). Di-n-butyl phthalate (DBP), a representative PAE, has been extensively studied for its sources, distribution and ecological risks. However, there are few studies on the adsorption of DBP by sediment from the TGR, and the adsorption characteristics of surface sediment on DBP are not clear. Therefore, based on the actual sediment contents and particle sizes in the TGR, the kinetics and isothermal adsorption characteristics of surface sediment on DBP were investigated in this study. The results showed that the equilibrium time was 120 min, the adsorption kinetics were more in line with the pseudo-second-order kinetic model, and the sediment in water from the Yangtze River exhibited a higher adsorption rate and maximum adsorption amount on DBP than that observed in deionized water. Additionally, a decrease in DBP adsorption was observed with increasing sediment content, while sediment particle size and specific surface area had a slight influence. Analysis using SEM, TGA and FTIR revealed that organic matter on the sediment surface significantly contributed to DBP adsorption. This study contributes valuable insights into the adsorption characteristics of DBP by the surface sediment from the TGR, providing a scientific foundation for understanding the migration and transformation of DBP in this critical reservoir in China.

Enigmatic vertebrate swimming trace fossils from the Wapiti Formation, Alberta, Canada, and their implications for paleoenvironmental reconstruction

Vertebrate ichnofossil research, when compared with invertebrate ichnological analyses, tends to put greater emphasis on identifying the trace makers rather than associating the trace fossils with animal behaviors to interpret local paleoenvironmental conditions. In 2011, several sandstone blocks bearing unusual deformational structures were collected from the Wapiti Formation exposed near Red Willow Falls, Alberta, Canada. The sandstone blocks were analyzed for their sedimentary characteristics and the morphology of the enigmatic structures in order to identify their origins and their significance for paleoenvironmental interpretation. The deformational features are interpreted to be the swim tracks of small vertebrates attempting to escape a flash flood event. The sedimentology of the sandstone suggests a rapid increase in water flow in an overbank setting, and the orientation of the traces indicate that the trace maker was initially moving against, and then moving perpendicular to, the current. This is likely the first case of a trace fossil exhibiting clear association between vertebrates and flash flood events. As such, these traces provide an excellent example of the utility of vertebrate trace fossils for assessing organism response to changing environmental conditions, thus facilitating interpretation of local geological events.