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Marine fungi represent a treasure trove of bioactive secondary metabolites, with benzopyran compounds emerging as a significant class of these natural products. This review delves into the structural diversity, biological activities, and sources of benzopyran compounds, highlighting their isolation from marine fungi inhabiting diverse environments such as sponges, marine sediments, algae, mangroves, and corals. Our literature search, conducted from 2000 to 2023, has identified a wealth of benzopyran compounds, showcasing their potential as lead compounds in drug development. The characteristics of benzopyran from marine fungi are explored, encompassing various subclasses such as chromones, isocoumarins, citrinins, and other related compounds. These compounds exhibit a remarkable chemical diversity, which is crucial for their diverse biological activities. The potential of benzopyran compounds in drug development is also discussed, emphasizing their roles in anti-tumor, antibacterial, anti-inflammatory, and enzyme inhibitory activities. In recent years, a remarkable 210 bioactive benzopyran compounds have been isolated from the secondary metabolites of marine fungi. These findings underscore the importance of marine fungi as a source of novel bioactive compounds, offering a plethora of potential lead compounds for the development of marine-derived drugs. This review aims to provide a comprehensive overview of the current state of research on benzopyran compounds, setting the stage for future advancements in the field of marine natural products. [ABSTRACT FROM AUTHOR]

Globally, ocean dumping of chemical waste is a common method of disposal and relies on the assumption that dilution, diffusion, and dispersion at ocean scales will mitigate human exposure and ecosystem impacts. In southern California, extensive dumping of agrochemical waste, particularly chlorinated hydrocarbon contaminants such as DDT, via sewage outfalls and permitted offshore barging occurred for most of the last century. This study compiled a database of existing sediment and fish DDT measurements to examine how this unique legacy of regional ocean disposal translates into the contemporary contamination of the coastal ocean. We used spatiotemporal modeling to derive continuous estimates of sediment DDT contamination and show that the spatial signature of disposal (i.e., high loadings near historic dumping sites) is highly conserved in sediments. Moreover, we demonstrate that the proximity of fish to areas of high sediment loadings explained over half of the variation in fish DDT concentrations. The relationship between sediment and fish contamination was mediated by ecological predictors (e.g., species, trophic ecology, habitat use), and the relative influence of each predictor was context-dependent, with habitat exhibiting greater importance in heavily contaminated areas. Thus, despite more than half a century since the cessation of industrial dumping in the region, local ecosystem contamination continues to mirror the spatial legacy of dumping, suggesting that sediment can serve as a robust predictor of fish contamination, and general ecological characteristics offer a predictive framework for unmeasured species or locations. [ABSTRACT FROM AUTHOR]

Marine plastic pollution has become a major concern as it threatens marine life and human health. Most of the plastic that enters the ocean is either consumed by animals and/or trapped in sediments. However, there is little information on how sediment properties might be affected. In this article, we explore the impact of microplastic inclusions in marine settings by using PVC plastic chips and two soil samples as analogues. We conducted a comprehensive experimental study to investigate changes in compressibility, strength, stiffness, thermal and hydraulic conductivity, and particle migration by varying plastic content. Results show that as low as 1% of plastic content by volume can lead to irreversible consequences in sediment behavior while coarse particles display a heightened sensitivity than pure fines. As plastic content in sediment increases year-by-year, we anticipate significant repercussions in marine life, the future landscape of the seafloor and subsurface phenomena. [ABSTRACT FROM AUTHOR]

The determination of rare earth elements (REEs) in seawater, especially marine sediment porewater and open-ocean seawater, is challenging because of their ultra-trace concentrations (ng L−1 to pg L−1) and the high salinity of the matrix (approximately 35‰ NaCl), which limits their application in marine science. Herein, we developed an online method for accurate analysis of ultra-trace REEs in seawater using a traditional Q-ICP-MS. The key aspects were: (i) high sensitivity detection in standard mode with no collision/reaction cell functioned, (ii) online automated matrix removal and preconcentration using a commercially available seaFAST system, (iii) use of membrane desolvation to enhance the sensitivity and limit the interferences of LREE oxides on HREEs, and (iv) monitoring and correction of variations in REE signal intensities caused by instrument drift using standard–samples–standard bracketing and an indium internal standard for normalization. The detection limits (0.1–8.0 pg L−1) and procedural blank values (<3 pg L−1 except for La, Ce, and Nd) of this method were low enough for accurate determination of REEs in seawater, even for REE concentrations at tens of picograms per liter level. The good accuracy and long-term precision (30 h, average: 3.5%, 1σ RSD, n = 10) were achieved for all the REEs as verified using certified seawater reference standards NASS-7 and CASS-6, and a 10 ng L−1 artificial seawater standard, respectively. Each run required only approximately 8 mL of sample and 12 min for the measurement, which are suitable values for practical application. The developed method was used to analyze various natural seawater samples, which demonstrated its effectiveness for exploring subtle changes in REE concentrations, fractionation patterns and anomalies in different marine environments. [ABSTRACT FROM AUTHOR]

A large part of ocean surface is covered by calcareous deposits. The Low stiffness and weak particles of calcareous soils deposited by marine organisms showed significant particle breakage under applied loads, which resulted in different behavior compared to terrigenous soils. A series of compression drained triaxial tests were carried out to evaluate the monotonic shear behavior of crushable and non-crushable soils. Three different soils, including Firoozkuh siliceous sand (as a non-crushable soil) and Hormuz and Bushehr calcareous sands (as crushable soils) which were different in mineralogy compositions were obtained from northern and southern Iran. The specimens were prepared in different relative densities (i.e., loose, medium and dense conditions) and consolidated under confining pressures ranging from 100 to 600 kPa. The monotonic shear and dilatancy behaviors of the soils have been presented in detail and the effect of particle breakage has been discussed. The results showed that particle breakage has a significant effect on the mobilized friction and dilatancy angles of marine crushable soils. There is a linear relationship between the amount of particle breakage occurring during a triaxial test and breakage angle. In addition, the mineralogical difference influences the breakage properties of calcareous deposits. [ABSTRACT FROM AUTHOR]

The Pacific coast of eastern Japan contains specific aeolian landforms of geomorphological interest in terms of their formation processes in humid climates and Holocene paleoenvironments. Wind erosion landforms, characterised by blowouts, were observed at the heads of coastal cliffs which consisted of marine gravel sediments, weathered volcanic ash layers (WVALs) and black soil layers (BSLs). The blowouts were accompanied by downwind tephric loess dunes. We analysed the physicochemical properties of the WVAL, BSL and dune sediment samples. The results revealed that clay and silt contents in dune sediments were 5–48% and 20–35%, respectively. The fine particles were in the form of aggregates in the WVALs, BSLs and dune sediments, with contributions from andic properties. WVAL and BSL aggregates were prone to movement in saltation, depositing into the dunes in a formation process similar to that of clay dunes in semiarid zones. The tephric loess dunes were characterised as clay dunes based on their high clay and silt contents. In addition, the dunes were characterised by durable aggregates derived from short-range-order minerals, such as allophane. The prevailing northeasterly winds caused by intense low pressures were responsible for dune formation in the study areas. Radiocarbon dating revealed two active wind periods. The first was approximately 1005–895 cal. BC to 358–281 cal. BC, and the second was 771–886 cal. AD to 1021–1155 cal. AD. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) preserved in marine sediments is increasingly being used to study past ecosystems. However, little is known about how accurately marine biodiversity is recorded in sediment eDNA archives, especially planktonic taxa. Here, we address this question by comparing eukaryotic diversity in 273 eDNA samples from three water depths and the surface sediments of 24 stations in the Nordic Seas. Analysis of 18S‐V9 metabarcoding data reveals distinct eukaryotic assemblages between water and sediment eDNA. Only 40% of Amplicon Sequence Variants (ASVs) detected in water were also found in sediment eDNA. Remarkably, the ASVs shared between water and sediment accounted for 80% of total sequence reads suggesting that a large amount of plankton DNA is transported to the seafloor, predominantly from abundant phytoplankton taxa. However, not all plankton taxa were equally archived on the seafloor. The plankton DNA deposited in the sediments was dominated by diatoms and showed an underrepresentation of certain nano‐ and picoplankton taxa (Picozoa or Prymnesiophyceae). Our study offers the first insights into the patterns of plankton diversity recorded in sediment in relation to seasonality and spatial variability of environmental conditions in the Nordic Seas. Our results suggest that the genetic composition and structure of the plankton community vary considerably throughout the water column and differ from what accumulates in the sediment. Hence, the interpretation of sedimentary eDNA archives should take into account potential taxonomic and abundance biases when reconstructing past changes in marine biodiversity. [ABSTRACT FROM AUTHOR]

Land reclamations often demand large quantities of fill materials. However, many countries commonly engaged in land reclamation are facing an escalating scarcity of natural fill sources. To address this issue, this study proposes a sustainable land reclamation approach that involves dredged marine sediments as fill materials. The dredged marine sediments are improved by a combined method that incorporates the use of horizontal drains with vacuum preloading for preliminary soil treatment and vertical drains with vacuum preloading for further improvement. A field trial has been designed and conducted to verify the performance of the proposed preliminary treatment of marine sediment slurry using prefabricated horizontal drains (PHDs) and vacuum preloading under a "membrane-free" condition. Field measurements, including settlement, pore pressure, effective earth pressure, vacuum pressure, water content, and undrained shear strength, were systematically recorded during the field trial period. After a four-month treatment, the average water content of the filled soil was slightly below 50%, which is one-third of the initial water content. Owing to the combined effect of the vacuum preloading and drying process, a crust layer with the undrained shear strength of 40 kPa was formed on the top of the treated soil. Below the crust layer, the average undrained shear strength of the treated marine deposits was approximately 32 kPa. Overall, the notable effect of using PHDs and the "membrane-free" vacuum preloading method to rapidly consolidate marine deposits slurry has been successfully demonstrated with field monitoring under the site trial condition. [ABSTRACT FROM AUTHOR]

This study was conducted to assess sediment trace metals (Cd, Cr, Cu, Pb, Ni and Zn) contamination using a systematic approach by collecting sediment samples from 8 transects along the Dubai coastline, each 10 km long, and each transect included its nearshore sediment sampling station. Additionally, 10 sediment samples were collected from the Dubai creek and other potential sources of metal pollution. The sediment samples were collected in December and again in August. However, no significant difference in sediment metal concentration was found between the two sampling campaigns. The sediment trace metal concentrations (0.92–1.31 mg Cd/kg, 2.82–176.6 mg Cr/kg, 2.27–621.67 mg Cu/kg, 0.88–23.6 mg Pb/kg, 1.92–192.2 mg Ni/kg and 9.1–391.05 mg Zn/kg) showed considerable variability, except for Cd (1.08 ± 0.06 mg/kg, 5.55% variability). Despite this, no significant differences in sediment metal concentrations were found between the sampled transects. However, significant variations in Cr, Cu, Pb and Zn were evident between distances from the shoreline to offshore stations along the Dubai coast, and the nearshore locations presented clear evidence of elevated/maximum sediment metal concentrations. Most of the sediment trace metal concentrations, however, were found well within the sediment quality guidelines (SQGs) for nearshore sediments. Trace metal contamination hotspots, nonetheless, were identified at some nearshore stations as determined by metal level exceedance over the SQGs, background levels and the pollution load index, with limited potential ecological risk. Overall, the findings suggest that sediments in the Dubai coastal environment are mainly influenced by anthropogenic activities in stations located in the proximity of ship maintenance, ports, and industrial areas such as Dry Dock, Jaddaf, Jebel Ali Port, Wharfage, Hamriya and DUBAL. [ABSTRACT FROM AUTHOR]

The geochemistry of marine sediment is a massive archive of (paleo)oceanographic information. Accessing that information requires "unmixing" the various influences on marine sediment geochemistry to understand individual sources and marine geochemical processes. Q‐mode factor analysis (QFA) and independent component analysis (ICA) are multivariate statistical techniques that have successfully been applied to large datasets of marine sediment element concentrations to identify the number and composition of marine sediment sources or end‐members. In this study, we apply both techniques to two datasets of marine sediment geochemistry, compare the output, and discuss the advantages of each approach. In both datasets, ICA identified a mixing trend between carbonates and dust, whereas QFA represented the end‐members as two separate factors. In the Pacific and Indian Oceans dataset, both techniques produced three factors or independent components involving rare earth elements, but two of the QFA factors explained a small, almost negligible, amount of the variability of the dataset. Also, QFA identified more aluminosilicate end‐members (dust or volcanic ash) than ICA. In the Indian Ocean Sites 738 and 752 dataset, ICA identified two processes affecting Sr and Ba concentrations as separate independent components, while QFA created a factor representing the covariation of Sr and Ba over intervals of the site's paleoceanographic history. The results of this study exemplify that QFA identifies covariances and finds discrete end‐members contributing to the bulk mass of sediment. ICA works best with non‐Gaussian element distributions and finds geochemical signals and mixing trends that constitute the characteristic structure of the multielemental data. [ABSTRACT FROM AUTHOR]

Research on fungal volatile organic compounds (VOCs) has increased worldwide in the last 10 years, but marine fungal volatilomes remain underexplored. Similarly, the hormone‐signaling pathways, agronomic significance, and biocontrol potential of VOCs in plant‐associated fungi make the area of research extremely promising. In the current investigation, VOCs of the isolates—Aspergillus sp. GSBT S13 and GSBT S14 from marine sediments, and Bulbithecium sp. GSBT E3 from Eucalyptus foliage were extracted using Head Space solid phase microextraction, followed by gas chromatography‐mass spectrometry, identification, statistical analyses, and prediction of functions by KEGG COMPOUND and STITCH 5.0 databases. The significance of this research is fingerprinting VOCs of the isolates from distinct origins, identification of compounds using three libraries (NIST02, NIST14, and W9N11), and using bioinformatic tools to perform functional analysis. The most important findings include the identification of previously unreported compounds in fungi—1‐methoxy naphthalene, diethyl phthalate, pentadecane, pristane, and nonanal; the prediction of the involvement of small molecules in the degradation of aromatic compound pathways and activation, inhibition, binding, and catalysis of metabolites with predicted protein partners. This study has ample opportunity to validate the findings and understand the mechanism or mode of action, the interspecies interactions, and the role of the metabolites in geochemical cycles. [ABSTRACT FROM AUTHOR]

We adapted a recently developed technique of oriented drill coring (100 m in depth) for paleomagnetic measurements, including additional techniques such as half-cutting of the drill cores and accurate cube sampling using an apparatus that precisely guides the cube into the half-cut drill core surface. Our techniques were successfully applied to sequential tephra layers (including loess) at Akan Quaternary caldera volcano in eastern Hokkaido, Japan. Directions of remanent magnetization for a total of 129 specimens were measured by Spinner magnetometer with thermal and alternating field demagnetizations. We detected clear Matuyama–Brunhes geomagnetic reversal between the depths of 20.59 m and 21.30 m, where inclinations change from 65.1 to –44.3°. With these techniques, we can in future obtain useful geologic information (e.g., radiometric ages and absolute paleo-intensities) from volcanic rocks around the Matuyama–Brunhes boundary in Akan volcano. This will clarify more detailed processes of the geomagnetic polarity transition. Our study demonstrates the utility of oriented drill cores from successive tephra and loess layers for high resolution investigate of continuous paleo-geomagnetic records. The new techniques can be adopted to other geological fields on Earth, like in studies of marine sediments, providing continuous paleomagnetic direction data from drill core. [ABSTRACT FROM AUTHOR]

The research on the source of marine sediments has a vital impact on identifying material sources, transport mechanism, and the evolution of sedimentary environments. Previous studies have shown many outstanding achievements on the source analysis of the South China Sea, but there are still some controversies over the complex source and transport mechanisms of the Zhongjiannan Basin. In this study, we took a gravity core (583cm) from the Zhongjiannan Basin and analyzed the particle size, rare earth elements, and Sr-Nd isotopes of the core sediments to further reveal the source and transport mechanism. The surface sediments in the Zhongjiannan Basinwere relatively stable, with an average particle size ranging from 5.66 to 17.74 mm. The normalized standard curve of chondrite exhibited the depletion of Eu, with LREE dominated in REE. As the depth increased, 87Sr/86Sr ratios showed a gradually increasing trend, while dNd change was relatively complex. On the whole, 87Sr/86Sr ratios (from 0.721537 to 0.725322) and dNd (from -11.561617 to -12.289374) were in a relatively narrow range. Based on the particle size characteristics, we found the geochemical characteristics of sediment largely resulted fromdifferent sediment sources. By comparing rare earth elements and Sr-Nd isotopes, we concluded the sediment of the Zhongjiannan Basin was from mainly terrigenous contribution. In addition, taking into account factors such as terrain, migration distance, and river drainage system, we conclude the sediment were mainly from the Mekong River, the Red River, Taiwan Island, and Hainan Island. The surface current along the northeast direction was the main transportation route for the sediments of the Mekong River. The Guangdong coastal current and the southwest surface current transported sediment from the Red River and Hainan Island to the Zhongjiannan Basin. The surface current and deep-water current in the southwest direction carried sediment from Taiwan Island to the study area, while the Kuroshio also had some impacts on the sediment transportation of Taiwan Island. This study has reinforced the research on provenance in the South China Sea Basin and has an important significance on evolution of sedimentary environments, evolution of ancient oceans. [ABSTRACT FROM AUTHOR]

Cold seeps, featured by their extremely methane-rich sedimentary environments, play a significant role in the geological history and are common in marine sediments across the seafloor. Primary dolomite, possibly mediated by microorganisms, can be widely discovered in methane-rich environments. Hence, cold seeps may provide new insights into the 'dolomite problem', which has confused geologists for decades. Magnesium isotope geochemistry of seep carbonates contributes to the understanding of the dolomite formation mechanism in marine environments. In this paper, magnesium geochemical characteristics of carbonates in modern sediments are summarized, along with rare researches on magnesium isotopes of seep carbonates. Methane vigorously interacts with sulfate by anaerobic oxidation of methane at cold seeps, producing vast amounts of dissolved sulfide which can significantly promote dolomitization of seep carbonates. Compared with temperature, alkalinity, mineralogy, etc., the competition between rapid carbonate precipitation rates and aqueous ligands may be the main factor of the magnesium fractionation at cold seeps, which is controlled by the kinetic effect. The range of magnesium isotopes of seep carbonates is narrow (from -3.46‰ to -2.36‰), and an upper limit of magnesium content seems to exist. This characteristic may be a good indicator for identifying dolomitization related to anaerobic oxidation of methane. Whereas, mechanisms of magnesium isotope fractionation and dolomitization at cold seeps remain unclear, necessitating more natural samples tested, stimulated calculation and laboratory experiment. [ABSTRACT FROM AUTHOR]

Endo-β-1,3-glucanase is a glycoside hydrolase (GH) that plays an essential role in the mineralization of β-glucan polysaccharides. In this study, the novel gene encoding an extracellular, non-modular GH16 endo-β-1,3-glucanase (GluH) from Hymenobacter siberiensis PAMC 29290 isolated from Arctic marine sediment was discovered through an in silico analysis of its whole genome sequence and subsequently overexpressed in Escherichia coli BL21. The 870-bp GluH gene encoded a protein featuring a single catalytic GH16 domain that shared over 61% sequence identity with uncharacterized endo-β-1,3-glucanases from diverse Hymenobacter species, as recorded in the National Center for Biotechnology Information database. The purified recombinant endo-β-1,3-glucanase (rGluH: 31.0 kDa) demonstrated peak activity on laminarin at pH 5.5 and 40°C, maintaining over 40% of its maximum endo-β-1,3-glucanase activity even at 25°C. rGluH preferentially hydrolyzed D-laminarioligosaccharides and β-1,3-linked polysaccharides, but did not degrade D-laminaribiose or structurally unrelated substrates, confirming its specificity as a true endo-β-1,3-glucanase without ancillary GH activities. The biodegradability of various substrate polymers by the enzyme was evaluated in the following sequence: laminarin > barley β-glucan > carboxymethyl-curdlan > curdlan > pachyman. Notably, the specific activity (253.1 U mg–1) and catalytic efficiency (kcat/Km: 105.72 mg–1 s–1 mL) of rGluH for laminarin closely matched its specific activity (250.2 U mg–1) and kcat/Km value (104.88 mg–1 s–1 mL) toward barley β-glucan. However, the kcat/Km value (9.86 mg–1 s–1 mL) of rGluH for insoluble curdlan was only about 9.3% of the value for laminarin, which correlates well with the observation that rGluH displayed weak binding affinity (< 40%) to the insoluble polymer. The biocatalytic hydrolysis of D-laminarioligosaccharides with a degree of polymerization between 3 and 6 and laminarin generally resulted in the formation of D-laminaribiose as the predominant product and D-glucose as the secondary product, with a ratio of approximately 4:1. These findings suggest that highly active rGluH is an acidic, cold-adapted D-laminaribiose- and D-glucose-releasing GH16 endo-β-1,3-glucanase, which can be exploited as a valuable biocatalyst for facilitating low temperature preservation of foods. [ABSTRACT FROM AUTHOR]

Streptomyces sp. VB1, an actinomycete isolated from marine sediments in Valparaíso Bay, Chile, synthesizes antimicrobial and antiproliferative compounds. This study presents comprehensive metabolomics and comparative genomics analyses of strain VB1. LC-HRMS dereplication and Molecular Networking analysis of crude extracts identified antibiotics such as globomycin and daunorubicin, along with known and potentially novel members of the arylomycin family. These compounds exhibit activity against a range of clinically relevant bacterial and cancer cell lines. Phylogenomic analysis underscores the uniqueness of strain VB1, suggesting it represents a novel taxon. Such uniqueness is further supported by its Biosynthetic Novelty Index (BiNI) and BiG-SCAPE analysis of Gene Cluster Families (GCFs). Notably, two Biosynthetic Gene Clusters (BGCs) were found to be unique to VB1 compared to closely related strains: BGC #15, which encodes potentially novel anthracycline compounds with cancer cell growth inhibition properties, and BGC #28, which features a non-canonical configuration combining arylomycin, globomycin, and siamycin BGCs. This supercluster, the first described to consist of more than two adjacent and functional BGCs, co-produces at least three antimicrobial compounds from different antibiotic families. These findings highlight Streptomyces sp. VB1’s potential for discovering new bioactive molecules, positioning it as a promising candidate for further research. [ABSTRACT FROM AUTHOR]

We report the δ142/140Ce values for thirty‐three widely available geological reference materials (RMs), including igneous rocks, metamorphic rocks, sediments and soils. The Ce isotope ratios of twenty‐two Chinese RMs are reported for the first time. After chemical purification using TODGA resin (50–100 μm, Eichrom, USA), Ce isotope measurements of these RMs were conducted by multi‐collector inductively coupled plasma‐mass spectrometry (MC‐ICP‐MS) with a combined standard‐sample bracketing (SSB) and Sm‐doping technique. The data quality of the Ce isotope results was assessed by repeated measurement of pure Ce reference solutions (NIST SRM 3110, JMC304, CDUT‐Ce) and well‐characterised geological RMs (BHVO‐2, BCR‐2, Nod‐A‐1, Nod‐P‐1, etc.). Our results are in excellent agreement with previously reported values within intermediate measurement precision (±0.04‰, 2s). The igneous rock and soil RMs showed limited variations in δ142/140Ce values, which ranged from ‐0.036 ± 0.018‰ to 0.062 ± 0.046‰ and ‐0.015 ± 0.015‰ to 0.029 ± 0.009‰, respectively. The river/marine sediments and Mn nodules displayed variable Ce isotope ratios ranging from ‐0.005 ± 0.018‰ to 0.141 ± 0.023‰, suggesting detectable Ce isotopic fractionation during low‐temperature processes. [ABSTRACT FROM AUTHOR]

Marine heatwaves (MHWs) are warm sea surface temperature (SST) anomalies with substantial ecological and economic consequences. Observations of MHWs are based on relatively short instrumental records, which limit the ability to forecast these events on decadal and longer timescales. Paleoclimate reconstructions can extend the observational record and help to evaluate model performance under near future conditions, but paleo-MHW reconstructions have received little attention, primarily because marine sediments lack the temporal resolution to record short-lived events. Individual foraminifera analysis (IFA) of paleotemperature proxies presents an intriguing opportunity to reconstruct past MHW variability if strong relationships exist between SST distributions and MHW metrics. Here, we describe a method to test this idea by systematically evaluating relationships between MHW metrics and SST distributions that mimic IFA data using a 2000-member linear inverse model (LIM) ensemble. Our approach is adaptable and allows users to define MHWs based on multiple duration and intensity thresholds and to model seasonal biases in five different foraminifera species. It also allows uncertainty in MHW reconstructions to be calculated for a given number of IFA measurements. An example application of our method at 12 north Pacific locations suggests that the cumulative intensity of short-duration, lowintensity MHWs is the strongest target for reconstruction, but that the error on reconstructions will rely heavily on sedimentation rate and the number of foraminifera analyzed. This is evident when a robust transfer function is applied to new core-top oxygen isotope data from 37 individual Globigerina bulloides at a site with typical marine sedimentation rates. In this example application, paleo-MHW reconstructions have large uncertainties that hamper comparisons to observational data. However, additional tests demonstrate that our approach has considerable potential to reconstruct past MHW variability at high sedimentation rate sites where hundreds of foraminifera can be analyzed. [ABSTRACT FROM AUTHOR]

Organic carbon (OC) burial in the Antarctic marginal seas is essential for regulating global climate, particularly due to its association with ice shelf retreat. Here, we analyzed total OC (TOC), total nitrogen (TN), radiocarbon isotope, n-alkanes and relative indicators in surface and core sediments from the Ross Sea, West Antarctica. Our aim was to investigate spatial and historical changes in OC sources, and to explore the influencing factors and implications for ice shelf retreat since the last glacial maximum (LGM). Our results revealed distinct spatial patterns of OC sources as indicated by n-alkane indicators in surface sediments. In the Western Ross Sea, n-alkanes predominantly originated from phytoplankton and bacteria, as evidenced by their unimodal distribution, low carbon preference index (CPI) of short-chain n-alkanes (CPIL = 1.41 ± 0.30), and low terrestrial/aquatic ratio (TAR = 0.22 ± 0.14). In the Southwest Ross Sea, n-alkanes were derived from marine algae and terrestrial bryophytes, indicated by bimodal distribution, low ratio of low/high molecular-weight n-alkanes (L/H = 0.62 ± 0.21), low CPI of long-chain n-alkanes (CPIH = 1.18 ± 0.16), and high TAR (1.26 ± 0.66). In contrast, the Eastern Ross Sea exhibited n-alkanes that were a combination of phytoplankton and dust from Antarctic soils and/or leaf waxes from mid-latitude higher plant, as suggested by both unimodal and bimodal distributions, high L/H (1.60 ± 0.58) and CPIH (2.04 ± 0.28), and medium TAR (0.61 ± 0.30). Geologically, during the LGM (27.3 -- 21.0 ka before present (BP)), there was an increased supply of terrestrial OC (TOC/TN = 13.63 ± 1.29, bimodal distribution of n-alkanes with main carbon peaks at nC17/nC19 and nC27). From 21.0 to 8.2 ka BP, as glaciers retreated and temperatures rose, the proportion of marine n-alkanes significantly increased (TOC/TN = 9.09 ± 1.82, bimodal distribution of n-alkanes with main carbon peaks at nC18/nC19 and nC25). From 8.2 ka BP to the present, as the ice shelf continued to retreat to its current position, the marine contribution became dominant (TOC/TN = 8.18 ± 0.51, unimodal distribution of n-alkanes with main carbon peak at nC17/nC18/nC19, and low TAR (0.41 ± 0.32)). This research has significant implications for understanding the variations in Antarctic OC sources and their climatic impacts in the context of accelerated glacier melting. [ABSTRACT FROM AUTHOR]

Background: Marine actinomycetes, especially Streptomyces, are recognized as excellent producers of diverse and bioactive secondary metabolites on account of the multiplicity of marine habitations and unique ecological conditions, which are yet to be explored in terms of taxonomy, ecology, and functional activity. Isolation, culture and genome analysis of novel species of Streptomyces to explore their potential for discovering bioactive compounds is an important approach in natural product research. Results: A marine actinobacteria, designated strain SCSIO 75703 T, was isolated, and the potential for bioactive natural product discovery was evaluated based on genome mining, compound detection, and antimicrobial activity assays. The phylogenetic, phenotypic and chemotaxonomic analyses indicate that strain SCSIO 75703 T represents a novel species in genus Streptomyces, for which the name Streptomyces sediminicola sp. nov. is proposed. Genome analysis revealed the presence of 25 secondary metabolite biosynthetic gene clusters. The screening for antibacterial activity reveals the potential to produce bioactive metabolites, highlighting its value for in-depth exploration of chemical constituents. Seven compounds (1–7) were separated from the fractions guided by antibacterial activities, including three indole alkaloids (1–3), three polyketide derivatives (4–6), and 4-(dimethylamino)benzoic acid (7). These primarily antibacterial components were identified as anthracimycin (4), 2-epi-anthracimycin (5) and β-rubromycin (6), presenting strong antibacterial activities against Gram-positive bacteria with the MIC value ranged from 0.125 to 16 μg/mL. Additionally,, monaprenylindole A (1) and 3-cyanomethyl-6-prenylindole (2) displayed moderate inhibitory activities against α-glucosidase with the IC50 values of 83.27 and 86.21 μg/mL, respectively. Conclusion: Strain SCSIO 75703 T was isolated from marine sediment and identified as a novel species within the genus Streptomyces. Based on genomic analysis, compounds isolation and bioactivity studies, seven compounds were identified, with anthracimycin and β-rubromycin showing significant biological activity and promising potential for further applications. [ABSTRACT FROM AUTHOR]

The article discusses a study conducted at Lake Tenndammen in Svalbard, focusing on the sedimentary units and pollen analysis. The lake is located in a biodiversity hotspot with a variety of plant species. The study involved radiocarbon dating and analysis of pollen types to understand the environmental changes over time. The findings suggest a correlation between human activities and changes in the pollen spectra, reflecting the industrial and post-industrial history of the region. [Extracted from the article]

Mangroves can retain both autochthonous and allochthonous marine and/or terrestrial organic carbon (OC) in sediments. Accurate quantification of these OC sources is essential for the proper allocation of blue C credits. Here, we conduct a global-scale analysis of sediments autochthonous and allochthonous OC contributions in estuarine and marine mangroves using stable isotopes. Globally, mangrove-derived autochthonous OC was the main contributor to estuarine and marine mangrove top-meter soil organic carbon (SOC) (49% and 62%, respectively). Less marine allochthonous OC (21%) was deposited than terrestrial allochthonous OC (30%) in estuarine mangrove sediments. Estuarine mangroves accumulated more SOC in sediments than marine mangroves (282 ± 8.1 Mg C ha−1 and 250 ± 5.0 Mg C ha−1, respectively), primarily due to the additional terrestrial OC inputs. Globally, marine mangroves held 67% of the total mangrove SOC, reaching 3025 ± 345 Tg C, while 1502 ± 154 Tg C was stored in estuarine mangrove sediments. The findings emphasize the substantial influence of coastal environmental settings on OC contributions, underlining the necessity of accurate OC source quantification for the effective allocation of blue carbon credits. Mangrove-derived organic carbon (OC) contributes 49% and 62% to estuarine and marine mangrove soil OC (SOC). Globally, 1502 Tg and 3025 Tg SOC were stored in estuarine and marine mangroves. [ABSTRACT FROM AUTHOR]

Vertical stratification in marine sediment profiles indicates physical and chemical sedimentary processes and, thus, is the first step in sedimentary research and in studying their relationship with global climate change. Traditional technologies for studying vertical stratification have low efficiency; thus, new technologies are highly needed. Recently, visible and near-infrared spectroscopy (VNIR) has been explored to rapidly determine sediment parameters, such as clay content, particle size, total carbon (TC), total nitrogen (TN), and so on. Here, we explored vertical stratification in a sediment column in the South China Sea using VNIR. The sediment column was 160 cm and divided into 160 samples by 1 cm intervals. All samples were classified into three layers by depth, that is, 0–50 cm (the upper layer), 50–100 cm (the middle layer), and 100–160 cm (the bottom layer). Concentrations of TC and TN in each sample were measured by Elementa Vario EL III. Visible and near-infrared reflectance spectra of each sample were collected by Agilent Cary 5000. A global model and several classification models for vertical stratification in sediments were established by a Support Vector Machine (SVM) after the characteristic spectra were identified using Competitive Adaptive Reweighted Sampling. In the classification models, K-means clustering and Density Peak Clustering (DPC) were employed as the unsupervised clustering algorithms. The results showed that the stratification was successful by VNIR, especially when using the combination of unsupervised clustering and machine learning algorithms. The correct classification rate (CCR) was much higher in the classification models than in the global model. And the classification models had a higher CCR using K-means combined with SVM (94.8%) and using DPC combined with SVM (96.0%). The higher CCR might be derived from the chemical classification. Indeed, similar results were also found in the chemical stratification. This study provided a theoretical basis for the rapid and synchronous measurement of chemical and physical parameters in sediment profiles by VNIR. [ABSTRACT FROM AUTHOR]

Most organic carbon delivered to the seafloor is degraded within the bioturbated layer. Theory and empirical evidence have shown that organic carbon reactivity relates to the age of a particle. However, due to particle mixing, the age‐depth linear relation induced by sediment accretion is obfuscated. Here we combine a Lagrangian particle tracking model that resolves the age distribution of particles in the bioturbated zone and couple it to age‐dependent organic carbon degradation. Depth profiles for organic carbon concentration, reactivity and degradation rate are presented for sediments receiving low and high reactivity organic carbon in coastal, continental slope and deep‐sea environments. Our results show that a simple first‐order kinetics model suffices for well‐mixed sediments and systems receiving pre‐processed materials. A reactive continuum approach is needed for poorly mixed sediments receiving highly reactive organic carbon and for sediments below the bioturbated layer. Plain Language Summary: Animals inhabiting marine sediments mix particles and impact organic carbon degradation kinetics and degradation rates. Experiments and theory have shown that organic carbon reactivity declines as degradation progresses with time. However, most studies employ a constant reactivity. Here we couple an individual particle mixing model with age‐dependent reactivity and show that a constant reactivity model is adequate for well‐mixed sediments and for sediments receiving organic carbon that has already been degraded elsewhere. An age‐dependent reactivity model is needed for poorly mixed sediments receiving highly reactive organic carbon. Key Points: Age‐dependent organic carbon kinetics is coupled to a Lagrangian particle tracking modelOrganic carbon concentrations, reactivities and degradation rates in the bioturbated zone are presentedA simple first‐order (one‐G) model suffices for well‐mixed sediments and sediments receiving pre‐processed organic carbon [ABSTRACT FROM AUTHOR]

We present a suite of major element stable isotope (δ13C, δ18O, δ44/40Ca, δ26Mg), and selected trace element (Sr/Ca and Mg/Ca) data from Pleistocene sediments from the Great Barrier Reef (IODP Expedition 325), as well as Holocene surface sediments from the Bahamas (Triple Goose Creek, Andros Island) to identify geochemical fingerprints associated with early marine and meteoric diagenesis. Sediments from both sites exhibit co-variation in δ13C and δ18O values, depletion in trace elements, and distinct geochemical trends in δ26Mg and δ44/40Ca values that reflect differences between diagenetic alteration in marine and meteoric fluids. While marine diagenesis results in lower Sr/Ca ratios, higher δ44/40Ca values, and little effect on bulk sediment δ26Mg values, meteoric diagenesis leads to lower Sr/Ca ratios, lower δ44/40Ca values, and lower δ26Mg values. Using a numerical model of diagenesis, we show how diagenetic alteration by meteoric fluids must occur after an initial period of diagenetic alteration by marine fluids, a two-stepped diagenetic history that complicates the interpretation of geochemical data in meteorically altered marine carbonate sediments. Finally, we discuss how paired metal isotopes may serve as a robust indicator of meteoric alteration in ancient shallow-water marine carbonate sediments. [ABSTRACT FROM AUTHOR]

ABSTRACT This study is based on stable isotope analysis of a rich ammonite assemblage from the Sogukcam Formation, which is widely exposed in Yesilbaglar (Olur‐Erzurum, NE Türkiye). The presence of ammonid, planktic, and benthic foraminifers in the marine sediments suggests that they are from the early Cretaceous period. The late Valanginian‐early Aptian‐rich ammonite assemblage includes the following genera and species: Acrioceras sp., Barremites difficilis, Barremites sp., Crioceratites duvalii, Crioceratites sp., Deshayesites aff. dechyi, Deshayesites sp.1, Deshayesites sp.2, Deshayesites sp.3, Deshayesites sp., Dufrenoyia cf. dufrenoyi, Dufrenoyia cf. furcata, Dufrenoyia sp., Hemihoplites sp., Heteroceras sp., Neocomites sp., Phyllopachyceras infundibulum, Protetragonites cf. quadrisulcatus, Protetragonites sp., Ptychoceras sp., Turkmeniceras cf. geokerense, and Turkmeniceras sp. This assemblage suggests that the Sogukcam Formation's deeper facies formed in the late Valanginian to early Aptian period. Fossils and δ18O data show normal paleosalinity levels. During the late Valanginian‐early Aptian period, δ18O values ranged from −3.67‰ to −2.24‰, with paleotemperatures ranging from 21.3°C to 27.9°C. δ13C positive values range from +0.65‰ to +2.86‰. δ13C isotope data show the oxygen minimum zone (OMZ) and changes in sea level and productivity. The presence of planktonic foraminifera and the ammonite assemblage indicates that the formation was deposited in warm subtropical waters ranging from the outer shelf to the open sea. [ABSTRACT FROM AUTHOR]

The assessment of potential radiation hazards in accumulated sediments in aquatic ecosystems is vital for the management and disposal of sediments. Furthermore, preemptive management of radionuclides in terrestrial ecosystems is critical for marine ecosystem conservation. We analyzed the activity concentrations of natural radionuclides (226Ra,232Th, 238U, and 40K) in the surface sediments of major river watersheds in Korea and evaluated the radiation hazards stemming from these activity concentrations. The mean activity concentrations of 226Ra and 238U were lower than the global average, whereas those of 232Th and 40K were higher. The mean values of radium equivalent activity, external hazard index, and internal hazard index calculated from these activity concentrations did not exceed the recommended maximum values. The mean values of absorbed gamma dose rate in air and annual outdoor effective dose rate (AEDRout) were higher than the global average by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) but remarkably lower than the recommended and background values by the International Commission on Radiological Protection (ICRP) and the Korea Institute of Nuclear Safety (KINS). The contribution of 40K and 232Th to the AEDRout mean value was predominant. In conclusion, the surface sediments of major river watersheds in Korea are associated with negligible radiation hazards. These findings provide fundamental data for the management and treatment of sediments in terrestrial and marine ecosystems. [ABSTRACT FROM AUTHOR]

Background: Marine sediments represent one of the planet's largest carbon stores. Bottom trawl fisheries constitute the most widespread physical disturbance to seabed habitats, which exert a large influence over the oceanic carbon dioxide (CO2) sink. Recent research has sparked concern that seabed disturbance from trawling can therefore turn marine sediments into a large source of CO2, but the calculations involved carry a high degree of uncertainty. This is primarily due to a lack of quantitative understanding of how trawling mixes and resuspends sediments, how it alters bioturbation, bioirrigation, and oxygenation rates, and how these processes translate into carbon fluxes into or out of sediments. Methods: The primary question addressed by this review protocol is: how does mobile bottom fishing affect benthic carbon processing and storage? This question will be split into the following secondary questions: what is the effect of mobile bottom fishing on: (i) the amount and type of carbon found in benthic sediments; (ii) the magnitude and direction of benthic-pelagic carbon fluxes; (iii) the biogeochemical, biological, and physical parameters that control the fate of benthic carbon; and (iv) the biogeochemical, biological, and physical parameters that control the fate of resuspended carbon. Literature searches will be conducted in Web of Science, SCOPUS, PROQUEST, and a range of grey and specialist sources. An initial scoping search in Web of Science informed the final search string, which has been formulated according to Population Intervention Comparator Outcome (PICO) principles. Eligible studies must contain data concerning a change in a population of interest caused by mobile bottom fishing. Eligible study designs are Before and After, Control and Impact, and Gradient studies. Studies included at full-text screening will be critically appraised, and study findings will be extracted.Extracted data will be stored in an Excel spreadsheet. Results will be reported in narrative and quantitative syntheses using a variety of visual tools including forest plots. Meta-analysis will be conducted where sufficient data exists. [ABSTRACT FROM AUTHOR]

Background : Nematodes are the most abundant metazoans in marine sediments, many of which are bacterivores; however, how habitat bacteria affect physiological outcomes in marine nematodes remains largely unknown. Results: Here, we used a Litoditis marina inbred line to assess how native bacteria modulate host nematode physiology. We characterized seasonal dynamic bacterial compositions in L. marina habitats and examined the impacts of 448 habitat bacteria isolates on L. marina development, then focused on HQbiome with 73 native bacteria, of which we generated 72 whole genomes sequences. Unexpectedly, we found that the effects of marine native bacteria on the development of L. marina and its terrestrial relative Caenorhabditis elegans were significantly positively correlated. Next, we reconstructed bacterial metabolic networks and identified several bacterial metabolic pathways positively correlated with L. marina development (e.g., ubiquinol and heme b biosynthesis), while pyridoxal 5'-phosphate biosynthesis pathway was negatively associated. Through single metabolite supplementation, we verified CoQ10, heme b, acetyl-CoA, and acetaldehyde promoted L. marina development, while vitamin B6 attenuated growth. Notably, we found that only four development correlated metabolic pathways were shared between L. marina and C. elegans. Furthermore, we identified two bacterial metabolic pathways correlated with L. marina lifespan, while a distinct one in C. elegans. Strikingly, we found that glycerol supplementation significantly extended L. marina but not C. elegans longevity. Moreover, we comparatively demonstrated the distinct gut microbiota characteristics and their effects on L. marina and C. elegans physiology. Conclusions: Given that both bacteria and marine nematodes are dominant taxa in sedimentary ecosystems, the resource presented here will provide novel insights to identify mechanisms underpinning how habitat bacteria affect nematode biology in a more natural context. Our integrative approach will provide a microbe–nematodes framework for microbiome mediated effects on host animal fitness. [ABSTRACT FROM AUTHOR]

The origin of alkali basalts with distinctive time-integrated low U/Pb (low μ , LOMU) from East Asia is controversial due to the complex geochemical and tectonic signatures reported from this region. We report new data on the petrology and geochemistry of the Higashi-Matsuura and Kita-Matsuura alkali basalts from Southwest Japan, which confirm the presence of a LOMU-type mantle component below the Japanese Islands, similar to East Asian intraplate volcanoes. We use whole rock geochemistry and mineral chemistry to determine mantle melting, magma evolution conditions and isotopic evolution of the LOMU mantle source. Petrological studies show that the Higashi-Matsuura alkali basalts (~3 Ma) were derived from a hydrous mantle source with ~880 μg/g H2O, at a pressure of 1.8 to 2.3 GPa at a mantle potential temperature of ~1300°C. Trace element modelling concludes that these basalts may have been generated through the hydrous upwelling and partial melting of the asthenospheric mantle containing ~15% dehydrated eclogitic component. Higashi-Matsuura alkali basalts show 206Pb/204Pb values of 17.72 to 18.04 which are among the lowest values from Southwest Japan. Relatively older (6–8 Ma) alkali basalts from the Kita-Matsuura area showing similar physicochemical characteristics, do not show LOMU-type isotopic trends. Trace element and Pb–Sr–Nd isotopic data indicate that the Higashi-Matsuura mantle component is similar to the extreme LOMU components reported from the Northeast China alkali basalts, as well as the recently discovered Petit Spot volcanoes on the Pacific Plate. We model the origin of the LOMU signature from the lowest reported Pb isotope ratios in East Asia, from intraplate alkali basalts in Northeast China. Our model suggests that at least two separate subduction events of marine sediments, at 1.8 and 2.2 Ga, are required to explain the observed Pb isotopic variation in the East Asian region. Other LOMU type basalts from East Asia, including Southwest Japan and Petit Spot, define a linear trend between the Xiaogulihe basalts and lithospheric mantle xenoliths, with 40% to 60% Pb in Higashi-Matsuura basalts being derived from the lithospheric mantle during upwelling. This suggests that the LOMU array in East Asia may have been formed by mixing between multiple ancient, subducted sediment components accumulated at the mantle transition zone for about 2 billion years, and its recent upwelling due to dehydration of the stagnant Pacific slab and related melting of the metasomatised asthenospheric mantle. [ABSTRACT FROM AUTHOR]

A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland Basin. Based on the study of more than 1 000 rock samples, nine carbonate microfacies and three terrigenous facies were identified. The study reveals that the Maastrichtian succession was deposited in a widespread homoclinal ramp in the High Zagros Basin. Three (Gandom Kar area), two (Ardal area), seven (Gardbishe area), five (Shirmard area), two (Kuh-e-Kamaneh area), three (Kuh-e-Balghar area), and six (Murak area) of depositional sequences (3rd order) were identified. The thickness of the lowstand systems tract (LST) due to activities of local faults and subsidence in the southeast is more than in the central and northwest of the High Zagros Basin during the Early and Early Middle Maastrichtian. During the Middle Maastrichtian, the shallow and deep marine deposits were formed during the transgressive systems tract (TST) and highstand systems tract (HST) in this basin and the rate of subsidence in the center of this basin (Gardbishe area) is higher than in other areas and the platform was drowned in this area. The falling relative sea-level due to activities of local faults led to that marine deposits were absent in all parts of the High Zagros Basin (except the south part) during the Late Maastrichtian. Paleogeographical studies on the Zagros Basin during the Late Campanian–Maastrichtian showed the following results: shallow marine environments were developed in the south-east of this basin, and the turbidite, delta, and fluvial environments in the northwest were developed more than in other areas. [ABSTRACT FROM AUTHOR]

Recent concerns that commercial bottom trawling can contribute to a significant release of sequestered marine carbon have highlighted a need for research in this area. Here, a Before-After Control-Impact (BACI) experimental design was utilized in a previously untrawled area of the eastern Bering Sea. Six pairs of experimental and control corridors were sampled before, after, and 1 year after a trawl disturbance. Each experimental corridor was fished four consecutive times over ∼12 h with a commercial otter trawl. Results were contextualized with minimum detectable effects (MDE), and showed no evidence of a trawl effect on total organic carbon (P  = .999, MDE ± 0.05% TOC), total nitrogen (P  = .999, MDE ± 0.02% TN), δ13C, and δ15N isotope ratios and sediment size classes. Interannual changes observed in δ15N, sand, silt, and clay are attributed to natural variation. The study suggests that the characteristics of the study site, such as storm disturbances, high sand content, and low carbon content, limited the bottom-trawl effect on sediment composition following this initial trawl disturbance. The findings highlight the importance of site-specific studies that account for local conditions to support best management practices for commercial bottom trawling. [ABSTRACT FROM AUTHOR]

The Sr chemostratigraphic characteristics of marine sediments of the Lower Permian in the Omolon massif of Northeast Asia have been obtained for the first time based on a study of well-preserved brachiopod shells. The 87Sr/86Sr ratio in brachiopods from the Lower Permian regional horizons (regional stages) is within the following ranges: 0.70786–0.70794, Orochian; 0.70744–0.70786, Ogonerian; 0.70745–0.70748, Koargychanian; and 0.70742–0.70735, Khalalian. The obtained Sr-isotope data demonstrate good agreement with the standard variation curve of the 87Sr/86Sr ratio in the Permian Ocean. New Sr-isotope data can be used to correlate the units of the Regional Stratigraphic Scale of Northeast Russia directly with the stages of the International Permian Stratigraphic Scale. Based on recent data, the Asselian age of the Orochian regional stage of the lower part of the Permian section in the Omolon massif has been proved, and the regional correlation of the Upper Sakmarian interval established previously from biostratigraphic data has been refined. [ABSTRACT FROM AUTHOR]

A comprehensive study of marine sediments deposited on the southwestern margin of the Primorye region (near the settlement of Khasan) allowed us to consider in detail the paleogeography of the coast in the second half of the Atlantic Period of the Holocene, about 6500–6000 BP/7400–6800 cal BP. Marine environment sedimentation, as a result of the development of postglacial oceanic transgression, began around 6500 BP/7400 cal BP. A shallow marine gulf formed on the coastal accumulation plain, into which flowed the Tumannaya (Tumangan) River, the largest in the Sea of Japan Basin. The estuarine area of the river created an avalanche sedimentation environment in the bay, which developed at an average rate of 16–24 mm/year. The final sedimentation phase, which occurred after 6200 BP/7100 cal BP, did so at a time when the sea transgression slowed and sea level reached its maximum height of +1 m in this coastal area. The distribution of multispecies broadleaved forests predominated by oak and with increased participation of thermophilic hornbeam in the area adjacent to the coast at this time clearly indicates optimal climatic conditions. The end of marine sedimentation occurred around 6000 BP/6800 cal BP. It did not resume for a long time, until the middle of the Sub-Atlantic Period of the Holocene. [ABSTRACT FROM AUTHOR]

Introduction: Natural microbial communities interact to develop mutualistic relationships creating a competitive environment stimulating secondary metabolite production which may be developed as a potential drug against drug-resistant bacteria. The current research delves into the possibility of co-culturing marine actinomycetes to elevate the production of novel bioactive compounds with enhanced antimicrobial activity against Methicillinresistant Staphylococcus aureus (MRSA). Method:. Actinomyocyte was isolated from marine sediments, identified as Streptomyces rubrogresius was cocultured with S. aureus. The bioactive compounds were extracted and evaluated for activity against MRSA variants. The extracts exhibiting significant activity were further characterized using GC-MS. Results: The study demonstrated a significant increase in the production of bioactive compounds in co-culture compared to the monoculture. When tested against MRSA strains, inhibition zones obtained from ethyl acetate extracts of co-culture (40mm) revealed substantial differences when compared with that of monocultures (MIC: 10 μg/ mL). GC-MS analysis identified unique chemical compositions and potential synergistic outcomes in the coculture rather than monoculture. Conclusions: The findings from this study are of paramount importance as they aid in the discovery of novel antibiotics effective against MRSA. [ABSTRACT FROM AUTHOR]

A comprehensive examination of uplifted mid-late Pleistocene marine terraces along the eastern coast of Korea offers valuable insights into the temporal and spatial variability of uplift rates spanning ∼200 ka. Focusing on the Gangneung–Samcheok region of the Korean peninsula's east coast, the study area is delineated into three distinct areas (i.e., Anin, Jeongdongjin–Donghae, and Samcheok) by two NNE-SSW to NE-SE-striking faults. Three flights of marine terraces are developed in each area, with terraces typically observed at elevations of 10 to 20 m and 20 to 35 m across all three areas. Conversely, upper terraces exceeding these elevations are mainly observed at 50 to 60 m or 60 to 80 m, with regional variations noted. Quartz optically stimulated luminescence dating (OSL) was used for dating marine terrace deposits. However, it could not be applied to older deposits beyond the upper limit of quartz OSL. Therefore, IRSL and post IR-IRSL dating using K-rich feldspar, which has a higher upper limit than quartz OSL, were applied in this study. The results indicate that marine terraces at elevations of 10 to 20 m and 20 to 35 m formed during MIS 5a and MIS 5e. Depositional ages of MIS 7 were obtained from terraces ranging from 50 to 60 m or 60 to 80 m, exhibiting elevation differences across regions. Consequently, the estimated temporal variation in uplift rates revealed an average uplift rate of 0.52–0.79 m/ka from MIS 7 to MIS 5e, followed by 0.2–0.3 m/ka after MIS 5e. Spatial variation in uplift rates was observed from MIS 7 to MIS 5e. Specifically, the uplift rate in the Jeongdongjin–Donghae area, located in the middle part of the study area, was 0.79 m/ka (Min. 0.68 m/ka, Max. 0.90 m/ka), whereas the uplift rate in the other study areas was 0.52 m/ka (Min. 0.41 m/ka, Max. 0.62 m/ka). This discrepancy is probably attributed to the influence of the two faults that subdivide the study area. [ABSTRACT FROM AUTHOR]

Before the increase in anthropogenic activities, the global coastal ocean was a net autotrophic system. From human activity and the evolution of the earth, changes have been generated in its continents, oceans, atmosphere and life. Transport of sediments and bioelements to the coastal zone has been drastically altered, and there is debate about whether this zone is autotrophic or heterotrophic. This work carried out an exploratory study of five sandy beaches in the central coastal area of the state of Veracruz, three urban beaches on a gradient of anthropogenic activities in the Metropolitan Zone of Veracruz (ZMV) and two natural, non-urbanized beaches far from the ZMV to determine the concentrations and biochemical characteristics of the heterotrophic bacterial groups found in samples of surface marine sediments during two contrasting seasons in the region: dry season and rainy season. The presence of heterotrophic bacteria reflected the degree of anthropogenic disturbance that each beach presents, with a tendency to concentrate mainly on those close to urban centers. On the other hand, the anthropogenic disturbance gradient did not influence the diversity of biochemical characteristics of heterotrophic bacteria. [ABSTRACT FROM AUTHOR]

The ring penetrometer is a shallow rotational penetrometer that has been developed to characterise the mechanical behaviour of surficial marine sediments. The strain-rate dependency of soils is crucial to the design of a wide range of offshore geotechnical infrastructure founded in the upper layers of the seabed (e.g. pipelines, cables and shallow foundations). This paper explores the potential application of a ring penetrometer test to measure the strain-rate dependency of the interface friction generated in soft soils at low stresses. Large-deformation numerical models of the test are developed using an elastoplastic constitutive model and a viscoplastic variant with strain softening. Using parameters representative of kaolin clay and a calcareous silt from an offshore location, the numerical analyses demonstrate a clear and measurable influence of both the viscous and strain-softening behaviours on the device–soil interface friction. These simulations were used to design suitable experimental protocols for multi-rate ring penetrometer tests, the results of which yielded a strain-rate dependency of 9–16% and 22–26% per log cycle in the kaolin clay and calcareous silt, respectively, which compare favourably with measurements derived from T-bar twitch experiments. Finally, models are presented that can be applied in the interpretation of varying-rate ring penetrometer test data for application in practice. [ABSTRACT FROM AUTHOR]

The global carbon and iron cycles are intimately linked as redox-sensitive iron oxides readily bind organic carbon in a variety of environmental settings, including marine and lacustrine sediments. While these iron-organic carbon complexes sequester vast quantities of organic carbon, the composition of the organic matter within them remains unknown for lacustrine environments. Here we present C K 1s and Fe L 3,2 edge Near Edge X-ray Absorption Fine Structure (NEXAFS) spectra of surface sediments and authigenic iron complexes from adjacent basins of a pristine boreal lake located in Québec, Canada, with contrasting oxygen exposure regimes. We demonstrate differences in organic carbon speciation in sediments from both basins, as well as co-localization of organic carbon and iron on a sub-micron scale in 100 nm thick samples. Differences in redox cycling across these two basins allow for a direct comparison of the effect of oscillating redox conditions on the composition of organic carbon sequestered by iron. Our results suggest that reactive organic molecules, which may be polysaccharides, were found preferentially associated with iron in the perennially oxic sediments compared to more phenol rich organics in the seasonally anoxic sediments, highlighting the importance of iron oxides in the protection and preservation of labile organic compounds. Traces of aliphatic carbon were observed in sediments from the anoxic basin, alongside carboxyl and aromatic functionalities. This carboxyl-rich aliphatic material could possibly interact with the sediment mineral matrix either through a ligand exchange mechanism between the mineral phases and the carboxyl functionalities, or via non-specific hydrophobic interactions involving the aliphatic moieties. Finally, our work also shows that OC:Fe ratios should be used with caution when inferring a binding mechanism between OC and iron oxides. [ABSTRACT FROM AUTHOR]

Titanium (Ti), a typical rock-forming element, is traditionally considered to be lithophile, incompatible, and fluid-immobile, and is recognized as a significant proxy for understanding the oceanic environments, such as the content of terrestrial materials in modern marine sediments. However, recent investigations have revealed the production of various titania minerals through the alteration of volcanic rocks. Considering the occurrence of abundant volcanic rocks (e.g., volcanoclastics, seamounts, and oceanic crusts) in the oceanic environments, the activities of Ti may have been underestimated. Our study provides novel findings on the occurrence and growth mechanism of authigenic titania in the completely altered volcanic glasses collected from Line and Marshall seamounts by using multiple microanalytical methods. Both specimens primarily consist of mixed-layer illite/smectite (I/S), phillipsite, and carbonate-bearing fluorapatite, revealing that the volcanic glasses underwent palagonization processes. Scanning electron micrographs reveal numerous spherical Ti-rich shells with thicknesses of 450–1000 nm, enveloping spherical mixed-layer I/S aggregates with diameters of dozens to hundreds of microns. From the center to the edge of the spherule-shell structures, the concentration of Ti significantly increased. Further analysis using transmission electron microscopy confirms the presence of authigenic Fe-bearing titania particles within these Ti-rich shells. These titania shells likely form as a result of the migration of dissolved Ti(IV) ions and titania nanoparticles, which fill, nucleate, and aggregate at the interfaces of microspherules originally present in the volcanic glasses, ultimately coalescing into micron-sized particles through oriented attachment. Additionally, numerous titania nanoparticles, with aggregate sizes of 4–32 nm, were observed in the pore spaces of the mixed-layer I/S aggregates, likely be those trapped during Ti migration. Brookite is the dominant titania phase in both the titania shells and the smectite pores, with rutile and anatase occasionally present in the titania shells, implying the continuous mineral phase evolution during the growth of titania particles. The occurrence and distribution of titania suggest short-distance migration of Ti during palagonization processes. These findings offer new insight into the brookite formation and the Ti mobilization in basic and oxygen-rich marine environments, which is crucial for understanding the marine geochemical behaviors of Ti. [ABSTRACT FROM AUTHOR]

We report on an articulated fossil boxfish (Tetraodontiformes, Ostraciidae) recently recovered from the Pliocene of the North Island of New Zealand. The specimen was collected from the Tangahoe Formation, a mid-Pliocene (c. 3.0-3.4 Ma) shallow marine deposit, at Waihi Beach, South Taranaki. The fossil boxfish measures 10.7 cm in standard length, with an estimated total length of c. 13–14 cm (the caudal fin is not preserved). The fish is preserved in right lateral view, lying on its side, and has an intact body covering of fused hydroxyapatite plates that rigidly encase the fish, as is characteristic of boxfishes. The plates are hexagonal to subhexagonal in shape and largest close to the dorsal midline. Fossil boxfish have previously been recorded from Northern Hemisphere sites ranging in age from Palaeocene to Quaternary, but not from the Southern Hemisphere. Recent reports note that boxfishes and several other tropical Pacific fish species are now being seen off of northern New Zealand – the Pliocene boxfish from Taranaki, as well as an intriguing addition to New Zealand's paleohistory, may also reflect how the ongoing impact of climate change will return New Zealand to a warmer marine ecosystem – similar to what prevailed during the Pliocene. [ABSTRACT FROM AUTHOR]

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This study comprehensively explores the intricate hydrodynamic and geomorphological processes that affect the Sulina Channel and bar area. It employs advanced hydrodynamic, wave, and sediment transport models to simulate the influence of marine currents, waves, and shipping traffic on sediment transport and deposition patterns, providing valuable insights for maintaining navigable conditions in the Sulina Channel. It is shown that sediment deposition is highly dynamic, particularly in the Sulina bar area, where rapid sediment recolonization occurs within one to two months after dredging. The simulation indicates that vessels with drafts of 11.5 m cause notable erosion. In comparison, drafts of 7 m have a minimal impact on sediment transport, emphasizing the importance of managing vessel drafts to mitigate sediment disturbances. This research highlights and quantifies the siltation phenomenon from the Black Sea to the mouth of the Sulina Channel, effectively addressing the challenges posed by natural and anthropogenic factors to ensure the Channel's sustainability and operational efficiency. [ABSTRACT FROM AUTHOR]

[Objective] Dielectric permittivity and electrical conductivity are key parameters for characterizing the electrical properties of hydrate-bearing sediments and predicting hydrate saturation. Thus, petrophysical models based on the two electrical parameters for interpreting the dielectric and resistivity logging data need to be established. However, because of the peculiarity of marine sediments containing gas hydrates, effective petrophysical models for accurately evaluating hydrate saturation are lacking. Considering the high cost of obtaining real hydrate-bearing sediment samples from field drilling, researchers usually conduct simulation experiments in the laboratory to prepare hydrate-bearing samples and perform electrical tests. Time-domain reflectometry (TDR) has the advantage that both permittivity and conductivity can be derived from TDR responses. However, traditional TDR probes cannot be used in high-conductivity marine sediments because of the high attenuation of electromagnetic signals along the probe rods. Thus, the development of new TDR probes applicable to hydrate-bearing marine sediments with high porewater salinity is of great significance. [Methods] First, a new type of probe, called a segmented coating TDR probe, was designed. Then, a testing platform for hydrate simulation experiments in marine sediments and TDR testing was developed. To derive the permittivity and conductivity from the TDR responses, the TDR probe parameters, such as the real length of rods and geometric factor, were determined based on standard calibration tests. To correct the impacts of the segmented coatings on the derived electrical parameters, two groups of tests were designed and conducted. One group of tests was performed on standard materials with permittivity from 1 to 80, including air, ethanol, ethylene glycol, and deionized water. The other group of tests was performed on sodium chloride aqueous solutions with mass fractions up to 4%. Correction models were established based on the regression between the permittivity and conductivity derived from the TDR responses and reference values. The tetrahydrofuran hydrate simulation experiments in simulated sediments and TDR tests were conducted. The reliability of the testing platform was verified by analyzing the dynamic changes in the apparent permittivity and conductivity in TDR tests during the formation of the hydrates and by discussing the influences of hydrate saturation. Hydrate saturation evaluation models based on the apparent permittivity, conductivity, and their combination were established. [Results] Results showed that 1 the hardware part of the testing platform mainly includes a sample container, TDR testing unit, and temperature measurement unit, whereas the software part includes two sets of software that are matched with the TDR testing unit and temperature measurement unit; 2 the real length of rods and geometric factor of the segmented coating TDR probe are 150.60 mm and 3.36 m-1, respectively; and 3 the root--mean--square errors of hydrate saturation predicted by the permittivity-based, conductivity-based, and joint models are 4.95%, 6.62%, and 4.79%, respectively. [Conclusions] The testing platform developed based on the new TDR probe, i.e., segmented coating TDR probe, can be used to measure the apparent permittivity and conductivity of high-conductivity marine sediments containing hydrates simultaneously. The joint model of hydrate saturation based on the combination of two electrical parameters, i.e., apparent permittivity and conductivity, performs better than the permittivity-based and conductivity-based models. This result can be attributed to the incorporation of dielectric polarization and electrical conduction mechanisms into the joint model. This study provides a platform for the electrical testing of marine sediment samples containing natural gas hydrates and a petrophysical model for the interpretation of electrical logging data from hydrate reservoirs. [ABSTRACT FROM AUTHOR]

Ocean anoxia is considered a key driver of the end‐Permian mass extinction (EPME). However, it is much debated whether there was an ocean reoxygenation phase during, and in the aftermath, of the EPME. Evidence for ocean reoxygenation is often inferred from the absence of framboidal pyrite in some boundary marine sediments (termed the "framboid gap"). To reconstruct ocean redox evolution across the EPME, we investigated the carbon isotopic, sedimentological, and redox records of the Ruichang and Ehtan sections in South China. These documents two negative δ13Ccarb excursions and the development of anoxia associated with deepening leading up to the Permian‐Triassic boundary. Above the level at which most siliceous organisms became extinct, pyrite framboid and iron proxies indicate that water column redox conditions were predominantly oxygenated but sporadically anoxic/ferruginous [non‐sulfidic, free Fe(II) in the water] at Ruichang, while ferruginous conditions were more widely developed at Ehtan. These contrasting redox states are characteristic of a dynamic ocean redox landscape in the extinction interval. The "framboid gap" is seen in strata deposited under both oxic and ferruginous conditions, suggesting that the availability of decomposable organic matter for sulfate reduction additionally controlled framboid genesis. Our data confirm that oxygenated conditions were developed in some deep water basins during the EPME. Plain Language Summary: Ocean oxygen levels across the Permian‐Triassic boundary, which saw Earth's greatest mass extinction (the End Permian Mass Extinction; EPME) have long been debated. Oxygen‐poor (anoxic) conditions are widely implicated in the EPME. A gap in the record of pyrite framboids (small aggregates of pyrite that are commonly found in sedimentary rocks that were deposited in oxygen‐poor marine environments) in some settings during the EPME is generally considered to be a function of reoxygenation at that time. We analyzed iron phase partitioning proxies (which can reveal ocean oxygen levels at the time of deposition) from two chert‐bearing sections in South China. Our iron data indicate that the "framboid gap" is manifest in marine sedimentary archives that were not only well oxygenated at the time of deposition but also anoxic and ferruginous (non‐sulfidic, free Fe(II) in the water). This highlights the ambiguity of the "framboid gap" in implying oxygenated conditions as well as the heterogeneous spatial nature of ocean oxygen states during the EPME. Key Points: Water column reoxygenation during the end‐Permian mass extinction (EPME) is controversialRedox proxies reveal large redox heterogeneity, with deep waters experiencing oxygenated conditions during the extinction intervalBoth ocean reoxygenation and the development of ferruginous conditions contributed to the Lower Triassic pyrite framboid gap [ABSTRACT FROM AUTHOR]

We investigate full vector paleomagnetic changes recorded in high‐resolution sediments of Petermann Fjord, North Greenland, deposited over the last 6 kyr, in the context of the recent rapid changes in the geomagnetic field. A Paleomagnetic Secular Variation (PSV) stack (inclination, declination, and relative paleointensity) was reconstructed using four marine sediment cores with an independent age model constrained by seven radiocarbon ages. Magnetic investigations demonstrate that the paleomagnetic signal is carried by low coercivity ferrimagnetic minerals and is well reproduced in all cores, attesting to the quality and reliability of the paleomagnetic recording of these sediments. This signal is broadly consistent in directional changes with distant records in North America and the northern North Atlantic at centennial and millennial timescales, and has millennial scale intensity variations that are consistent with model predictions. The offset between a magnetization age determined through comparison with a northern North Atlantic PSV reference curve, GREENICE, and the radiocarbon age model indicates either a reasonable lock‐in depth of magnetization (∼11 cm from the coretop) or centennial‐scale reservoir age variation through time in the fjord. Reconstructed virtual geomagnetic pole (VGP) migration for the last 6 kyr shows that the recent migration of the magnetic North Pole is consistent with secular paleomagnetic variations on geologic timescales. Our results suggest that magnetic field intensity variations (temporal and spatial) are linked to magnetic flux lobe dynamics and influence the VGP migration. Plain Language Summary: The magnetic field of the Earth is generated by convection in the outer core of the Earth. Magnetic sediments deposited on the ocean seafloor record the Earth's magnetic field and are important archives of its past fluctuations (intensity and direction). Studying the geomagnetic field is important as it gives us information about processes in the Earth's core and can be used for correlating sediment cores together and for establishing the chronology of sedimentary sequences. In this study, we used sediment cores from Petermann Fjord (Nares Strait, Northern Greenland) to study past geomagnetic variations. Petermann Fjord is an excellent site to conduct such studies because of its close location to the North Magnetic Pole (NMP) and because of the high sediment accumulation rates that enable us to conduct studies with a high temporal resolution. We hypothesize that the NMP migration during the last millennia could have been driven by strong regional intensity features of the geomagnetic field and that the recent rapid migration of the NMP is not unusual because such amplitudes of migration happened in the past, without necessary leading to a reversal of the poles. Key Points: Paleomagnetic secular variations (inclination, declination and relative paleointensity) reconstituted in Petermann Fjord for the last 6 kyrGeomagnetic flux lobes could play a role in the virtual geomagnetic pole migrationThe recent migration of the North Magnetic Pole is consistent with Holocene paleomagnetic secular variations [ABSTRACT FROM AUTHOR]

BACKGROUND: Marine archaea have gained special attention for their unique ability to survive in extreme salt concentrations. Some archaeal isolates have been found to thrive in the presence of radioactive contaminants. In this study, Halococcus sp. ENMS8 has been isolated from marine sediment sample with special emphasis on bioremediation of radionuclide cesium. RESULTS: Halococcus sp. ENMS8 has the ability to remove 76.46% of cesium ions noted at a concentration of 100 mmol L−1 followed by 60.5%, 52.16% and 42.9% of cesium ion adsorption at concentrations of 150, 200 and 250 mmol L−1 Cs+, respectively. The minimal level of 4.43% of cesium adsorption was noted at 500 mmol L−1 concentration in the presence of 106 archaeal cells per milliliter. Similarly, adsorption of cesium (500 mmol L−1) at various concentrations of archaeal extracellular polymeric substances (EPS) has been shown to be 76.4% of Cs+ adsorption at 1 g L−1. The composition of extracted EPS from ENMS8 in the presence of CsCl and control has been estimated. Cesium adsorption was further confirmed with Fourier transform infrared spectroscopy, and scanning electron microscopy was used to obtain high‐resolution images of the surface topology of Halococcus sp. ENMS8 EPS in the presence of cesium. The crystallographic structure and properties of cesium were studied by energy‐dispersive X‐ray spectroscopy. CONCLUSION: The present study concluded that Halococcus sp. ENMS8 can immobilize cesium through EPS in an eco‐friendly approach. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Turbidites, deposited by sub‐aqueous gravity flows, are common in sedimentary archives worldwide and present a unique challenge and opportunity when reconstructing past vegetation through pollen analysis. When sampling pollen from a sediment core for palaeovegetation records, it is common practice to target background sediments (i.e. pelagic sediment) and avoid sampling turbidites, as they are presumed to portray a misleading picture of past vegetation. This assumption stems from our limited understanding of pollen abundance and distribution through turbidites, meaning that palynologists overlook deposits that could potentially be used to reconstruct past vegetation and climate. We present pollen assemblage and sedimentological data from four recent (<150 years) deep marine turbidite deposits from the Hikurangi Subduction Margin, Aotearoa‐New Zealand, with the aim of understanding the abundance and distribution of pollen in fine‐grained turbidites. We find that pollen is diluted in the bases of turbidites, but despite this dilution, the proportions of different pollen taxa remain consistent through each turbidite. These results confirm that pollen can be sampled from turbidites for palaeovegetation reconstructions and that sampling the fine‐grained upper parts of turbidites will provide the best pollen recovery. [ABSTRACT FROM AUTHOR]

Paleoclimate proxy records from regions sensitive to humidity/aridity extremes provide crucial insights into the natural forcing mechanisms underlying long‐term climate variability in broader regions. One such area is Northwest Australia, where the Australian monsoon impacts its northernmost fringes, which are bordered by the Great Sandy Desert inland. Marine sediments from the Australian Northwest Shelf record fluvial run‐off and eolian dust input during the wet and dry seasons, respectively. The location is therefore ideal for investigating long‐term variability in the Australian monsoon and Northwest Australian dust flux over orbital timescales. However, there are few continuous, high‐resolution paleoclimate records from this region spanning the early Pleistocene, when strong ice‐climate feedbacks of the late Pleistocene did not yet dominate global climate. Here, we present geochemical and environmental magnetic proxy records that reveal %CaCO3 and dust‐flux variability between 2.9 and 1.6 million years (Myr) ago from International Ocean Discovery Program Expedition 356 Site U1464 on the Australian Northwest Shelf. We establish a new, orbitally‐tuned chronology for Site U1464, primarily based on ∼400 thousand year (kyr) eccentricity cyclicity in %CaCO3, and observe strong obliquity variability (41 and 54 kyr periodicities) but almost no precession signal in the dust‐flux records. We propose that the 41 kyr cycle in Northwest Australian dust flux could be a linear response to East Asian winter monsoon intensity and/or the summer inter‐tropical insolation gradient (SITIG), whereas the 54 kyr cyclicity might be a non‐linear response to obliquity amplitude modulation via the SITIG effect on the cross‐equatorial atmospheric circulations. Key Points: This study establishes a new orbitally‐constrained chronology for International Ocean Discovery Program Site U1464Australian Northwest shelf sediments preserve ∼400 kyr eccentricity cycles in %CaCO3 and ∼41 kyr obliquity cycles in dust proxy recordsObliquity in Northwest Australian dust flux may be related to the East Asian winter monsoon and summer inter‐tropical insolation gradient [ABSTRACT FROM AUTHOR]

The early Paleogene, including the Paleocene and Eocene, is characterized by Warmhouse and Hothouse climate states with superimposed transient warming events known as hyperthermals. While these paleoenvironmental changes are well‐documented in the Pacific and Atlantic Oceans, records of such changes in the Indian Ocean are limited. Here, we present a new data set of bulk chemical composition and stable isotopic ratios from the late Paleocene to middle Eocene sediments on the Exmouth Plateau in the mid‐latitude eastern Indian Ocean. The bulk δ13C and δ18O suggest a warming period called the Early Eocene Climatic Optimum (EECO) and cooling toward the middle Eocene in a long‐term perspective. In the short‐term, we identified at least six hyperthermals (Paleocene–Eocene Thermal Maximum, H2, I1, J, ETM3, and L) in the studied sections. By applying independent component (IC) analyses (ICA) to the bulk chemical composition data, we identified six ICs corresponding to sediment source materials and post‐depositional processes. The ICA result infers an increase in detrital materials or a decrease in carbonate rain flux, and an increased population of higher‐order consumers in the oceanic ecosystem during both long‐term (EECO) and short‐term (hyperthermal) warmings around the Exmouth Plateau. Furthermore, ICs representing diagenetic processes and post‐depositional remobilization of elements showed excursions across the hyperthermal horizons, indicating that changes in the redox state of pore or bottom water are associated with hyperthermals. This study provides critical insights into the paleoceanography of the Indian Ocean, highlighting the response of marine environments to both long‐term and short‐term climatic events during the early Paleogene. Plain Language Summary: This study examined marine sediments from the mid‐latitude eastern Indian Ocean dating back to the early Paleogene period, approximately 57 to 40 million years ago. During this time, Earth's climate was much warmer than today, with several short‐term warming events known as hyperthermals. By analyzing the stable carbon and oxygen isotope ratios and the bulk chemical composition of these sediments, we identified six distinct hyperthermals, including the Paleocene–Eocene Thermal Maximum, which was the severest global warming event among the early Paleogene hyperthermals. By applying a multivariate statistical method called independent component analysis to the bulk chemical composition data set, we extracted geochemical features of sediments, including the contributions of source materials (detrital materials, biogenic materials), and signatures of post‐depositional chemical processes. The analysis indicated that inputs of detrital materials from continents and populations of higher consumers in the ocean, such as fish, increased during both long‐ and short‐term warmings. Additionally, several elements were remobilized within the sediment because of changes in the redox state of pore or bottom water. This research provides valuable insights into the link between past climate events and changes in ocean and sediment chemistry, helping us understand how warm periods shaped marine ecosystems and oceanic environments. Key Points: Here, we report bulk δ13C, δ18O, and chemical compositions of early Paleogene sediments from Hole 762C in the Indian OceanWe updated age model of Hole 762C by multiple Eocene hyperthermal horizons, indicated by the bulk δ13C recordIndependent component analysis on bulk compositions revealed Paleogene climate upheavals affected depositional environments at the site [ABSTRACT FROM AUTHOR]