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Ice-free areas are habitats for most of Antarctica's terrestrial biodiversity. Although fungal communities are an important element of these habitats, knowledge of their assemblages and ecological functions is still limited. Herein, we investigated the diversity, composition, and ecological functionality of fungal communities inhabiting sediments from ice-free areas across pristine and anthropogenically impacted sites in the Fildes Peninsula on King George Island, Antarctica. Samples were collected from both pristine and disturbed areas. We used the internal transcribed spacer (ITS1) region via Illumina sequencing of 34 sediment samples for fungal identification. The Ascomycota (14.6%) and Chytridiomycota (11.8%) were the most dominant phyla, followed by Basidiomycota (8.1%), Rozellomycota (7.0%), Mucoromycota (4.0%), while 34.9% of the fungal diversity remained unidentified. From a total of 1073 OTUs, 532 OTUs corresponded to 114 fungal taxa at the genus level, and 541 OTUs remained unassigned taxonomically. The highest diversity, with 18 genera, was detected at site A-3. At the genus level, there was no preference for either pristine or disturbed sites. The most widely distributed genera were Betamyces (Chytridiomycota), occurring in 29 of the 34 sites, and Thelebolus (Ascomycota), detected in 8 pristine sites and 7 disturbed sites. The Glomeraceae gen. incertae sedis was more common in disturbed sites. A total of 23 different ecological guilds were recorded, with the most abundant guilds being undefined saprotrophs, plant pathogens, plant saprotrophs, pollen saprotrophs, and endophytes. The fungal communities did not show significant differences between pristine and disturbed sites, suggesting that the anthropogenic impact is either not too intense or prolonged, that the spatial distance between the sampled sites is small, and/or that the environmental factors are similar. Although our study revealed a high fungal diversity with various ecological specializations within these communities, nearly one-third of the diversity could not be assigned to any specific taxonomic category. These findings highlight the need for further taxonomic research on fungal species inhabiting ice-free areas. Without identifying the species present, it is difficult to assess potential biodiversity loss due to environmental changes and/or human activities. [ABSTRACT FROM AUTHOR]

Surface sediment samples were collected from the surrounding waters of the two largest tourist islands in Sanya, China, to compare and evaluate the sources, distribution, and ecological risks of 21 organochlorine pesticides (OCPs). The total concentration of OCPs ranged from 1.35 to 5.0 ng/g. Among the OCPs, ΣDDTs accounted for the largest proportion, followed by ΣHCHs. The concentrations of HCHs and DDTs from the west side of West Island were significantly higher than those from the east side, and fine-grained sediments exhibited a stronger adsorption effect on OCPs. Source analysis indicated that the area experienced new inputs of HCH pollutants, while historical residues of HCHs remained high. Residual OCPs are still widely present in the environment, transported mainly by river runoff, with a smaller portion originating from atmospheric deposition and ship paints. Ecological risk assessment results showed that factors occasionally causing adverse biological effects include Heptachlor epoxide, 4,4'-DDE, ΣDDT, Dieldrin, Endrin, and γ-HCH, while other factors rarely caused negative biological effects. Potential ecological effect evaluations indicated that stations SY03, SY04, SY06, and SY09 were classified as having moderate ecological effect levels, while other stations were classified as having no ecological effects. Strengthened investigation, monitoring, and control of pollutant sources in ecologically impacted areas are necessary. This study fills a data gap for the region and provides an academic foundation for environmental protection and the sustainable development of tourism resources. [ABSTRACT FROM AUTHOR]

The prevalence and fate of microplastics in macrophytes are insufficiently understood, and data on the abundance of microplastic (MP) accumulation in macrophyte ecosystems are urgently needed to fill this knowledge gap. The main objectives of this study were to quantify and characterize the microplastics that accumulate in macrophytes, associated sediments, and water in Negombo Lagoon, Sri Lanka. The investigation was conducted with specialized sampling and extraction techniques. Microplastics were detected by the fluorescence tagging of polymers using Nile red, and polymer identification was conducted by ATR-µFTIR and ATR-FTIR. This study revealed variations in microplastic abundance across different macrophyte species. Gracilaria sp. had a higher abundance of 9 ± 3 items g−1 wet weight, followed by Chaetomorpha sp. at 8 ± 3 items g−1 wet weight and Halodule pinifolia at 6 ± 1 items g−1 wet weight. The root surfaces of these species had slightly similar levels of abundance. Both blue and transparent microplastics were predominant. Fragments (>47%) were found at a higher percentage in macrophyte samples, but high fiber contents (>60%) were found in associated sediment and water samples. Nevertheless, macrophyte samples contained a higher percentage of fragments in the size range of 50–150 μm. This comprehensive study contributes to expanding our awareness regarding the influence of microplastic pollution on macrophyte ecosystems. [ABSTRACT FROM AUTHOR]

This study involved analyzing 76 sediment samples from the Persian Gulf and Oman Sea. The concentration of 18 prevalent PCB congeners was determined. Results indicated that the highest concentration of PCB-52, reaching 636.1 pg/g dw, was found at the T11S3-2 station in the Oman Sea, while PCB-28 had a concentration of 139.0 pg/g dw at the T0S1 station in the Persian Gulf. Furthermore, the average concentration of PCB-28 was 114.5 pg/g dw, in conformity with other regional studies. The average PCB concentration was 12.8 pg/g dw in the Persian Gulf and 35.0 pg/g dw in the Oman Sea. Risk assessment based on ecological risk index (ERI) and sediment quality guidelines (SQGs) indicated that both regions fell within acceptable limits of PCB pollution, except for the T11S3-2 station in the Oman Sea, which was categorized as having a medium risk range due to a concentration of 636.1 pg/g dw. However, the average PCB concentration across all sampled stations consistently stays below the threshold for minimal risk. These values indicate concentrations that are relatively low compared to those found in numerous industrial and urban regions worldwide. [ABSTRACT FROM AUTHOR]

The aim of this study is to verify the possibility of detecting oil in the bottom sediment using a fibre optic system. The presence of oil is assessed on excitation–emission spectra obtained from spectral fluorescence signals of the sediment sample. A factory spectrofluorometer coupled with an experimental fibre optic measurement system was used. During the determination of spectra, the fibre optic system is set at a 45° angle to the sediment surface and placed above its surface. The light exciting the fluorescence and the light emitted by the sediment are transmitted in a combined bundle of fibre optic threads. The analysis of excitation–emission spectra of sediments contaminated with oil shows variability of the shapes of fluorescence spectra depending on the type and degree of oil contamination, which indicates the feasibility of the sensor design for detecting oil in the sediment in situ. [ABSTRACT FROM AUTHOR]

The current findings intended to assess the concentrations of natural radioactivity in water, sediment, and polychaete worms Marphysa madrasi and Namalycastis jaya in 12 distinct places along the southeast coast, of Chennai, Tamil Nadu, India. Mean gross alpha and beta activity in water samples from 12 locations ranged 0.43 ± 0.02 mBq/L and 1.65 ± 0.12 mBq/L, respectively. Similarly, for sediment samples, the average activity concentration for gross alpha and beta were 196.67 ± 0.23 and 1190. ± 0.34 Bq/Kg, respectively. The net radioactivity (gross alpha and gross beta) in Marphysa madrasi ranged 32.97 ± 0.13 & 528.24 ± 0.32 Bq/Kg, respectively and in Namalycastis jaya, the gross alpha activity's average ranged 29.07 ± 0.20 Bq/Kg and a gross beta activity average of 280.36 ± 0.23 Bq/Kg. According to the findings, the highest radiation levels were found in Nemilli (S7) for polychaetes. The least radiation levels in polychaetes were found in Pattinapakkam (S3) and Muttukaadu (S6) for Marphysa madrasi and Neelankarai (S4) for Namalycastis jaya. Conversely, across all 12 selected sites, the gross beta activity of water, sediment, and polychaete worms is greater than the gross alpha activity. [ABSTRACT FROM AUTHOR]

Chironomidae, so‐called non‐biting midges, are considered key bioindicators of aquatic ecosystem variability. Data derived from morphologically identifying their chitinous remains in sediments document chironomid larvae assemblages, which are studied to reconstruct ecosystem changes over time. Recent developments in sedimentary DNA (sedDNA) research have demonstrated that molecular techniques are suitable for determining past and present occurrences of organisms. Nevertheless, sedDNA records documenting alterations in chironomid assemblages remain largely unexplored. To close this gap, we examined the applicability of sedDNA metabarcoding to identify Chironomidae assemblages in lake sediments by sampling and processing three 21–35 cm long sediment cores from Lake Sempach in Switzerland. With a focus on developing analytical approaches, we compared an invertebrate‐universal (FWH) and a newly designed Chironomidae‐specific metabarcoding primer set (CH) to assess their performance in detecting Chironomidae DNA. We isolated and identified chitinous larval remains and compared the morphotype assemblages with the data derived from sedDNA metabarcoding. Results showed a good overall agreement of the morphotype assemblage‐specific clustering among the chitinous remains and the metabarcoding datasets. Both methods indicated higher chironomid assemblage similarity between the two littoral cores in contrast to the deep lake core. Moreover, we observed a pronounced primer bias effect resulting in more Chironomidae detections with the CH primer combination compared to the FWH combination. Overall, we conclude that sedDNA metabarcoding can supplement traditional remain identifications and potentially provide independent reconstructions of past chironomid assemblage changes. Furthermore, it has the potential of more efficient workflows, better sample standardisation and species‐level resolution datasets. [ABSTRACT FROM AUTHOR]

The critical bed-shear stress (cbs) for erosion of mud–sand bed mixtures was studied in laboratory and field conditions with currents, waves, and combined currents and waves. Three types of erosion were distinguished: particle/floc erosion, surface erosion, and mass erosion. Important influencing parameters were found to be sediment composition (percentage clay, silt, and sand), presence of organic and carbonate materials, type of bed (homogeneous, remolded, layered by depositional processes), and the dry bulk density (consolidation stage). The laboratory and field results reveal that the critical bed-shear stress is not much influenced by cohesive effects if the percentage of fines (<63 μm) is smaller than approximately 15%. For pfines>15% up to approximately 50%, the critical bed-shear stress increases for increasing values of pfines but decreases again for pfines>50%. The fine fraction includes the clay fraction (pclay≅0.2 to 0.4 pfines), which contributes primarily to the cohesive effects. In addition, the bulk density depending on the soil composition (clay, silt, sand content, and consolidation stage) has a strong effect on the cbs for surface erosion. Small bed irregularities (local disturbances) also play an important role by creating local accelerations and decelerations with enhanced turbulence and initiating particle movements. A new empirical relation is suggested to predict the critical bed-shear stress for erosion based on the dry bulk density of the sediment samples. This relation is successfully applied in a morphodynamic model of a schematized tidal basin to represent spatial variations in the erodibility of fines between sandy channels and (relatively) muddy shoals. [ABSTRACT FROM AUTHOR]

The characteristics of chemical elements in marine pore-water are significant for investigating and evaluating the marine sediment environment (especially vertical distribution characteristics, etc.). Therefore, sampling high-quality pore-water is necessary for marine scientific research. This paper proposes an in-situ portable pore-water sampler that utilizes the compression spring structure, allowing the potential energy generated by the spring to be converted into kinetic energy for the sampling process. The sampler requires no other power and can be portable for marine pore-water sampling. We first described the sampler's mechanical design, which can obtain one sediment-overlying water and three sediment pore-water samples at different depth profiles. Secondly, to judge the force state of the power spring, we designed laboratory experiments and simulation tests based on COMSOL Multiphysics to analyze the force during the working process of power springs. Finally, we deployed the sampler offshore in Zhoushan Islands for actual sampling, and we tested and compared the in-situ samples with the centrifugal samples to analyze the vertical distribution of chemical elements. The successful sea trials verified the reasonableness of the mechanical design, theoretical calculation and experimental analysis of the sampler. Furthermore, we will continue to optimize the sampler and apply it more widely. [ABSTRACT FROM AUTHOR]

In Guyana, mangroves are vital for coastal protection, mitigating erosion, and supporting local fisheries. However, these ecosystems are threatened by marine pollution, particularly plastic debris. The fragmentation and biodegradation of these plastic items introduce microplastics in marine environments such as mangrove ecosystems. This study investigated the presence and characteristics of microplastics in sediments collected in the landward (the area farthest from the sea), middle (the area between landward and seaward zones), and seaward (the area closest to the seas) zones of three mangrove locations in Guyana. Microscopic examinations were done under a spectroscopic microscope to identify and count the microplastics’ characteristics. All mangrove sediment samples examined were contaminated with microplastics. Two thousand and sixty-five microplastic items/kg of sediment were collected from three mangrove locations. The Kruskal-Wallis test revealed significant differences (p < .05) between the microplastic abundance in the landward, middle, and seaward zones. Fibers, films, and fragments were observed, with fibers being the most common. The observed microplastics were blue, green, red, black, and brown, with blue most common. The identified shapes of plastic items indicated that the microplastics were from secondary sources. Our findings confirm the presence of microplastics in Guyana’s mangroves, and emphasize the urgent need for targeted local policies to manage waste and reduce plastic pollution. [ABSTRACT FROM AUTHOR]

Solid bed extraction technique as an efficient analytical method was exploited for developing a one step process of extraction and separation of organic pollutants; polychlorinated biphenyls and Hexachlorohexane, PCBs and HCH, respectively, from sediment/soil samples. The method was established using partition chromatography through 12% deactivated alumina column serially connected to 2% deactivated silica column. The extraction method was applied for the analysis of mixed standard PCB and HCH in different types of simulated contaminated samples; fortified sea sand and deutated soil samples. This method allows analysis of these contaminants in sediments at trace levels as low as 1.0 μg/g for PCBs and HCHs with a percent recovery range 98–120%. HCH was fully isolated from the PCBs using different eluent. [ABSTRACT FROM AUTHOR]

The main objective of this study was to evaluate the health and ecological risks of natural radionuclides and heavy metals based on 23 sediment and water samples collected from some sediment at the Red Sea Coast in Egypt. The studied area is characterised old harbour used for shipping and processing phosphate ore. The results revealed that Cd and Zn contents in some water and sediment samples exceeded the standard limit, their concentrations reached (0.027–0.09) mg/L in water and (4.5–236) mg/Kg in sediment samples respectively. While the other analysed trace elements Fe, Mn, Ni, pb and Cu remain below permissible limits. The estimated contamination degree varied from low to considerable while the ecologic risk indices revealed that sediment ranged 10.8 to 466.6 as from low to moderately contaminate with trace elements. The average activity concentrations of 238U, 232Th, and 40K were 3.4, 0.83 and 5.5 Bq/L in water and 63.5, 16.5 and 556 Bq/Kg in sediment samples which were below the recommended limits except for the activity concentrations of 238U and 40K in some water and sediment samples above the permissible limits. The total annual effective dose rates from the exposure pathway were 0.09 to 0.26 mSv y−1. The estimated excess lifetime cancer risk values for workers were slightly higher than that of the sediment world average. [ABSTRACT FROM AUTHOR]

In this study, quantitative and qualitative chromatographic analysis for the content measurements of sediments collected from the Gulf of Aqaba/Jordan-Red Sea and Tripoli Port/Lebanon-Mediterranean Sea, were carried out. Sediment hydrocarbon contents were examined by GC-FID. The outcomes showed that 16 hydrocarbons were quantified and identified. Dotriacontane, tritriacontane, hentriacontane, octacosane, heptacosane, pentatriacontane, docosane, tetracosane, and hexatriacontane displayed the major contents at the Gulf of Aqaba. Regarding Tripoli Port sediments; nonacosane, pentatriacontane, pentacosane, dotriacontane, heptacosane, docosane and tetratriacontane were detected. GC-FID data were exposed to PCA and HCA to reveal: the variations of sediment chemical profiles as a result of geographical areas, to show the hydrocarbons that were responsible for clustering, and finally, to facilitate the future profile prediction and areas clustering of unknown sediments based on their chemical profile. By HCA and PCA, the six sediment-origin samples of Aqaba were classified into three clusters; Industrial area alone due to the distinct content of dotriacontane, tritriacontane, hentriacontane and octacosane, Central Power Station, Tala Bay and Hotel Areas in one cluster which was related to the close content of heptacosane and finally the National Tourist Camp and Marine Science in one cluster since they have pentatriacontane with close levels. Regarding Tripoli Port sediment samples, the two clusters revealed that the Current Waste Dump along with the Wastewater Treatment Plant were grouped together, where the Fishing Port, Tripoli Harbour and the Closed Waste Dump areas were clustered in one group. Nonacosane and pentatriacontane were dominant to separate the Tripoli Harbour, Fishing Port area and the Closed Waste Dump, where pentacosane, dotriacontane, heptacosane, docosane and tetratriacontane were responsible to isolate the Wastewater Treatment Plant and the Current Waste Dump together. Classification of sediments based on GC-FID profile will accelerate the future profile prediction and origin-clustering of unknown sediment based on their profile. [ABSTRACT FROM AUTHOR]

ABSTRACT 1. The trophic state of water significantly affects the structure of bacterial communities in sediments. The direct and indirect impacts of trophic state, along with trophic‐induced changes in the properties of organic matter, on the composition and distribution of bacteria in sediments, remain largely unknown.2. We collected surface sediments from 21 sites across five areas of Lake Taihu, the third largest freshwater lake in China. These sites represented a range of trophic states from mesotrophic to moderately eutrophic. We investigated how trophic state influences bacterial composition and distribution in the surface sediments of Lake Taihu.3. Proteobacteria, Firmicutes and Bacteroidetes were the most abundant phyla identified in the DNA sequences of surface sediments from the sampling sites in Lake Taihu, regardless of the water trophic state. The relative abundance of Proteobacteria and Firmicutes in the surface sediments increased with trophic level index (TLI) of the water column. In contrast, the relative abundance of Bacteroidetes, Acidobacteria and Fibrinobacteria decreased with increasing TLI. The α‐biodiversity of the sediment bacterial community in Lake Taihu did not vary significantly among different water trophic states. However, surface sediments from sites with varied trophic states exhibited different groups of bacteria that were either specifically present or in higher relative abundance.4. Several factors influenced the sediment bacterial communities in Lake Taihu, including sediment total nitrogen, sediment total phosphorus, sediment organic carbon, δ13C and trophic state. However, the primary influencing factors varied between sites and trophic states. For mesotrophic states, sediment organic carbon was the most important factor, while for moderately eutrophic states, trophic state was the most significant factor.5. Our findings provide evidence for both the direct and indirect influences of water trophic state on the composition and distribution of bacteria in sediments. [ABSTRACT FROM AUTHOR]

Analytical methods for the determination of microplastics in sediments typically involve matrix drying, sieving, grinding, and flotation as part of the sample treatment. However, the real need for these steps and analytical validation studies are scarce. This work proposes a method that avoids the drying, sieving, and flotation procedures by using a direct acid attack of HNO₃/HCl (3:1) on wet sediment samples, assisted by microwave digestion. For detection, induced fluorescence using a UV camera, with Nile Red (NR) as the fluorophore and a cell phone camera for image capture were used. The results showed that when the digestion temperature was raised to 120°C, PET recovery decreased due to plastic particle fusion. However, at 60°C, microwave digestion resulted in a 97% recovery of PET particles, eliminating chitin interference and canceling cellulose fluorescence without the need for flotation. This method proved effective for monitoring plastic microparticles in sediments from the Loa River, Chile, revealing that the river is predominantly contaminated with PET microparticles, particularly upstream in the Taira area. [ABSTRACT FROM AUTHOR]

Recent silicoflagellate distributions have been examined in 195 surface sediment samples from the North Pacific to establish the silicoflagellate assemblage dataset from surface sediments across the North Pacific for paleo sea surface temperature (SST) reconstruction. The relative abundance data of all seven silicoflagellate taxa identified in this study were used for the modern analog method to reconstruct past SST. The SST reconstruction based on the silicoflagellate modern analog technique was applied to the two sediment cores from the Japan Sea. With the development of ice sheets, the Japan Sea experienced a low salinity isolation event during the Last Glacial Maximum (LGM: 19 ka–26.5 ka), which hampers the SST reconstruction employing geochemical proxies such as alkenone and Mg/Ca thermometry. The reconstructed glacial SST between 25 and 15 ka was ~ 5 °C in the northern and southern Japan Sea, indicating significant southward migration of the glacial subpolar front. The timings of the deglacial SST rises were ~ 14 ka at the south core site and ~ 10 ka at the north core site, indicating a latitudinal lag. This lag likely reflects a gradual increase in the fluxes of the Tsushima Warm Current from the East China Sea through the Tsushima Strait. Compilation of the silicoflagellate assemblages in the North Pacific surface sediments used for the modern analog technique to reconstruct past sea surface temperature (SST), revealing the Japan Sea SST during the last glacial maximum ~20 ka ago. [ABSTRACT FROM AUTHOR]

Introduction: The quantitative distribution of grain size of sediments could imply the hydrodynamic conditions as well as terrestrial material composition; and thus, it is indicative of sea-level fluctuations, regional sources and climate changes. The environmentally sensitive components extracted from grain size data serve as excellent indicators of the sedimentary environment and monsoon intensity. Material and methods: The drilling data from the shelf margin of the northwestern Qiongdongnan Basin provide an excellent opportunity for studying hydrodynamics and climate change in the Quaternary South China Sea (SCS). The 49 obtained samples of Quaternary sediments are primarily composed of clay and silt, with a low sand content. The environmentally sensitive components are extracted from the sediment samples, based on multiple attempts including grain size-standard deviation, the end-member modelling analysis and the principal component factor analysis methods. Results: The increased grain size as supplemented by ratios of rolling movement on the sediment probability accumulation curves indicate enhanced hydrodynamic conditions in the Quaternary northwestern SCS. The alternative indicators of the Quaternary East Asian monsoon are obtained after a comprehensive comparative analysis. The changes in the content of the grain size components of 5.21-6.72 μm and 27.4-35.3 μm are used as the proxy indicators for the Quaternary East Asian summer and winter monsoon of the NW-SCS, respectively. It is likely indicated that the East Asian winter monsoon remarkably strengthened since 1.3 Ma but reached its maximum intensity around 0.8 Ma. During this period, the magnitude of both climatic temperature and sea-level fluctuations are significant, thus, the coarse-grained component increased at falling or low sea-level stages. Discussion: The grain size characteristics of the Quaternary shelf margin sediments are indicative of hydrodynamic conditions, source-sink systems and environmental monsoon climate changes in the northwestern SCS. [ABSTRACT FROM AUTHOR]

The seabed surface is an important boundary for ocean exploration and foundation for ocean engineering construction. Accurate acquisition of seabed sediment mechanical properties and environmental parameters is critical to the development of marine resources and marine engineering. In this study, by designing the Seabed Cone Penetration Test (CPT) and Sampling System, multiparameter in situ testing and low-disturbance sampling of 3,000-m deep-sea seabed sediments are performed. Accounting for the stable penetration speed of the probe rod is the basis for ensuring the accuracy of the static penetration test results. The system adopts electrohydraulic proportional position control and a fuzzy proportional integral derivative (PID) controller to precisely control the position of the piston of the hydraulic circuit, which can improve the accuracy of the cone test data and reduce the interference of the sampling tube with the original sediment during the sampling process. Moreover, electrohydraulic co-simulation of the hydraulic control system was conducted with the AMESim and Simulink software, and the position control and speed control effects of the system were verified. The entire system was tested on site in the Shenhu Sea area of the South China Sea. This test successfully obtained nine in situ parameters, including physical and chemical parameters, for sediments within a depth range of 2.66 m on the seabed surface at a depth of 1,820 m. This system accurately and efficiently reflects the property characteristics of seafloor sediments in an in situ environment and can be widely used in marine engineering geological investigations. [ABSTRACT FROM AUTHOR]

Diatoms have been extensively used as paleolimnological indicators because they acutely respond to changes in their environment. Diatom assemblages recovered from sediment cores are a mixture of benthic and planktic assemblages that may have been transported away from their source environment or deposited near their habitat. Thus, there is an inherent variability in the diatom deposition across the sediments of a lake. With the aim of characterizing this variability and identifying how it may affect palaeoecological reconstructions, we identified diatom communities and assemblages from a series of sediment cores, surface sediment samples, and samples from different lake microenvironments (submerged macrophytes, sediments, marsh, meadow and attached algae). Comparing the sediment cores, we found differences in the timing of diatom assemblage shifts, which we attribute to differences in the diatom distribution in the sediments. Additionally, we identified gradients of diatom deposition where benthic and tychoplanktic diatoms dominate assemblages near shorelines and planktic assemblages dominate toward the lake center. We attribute benthic and tychoplanktic distribution to distance to the source and recognize that diatoms associated with modern microenvironments are underrepresented in the sediments because of their attachment to a substrate. [ABSTRACT FROM AUTHOR]

The present study deals with investigating the spatial variation of suspended sediment properties in the Sutlej river basin (SRB). Twenty sampling locations were selected in the Sutlej river and its tributaries, and sediment sampling was carried out during monsoon season. The suspended sediment properties, namely suspended sediment concentration (SSC), particle size distribution (PSD), shape, and mineralogy, were measured through dynamic imaging, laser diffraction, and x-ray diffraction techniques. It was found that there is a wide variation of SSC, whereas there is an insignificant variation of PSD, shape, and mineralogy in the SRB. The highest SSC (2841 mg/l) was observed in the Kiran tributary, whereas the lowest (131 mg/l) was in the Titang tributary. The highest SSC (1749 mg/l) in the Sutlej main stem was observed at Khab, the topmost sampling location. The mean particle size varies from 6.00 to 25.36 µm (5.53–7.53 Φ). Shape analysis showed high degree of sphericity varying from 0.81 to 0.88 and slight elongation varying from 0.70 to 0.8. Mineralogical analysis depicts the dominance of quartz (66.73–82.25%) in the SRB. International Electrotechnical Commission IEC 62364 (IEC 62364 (2019) Hydraulic machines—Guidelines for dealing with hydro-abrasive erosion in Kaplan, Francis, and Pelton turbines, 2nd edn. Geneva, Switzerland) based average shape and hardness factors for SRB were estimated as 1.36 and 0.85, respectively. The maximum particle load for SRB was estimated as 0.014 kg/m3. [ABSTRACT FROM AUTHOR]

The Saihanba Mechanical Forest is an artificial national forest park with a forest-steppe landscape. The flora and fauna have been extensively studied, but a comprehensive understanding of the bacterial community composition and structure of the natural rainwater lakes present in the area has rarely been reported. In this study, the structure and functional characteristics of bacterial communities in lake sediments and water samples in the Saihanba artificial forest were investigated using 16s rRNA high-throughput sequencing. Microbial diversity analyses revealed that Proteobacteria, Acidobacteria, Bacteroidota and Verrucomicrobiota microbiota dominated. The abundance of Proteobacteria and Actinobacteriota was significantly higher (p <.05) in water samples compared to sediment samples. PICRUSt2 functional analysis predicted genes associated with the degradation of xenobiotics and the execution of essential metabolic processes. Here, we report differences in the composition of native bacterial communities in sediments and water under the Saihanba artificial forest and make functional gene predictions. This study provides a reference for further exploring the structure and functional characteristics of microbial communities in water samples and sediment environments of lakes under planted forests. [ABSTRACT FROM AUTHOR]

This study aimed to examine the bacterial communities present in the macrophyte- (MDZs) and algae-dominated zones (ADZs) of the Chengdong Lake, by utilizing high-throughput sequencing techniques. The physicochemical characterization showed that there were obvious differences in the trophic statuses of the two lake regions, which were mainly due to the differences in pollutant concentration and hydrophyte coverage. The results obtained through the analysis of Shannon indices indicated that the biodiversity of water samples in the ADZs was greater compared to the MDZs. However, no statistically significant difference was observed in sediment samples across different regions of the lake. Our findings indicate that Cyanobacteria phylum abundance was highest in the ADZs, while the MDZs had Proteobacteria as the most abundant phylum, comprising over 30% of the bacterial community. The db-RDA analysis revealed that total nitrogen (TN) and total phosphorus (TP) in the water, as well as organic matter (OM) in the sediment, were the primary environmental factors influencing the variation in bacterial communities. This study contributes fundamental data towards comprehending the diversity variation of bacterial communities across different habitats within Chengdong Lake. [ABSTRACT FROM AUTHOR]

Microplastic pollution is a growing concern worldwide, with rivers and their tributaries playing a pivotal role in transporting and distributing these particles throughout ecosystems. This study provides a comprehensive analysis of microplastic pollution in Fishkill Creek, a tributary of the Hudson River, for two seasons (fall and spring) with the valuable assistance of K-12 students in sample collection from three distinct sites, Sarah Taylor Park, Doug Phillips Park, and Hopewell Recreation Beach in Fishkill, NY. The investigation encompassed the collection and analysis of water, bed load, and suspended sediment load samples to determine the abundance and distribution of microplastics in a creek system as well as to determine the relationship between microplastic concentration and the creek flow rate. The average microplastic concentration was found to be 6.86 ± 1.97 items/L, 238.40 ± 32.46 items/kg, and 3.89 ± 1.15 items/L for water, bed load, and suspended sediment load, respectively. From the relationship between microplastic concentration and the historic flow rate of Fishkill Creek, it was found that a higher flow rate significantly dilutes the microplastic concentration in the measured compartments in the creek system. Physical and chemical properties of the microplastic samples were characterized, including size, shape, color, and polymer type. Microplastics displayed diverse physical attributes, with irregular shapes and varying polymer types, suggesting multiple sources and degradation processes. These findings underscore the pressing need for mitigation strategies to address microplastic pollution in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) are well-proven ecologically engineered systems that remove nutrients, pathogens, and other contaminants from wastewater. The inherent role of CWs as wastewater polishing systems makes them hotspots for microplastic accumulation. To investigate the transport and characteristics of microplastic pollution in full-scale surface flow municipal CWs, environmental microplastic samples were collected from the Se7en/Seven Wetlands in Lakeland (Florida), one of the largest wastewater CWs in the United States (650 hectares). Both water and sediment samples were collected at eight control stations in each of the seven wetland cells and at six locations in the influent distribution channel to investigate the linkage between water and sediments in microplastic fate and transport. This study found that the Se7en Wetlands has a near complete retention of microplastics greater than 300 μm. Concentrations at each sampling site in the CW ranged from 0 to 17 particles/m3 in water and 0–1217 particles/kg dry weight in sediment. The highest concentrations of particles were found in sediment samples, especially those found in locations of reduced flow, signaling settling occurring as water velocities decrease. Microplastics were also analyzed for size, shape indicators, and polymer type to inform how their properties change as they travel through the system. Particles were extracted visually and analyzed using ImageJ and Raman spectroscopy. Polyethylene and polypropylene were the most abundant polymer types with the highest proportion of particles being fragments between 1 and 5 mm in size. Shape indicators (particle area, circularity, and solidity) in water decreased through the treatment stream, whereas sediment samples saw no clear trend. Overall, this study finds that large CWs retain a vast amount of microplastics. It sheds light on how the dynamics of natural processes affect the fate and transport of microplastics as well as the importance of evaluating multimedia concentrations in CWs. [ABSTRACT FROM AUTHOR]

Background and aims: Studying plant dynamics through past pollen records may contribute to a better understanding of long-term changes in plant communities. Thus, this study aims to establish whether surface pollen composition and richness of the Argentinean Coastal Dune System reflect landscape heterogeneity in coastal dune environments. M&M: Twenty-four sediment surface samples were collected in small lagoons. Landscape-scale heterogeneity up to 2000 m was mapped and classified in landscape units. Multivariate analyses were used to classify pollen samples and compare them to landscape unit coverage (%). Also, we evaluate plant species and pollen richness relationship by linear regression models. Results: The relationship between plant and pollen richness is influenced by taxonomic smoothing, pollen production and taphonomic constraints (dispersal and preservation). The pollen assemblages and pollen richness from surface sediments of small lagoons and interdune slacks reflect plant richness and vegetation heterogeneity at the landscape scale (ca. 1000-2000 m). The main contributors to pollen richness are anemophilous pollen types, although some entomophilous pollen types are useful to infer some local heterogeneity. Conclusions: We report the first quantitative analysis on pollen-vegetation relationship of coastal ecosystems showing that pollen records reflect landscape vegetation attributes, encouraging the study of past plant diversity and landscape variability based on pollen records. [ABSTRACT FROM AUTHOR]

Natural radioactivity was assessed in sediment samples collected along southern coastline of Tamil Nadu. Average activity concentrations of 238U, 232Th, and 40K were determined (29 ± 3, 218 ± 6, and 80 ± 5 Bq kg–1, respectively). Calculated parameters included radium equivalent activity (347 ± 12 Bq kg–1), absorbed dose rate (273 ± 10 nGy h–1), annual effective dose rate (0.33 ± 0.01 mSv y–1), external hazard index (0.94 ± 0.03), annual gonadal dose equivalent (1026 ± 35 mSv y–1), and excess lifetime cancer risk (1.17 ± 0.03). Multivariate statistical analyses were employed to examine correlations among the radioactive variables. The presence of heavy minerals in the samples was confirmed using X-ray diffraction. [ABSTRACT FROM AUTHOR]

The standard calibrator–instrumental neutron activation analysis method was used to characterize the mass fractions of Co, Cr, and Zn in a lake sediment certified reference material (CRM) developed by the Korea Research Institute of Standards and Science. The method was validated for each element and sediment matrix, and the CRM analysis was repeated to ensure reproducibility and address potential matrix interferences. To verify measurement reliability, quality control samples were also assessed. For lake sediment samples with a small Zn peak and dominant adjacent peaks of Eu and Sc, sequential measurements were performed to obtain accurate Zn concentrations. The optimal measurement timing was when the Sc peak sufficiently decayed and the intensity of the Zn peak remained larger than that of Eu. Moreover, an appropriate fitting program capable of deconvoluting complex peak regions is necessary. [ABSTRACT FROM AUTHOR]

To assess the sources, levels, spatial distributions and exposure to human health, the concentration of heavy metals Pb, Cu, Mn, Zn, and Fe in the sand/sediment of the Parki Beach area of Anowara, Chattogram, Bangladesh are determined using Atomic Absorption Spectroscopy (AAS) for the first time. A total of 40 surface and subsurface sand and sediment samples were collected from 20 different sampling points along the 15 km long Parki Beach area, Bangladesh. Average concentrations of Pb, Cu, Mn, Zn and Fe in surface samples are 14.60, 10.10, 283, 407 and 25,256 mg/kg respectively and 9.95, 4.20, 193, 156.6 and 24,404 mg/kg for sub-surface samples, respectively, which shows that the values are higher in surface samples than those in sub-surface samples. According to the Consensus-Based Sediment Quality Guidelines (CBSQG), the northern part of the beach becomes moderately polluted by Mn and Fe, and a smaller area of the southern part is highly polluted by Zn. The average Contamination Factor (CF) of Zn was greater than 1(CF > 1), while the CF of other metals was less than 1(CF < 1). CF of Zn in some sampling points was exceptionally high. Geo-accumulation Index (Igeo) also shows that Zn slightly pollutes some sampling points. The enrichment Factor (EF) of Fe and Mn in samples in the northern part of the study area is quite high and the study reveals that high values of Fe and Mn are mainly derived from geogenic sources. Ecological risk factor (Er) indicates low ecological risk for all sampling points. The Pollution Load Index (PLI) was measured at all sampling stations, and the results showed that the overall level of heavy metal pollution is low. The health quotient (HQ), health index (HI), total health index (THI) and incremental life time cancer risk (ILCR values suggest that adults are safe from any health risk while children may experience non carcinogenic health risk due to the combined effect of the metals. Reduction of heavy metal in the beach is possible with the adaptation of multiple strategies. This data can be used by policymakers to develop strategies to reduce the potential impacts of soil contamination on the environment and public health. [ABSTRACT FROM AUTHOR]

The present study was aimed at investigating the source, quality, and quantity of organic matter and labile fraction of biochemical constituents in the surficial sediments of Arabian Sea Shoreline at Kollam, India, which gives an input into the processes associated with the subsurface geochemistry pattern. About 15 surface sediment samples were collected from the five beaches for this study during January 2021. The samples were analyzed for CHN, total organic carbon (TOC), and labile fraction such as carbohydrates (CHO), proteins (PRO), and lipids (LIP). The TOC/TN ratio revealed that the source organic matter (OM) in the samples was primarily of marine origin and autochthonous, except TM3 at Thirumullavaram. Thirumullavaram is a sheltered beach, and it has low hydrodynamic process. The high organic matter content in TM3 (13.9) may be the originated from the terrestrial input. The hierarchical cluster analysis revealed that TM3 indicate that unique character to other stations. Principal component analysis revealed that three components accounted for 78% of the total variance. PC1 variance was associated with carbon-based organic compounds. PC2 was predominantly influenced by CHO and LOM, suggesting that PC2 may encompass variability associated with these nutritional profiles. PC3 was influenced by LIP and LIP/CHO, showing it may be a lipid-related component. The PRO to CHO ratio is < 1, exhibiting old aged organic matter deposited in sediments and the meso-oligotrophic status. The LIP to CHO ratio, recorded as < 1, exhibits the poor quality of energetic (food) OM in sediments. The sediment samples exhibit the following trend CHO > PRO > LIP. [ABSTRACT FROM AUTHOR]

The Danjiangkou Reservoir is the largest artificial freshwater lake in Asia. This study investigated the spatiotemporal distribution of pesticides and polycyclic aromatic hydrocarbons (PAHs) in the Danjiangkou Reservoir to assess the ecological and human health risks associated with these pollutants. Twenty-three sampling sites in the Danjiangkou Reservoir each collected 23 surface water samples and 23 sediment samples. These samples were analyzed using gas chromatography–mass spectrometry (GC–MS), combined with risk quotient methods and health risk assessment models. The results indicated that the total concentration of PAHs (ΣPAHs) in the surface water ranged from 64.64 to 868.23 ng/L (average 217.97 ± 184.97 ng/L), and they primarily consisted of low molecular weight PAHs, with the compounds with the highest concentrations being naphthalene (10.43–116.97 ng/L), fluorene (22.74–87.61 ng/L), and phenanthrene (26.54–162.86 ng/L). The total concentration of pesticides in the surface water varied between 2.62 and 72.89 ng/L (average 22.99 ± 18.27 ng/L). In the sediment samples, the ΣPAH concentration ranged from 0.01 to 2.93 ng/g (average 0.69 ± 0.94 ng/g), and these predominantly consisted of high molecular weight PAHs, while pesticide concentrations ranged from non-detectable (nd) to 28.46 ng/g (average 7.99 ± 8.53 ng/g), with higher concentrations of malathion (0.62–9.16 ng/g) and chlorpyrifos (10.01–21.38 ng/g). Through risk assessment, it was found that although the risks posed by PAHs and pesticides to human health are very low, the ecological risk assessment indicated that certain PAHs (such as phenanthrene) and organophosphate pesticides (such as malathion and chlorpyrifos) may pose potential threats to aquatic organisms. [ABSTRACT FROM AUTHOR]

Gorgan Bay is located along the southeast Caspian Sea and surrounded with significant agricultural and urban areas. Plastic pollution is a significant issue that affects aquatic ecosystems globally. The accumulation and degradation of plastics into microplastics in aquatic ecosystems highlight the importance of studying them to assess pollution risks. So, an investigation was conducted for the assessment of MicroPlastics pollution (MPs) in water and sediment of this ecosystem. The study involved collecting water and sediment samples from 40 stations within the Bay. Microplastics (MPs) extracted from these samples were identified using microscopic detection methods, specifically visual observation under polarized light to SEM–EDX, and µ-Raman. A total of 16,360 MP particles per kilogram of sediment, and 211 particles per liter of water were detected. The research demonstrated that the river inlets situated within agriculturally intensive regions of the watershed exhibited the highest levels of microplastics (MPs) in both water and sediment samples. Fiber MPs were the most frequent (> 50%) shape in sediment and water. The size of mostly MPs (> 90%) was smaller than 1,000 µm. The dominant polymer within MPs in Gorgan Bay sediment identified as polypropylene (PP), polyethylene (PE), and polystyrene (PS), while polypropylene (PP) and polyethylene (PE) were the frequent polymer in water, respectively. The most amount of MPs was found in the areas close to the rivers and agricultural fields (including stations S4, S12, S13, S14, S22). [ABSTRACT FROM AUTHOR]

Mangrove ecosystems, critical intertidal zones at the land–ocean interface, are increasingly recognized for their role in microplastic (MP) pollution dynamics. Despite extensive research on the interaction of MPs with various chemical contaminants, the specific contamination levels of polychlorinated biphenyls (PCBs) associated with MPs in mangroves remain poorly understood. In this study, we quantified the concentrations of PCBs on MPs extracted from representative mangrove sediment samples across China, revealing values ranging from 9.80 to 13.91 ng/g. In contrast, PCB concentrations in sediment samples were found to vary between 25.67 and 69.85 ng/g. Our findings indicate a consistent level of PCB contamination on MPs across different sites, although these levels were marginally elevated compared to those in the surrounding sediments. Notably, Penta-PCBs were detected with the highest frequency across all samples analyzed. This study provides crucial insights into the occurrence and distribution of PCBs on MPs within the mangrove ecosystem, highlighting their significance in environmental contamination assessments. [ABSTRACT FROM AUTHOR]

Purpose: The aims of this research were to assess the sources of variability of particulate FRNs (7Be, 210Pbex and 137Cs) in river channels, the influence of sediment properties such as particle size distribution (PSD) and organic matter (OM) on FRN distributions, and to discuss the implications for sediment tracing in rivers. Methods: Suspended and channel bed sediment samples were collected in the River Avon (Devon, UK) during five strategic surveys involving a wide variation of river flows, including flood conditions. Particulate matter was analysed for 7Be, 210Pbex and 137Cs by gamma spectrometry, PSD by laser diffraction, and organic constituents, total organic carbon (TOC) and total nitrogen (TN) by elemental analysis. Results: FRNs activity concentrations vary significantly both spatially, characterised by changes in activity concentrations within and between locations, and temporally, with changes during the storm hydrograph and between seasons. Variability was attributed to changes in sediment sources and, on some occasions, to significant correlation of activity concentrations with sediment properties. The results also highlighted the influence of changes in channel characteristics and the magnitude and frequency of floods on FRN distributions. Conclusion: In the context of sediment tracing, attention should be given to seasonal changes in riverine conditions that have the potential to affect 7Be and 137Cs conservativeness. Application of FRNs in sediment fingerprinting studies should be accompanied by appropriate temporal characterisation of potential sediment sources. Finally, potential contribution of 7Be-depleted sediment from channel resuspension to the suspended load should also be considered. [ABSTRACT FROM AUTHOR]

The study aims to assess the marine environmental hazards resulting from some industrial activities areas being found at the Suez Bay. The survey was done to select five industrial locations along the studied areas where different water and sediment samples were collected during September 2020. The study methods showed that different concentrations were measured in the collected water and sediment samples, such as; Al, Fe, Mn, Hg, Cd, Cr, Co, Mo, V, Pb, Ni, Cu, Zn, where the digested samples were measured by using Inductively Coupled Argon Plasma spectroscopy (ICAP 6500 Duo), while the natural radioactivity concentrations of the selected radio-nuclides such as 238U, 226Ra, 232Th, 40K, were measured in both water and sediments samples by using Hyper germanium detector, as the radiological risk assessment of different samples was detected by using ERICA modeling software. The study results showed that the concentrations of the measured trace elements in the selected five industrial sites were slightly higher than the standard limits, while the measured radioactivity concentrations of the selected radio-nuclides in both water and sediment samples were below the standard limits. The results showed that the calculated distribution coefficient of the selected trace elements was (Kd Metal Pollution Index < 3), which indicated that the measured trace elements were more dissolved in the aqueous than the sediment medium. The study used the mean probable effect Level (m-PEL-Q) for estimating the metal concentration hazards in the sediment samples at the selected sites, where these values were ranged from 0.04 to 0.1, indicating that the combined concentration effects for these metals were caused 9% toxic probability. The study showed that both the calculated quotient risk (QR) and dose rate values of the marine organisms which were being calculated by the ERICA model were below the recommended limits. [ABSTRACT FROM AUTHOR]

Surface water is the main source of drinking water in Ifite Ogwari, Anambra State, South-East Nigeria. In aquatic environments, sediment functions as both a source and a sink of polycyclic aromatic hydrocarbons (PAHs). To determine the level of pollution, health concerns to people and the environment, and potential sources of PAHs in the surface water sediments in Ifite Ogwari, sediment samples were collected from 9 surface water sources used for drinking by Ifite Ogwari people and were analyzed using a Gas Chromatography/Flame Ionization Detector (GC-FID). In all sediment samples, only 11 PAHs out of 16 United States Environmental Protection Agency (USEPA) priority PAHs were detected while 5 were below detectable limits. The concentration of benzo[a]anthracene was high but detected in only 2 sediment samples while fluoranthene has a relatively close concentration across all samples. Benzo[k]fluoranthene has the highest concentration compared to other PAHs in the samples while benzo[a]pyrene has the lowest concentration across all samples. Atammele sediment was analyzed as the most carcinogenic followed by Isiachala with concentrations of 84.23 ng/µL and 51.92 ng/µL respectively. Ube stream sediment has the lowest concentration of PAHs (11.74 ng/µL). Ecological risk of the PAHs revealed a sediment-to-sediment variation in the risk profile. Human health risk assessment depicts that hazard index and total cancer risk for adults and children ranged from 2.3E-07 - 2.57E-05 and 4.85E-07 - 5.43E-05 respectively. Pyrogenic activities are the main source of PAHs in the sediments. The results provide a guide for monitoring PAHs pollution and protecting drinking water sources. [ABSTRACT FROM AUTHOR]

AbstractGamma spectrometry was employed to determine activity concentration of naturally occurring radionuclides 238U, 232Th and 40K in sediment samples collected from Vellanathuruthu to Thumpoly of Kerala Coast using NaI(Tl) detector and to evaluate the radiation hazards. The levels and distribution of radionuclides in sediments from this coastal area have been determined. The activities ranges and mean (in bracket) values for 238U, 232Th, and 40K are 78.92 to 1493 Bq kg−1 (552.63), 94.76 to 2856.46 (851.24) Bq kg−1 and 30 to 2399.20 (678.61) Bq kg−1 respectively. The mean activity of 238U, 232Th, and 40K are higher than the global average values (35 Bq kg−1 for 238U, 400 Bq kg−1 for 40K, and 30 Bq kg−1 for 232Th) of these radionuclides in the sediment and it may be due the presence of rich deposits of black sands. The radium equivalent activity was estimated to range from 216.74 to 5762.48 Bq kg−1 (1822.17). The average absorbed dose rate was determined to vary from 94.96 to 2515.83 nGyh−1 (797.97) and the annual effective dose was estimated to range from 0.12 to 3.09 mSvy−1 (0.98). Additionally, it was estimated that the average external hazard index was 4.92 and the average internal hazard index was 6.41 respectively. The computed radiation indices for all samples were compared to internationally accepted standards, showing that they are above the recommended limits. The results of the present investigation indicate that the radioactivity in the region is slightly above the global average values. [ABSTRACT FROM AUTHOR]

Dense polymetallic nodule fields are found in different areas of the Pacific and Indian Oceans. However, limited knowledge exists about microbial diversity, processes and functions in deep-sea polymetallic nodule sediments. This study investigated microbial diversity, composition and function in sediments from various locations and depths in a western Pacific polymetallic nodule province. Sediment cores were collected, DNA extracted, and the V3–V4 regions of the 16S rRNA gene were sequenced using Illumina MiSeq. The test results show that the abundance and diversity of microbial communities in sediments from different sites vary significantly. The dominant microbial communities at the family level in the three sediment samples were all mainly Marinobacteraceae and Alcanivoracaceae. Sediment samples from core 1 had similar microbial structures and microbial community functions. Surface sediment had higher species richness, diversity and evenness than the middle layer. The dominant phylum at different depths was consistent. There was significant spatial heterogeneity in the microbial community within sediments from polymetallic nodule regions. This study expands on our knowledge of the spatial and vertical distribution of microbial community diversity beneath polymetallic nodules in deep-sea settings. [ABSTRACT FROM AUTHOR]

We investigate how luminescence signals imprinted on fluvial sediments vary depending on the depositional environment and vary through time in the same river. We collected sediment samples from four geomorphically distinct locations on the modern floodplain and modern point bar on the Buffalo River in northwest Arkansas, USA, in order to determine if different depositional environments are associated with distinct bleaching characteristics in the sediments. Our analysis revealed that all samples from different depositional environments yielded ages consistent with modern deposition. The samples collected from the floodplain and bar head contained a higher proportion of grains with residual doses, indicative of incomplete bleaching during transport, while samples from the mid‐bar and bar tail appeared well bleached. Our results are particularly intriguing for two significant reasons. First, they highlight distinct equivalent dose distributions in different depositional environments. Second, they shed light on an intriguing relationship: despite generally well‐bleached modern floodplain samples, ancient sediments from corresponding terraces displayed equivalent dose (De) distributions that suggest partial bleaching in some cases. This research contributes to the growing body of work that seeks to establish a relationship between luminescence properties and sediment transport processes and offers valuable insight into how luminescence signals vary locally in modern fluvial deposits, which can help guide the interpretation of older fluvial deposits. [ABSTRACT FROM AUTHOR]

An alkaline active L-glutaminase (BALG) producing bacterium was screened and identified from seamount sediment samples of the Arabian Sea. The isolate was confirmed to be Bacillus australimaris NIOT30 based on morphological characteristics and 16 S rRNA gene sequencing. The glutaminase gene, balg was PCR amplified, cloned and expressed in E. coli BL21 (DE3) host. The molecular weight of purified BALG was estimated to be 36 kDa and the enzyme showed a specific activity of 507 ± 27 Umg−1 against L-glutamine under optimal assay conditions of pH 7.0 and temperature at 37 °C for 15 min. The enzyme showed maximum activity at pH 7 and retained 95% activity at pH 10. BALG retained a relative activity of about 82% and 45% at 45 °C and 60 °C respectively. The kinetic parameters of BALG, Km and Kcat/Km were determined to be of 210 ± 11 mM and 4.4 × 102 M s−1 respectively. Homology modeling and substrate ligand interaction studies revealed the stability of the enzyme-substrate complex. The present study highlights the characterization of a highly active L-glutaminase from B. australimaris NIOT30. Further, mutational analyses of ligand binding residues would show insights into the affinity of L-Glutaminase. [ABSTRACT FROM AUTHOR]

Benthic macrofauna are important and widely used biological indicators of marine ecosystems as they have limited mobility and therefore integrate the effects of local environmental stressors over time. Recently, environmental DNA (eDNA) analysis has provided a potentially more resource‐efficient approach for benthic biomonitoring than traditional morphology‐based methods. Several studies have compared eDNA with morphology‐based monitoring, but few have compared the two approaches using the exact same sediment cores. In addition, the meiofauna and pelagic organisms obtained as 'bycatch' using eDNA have largely been disregarded from comparisons. Here, we address these shortcomings through comparative invertebrate analyses of six sediment sample replicates from each of four stations in Denmark, using eDNA metabarcoding and morphological identification. Our results revealed large variation between the six replicates for both methods and little overlap in taxon compositions between methods. While the morphological dataset was dominated by molluscs and annelids, the eDNA dataset was dominated by arthropods and annelids. Using community composition data, we found that sampling stations could be distinguished both with eDNA and morphology. Finally, we inferred expected total richness from extrapolated accumulation curves of detected taxa from each method. This indicated that eDNA metabarcoding requires less replication than morphology for maximum coverage of diversity to be reached. However, both methods required high levels of replication, and our results on taxonomic composition add to the evidence that morphological and eDNA‐based methods should preferably be used as complimentary tools for marine bioassessment. [ABSTRACT FROM AUTHOR]

Seas worldwide are threatened by an emerging source of pollution as millions of tons of warfare materials were dumped after the World Wars. As their metal shells are progressively corroding, energetic compounds (EC) leak out and distribute in the marine environment. EC are taken up by aquatic organisms and pose a threat to both the marine ecosphere and the human seafood consumer because of their toxicity and potential carcinogenicity. Here, sediment samples and fish from different locations in the German North Sea of Lower Saxony were examined to determine whether EC transfer to fish living close to munition dumping areas. EC were found in sediments with a maximum concentration of 1.5 ng/kg. All analyzed fish muscle tissues/fillets and bile samples were positive for EC detection. In bile, the max. EC concentrations ranged between 0.25 and 1.25 ng/mL. Interestingly, while detected TNT metabolites in the muscle tissues were in concentrations of max. 1 ng/g (dry weight), TNT itself was found in concentrations of up to 4 ng/g (dry weight). As we found considerable higher amounts of non-metabolized TNT in the fish muscle, rather than TNT metabolites, we conclude an additional absorption route of EC into fish other than per diet. This is the first study to detect EC in the edible parts of fish caught randomly in the North Sea. [ABSTRACT FROM AUTHOR]

Temporary ponds are small‐sized limnic systems that dry periodically. The length of the wet phase defines the hydroregime and determines community assembly in temporary ponds. Zooplankton species have adapted to desiccation by adopting some dormant strategies, such as the formation of resting stages. Hatching from resting stages is a source of recolonization after drought events and the composition of hatching taxa is also influenced by hydroregime. We compared metacommunity structure and composition of the dormant sub‐community (resting stages); the pioneer active sub‐community (fauna present immediately after inundation of ponds); and the cumulative active sub‐community (fauna present at the initial, middle and final phases of hydroperiod) in a set of temporary ponds with semipermanent and seasonal hydroregimes in two areas with mediterranean climate: central Chile and eastern Spain. We aimed to determine the influence of hydroregime and identify whether metacommunity patterns are consistent between regions sharing a mediterranean climate.We selected five semipermanent and five seasonal ponds in each region to sample sediments and active zooplankton sub‐communities. By combining hatching experiments from the sediments with direct counts of active zooplankton from the field samples, we gathered data on both dormant and active sub‐communities to build unweighted bipartite networks of species occurrences in each pond. The obtained networks were analysed to determine seasonal trends in structural features of the metacommunities (diversity, nestedness and modularity) and their relation to hydroregime (semipermanent and seasonal) and geographical location (Chile and Spain).We observed consistent differences in community structure when comparing sub‐communities at different successional stages (dormant, pioneer active and cumulative active) and with different hydroregimes (semipermanent vs. seasonal). Both α‐ and γ‐diversity showed a consistent trend, being highest in cumulative active sub‐communities and lowest in dormant ones, and were consistently higher in seasonal ponds, regardless of the region. In addition, β‐diversity was higher in the pioneer active sub‐community in both regions, with no significant differences between hydroregimes. The species composition of cumulative active sub‐communities were less heterogeneous than that of the pioneer and dormant ones. No consistent patterns were found in modularity and nestedness values across sub‐communities and hydroregimes.In agreement with our hypotheses, we observed a gradual accumulation of taxa as well as community homogenization over time in both regions. Contrary to our expectations, hydroregime did not affect these patterns and, surprisingly, shorter hydroperiods exhibited higher regional diversity. Our results suggest that hydroregime as a single variable does not have a strong explanatory power for metacommunity assembly of temporary ponds. Therefore, a more comprehensive theory is needed to anticipate the effects of the upcoming hydroperiod shortening. [ABSTRACT FROM AUTHOR]

Microplastics (MPs), or plastic particles smaller than 5 mm, are emerging contaminants that potentially affect aquatic species and humans. More research has been undertaken in the marine environment; however, rivers that serve as a sink and pathways for plastic entering the ocean have received less attention. The current study investigated the presence of MPs in the sediments of the Cagayan de Oro River, one of the top plastic-emitting rivers listed in the Philippines. Sediment samples were collected from the six sampling stations from upstream to downstream using a Van Veen grab sampler. Through stereomicroscope and Fourier-transform infrared spectroscopy (FTIR), MPs were analyzed and categorized according to color, shape, size, and polymer type. All the sampling stations were contaminated with MPs ranging from 4.4 ± 2.57 to 33.3 ± 4.44 items/kg. The highest density of MPs was found close to the river mouth that drains into Macajalar Bay which suggests that riverine contributions are substantial contributory to MPs contamination in the marine environments. Prevalent types of MPs are blue-colored (41%), fiber-shaped (41%), 0.5–1.0 mm (43%), and polyethylene (43%) particles. Microplastic accumulation is generally higher downstream than upstream. [ABSTRACT FROM AUTHOR]

Amos, C.L.; Kassem, H.; Petrie, B.; Shaw, J., and Ivaldi, R., 2024. An evaluation of the Bagnold (1956) theories for sediment transport in Northumberland Strait, Canada. Journal of Coastal Research, 40(6), 1019–1036. Charlotte (North Carolina), ISSN 0749-0208. This study examines the seabed stability and sediment transport in the region of a proposed fixed link (bridge) across Northumberland Strait, Canada. The region is dominated by strong semidiurnal and diurnal tides that have eroded, transported, and deposited material that modify the character of the local seabed morphology. The seabed comprises rippled fine sand interspersed with a shelly gravel lag. The study provides an opportunity to examine the theories of R.A. Bagnold on sand transport that were deficient in the prediction of the transport of fine and very fine sand. A further purpose was to determine the mechanisms of the sand transport (waves, currents, or both). Representative sediment samples were collected and subjected to hydrodynamic forcing in a laboratory flume (Lab Carousel); relationships were derived between the applied stream power and sediment transport rates as bedload and in suspension. In addition, a multiparameter benthic lander (Ralph) was deployed at two sites in the nearshore regions of the fixed link for a total duration of 33 days. Flow velocity measurements derived from the lander were used to assess the transport potential using calibrations derived from the flume studies. The results showed that the total immersed bedload transport measured herein corresponded well to Bagnold's dimensionless stream power function when normalized to flow depth and grain size. They also showed that the tidal currents coupled with the mean flow in the region are sufficient in magnitude to erode and transport sand to the SE, where they are deposited to form a tidal delta. The sand transport in the shallow margins (depth < 10 m) took place mainly as bedload, although periodic suspension also took place. The nature of the predicted sand transport indicates that the seabed is in a continued state of evolution subject to the present-day hydrodynamic forcing. [ABSTRACT FROM AUTHOR]

Sediment pollution from potentially hazardous elements (PHE) generated by human activity has grown into a worldwide problem. In this regard, for the first time, surface sediment samples were obtained from six points along the Shahid Rajaee Reservoir for this investigation. Elements concentrations (Cu, Cr, Co, Mn, Fe, Pb, Ni, and Zn) were assessed using ICP-MS. Based on the individual indices (geoaccumulation index, contamination factor), all elements at all sample sites were found to be low in contamination, except Pb and Zn (at sites 1 and 2). The combined effect of PHEs in the sediment samples did not show a considerable concern, according to the synergistic indices. The health risk assessment revealed that recreational receptors were unlikely to face non-carcinogenic or carcinogenic hazards as a consequence of exposure to PHEs in sediments with unintentional ingesting and contact with the skin. The Tessier technique demonstrated that all PHEs were mostly connected with the oxidizable fraction. According to statistical study, while Cu, Co, Cr, Ni, Fe, and Mn were obtained from lithogenic sources, Pb and Zn came from natural as well as human-made sources. [ABSTRACT FROM AUTHOR]

Ganqu Wetland is a representative valley wetland in the Lhasa River Basin. In order to understand the distribution characteristics and environmental risks of heavy metals in the wetland, a total of 22 sediment samples were collected. The contents of eight heavy metals (Cd, Hg, As, Pb, Cr, Cu, Ni and Zn) were analyzed. The geo-accumulation index and Hakan-son potential ecological risk index were used for risk assessment, and the ecological risk in the study area was quantitatively assessed by coupling with Monte-Carlo simulation. Absolute principal component score-multiple linear regression model (APCS-MLR) was further used to analyze the sources of heavy metals. The results showed that the contents of Cd, Hg, As, Pb, Cr, Cu, Ni and Zn in wetland sediments were 0.15, 0.04, 15.05, 33.49, 47.36, 22.00, 19.18 and 76.41 mg/kg, respectively. The contents of As, Ni and Cr were lower than the background values of Tibet, while the contents of Cd, Hg, Pb, Cu and Zn were 1.88, 1.54, 1.16, 1.00 and 1.04 times of the background values, respectively. The geo-accumulation index showed that except for Cd (0.54), other elements were non-polluting. The comprehensive ecological risk index (RI) was 141.74, and the overall ecological risk in the study area was low. However, the results of the potential ecological risk index showed that Cd and Hg had a probability of 78.49% and 67.64%, respectively, which were medium ecological hazards and were the main factors causing ecological risks. The source apportionment of APCS-MLR model showed that the contribution rates of natural sources to Cu, Cr, Ni, Zn and Pb were 86.09%, 97.08%, 86.36%, 74.97% and 75.42%, respectively. The contribution rates of agricultural sources to Cd, As and Hg were 72.07%, 67.30% and 50.34%, respectively. At the same time, Hg was also contributed by 49.66% of natural sources, indicating that Hg was affected by both sources. [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]

In the present study, 18 polychlorinated biphenyl (PCB) compounds were measured in marine sediments collected from 49 offshore stations in the Persian Gulf and the Gulf of Oman in 2019. After the last oceanographic cruise in 2006, no study has been performed on the offshore sediments of this region, and this is the first study on the PCBs in this area. The total amount of PCB compounds in the sediment samples ranged from 74.38 ng kg−1 (near Abu Musa Island) to 1212.98 ng kg−1 (near Siri and Kish Island). The maximum and minimum values of the individual detected PCB compounds were 175.88 ng kg−1 (PCB52) and 2.09 ng kg−1 (PCB156), respectively. The levels of total PCBs detected in sediments were lower than the Canadian interim sediment quality guideline value of 21500 ng kg−1 for marine sediments. The sedimentary mass inventories for Σ18PCBs were 0.6 and 0.2 mt for the Persian Gulf and Gulf of Oman, respectively. [ABSTRACT FROM AUTHOR]

Carbon burial patterns in lakes and their dynamic changes significantly impact terrestrial carbon sink fluxes and global carbon budgets. In this study, multi-indicator analysis of sediment core samples (P1, P2, and P3) from Pipahai Lake was conducted. Integrating the chronological sequences of 210Pb and 137Cs, we identified the historical changes and spatial characteristics of total organic carbon (TOC) and inorganic carbon (TIC) burial in Pipahai Lake since 1884. The results show that the TOC content was higher than that of the TIC. They exhibited an increasing trend with decreasing depth. Linear regression results indicated that the variation of TOC is less directly affected by precipitation (R = 0.39) and temperature (R = 0.58), while temperature may have a greater impact on TOC. From 1884 to 1995, nutrients were not the primary factor influencing changes in TOC. The synchronous variation in TIC and TOC contents reflects a higher contribution of external inputs to carbon burial in the Pipahai Lake basin. After 1996, nutrients may have begun to affect variations in TOC. The TOC primarily originates from distal aeolian transport or autochthonous sources, though human activity has played a role in its evolution. The TIC content is controlled by the TOC content and autochthonous sources. This study will contribute to the understanding of the carbon cycling dynamics and their influencing mechanisms in a high-altitude lake ecosystem. [ABSTRACT FROM AUTHOR]

Dakhla Bay is a paralic environment distinguished by various potentialities, including fishing, aquaculture, and tourism. However, the development of these human activities can lead to negative impacts on this environment, posing a threat to human health. This situation requires special attention to the environment and the implementation of a program for the protection and preservation of this ecosystem. This study aims to identify solutions to protect the marine environment from cadmium contamination by the macroalgae Gracilaria gracilis. The results of cadmium analyses in different compartments of Dakhla Bay, including bivalve molluscs, seawater, sediment, and macroalgae, indicate a difference in cadmium accumulation across the various studied compartments. The highest levels of cadmium are noted in macroalgae, with concentrations ranging from a minimum of 0.9 mg/kg fresh weight in the summer of 2019 to a maximum of approximately 2.55 mg/kg fresh weight recorded during the summer of 2022 at the Lassargua station. In comparison, bivalve molluscs such as Perna perna showed Cd levels ranging from 0.2 mg/kg to 1.4 mg/kg fresh weight at the same station. The sediment samples revealed average Cd levels ranging from 0.02 to 1.39 mg/kg dry weight in samples collected from Lassargua, while seawater concentrations were recorded at approximately 0.65 µg/L. The decontamination of cadmium by the macroalgae Gracilaria gracilis without impacting the quality of the algae has been well confirmed. Indeed, cadmium levels noted in macroalgae remain below the thresholds set by the regulations in force. In conclusion, the results of this study encourage the use of algocultures in Dakhla Bay to protect its ecosystem from various types of pollution. [ABSTRACT FROM AUTHOR]