River Sediment Samples Research Articles

Pollution Status of Inland Waterways Serving as Receptacles to Plastic Waste in Rivers State, Nigeria

This study aimed at ascertaining the physicochemical characteristics of selected water bodies receiving solid plastic waste in Rivers State, Nigeria. Surface water and sediment samples were analysed for physicochemical parameters. Water, sediment and fish samples were monitored for presence of polychlorinated bisphenols (PCBs) and polycyclic aromatic hydrocarbons (PAHs). All physicochemical parameters monitored in Bonny River water and sediment samples were within WHO acceptable. However, the concentrations of nitrate and phosphate (62.675 and 1.28 ppm) in New Calabar River water samples were above WHO limits of 10 and 1 ppm respectively. The Cd values (0.045-8.27 mg/l) at both locations exceeded WHO 0.003 mg/l limit. Likewise, Mn concentrations (6.02-15.5 mg/l) exceeded WHO 5.5 mg/l. Mercury (0.075-1.39 mg/l) was the lowest occurring heavy metal in the water samples but the concentration was still high enough for concern, as the possibility for bioaccumulation in fish species in the river was high. Chloride levels (318.375-423.045 mg/l) in the water samples exceeded WHO limit of 250 mg/l for drinking water. The samples also had high iron content (0.635-16.19 mg/l). PAHs concentrations (252.0155-3533.14 ppm) in the water samples far exceeded the safe level of 10 mg/l for drinking water standard. PCBs levels in all fish samples (21.56-83.08 ppm) exceeded WHO maximum limit of 0.2 mg/kg Surface water, sediment and fish sampled contained objectionable concentrations of heavy metals, PCBs and PAHs. Users of these rivers for domestic purposes are at high risk of chemical poisoning from heavy metals, PCBs and PAHs.

Sedimentology, Mineralogy of Al-Dujaila River Sediments Project, Southeastern Kut City, Iraq

A sedimentological and mineralogical study was carried out on sediments of Al-Dujaila River Project, one of the branches of the Tigris River, southeastern Kut City, Iraq. The study aims to identify the nature and maturity of sediments in order to deduce the provenance of these sediments and the source area. The results of grain size analysis of ten river sediment samples indicated that the averages are: silt (44.97%), clay (34.06%), and sand (20.96%). According to Folk's classification (1974), the sediments are classified as sandy mud. A microscopic study of five sand fraction samples has shown the presence of light and heavy minerals. Light minerals (average 94.6%) include on average: a major share of rock fragments (64.8% including dominant carbonate, chert, igneous, metamorphic, and mudstone), quartz (24.1% including dominant monocrystalline and polycrystalline), feldspars (5% including orthoclase and plagioclase) while evaporates, and coated clays are subordinate. Heavy minerals (average 5.4 %) include opaques (average 54.2%) and non-opaques (average 45.8%) including pyroxene, amphibole, epidote, garnet, staurolite, chlorite, biotite, muscovite, zircon, tourmaline and rutile. Based on the mineralogical signatures, light and heavy minerals reflect metamorphic, mafic and felsic igneous rocks of the active margin of the unstable shelf in addition to carbonate, evaporate and mud of sedimentary rocks that could be sourced from the floodplain. According to sediment diversity and very poor grain sorting in the study area, as well as the values of indices of mineral maturity MI (0.34), MMI (0.76), and the ZTR (23.5%), all these results indicate that sediments are immature to extremely immature, which means the source area represents rather elevated topography, rapid erosion and transport in arid to the semi-arid environment and a short distance of transportation. The tectonic provenance of Al-Dujaila River sediments can be characterized as a lithic reworked of the recycled orogen as a result of the collision range of Taurus and Zagros Mountain range.

New data on the transformation of water and sediment runoff into the Lena river delta based on the results of expedition measurements in August 2022

Field hydrological measurements were performed in the Lena River delta from the 10th to the 16th of August 2022. 25 values of water discharge and 58 suspended sediment concentrations (SSC) were measured, multiple chemical composition water samples were taken, along with samples of bottom and bank river sediments, and thermal abrasion coasts were highlighted. Particle size and chemical composition analyses of the sediment samples were carried out. The aim of the study was to estimate the water flow distribution in the delta and to determine the directional SSC, sediment particle size and chemical composition changes along the delta and inside the depth of the river flow, and define the roles of the local hydrological and morphological factors of river flow transformation. Moreover, field measurements are crucial for SSC estimation and monitoring based on satellite image data. The laboratory analyses included particle size definition in suspended and bottom sediment samples, organic matter and SSC definition. The August 2022 expedition results were compared to the previous surveys. It was established that the flow distribution around the Stolb island corresponds with that of 2016: the Bykovsky, Trophimovsky, Tumatsky and Oleneksky branches receive 24.9–25.5, 58–59.2, 6 and 6.6 % of the water discharge from the Kusur gauging station on the Lena River, respectively. However, the role of the Main channel was slightly overestimated. The new data includes water discharges in the branches around the Samoilovsky island and in the channel systems of the Oleneksky and Tumatsky branches. SSC was relatively low and amounted to around 12–24 mg/l, rising from the water surface to the bottom 1.2–2 times. SSC decreased along the course of the Oleneksky and Tumatsky branches (1.5 and 1.1 times, respectively) due to the ratio between SSC and the potential stream transport capacity. SSC rose along the course of the Bykovsky branch, even though it wasn’t shown by the Landsat-8 satellite image (16th of August 2022). A significant sediment source in the delta are eroded and thermo eroded shores of the edoma island systems. The average sediment size proved to be from 0.011 to 0.019 mm. SSC does not vary much around the main channel and the nearest branches. Important relations between SSC, optical turbidity and ADCP backscatter intensity were estimated. The coarse diameter of 30 bottom sediment samples was 0.46 mm. The largest sediments were discovered in the Bykovsky branch, while the smallest sediments were found in the smaller transverse branches. Along the Tumatsky and Oleneksky branches the bottom sediments alternate from fine to medium sands.

Characterization of tire and road wear particles in urban river samples

Tire and road wear particles (TRWP) consist of tread rubber elastomers with pavement encrustations generated from tire-road friction. Our previous work utilized density separation and chemical mapping to characterize chemical and physical properties of individual TRWP. The current research extends the use of chemical mapping methods to urban river samples including sediment from the Seine River (France). TRWP were identified using a weight of evidence framework including density separation, optical imaging, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) mapping, and Fourier-transform infrared (FTIR) spectroscopy. River sediment collected immediately downstream of the Rouen urban area (with an average TRWP concentration of 930 mg TRWP/kg sediment; n = 3) subsequently density separated demonstrated an average TRWP size of 133 µm by number and 171 µm by volume. Sediment from a second location (190 mg TRWP/kg sediment; n = 1) was density separated and showed an overlap in features of tire tread and bitumen/asphalt in the FTIR signatures (operationally defined as weathered bitumen/TRWP). Average particle size for weathered bitumen/TRWP were 250 µm and 981 µm by number and volume, respectively. Pulverization pre-treatment of the second location sediment sample reduced larger particle agglomerates to an average weathered bitumen/TRWP particle size of 97 µm and 116 µm by number and volume, respectively. A quantitative TRWP or bitumen/TRWP size distribution in filtered suspended river solids (3300 mg TRWP/kg suspended solid) could not be determined due to lack of TRWP enrichment in pre- or post-density separation steps; however, average particle size for all collected river particles were 27 µm and 160 µm by number and volume, respectively. Additionally, TRWP were not identified in a river biota sample (bivalves) with or without chemical digestion and future research was discussed. Taken together, our single particle analysis methodologies were useful for the determination of particle size distribution (including bitumen and TRWP) in urban river sediment samples. These results are expected to help advance the methods for identification and characterization of TRWP and potentially other microplastics in various environmental matrices.

Heavy metal contamination of Batanghari River, Jambi, Indonesia: determination based on sediment enrichment factor value

Batanghari River is the primary source of water for the people of Jambi. Batanghari River’s condition nowadays is worrying because its color is no longer clear. This research focused on determining the content of heavy metals in the Batanghari River's water and sediment. The conducted analysis is an ICP-MS analysis to determine the level of heavy metal (Cu, Cr, Co, Cd, Hg), and an enrichment factor calculation is conducted to determine the source of pollution. The enrichment factor value from the Batanghari River sediment sample declined with the following sequence Cd>Hg>Cu>Cr>Co, in 10 pinpoint locations. These indicate a high degree of anthropogenic activities along the Batanghari River which become the source of heavy metals entering the Batanghari River. The average concentration of heavy metals in the Batanghari River showed that the metal concentrations of Cd, Cu, and Hg are higher than the quality standards that have been set, whereas the metal concentrations of Cr and Co are still by the quality standards that have been set in PP 22 the year 2021.

Assessment of physiochemical properties and bacteriological diversity of Otamiri river in Owerri eastern Nigeri

The physiochemical and bacteria diversity of Otamiri River was analyzed using standard microbiological methods. A total of seventy two (72) water and twenty four (24) sediment samples were collected. The routine plate count revealed that the number of heterotrophic bacteria present ranged from 1.00E+06 Cfu/ml to 9.70E+06 Cfu/ml, fecal coliform count 2.00E+05 Cfu/ml to 9.00E+06 Cfu/ml, Salmonella/Shigella count 3.50E+05 Cfu/ml to 1.52E+07 Cfu/ml, Staphylococcus count 2.00E+05 Cfu/ml to 1.79E+07 Cfu/ml, coliform count 3.50E+05 Cfu/ml to 4.59E+08 Cfu/ml, Vibrio count 1.50E+05 Cfu/ml to 3.52E+07 Cfu/ml. Anaerobic bacteria count ranged from 2.00E+05 Cfu/ml to 2.85E+06 Cfu/ml. The proportion of bacteria isolated from the samples showed that Alcaligens faecalis had the highest 68(94.44), 24(100), followed by Lysinibacillus macrolides 54(75), 21(87.5) while Lactobacillus spp had the least in water sample 6(8.33), Klebsiella aerogenes had the least in sediment 6(25). Among the physiochemical parameters analyzed in the river water and sediment samples had values above the recommended standard by WHO. The samples biophysical parameters did not meet the standard recommended by WHO for portable water. Therefore, to prevent potential health risks, those who use river water for domestic purposes must appropriately cleanse it before use. The government of the day should devise ways of disposing solid waste and effluent rather than channel same into the river and enact strict laws that will punish individual, agencies and firms that indulge in such in order to protect natural bodies of water from pollution. Statistical analysis using analysis of variance Posthoc = Tukey Alpha (0.05) indicated that the mean bacteria counts between the sampling stations differ significantly at the 0.05 level.

Evaluation of the characterization and heavy metals remediation potential of biosurfactant produced by Aeromonas hydrophila S62A

The evaluation of the heavy metals remediation potential and characterization of biosurfactant produced by Aeromonas hydrophilia strain S62A isolated from water and sediment samples of Imo River, Nigeria was studied. In this study, 12 bacterial isolates were isolated from contaminated water and sediment samples using spread plate technique and primarily screened for biosurfactant production using emulsification index, oil displacement and surface tension tests. Secondary biosurfactant production was carried out in a modified mineral salt medium under optimized conditions for 5 days and the produced biosurfactant was characterized and evaluated for its heavy metals removal efficiencies using standard analytical procedures. The result showed that the bacterial strain identified as Aeromonas hydrophilia S62A out of the 12 isolate strains had the highest and lowest values of 66.66 %, 23.76 cm and 90 mN/m for emulsification index, oil displacement and surface tension tests, respectively. The purified biosurfactant was found to be glycophospholipid as confirmed by the gas chromatographic (GC) and Fourier Transformed Infra-Red Spectroscopic (FTIR) profiles with 5 mg/mL critical micelles concentration (CMC). Statistically, significant differences (P < 0.05) were detected among the means of all surfactant CMC treatment in comparison to their untreated controls with 2 × CMC lead having the highest (98.92 %) and control (water) having the lowest (2.09 %) heavy metals removal efficiencies. Therefore, the present study has produced glycophospholipid biosurfactant with unique structural and chemical features and composition and could be exploited in environmental remediation of heavy metals contaminated ecosystems.

Characterization of a novel nornicotine-degrading strain Mycolicibacterium sp. SMGY-1XX from a nornicotine-degrading consortium and preliminary elucidation of its biodegradation pathway by multi-omics analysis

Nicotine and nornicotine are all toxic alkaloids involved in the formation of carcinogenic tobacco-specific nitrosamines. Microbes play an important role in removing these toxic alkaloids and their derivatives from tobacco-polluted environments. By now, microbial degradation of nicotine has been well studied. However, limited information is available on the microbial catabolism of nornicotine. In the present study, a nornicotine-degrading consortium was enriched from a river sediment sample and characterized by metagenomic sequencing using a combination of Illumina and Nanopore technologies. The metagenomic sequencing analysis demonstrated that Achromobacter, Azospirillum, Mycolicibacterium, Terrimonas, and Mycobacterium were the dominant genera in the nornicotine-degrading consortium. A total of 7 morphologically distinct bacterial strains were isolated from the nornicotine-degrading consortium. These 7 bacterial strains were characterized by whole genome sequencing and examined for their ability to degrade nornicotine. Based on a combination of 16 S rRNA gene similarity comparisons, 16 S rRNA gene-based phylogenetic analysis, and ANI analysis, the accurate taxonomies of these 7 isolated strains were identified. These 7 strains were identified as Mycolicibacterium sp. strain SMGY-1XX, Shinella yambaruensis strain SMGY-2XX, Sphingobacterium soli strain SMGY-3XX, Runella sp. strain SMGY-4XX, Chitinophagaceae sp. strain SMGY-5XX, Terrimonas sp. strain SMGY-6XX, Achromobacter sp. strain SMGY-8XX. Among these 7 strains, Mycolicibacterium sp. strain SMGY-1XX, which has not been reported previously to have the ability to degrade nornicotine or nicotine, was found to be capable of degrading nornicotine, nicotine as well as myosmine. The degradation intermediates of nornicotine and myosmine by Mycolicibacterium sp. strain SMGY-1XX were determined and the nornicotine degradation pathway in strain SMGY-1XX was proposed. Three novel intermediates, myosmine, pseudooxy-nornicotine, and γ-aminobutyrate, were identified during the nornicotine degradation process. Further, the most likely candidate genes responsible for nornicotine degradation in Mycolicibacterium sp. strain SMGY-1XX were identified by integrating genomic analysis, transcriptomic analysis, and proteomic analysis. The findings in this study will help to expand our understanding on the microbial catabolism of nornicotine and nicotine and provide new insights into the nornicotine degradation mechanism by consortia and pure culture, laying a foundation for the application of strain SMGY-1XX for the removal, biotransformation, or detoxification of nornicotine.

Hydrochemical characteristics and microbial community evolution of Pinglu River affected by regional abandoned coal mine drainage, Guizhou Province, China.

Pinglu River in southwestern China was continuously polluted by acid mine drainage (AMD) from abandoned coal mines, and AMD has become a major source of recharge to the river (43.26% of total flow), resulting in structural changes in the physicochemical properties and microbial communities of river water and sediments. In this study, we collected abandoned coal mine drainage, river water, and river sediment samples for comprehensive analysis. Results indicated that the hydrochemical types of AMD from abandoned coal mines were mainly SO4-Ca·Mg. The pH of river water in Pinglu River decreased from upstream to downstream due to AMD, with the hydrochemical type gradually changing from SO4·HCO3-Ca·Mg to SO4-Ca·Mg. The variation of pH along the river sediments was less than that of water samples, which remained weakly alkaline. However, high-throughput sequencing revealed a gradual decrease in microbial diversity in river sediments from upstream to downstream. The core bacteria groups in the upstream sediments were mainly attributed to the phylum Proteobacteria and Actinobacteriota, mainly including Geobacter, Anaeromyxobacter, Marmoricola, and Phycicoccus. The relative abundance of Gaiella, MND1, and Pseudolabrys in sediment samples gradually increased with the confluence of AMD, and the differences in microbial communities may be attributed to pH, TOC, and TP. Results of phenotype prediction demonstrated that the relative abundance of anaerobic microorganisms in river sediment gradually decreased from upstream to downstream (from 24.77 to 12.46%), presumably due to the large amount of oligotrophic AMD converge.

Methods optimization and application: Solid phase extraction, ultrasonic extraction and Soxhlet extraction for the determination of antiretroviral drugs in river water, wastewater, sludge, soil and sediment

The continuous release of antiretroviral drugs into the environmental has resulted in the interest to assess their occurrence in various environmental matrices. Their presence has led to antiretroviral drugs being considered the pollutants of concern due to their possible alterations of the ecosystem as well as the antiviral resistance that may develop upon their unintentional consumption. Therefore, in this work, solid phase extraction (SPE), ultrasonic extraction (UE), Soxhlet extration (SE) and liquid chromatography coupled to photodiode array detector (LC-PDA) methods have been optimized and validated. They were then applied for the simultaneous determination of abacavir, nevirapine and efavirenz antiretroviral drugs in wastewater, river water, sludge, soil and sediments. The percentage recoveries ranged from 71% to 112% for SPE, 88 – 108% for SE and 61 – 104% for UE. Good precision with a relative standard deviation less than 20% in all compounds for all methods was obtained. The LODs and LOQs ranged between 0.68 and 0.77 µg/L and 2.1–2.4 µg/L for SPE; 0.8–0.9 µg/kg and 2.3–2.8 µg/kg for SE and 1.6–2.8 µg/kg and 4.9 – 7.0 µg/kg for UE, respectively. The concentrations ranged from <lod - 102 µg/L, <lod – 814 µg/L, and <lod – 6759 µg/L, <lod − 138 µg/g, <lod - 98.9 µg/g, in river water, wastewater, sludge, soil and sediment samples, respectively. Abacavir was dominant in water while efavirenz was dominant in soil/sediments. The results showed that SE is more sensitive and more accurate than UE, hence it can be recommended for routine analysis despite its longer extraction times. The percentage removal efficiency ranged from 44% to 87% for nevirapine, 6–53% for efavirenz, and 75–91% for abacavir which indicates that these compounds were not completely removed during the WWTP processes, hence they ended up in river waters.

Radioactivity assessment in Euphrates river sediment samples

Radioactivity assessment in Euphrates river sediment samples

Radioactivity assessment in Euphrates river sediment samples

This study was carried out to investigate builds up a rule map on various radiological factors in and around the Euphrates River in Iraq. Radon levels, radium content and surface and mass radon exhalation rates for 20 sediment tests gathered from different districts along the Euphrates River, Iraq, (about 500km long) using the can technique, with the CR-39 plastic detector. Radon fixation esteems were viewed as going from 835.0 to 2797.7 Bq.m-3 with a normal worth of 1703.5 Bq.m-3. The normal worth of radium content was viewed as 12.5 Bg.kg-1 while the most minimal and most elevated determined upsides of radium content (CRa) were 6.1 and 20.5 Bq.kg-1, respectively. The radon exhalation rates (surface ES and mass Em) for the study sediment samples were found to vary from (0.41 to 1.37) Bq.m-2.h-1 and from (0.09 to 0.31) Bq.kg-1.h-1with average values of 0.83 Bq.m-2.h-1 and 0.19 Bq.kg-1.h-1, respectively. The values of CRa for all sediment samples were lower than the recommended value of 30 Bq.kg-1 given by UNSCEAR. Hence, the results show that the study area is safe as far as the health hazard effects are concerned, and the values of radium content in all surveyed sites are lower than the allowable limit.

Development of analytical method for veterinary antibiotics and monitoring of residuals in agricultural environment

Veterinary antibiotics (VAs) administered to livestock are introduced into the soil through livestock manure and compost. These antibiotics can run off to surface water or leach into groundwater during rainfall, causing problems such as antibiotic contamination or the occurrence of antibiotic-resistant bacteria. In this study, an analytical method for detecting four classes of VAs (penicillin, tetracyclines, macrolides, and sulfonamides) in river water and soil was developed, and the occurrence of residual antibiotics in the agricultural environment was monitored. Soil samples were extracted with the McIlvain buffer solution and pretreatment was conducted using solid-phase extraction, followed by liquid chromatography-tandem mass spectrometry to quantify target VAs. The results of this study showed that the recovery ranged from 62 to 121% in river water and 40.2–149.3% in soil. Among the other VAs, amoxicillin and spiramycin were observed to have low recoveries in all the samples. The method detection limit (MDL) was calculated in the range of 2.1–12.3 ng L−1 in river water and 1.2–13.2 ng kg−1 in soil, and the limit of quantification was 6.6–39.2 ng L−1 and 4.0–42.0 ng kg−1, respectively. This optimal method was then applied to measure the residual concentrations of VAs in river water, sediment, and soil samples around the Muhan watershed in Korea. A total of seven antibiotics were detected, and their concentrations ranged from 0.014 to 0.309 μg L−1in river water, and 1.45–9.04 μg kg−1 in sediment and arable soil. This method can be used to screen VAs in river water and soil and is expected to be used as primary data for examining the occurrence and fate of antibiotics in agricultural environments.

Spatio-temporal distribution of microplastics in water and sediment samples of the Plankenburg river, Western Cape, South Africa

Microplastic (MPs) pollution has become a subject of environmental concern due to its wide ubiquity in the environment. Microplastics are possible sources of other hazardous chemicals to aquatic organisms due to their composition and sorption properties. In this study, MPs occurrence in water and sediment samples of the Plankenburg River, Western Cape, South Africa was investigated. The physicochemical characterization of the river water was done onsite. 30 L water samples were collected and filtered in 10 L triplicates through a 250 μm mesh onsite using a metal bucket. An additional 12 L sample was collected and filtered in 4 L triplicates through 20 μm mesh in the laboratory. The extraction of MPs from water in the laboratory was by density separation. Sediment samples were also collected at the selected sites, oven-dried and microplastics in the laboratory. Sampling was conducted over four seasons – spring, summer, autumn, and winter. Microplastics were classified by visual observation and Fourier Transform Infrared Spectroscopy (FTIR-ATR). The seasonal distribution of MPs in the surface water samples varied across all sites. However, spring samples had the highest MPs occurrence (5.13 ± 6.62 MP/L) and the least, in autumn (1.52 ± 2.54 MP/L). The MPs in sediment samples were observed in spring (1587.50 ± 599.32 MP/kg). Fibres were the most dominant microplastic particle type (shape), with a size range of 500–1000 μm at the different sites. The infrared spectroscopic analysis confirmed the dominant polymer type to be polyethylene. This study provides an understanding of the microplastic occurrence in the Plankenburg River system and gives a baseline for future monitoring and assessment of water and sediment in the South African freshwater systems.

Occurrence of Antibiotic Resistance Genes, Antibiotics-Resistant and Multi-Resistant Bacteria and Their Correlations in One River in Central-Western Brazil

(1) Background: The uncontrolled increase in pollutants in the aquatic environment results in antibiotic-resistant bacteria and antibiotic resistance genes (ARBs and ARGs). The overuse and misuse of antibiotics is also a crucial factor for public health. (2) Methods: In this study, the presence of ARBs and the presence of 24 resistance genes from eight different classes of antibiotics were evaluated in addition to performing statistical correlations and intercorrelations. Samples of water and sediment were collected from a river in central-western Brazil, responsible for supplying water to more than 3 million people. Physicochemical analyses were performed on the water samples, as well as methodological approaches based on culture and molecular biology, such as real-time polymerase chain reaction (qPCR). (3) Results: The results of the analysis of apparent color, turbidity, thermotolerant coliforms and E. coli were not in accordance with Brazilian legislation. A total of 203 bacterial strains were isolated, of which 30.54% were from the Entero-bacteriaceae family and 29.06% from the Staphylococcaceae family. For the ARBs found, a higher prevalence of resistance to lyconsamides and β-lactams was detected. Among all isolated strains, a multi-drug resistance profile of 59.37% was found. The presence of ARGs was detected in all water and sediment samples; of the 24 genes searched, the presence of 22 was found, and the sul2 and ermC genes were detected in all samples. According to the statistical analysis, the Meia Ponte River is suffering a great anthropogenic impact, and the current Brazilian legislation is not sufficient to prevent it. This water environment is serving as a reservoir of resistance genes, and measures such as monitoring, depollution, management and preservation must be taken, so that the population does not suffer great damage. (4) Conclusions: This is the first study in the State of Goiás, Brazil, to indicate the existence of ARGs in samples of raw water and river sediments, supporting the worldwide investigation of ARBs and ARGs in a water environment. In addition, few studies address the correlations between the ARBs and ARGs groups, which is an important factor in the field of antimicrobial resistance.

Distributions of Antibiotic Resistance Genes and Microbial Communities in the Nearshore Area of the Yangtze River Estuary

Due to the extensive use of antibiotics, the resistance of microorganisms to antibiotics in the environment is increasing, and the problem of antibiotic resistance genes (ARGs) is becoming more and more severe, which seriously threatens ecological security and human health. In order to study the distribution characteristics of ARGs and the microbial community in different media in the coastal area of the Yangtze River Estuary, water and sediment samples from eight sites were collected through a field investigation. Two sulfonamide resistance genes ([STBX]sul1, sul2[STBZ]) and six tetracycline resistance genes (tetM, tetC, tetX, tetA, tetO, and tetQ), one integrase gene intI[STBX]1[STBZ], 16S rRNA gene, and the microbial community were detected and analyzed. The results showed that the detection rate of 10 resistance genes in the coastal area of the Yangtze River Estuary was 100%. [STBX]intI1[STBZ] was significantly positively correlated with various ARGs in the water samples. Proteobacteria and Bacteroidota were the dominant bacteria phyla in the water environment of the Yangtze River Estuary. Chloroplast was the main bacteria genus in water, and Chloroplast and Nitrospira were the main bacteria genera in sediment. In water, Nitrospirota was the common potential host of four tetracycline resistance genes (tetX, tetA, tetO, and tetQ). In sediments, Sva0485 was a potential host community shared by [STBX]sul1 and intI1[STBZ]. The distribution of the microbial community was an important factor affecting the migration and transformation of ARGs in the nearshore area of the Yangtze River Estuary.

Occurrence, distribution and environmental risk of 19 anthelmintic drugs in river water and sediment from the Jinjiang River, China.

This study explored the occurrence and distribution of 19 anthelmintic drugs (ADs) including the benzimidazole group, salicylanilide group, imidazothiazole group, tetrahydropyrimidine group, diphenylsulfide group, macrocyclic lactone group and hexahydropyrazine group in river water and sediment of the Jinjiang River in Sichuan, China, during summer and winter seasons. All targets were detected in river water (up to 74.64 ng L-1) and sediment (up to 1701 ng g-1) samples. The predominant ADs were benzimidazoles regardless of seasons and matrices, accounting for 43-82% of the total anthelmintic abundance. Obvious seasonal variation of AD concentrations in the two matrices was observed, which could be attributed to the seasonality of human and veterinary uses of ADs. Evident spatial variation (urban and rural areas) of ADs in winter was indicative of the influence of anthropogenic activities on the environmental concentration of ADs. Though benzimidazoles accumulated in the water and sediment with the highest concentration among all the ADs, macrocyclic lactones were of the highest risk to non-target organisms through ecological risk assessment, with an RQEcotox value up to 2713. This work contributes to comprehensively assessing the contamination level, ecological level and transmission characteristics of ADs in the environment.

The shared NDM-positive strains in the hospital and connecting aquatic environments

The spread of antibiotic-resistant priority pathogens outside hospital settings is, both, a significant public health concern and an environmental problem. In recent years, New Delhi Metallo-β-lactamase (NDM)-positive strains have caused nosocomial infections with high mortality and poor prognosis worldwide. Our study investigated the links of NDM-positive strains between the hospital and the connecting river system in Jinan city, Eastern China by using NDM-producing Escherichia coli (NDM-EC) as an indicator via whole genome sequencing. Thirteen NDM-EC isolates were detected from 187 river water and sediment samples, while 9 isolates were identified from patients at the local hospital. All NDM-EC isolates were resistant to imipenem, meropenem, cefotaxime, cefoxitin, ampicillin, tetracycline, fosfomycin, piperacillin-tazobactam. The blaNDM-5 (n = 20) and blaNDM-9 (n = 2) genes were identified, which were predominantly on IncX3 plasmids (n = 13), followed by IncFII plasmids (n = 5) and IncFIA plasmids (n = 2). Conjugation experiments showed that 21 isolates could transfer NDM-harboring plasmids. The well-conserved blaNDM-5 genetic environment (ISAba125-blaNDM-5/9-bleMBL-trpF-dsbD-IS26) of these plasmids suggested a common genetic origin. Nine sequence types (STs) were detected, including three international high-risk clones ST167 (n = 8), ST410 (n = 1), and ST617 (n = 1). Phylogenetic analysis showed ST167 E. coli from the river was genotypically related to clinical isolates recovered from patients. Furthermore, ST167 isolates showed high genetic similarities with other clinical strains from geographically distinct regions. The genetic concordance between isolates from different sampling sites in the same river (ST218 clone), and different rivers (ST448 clone) raises concerns regarding the rapid dissemination of NDM-EC in the aquatic environment. The emergence and spread of the clinically relevant NDM-positive strains, especially for E. coli ST167 clone, an international high-risk clone associated with multi-resistance and virulence capacity, within and between the hospital and aquatic environments were elucidated, highlighting the need for attention and action.

Lysobacter selenitireducens sp. nov., isolated from river sediment.

A Gram-stain-negative, yellow-pigmented, motile, flagellated and rod-shaped bacterium, designated as 13AT, was isolated from a river sediment sample of Fuyang River in Hengshui City, Hebei Province, PR China. Strain 13AT grew at 10-37 °C (optimum, 30 °C), at pH 5.0-11.0 (optimum, pH 7.0) and at 0-7 % (w/v) NaCl concentration (optimum, 0 %). Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain 13AT belongs to the genus Lysobacter, and was most closely related to Lysobacter spongiicola DSM 21749T (97.8 %), Lysobacter concretionis DSM 16239T (97.5 %), Lysobacter daejeonensis GIM 1.690T (97.3 %) and Lysobacter arseniciresistens CGMCC 1.10752T (96.9 %). Meanwhile, the type species Lysobacter enzymogenes ATCC 29487T was selected as a reference strain (95.2 %). The genomic size of strain 13AT was 3.0 Mb and the DNA G+C content was 69.0 %. The average nucleotide identity values between strain 13AT and each of the reference type strains L. spongiicola DSM 21749T, L. concretionis DSM 16239T, L. daejeonensis GIM 1.690T, L. arseniciresistens CGMCC 1.10752T and L. enzymogenes ATCC 29487T were 75.9, 76.1, 77.7, 78.0 and 73.2 %, respectively. The digital DNA-DNA hybridization values between strain 13AT and each of the reference type strains were 21.7, 22.2, 21.9, 22.7 and 23.2 %, respectively. The average amino acid identity values between strain 13AT and each of the reference type strains were 72.5, 72.9, 72.3, 75.0 and 69.2 %, respectively. The major fatty acids were iso-C15 : 0, iso-C16 : 0 and summed feature 9 (iso-C17 : 1 ω9c and/or C16 : 0 10-methyl). The sole respiratory quinone was identified as ubiquinone-8. The polar lipid profile contained phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, an unidentified aminolipid, an unidentified lipid, four unidentified phospholipids and two unidentified glycolipids. Based on the phenotypic, physiological, phylogenetic and chemotaxonomic data, strain 13AT represents a novel species of the genus Lysobacter, for which the name Lysobacter selenitireducens sp. nov. is proposed. The type strain is 13AT (=JCM 34786T=GDMCC 1.2722T).

Contamination and source of metals in surface sediments from the Nandu River of Hainan Island, China.

Concentrations of eight metals, organic carbon (Corg), and eight oxides were measured in 33 river sediment samples from the Nandu River. Sediment quality guidelines (SQGs) showed no severe pollution at all stations. However, according to the geo-accumulation index (Igeo), enrichment factor (EF), and potential ecological risk index (EI and RI), As and Cd were the primary pollutants in the survey area and caused low to moderate potential ecological risk. The positive correlations between Al2O3, TFe2O3, Mn, Corg, and metals indicated that clay, FeMn oxides, and organic carbon content were the main factors for metal accumulation in the study area. From the results of correlation (CA) and principal component analysis (PCA), we inferred that Cr, Ni, Cu, and Zn were mainly from natural sources, while As, Cd, Hg, and Pb were from anthropogenic activities in the Nandu River basin. This was the first study of metal pollution in the surface sediments of the Nandu River, which will serve as a reference for future research.