Mysterious Morphology: An Investigation of the Octopus Keel and Its Association with Burrowing

The octopus keel is a trait that has been hypothesized to be connected with burrowing in octopuses, but has never been explored in any detail. We investigated the association between these two traits using two approaches. First, we examined the phylogenetic correlation between the presence of a keel and known burrowing behavior in cirrate octopuses. Second, burrowing and non-burrowing captive Muusoctopus leioderma were evaluated for keel prominence to determine whether the keel is lost more rapidly in non-burrowing individuals. Pagel's test for the coevolution of binary characteristics showed the model of best fit for the resulting phylogenetic tree to be one of evolutionary interdependence, and that non-burrowing Muusoctopus leioderma lost their keels over time, while burrowing individuals maintained their keels. Together, these results indicate the keel may be a trait associated with burrowing in octopuses.

Improving the Technology of Primary Purification of the Safflower Oil Using Secondary Products of Processing on a Biological Basis

Safflower oil is a very valuable product for the body and human health. It is rich in macro- and microelements, vitamins and minerals, and also has antioxidant properties. The primary purification of safflower oil is an important stage of its production and directly affects the quality of the final product and its storage ability. Purifying safflower oil using a combination of filtration and sedimentation processes in an experimental cone-shaped centrifuge is a new direction in its processing. The purpose of this study was to determine the effects of flax fiber as a filter material for safflower oil. The Akmai variety of the safflower was tested. The results showed that the quality indicators of safflower oil before and after filtration through flax fiber are different. The amount of unsaturated fatty acids such as oleic (18.31 ± 0.874%) and cis-linoleic acid (82.52 ± 1.854%) increased, as well as the content of arginine (2.1), tyrosine (0.57), methionine (0.4), cystine (2.5), tryptophan (2.6), and other amino acids (in oil g per 100 g of protein). The increase in the total amount of phenols (322.12 ± 6 mgEAG/kg of oil) was observed, which directly caused the higher antioxidant activity (42.65 ± 8%) of the safflower oil. These results demonstrate that flax fiber can enrich safflower oil. To find the optimal conditions for safflower oil centrifugation in a cone-shaped sedimentary-filtering centrifuge, the thickness of the flax fiber and the distance between the inner and outer perforated filter rotor were tested. It was found that the optimal and effective thickness of the flax fiber is 1.5 × 107 nm, while the thickness of the sediment is 0.5 × 107 nm.

Extraction of Common Small Microplastics and Nanoplastics Embedded in Environmental Solid Matrices by Tetramethylammonium Hydroxide Digestion and Dichloromethane Dissolution for Py-GC-MS Determination

Determination of microplastics and nanoplastics (MNPs), especially small MPs and NPs (<150 μm), in solid environmental matrices is a challenging task due to the formation of stable aggregates between MNPs and natural colloids. Herein, a novel method for extracting small MPs and NPs embedded in soils/sediments/sludges has been developed by combining tetramethylammonium hydroxide (TMAH) digestion with dichloromethane (DCM) dissolution. The solid samples were digested with TMAH, and the collected precipitate was washed with anhydrous ethanol to eliminate the natural organic matter. Then, the MNPs in precipitate were extracted by dissolving in DCM under ultrasonic conditions. Under the optimized digestion and extraction conditions, the factors including sizes and concentrations of MNPs showed insignificant effects on the extraction process. The feasibility of this sample preparation method was verified by the satisfactory spiked recoveries (79.6-91.4%) of polystyrene, polyethylene, polypropylene, poly(methyl methacrylate), polyvinyl chloride, and polyethylene terephthalate MNPs in soil/sediment/sludge samples. The proposed sample preparation method was coupled with pyrolysis gas chromatography-mass spectrometry to determine trace small MPs and NPs with a relatively low detection limit of 2.3-29.2 μg/g. Notably, commonly used MNPs were successfully detected at levels of 4.6-51.4 μg/g in 6 soil/sediment/sludge samples. This proposed method is promising for evaluating small solid-embedded MNP pollution.

Roles of sulfate-reducing bacteria in sustaining the diversity and stability of marine bacterial community

Microbes play central roles in ocean food webs and global biogeochemical processes. Yet, the information available regarding the highly diverse bacterial communities in these systems is not comprehensive. Here we investigated the diversity, assembly process, and species coexistence frequency of bacterial communities in seawater and sediment across ∼600 km of the eastern Chinese marginal seas using 16S rRNA gene amplicon sequencing. Our analyses showed that compared with seawater, bacterial communities in sediment possessed higher diversity and experienced tight phylogenetic distribution. Neutral model analysis showed that the relative contribution of stochastic processes to the assembly process of bacterial communities in sediment was lower than that in seawater. Functional prediction results showed that sulfate-reducing bacteria (SRB) were enriched in the core bacterial sub-communities. The bacterial diversities of both sediment and seawater were positively associated with the relative abundance of SRB. Co-occurrence analysis showed that bacteria in seawater exhibited a more complex interaction network and closer co-occurrence relationships than those in sediment. The SRB of seawater were centrally located in the network and played an essential role in sustaining the complex network. In addition, further analysis indicated that the SRB of seawater helped maintain the high stability of the bacterial network. Overall, this study provided further comprehensive information regarding the characteristics of bacterial communities in the ocean, and provides new insights into keystone taxa and their roles in sustaining microbial diversity and stability in ocean.

[Occurrence Characteristics of Microplastics in Baiyangdian Lake Water and Sediments]

In order to explore the occurrence characteristics of microplastics in the freshwater environment of Baiyangdian Lake in China, ten overlying water samples and ten sediment samples were collected in Baiyangdian Lake of Hebei Province in October 2021, and the abundance distribution, shape, particle size, and polymer type of microplastics in the samples were identified using laboratory pretreatment, microscope observation, and laser infrared spectroscopy. The sedimentation law of microplastics at the overlying water-sediment interface was studied using the Stokes sedimentation formula, and their pollution characteristics and potential sources were analyzed. The abundances of microplastics in the overlying water and sediments in Baiyangdian Lake ranged from 474-19382 n·m-3 and 95.3-29542.5 n·kg-1, respectively, with an average value of 6255.4 n·m-3 and 11088 n·kg-1. The main polymer of the microplastics in the overlying water was polyethylene terephthalate[PET, (17.20±0.26)%], and the microplastics in the sediments were mainly chlorinated polyethylene[CPE, (46.11±1.30)%]. The sedimentation velocities of microplastics in the sedimentation zone ranged from 0.0793-111.7547 mm·s-1. The particles with larger particle size had higher sedimentation velocity and easily settled and remained in the sediments. The main sources of microplastic pollution in the study area were the discharge of textile fibers from washing wastewater and the wear and tear of ship paint, ship rubber, and building materials.

Exploration of the candidate beneficial bacteria for Penaeus vannamei culture by core microbiome analysis using amplicon sequencing

Globally, Penaeus vannamei is the vital species in aquaculture production. Beneficial bacterial exploration of gut, sediment, and water were investigated in P. vannamei culture using Illumina Miseq sequencing of 16S RNA V3-V4 hypervariable regions. Predominant phyla identified were Proteobacteria, Tenericutes, Bacteroidetes in gut; Proteobacteria, Bacteroidetes, Planctomycetes in sediment and Cyanobacteria, Proteobacteria, and Planctomycetes in water. In total, 46 phyla, 509 families and 902 genera; 70 phyla, 735 families and 1255 genera; 55 phyla, 580 families and 996 genera were observed in gut, sediment and water, respectively. Diversity of microbial communities in respect of observed Operational Taxonomic Units, diversity indices (Shannon and Simpson), richness index (Chao1) were significantly high P (<0.05) in 60 DoC in gut and 30 DoC in sediment. Beta diversity indicated separate clusters for bacterial communities in gut, sediment and water samples and formation of distinct community profiles. Core microbiome in P. vannamei rearing ponds over a time consisted of 9, 21, and 20 OTUs in gut, rearing water and sediment, respectively. This study helps to intervene with suitable beneficial microbes to establish an aquaculture system thereby contributes to enhance the productivity, improve water quality and pond bottom condition, and control the pathogenic agents at each stage of the culture.

Thiovibrio frasassiensis gen. nov., sp. nov., an autotrophic, elemental sulphur disproportionating bacterium isolated from sulphidic karst sediment, and proposal of Thiovibrionaceae fam. nov

A novel, autotrophic, mesophilic bacterium, strain RS19-109T, was isolated from sulphidic stream sediments in the Frasassi Caves, Italy. The cells of this strain grew chemolithoautotrophically under anaerobic conditions while disproportionating elemental sulphur (S0) and thiosulphate, but not sulphite with bicarbonate/CO2 as a carbon source. Autotrophic growth was also observed with molecular hydrogen as an electron donor, and S0, sulphate, thiosulphate, nitrate and ferric iron as electron acceptors. Oxygen was not used as an electron acceptor and sulphide was not used as an electron donor. Weak growth was observed with sulphate as an electron acceptor and organic carbon as an electron donor and carbon source. The strain also showed weak growth by fermentation of tryptone. It grew at pH 5.5–7.5 (optimum, pH 7.0), 4–35 °C (optimum, 30 °C) and between 0–1.7 % NaCl. Strain RS19-109T was found to be phylogenetically distinct based on 16S rRNA gene sequence similarity (89.2 %) to its closest relative, Desulfurivibrio alkaliphilus AHT2T. The draft genome sequence for strain RS19-109T had average nucleotide identity, average amino acid identity and in silico DNA–DNA hybridization values of 72.2, 63.0 and 18.3 %, respectively, compared with the genome sequence of D. alkaliphilus AHT2T. On the basis of its physiological and genomic properties, strain RS19-109T is proposed as the type strain of a novel species of a novel genus, Thiovibrio frasassiensis gen. nov., sp. nov. A novel family, Thiovibrionaceae fam. nov., is proposed to accommodate Thiovibrio within the order Desulfobulbales . Strain RS19-109T has been deposited at the DSMZ-German Collection of Microorganisms and Cell Cultures (=DSM 115074T) and the American Type Culture Collection (=ATCC TSD-325T).

Shinella sedimenti sp. nov., isolated from sediment of Zhairuo Island located in the East China Sea

A Gram-negative, rod-shaped and aerobic bacterial strain B3.7T, was isolated from the sediment of Zhairuo Island, Zhoushan city, Zhejiang Province, PR China. Maximum growth of strain B3.7T was observed at 30 °C when cultured in a medium containing 0.5 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain B3.7T belonged to the genus Shinella; it showed the highest sequence similarity of 98.47 % to Shinella kummerowiae CCBAU 25048T. The average nucleotide identity and digital DNA-DNA hybridization values between strain B3.7T and its reference strains were 82.9-84.2 % and 26.1-27.3 %, respectively. Chemotaxonomic analysis indicated that the sole respiratory quinone was Q-10 and the predominant cellular fatty acids were C19 : 0 cyclo ω8c, C16 : 0, C18 : 1  ω7c 11-methyl and summed feature 8 (C18 : 1  ω7c and/or C18 : 1  ω6c). The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified phospholipids and two unidentified aminolipids. Collectively, strain B3.7T can be considered to represent a novel species, for which the name Shinella sedimenti sp. nov. is proposed. The type strain is B3.7T (=MCCC 1K07163T=LMG 32559T).

Effects of Florfenicol on nirS-Type Denitrification Community Structure of Sediments in an Aquatic Microcosm Model

Florfenicol is one of the most widely used antibiotics in aquaculture and veterinary clinics because of its low side effects and strong bactericidal effect. A total of 45~60% of florfenicol is not absorbed by the animal body and accumulates in the aquatic environment through a variety of pathways, which affects denitrification. Indoor aquatic microcosm models were constructed and sediment samples were collected at different florfenicol concentrations (0.1, 1, 10, and 100 mg/L) on days 0, 7, 30, and 60 to extract the microbial genome DNA and determine the water properties. qPCR and amplicon sequencing were used to study the dynamic changes in the nirS gene and nirS-type denitrification community structure, diversity, and abundance, respectively. The results showed that high florfenicol stress influenced the sediment's physicochemical properties, reducing conductivity, alkaline dissolved nitrogen, and organic matter content. In addition, the abundance of nirS, a functional denitrification gene, increased obviously with increased florfenicol concentrations but decreased the diversity of nirS-type denitrification microorganisms. Proteobacteria was the dominant denitrifying phylum in the sediment. Our study provides a scientific basis for the rational use of florfenicol in aquaculture to maintain a healthy and stable microecological environment and also provides a preliminary understanding of the response characteristics of water denitrifying microorganisms to florfenicol exposure.

Marine Pollution and Advances in Biomonitoring in Cartagena Bay in the Colombian Caribbean

Coastal zones sustain extensive biodiversity, support key processes for ocean dynamics, and influence the balance of the global environment. They also provide resources and services to communities, determine their culture, and are the basis for their economic growth. Cartagena Bay in the Colombian Caribbean is the place of the establishment of one of the country's main cities, which has a great historical and tourist attraction, and it is also the location of the main commercial port and a great variety of industries. Historically, it has been affected by several environmental impacts and intense pollution. This situation has gained the attention of different researchers, so herein is presented a literature review with a systematic approach using RStudio's bibliometrix on the presence of pollutants and the impact on biodiversity in recent decades, providing a critical analysis of the state of Cartagena Bay and its future needs to ensure its recovery and conservation. In addition, the socioeconomic dynamics related to the environmental state of Cartagena Bay are presented from the framework drivers, pressures, status, impacts, and responses (DPSIR). The update and critical understanding of the sources, fate, and effects of pollution are important not only for the knowledge of the status of this singular ecosystem but also to encourage future research and entrench evidence to support decision makers' actions. This review highlights that several pollutants that have been detected exceeding sediment quality guidelines, like As, Cd, Hg, and PAH, are also reported to bioaccumulate and cause damage throughout the trophic levels of the coastal environment. In addition, the potential use of sentinel species and biomarkers for their monitoring is discussed. Finally, the factors that cause pollution and threaten the state of the bay continue to exert pressure and impact; thus, there is a call for the further monitoring of this ecosystem and the strengthening of policies and regulations.

Benthic Heterotrophic Protist Communities of the Southern Baltic Analyzed with the Help of Curated Metabarcoding Studies

Heterotrophic protists are key components of marine ecosystems. They act as controllers of bacterial and microphytobenthos production and contribute significantly to the carbon flux to higher trophic levels. Still, metabarcoding studies on benthic protist communities are much less frequent than for planktonic organisms. Especially in the Baltic Sea, representing the largest brackish water environment on earth, so far, no extensive metabarcoding studies have been conducted to assess the diversity of benthic protists in this unique and diverse habitat. This study aims to give first insights into the diversity of benthic protist communities in two different regions of the Baltic Sea, Fehmarnbelt, and Oderbank. Using amplicon sequencing of the 18S rDNA V9 region of over 100 individual sediment samples, we were able to show significant differences in the community composition between the two regions and to give insights into the vertical distribution of protists within the sediment (0-20 cm). The results indicate that the differences in community composition in the different regions might be explained by several abiotic factors such as salinity and water depth, but are also influenced by methodological aspects such as differences between DNA and RNA results.

[Bacterial Community Diversity in Channel Sediments of Different Disturbance Sections of the Jialing River]

In order to explore the impact of different anthropogenic disturbances on the ecological environment of natural rivers, the bacterial community in the channel sediments of the Jialing River was taken as the research object, and the high-throughput sequencing technique was used to analyze the community composition and functional changes of bacteria in the channel sediments of rivers with engineering disturbance, tributary disturbance, sand mining disturbance, reclamation disturbance, and undisturbed section. The results showed that there were significant differences in the physical and chemical properties of channel sediments and bacterial community diversity in different disturbance sections of the Jialing River (P<0.05). The undisturbed section had the highest bacterial community diversity, whereas the sand mining disturbance and undisturbed section had the highest bacterial community uniformity, and tributary disturbance and reclamation disturbance both resulted in a decrease in bacterial community diversity and uniformity. The effect of engineering disturbance on bacterial community composition was significantly different from that of the other four disturbance sections. The dominant bacterial phyla were Proteobacteria, Actinobacteriota, Acidobacteriota, and Chloroflexi, and the dominant bacterial classes were γ-Proteobacteria, α-Proteobacteria, and Vicinamibacteria. Sand mining disturbance led to the increase in Actinobacteria, and engineering disturbance promoted the increase in Acidobacteria. Moisture content, total organic carbon, total nitrogen, and total phosphorus were the main environmental factors affecting the changes in sediment microbial communities. The bacterial communities mainly involved four categories of primary metabolic functions, including metabolism, genetic information processing, environmental information processing, and cellular processes, and 18 categories of secondary metabolic functions, such as global and overview maps, carbohydrate metabolism, amino acid metabolism, cofactor and vitamin metabolism, and energy metabolism. Human interference led to significant changes in energy metabolism, cofactor and vitamin metabolism, nucleotide metabolism, replication and repair, and translation (P<0.05). In conclusion, anthropogenic disturbance led to the mutation of bacterial community diversity and function, which destroyed the stability of the microbial community structure in Jialing River sediments.

Experimental evidence associates burrowing behavior of Castalia ambigua (Bivalvia: Hyriidae) with shell shape and density

Information on freshwater mussel behavior in the sediment is scarce worldwide, especially in the Amazon. Laboratory experiments were used to measure the responses of the single mussel species Castalia ambigua in relation to combinations of two co-occurring different morphotypes (Morphotype I with an elongated shell and Morphotype II with a rounded shell), and three different densities (four, eight, and 16 mussels). Horizontal movements (cm) were calculated by summing changes in the position of each specimen and the shell exposure at the sediment-water interface was obtained by measuring (mm) the exposed part of the shell. Castalia ambigua presented different patterns of shell exposure and horizontal movements linked with shell shape and density. Castalia ambigua Morphotype I remained less exposed with 4 mussels. In contrast, this morphotype was more exposed and tended to aggregate in treatments with 8 and 16 mussels, similar to observations of Morphotype II at all densities. Morphotype II is mainly found in low hydrodynamic energy habitats, suggesting that patches with high densities may stabilize the substrate around the shells of Morphotype I, which is associated with high hydrodynamic energy habitats. We suggest that these patterns may be associated with intrinsic factors of the species, such as reproduction, sexual dimorphism and feeding. Moreover, additional studies using other mussel species belonging to the families Hyriidae and Mycetopodidae are important, since the behavior of these mussels in the sediment may provide useful information on their functional roles in river ecosystems.

[Determination of bisphenols in sediment by accelerated solvent extraction and solid-phase extraction purification coupled with ultra performance liquid chromatography-tandem mass spectrometry]

Bisphenols are endocrine disruptors that are characterized with bioaccumulation, persistence, and estrogenic activity. Even low contents of bisphenols can exert adverse effects on human health and the ecological environment. Herein, a method combining accelerated solvent extraction and solid-phase extraction purification with ultra performance liquid chromatography-tandem mass spectrometry was developed for the accurate detection of bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF), bisphenol S (BPS), bisphenol Z (BPZ), bisphenol AF (BPAF), and bisphenol AP (BPAP) in sediments. The mass spectrometric parameters of the seven bisphenols were optimized, and the response values, separation effects, and chromatographic peak shapes of the target compounds were compared under three different mobile phase conditions. The sediment samples were pretreated by accelerated solvent extraction, and orthogonal tests were used to optimize the extraction solvent, extraction temperature, and cycle number. The results showed that the use of 0.05% (v/v) ammonia and acetonitrile as the mobile phase for gradient elution could rapidly separate the seven bisphenols on an Acquity UPLC BEH C₁₈ column (100 mm×2.1 mm, 1.7 μm). The gradient program was as follows: 0-2 min, 60%A; 2-6 min, 60%A-40%A; 6-6.5 min, 40%A; 6.5-7 min, 40%A-60%A; 7-8 min, 60%A. Orthogonal experiments indicated that the optimal extraction conditions were as follows: extraction solvent of acetonitrile, extraction temperature of 100 ℃, and cycle number of three. The seven bisphenols showed good linearity in the range of 1.0-200 μg/L, with correlation coefficients (r²) greater than 0.999, and the limits of detection were 0.01-0.3 ng/g. The recoveries for the seven bisphenols ranged from 74.9% to 102.8% at three spiking levels (2.0, 10, 20 ng/g), with relative standard deviations ranging from 6.2% to 10.3%. The established method was applied to detect the seven bisphenols in sediment samples collected from Luoma Lake and its inflow rivers. BPA, BPB, BPF, BPS, and BPAF were detected in the sediments of the lake, and BPA, BPF, and BPS were detected in the sediments of its inflow rivers. The detection frequency of BPA and BPF was 100%, and the contents of these bisphenols in the sediment were 11.9-38.0 ng/g and 11.0-27.3 ng/g, respectively. The developed method is simple, rapid with high accuracy and precision, and is suitable for the determination of the seven bisphenols in sediment.

Risk Threshold and Assessment of Chloramphenicol Antibiotics in Sediment in the Fenhe River Basin, China

Chloramphenicol antibiotics (CAs) are broad-spectrum antibiotics which are widely used in the prevention and treatment of infectious diseases in livestock and poultry breeding. However, overused CAs can enter the watershed and eventually enter the sediment. Antibiotics in sediment can cause secondary pollution through disturbance and suspension. In this study, taking the Fenhe River Basin as the research area, the risk of CAs in sediment were assessed by collecting sediment samples. The results showed that CAs were detected in all sediment samples of the Fenhe River Basin. The mean concentration of CAs was 79.1 μg/kg, and the concentration of thiamphenicol (THI) was dominant, which was up to 58.3 μg/kg. Temporally, there are great differences in different seasons; the concentration of CAs was higher in winter than that in summer, up to 4.79-174 times. Spatially, the mean concentration of CAs in midstream was 83.5 μg/kg, which was higher than that in the upstream and downstream. The concentration of CAs in tributaries were generally higher than that in the main stream, and the mean concentration of tributaries was 1.1 times that of the main stream. CAs in S2 (Lanhe River) was the most prominent among all sample sites; the concentration of CAs was 190.8 μg/kg. The risk threshold of CAs in the sediment was calculated using the Equilibrium Partitioning approach (EqP), based on the distribution coefficient (Kp) and the predicted no-effect concentration (PNEC) in the water, and the values were 0.091-1.44 mg/kg. Based on the risk threshold, the ecological risk of the CAs in sediment was assessed using risk quotients (RQ). The results showed that the Chloramphenicol (CHL) was the most prominent in the Fenhe River Basin, and the proportion of medium-risk areas reached 21.7%, while all the other areas showed low risk. Secondly, the proportion of medium-risk areas was 17.4% for THI, and all the other areas showed low risk. The risk for Florfenicol (FF) was least among all CAs, and the proportion of low-risk areas was only 8.7%, while all the other areas were of insignificant risk.

Toxicity Evaluation of a Heavy-metal Polluted River: Pollution Identification and Bacterial Community Assessment

The Salt River is an important urban river in Kaohsiung, Taiwan. In this study, the source identification and risk and toxicity assessment of the heavy-metal contaminated sediments in the Salt River were investigated. The geo-accumulation index (Igeo), enrichment factor (EF), sediment quality guidelines (SQGs), potential ecological risk index (RI), pollution load index (PLI), and toxic units (TU) were applied to determine effects of heavy metals on microbial diversities and ecosystems. Results from the ecological and environmental risk assessment show that high concentrations of Zn, Cr, and Ni were detected in the midstream area, the sum of toxic units (ΣTUs) in the midstream (7.2 - 32.0) is higher than in the downstream (14.0 - 19.7) and upstream (9.2 - 17.1). It could be because of the continuous inputs of heavy-meta-contained wastewaters from adjacent industrial parks. Results also inferred that the detected heavy metals in the upstream residential and commercial areas were possibly caused by nearby vehicle emissions, non-point source pollution, and domestic wastewater discharges. Results of metagenomic assays show that the sediments contained significant microbial diversities. Metal-tolerant bacterial phyla (Proteobacteria: 24.4% to 46.4%, Bacteroidetes: 1.3% to 14.8%, and Actinobacteria: 2.3% to 11.1%) and pathogenic bacterial phyla (Chlamydiae: 0.5% to 37.6%, and Chloroflexi: 5.8% to 7.2%) with relatively high abundance were detected. Metal-tolerant bacteria would adsorb metals and cause the increased metal concentrations in sediments. Results indicate that the bacterial composition in sediment environments was affected by anthropogenic pollution and human activities, and the heavy-metal-polluted ecosystem caused the variations in bacterial communities.

[Phosphorus Adsorption in Water and Immobilization in Sediments by Lanthanum-modified Water Treatment Sludge Hydrochar]

Using water treatment sludge and lanthanum chloride as raw materials, lanthanum-modified water treatment sludge hydrothermal carbon was prepared through one-step hydrothermal carbonization and loading lanthanum. SEM-EDS, BET, FTIR, XRD, and XPS were used to characterize the materials. The initial pH of the solution, adsorption time, adsorption isotherm, and adsorption kinetics were investigated to study the adsorption characteristics of phosphorus in water. The results showed that the specific surface area, the pore volume, and the pore size of the prepared materials were significantly increased, and the phosphorus adsorption capacity was greatly improved compared with that of the water treatment sludge. The adsorption process conformed to the pseudo-second-order kinetic model, and the Langmuir model fitted the maximum phosphorus adsorption capacity to 72.69 mg·g^-1. The main adsorption mechanisms were electrostatic attraction and ligand exchange. Adding lanthanum-modified water treatment sludge hydrochar into the sediment could effectively control the release of endogenous phosphorus from the sediment to the overlying water. According to the analysis of phosphorus forms in sediment, the addition of hydrochar promoted the transformation of unstable NH₄Cl-P, BD-P and Org-P into the very stable HCl-P in the sediment, which reduced the content of potential active phosphorus and also significantly reduced the content of biologically available phosphorus. This indicated that lanthanum-modified water treatment sludge hydrochar could effectively adsorb and remove phosphorus in water and could also be used as sediment improvement material to effectively stabilize endogenous phosphorus in sediment and control phosphorus content in water.

[Composition Structure and Influence Factors of Bacterial Communities in the Miyun Reservoir]

As the largest reservoir in North China, the Miyun Reservoir is the most important surface drinking water source in Beijing. Bacteria are key regulators of reservoir ecosystem structure and function, and exploring the community distribution characteristics of bacteria is important for maintaining water quality safety in reservoirs. The spatiotemporal distribution and environmental factors of bacterial communities in the water and sediment of the Miyun Reservoir were explored using the high-throughput sequencing method. The results showed a higher α-diversity and non-significant seasonal variation of the bacterial community in the sediment, and the abundant sedimental species were affiliated with Proteobacteria. For planktonic bacteria, Actinobacteriota was the dominant phylum, and the seasonal variance was represented by CL500-29_marine_group and hgcI_clade in the wet season and Cyanobium_PCC-6307 in the dry season. Additionally, obvious differences in key species were also found in water and sediment, and more indicator species were obtained in sedimental bacteria. Further, a more complex co-existence network was identified in water compared to that in sediment, indicating the strong ability of planktonic bacteria to resist environmental changes. Environmental factors had a significantly higher effect on the bacterial community of the water column than that of the sediment. Furthermore, SO^2-₄ and TN were the main factors affecting planktonic bacteria and sedimental bacteria, respectively. These findings revealed the distribution patterns and driving forces of the bacterial community in the Miyun Reservoir, which will provide important guidance for reservoir management and water-quality assurance.

The effects of Cyclina sinensis bioturbation on alkaline phosphatase (APA) and total microbial hydrolytic activities (MBA) in marine clam-shrimp integrated ponds

This study investigated the influence of Venus clam Cyclina sinensis bioturbation activities on the total benthic microbial and phosphatase activities and selected sediment properties: total phosphorous TP, total organic nitrogen-TON and total organic carbon-TOC. Sediments samples from clam-shrimp integrated-pond and non-clam integrated-pond were sampled for the study in which microbial activity (MBA) and alkaline phosphatase activity (APA), sediment organic contents: TP, TON, TOC, TOM and water quality parameter (dissolved oxygen, temperature, pH and moisture content were analyzed. The p-nitrophenyl phosphate disodium (p-NPP) and Fluorescein diacetate-(FDA) were adopted to measure APA and MBA respectively. Results indicated that microbial activity-MBA and alkaline-phosphatase activity-APA in sediments significantly increased in the pond cultured with clam/shrimp compared to non-clam cultured pond. Phosphate concentration increased significantly and varied among months (p<0.05) implying increased nitrogen concentration in the sediments. The concentrations of total organic nitrogen and total organic carbon didn't differ significantly among months and with the treatments (p>0.05), implying increased TON mineralization. Correlation analyses showed that there was positive correlation with the total microbial activity, alkaline-phosphatase activity, phosphorous concentration and organic matter content within the sediments bioturbated by the Venus clam. The results suggest that, the Venus clam sediment reworking mechanisms in sediment influenced the sediment microbial and APA activities and mineralization thereby affecting the pond alkaline phosphatase enzyme related activities.

[Determination of polybrominated diphenyl ethers in marine sediments by composite chromatography column purification-gas chromatography-negative chemical ionization-mass spectrometry]

Polybrominated diphenyl ethers (PBDEs) are used as additive flame retardants. Because they lack the ability to form chemical bonds, PBDEs can easily enter the sediment environment. The accurate qualitative and quantitative analysis of PBDEs in sediments is of great importance for the accurate assessment of PBDE pollution in this environment. Sediments contain many impurities. Therefore, PBDEs in sediment should be purified before analysis to reduce the matrix effect. A method based on gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI/MS) was developed to determine 13 PBDEs in marine sediment samples using a column packed with deactivated silica gel, acidified silica gel, Florisil, and anhydrous sodium sulfate. Sediment samples were extracted by ultrasonication with a mixed solvent of n-hexane-dichloromethane (3∶1, v/v). After two cycles of ultrasonic extraction, the extract was purified by a composite chromatographic column and eluted with n-hexane-dichloromethane (3∶1, v/v). Thirteen PBDEs were determined by GC-NCI/MS in selected-ion monitoring (SIM) mode. The effects of different fillers, eluents, and elution volumes on the purification of PBDEs in the composite column were compared and analyzed, and the GC-NCI/MS analysis conditions were optimized. Three different packing columns were used to purify the sample extract. The first column was packed with 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, 3 g of Florisil, and 6 g of anhydrous sodium sulfate; the second column was packed with 3 g of Florisil, 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, and 6 g of anhydrous sodium sulfate; and the third column was packed with 3 g of deactivated silica, 6 g of acidified silica, 3 g of deactivated silica, and 6 g of anhydrous sodium sulfate. Among these columns, that packed with 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, 3 g of Florisil, and 6 g of anhydrous sodium sulfate showed the best purification effect. The 13 PBDEs showed good linearity in the mass concentration range of 0.1-20 μg/L with correlation coefficients (r²) greater than 0.995 (decabromodiphenyl oxide (BDE-209), r²>0.99). The limits of quantification (S/N=10) was 0.002-0.126 μg/kg. The average recoveries of the 13 PBDEs at three spiked levels of 0.2, 1.0, and 4.0 μg/kg were 85.3%-101.3%, 84.8%-113.6%, and 86.3%-94.7% with relative standard deviations of 4.4%-14.0%, 0.4%-4.9%, and 1.9%-6.6%, respectively. These findings indicate that the method has high sensitivity and accuracy as well as good precision. Finally, the method was applied to the analysis and detection of PBDEs in actual marine sediment samples. The results revealed that the sediment samples contained different contents of the 13 PBDEs, and high detection rates were obtained for lower-brominated PBDE homologs. The detection rate of bis(4-bromophenyl) ether (BDE-15) was 100%, and the detected content of BDE-209 was as high as 60.49 μg/kg. These results demonstrate that the developed method is suitable for the accurate qualitative and quantitative analysis of PBDEs in marine sediment samples.

Electroactive Bacteria in Natural Ecosystems and Their Applications in Microbial Fuel Cells for Bioremediation: A Review

Electroactive bacteria (EAB) are natural microorganisms (mainly Bacteria and Archaea) living in various habitats (e.g., water, soil, sediment), including extreme ones, which can interact electrically each other and/or with their extracellular environments. There has been an increased interest in recent years in EAB because they can generate an electrical current in microbial fuel cells (MFCs). MFCs rely on microorganisms able to oxidize organic matter and transfer electrons to an anode. The latter electrons flow, through an external circuit, to a cathode where they react with protons and oxygen. Any source of biodegradable organic matter can be used by EAB for power generation. The plasticity of electroactive bacteria in exploiting different carbon sources makes MFCs a green technology for renewable bioelectricity generation from wastewater rich in organic carbon. This paper reports the most recent applications of this promising technology for water, wastewater, soil, and sediment recovery. The performance of MFCs in terms of electrical measurements (e.g., electric power), the extracellular electron transfer mechanisms by EAB, and MFC studies aimed at heavy metal and organic contaminant bioremediationF are all described and discussed.

Paenibacillus sedimenti sp. nov., isolated from freshwater wetland sediment

A Gram-stain-positive, motile, rod-shaped, facultatively anaerobic bacterium, designated strain WST5^T, isolated from sediment was characterized using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain WST5^T was most closely related to Paenibacillus aestuarii CJ25^T (96.8 % similarity). The genome size of the WST5^T was 6.5 Mb, contained 4500 predicted protein-coding genes, and had a DNA G+C content of 46.6%. The values of whole-genome average nucleotide identity analysis and digital DNA-DNA hybridization between strain WST5^T and its closely related type strains were less than 76 and 25.6 %, respectively. The predominant cellular fatty acids (>10 %) were anteiso-C_15 : 0 and C_16 : 1 ω5c and the main menaquinone was MK-7. The major polar lipids were identified as diphospholidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and two unknown aminophospholipids. Based on the results of phenotypic, genotypic, chemotaxonomic and phylogenetic analyses, strain WST5^T is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus sedimentum sp. nov. is proposed. The type strain is WST5^T (=NBRC 115194 ^T=CGMCC 1.18706^T).

Effect of Anthropogenic Disturbances on the Microbial Relationship during Bioremediation of Heavy Metal-Contaminated Sediment

Soil, sediment, and waters contaminated with heavy metals pose a serious threat to ecosystem function and human health, and microorganisms are an effective way to address this problem. In this work, sediments containing heavy metals (Cu, Pb, Zn, Mn, Cd, As) were treated differently (sterilized and unsterilized) and bio-enhanced leaching experiments were carried out with the addition of exogenous iron-oxidizing bacteria A. ferrooxidans and sulfur-oxidizing bacteria A. thiooxidans. The leaching of As, Cd, Cu, and Zn was higher in the unsterilized sediment at the beginning 10 days, while heavy metals leached more optimally in the later sterilized sediment. The leaching of Cd from sterilized sediments was favored by A. ferrooxidans compared to A. thiooxidans. Meanwhile, the microbial community structure was analyzed using 16S rRNA gene sequencing, which revealed that 53.4% of the bacteria were Proteobacteria, 26.22% were Bacteroidetes, 5.04% were Firmicutes, 4.67% were Chlamydomonas, and 4.08% were Acidobacteria. DCA analysis indicated that microorganisms abundance (diversity and Chao values) increased with time. Furthermore, network analysis showed that complex networks of interactions existed in the sediments. After adapting to the acidic environmental conditions, the growth of some locally dominant bacteria increased the microbial interactions, allowing more bacteria to participate in the network, making their connections stronger. This evidence points to a disruption in the microbial community structure and its diversity following artificial disturbance, which then develops again over time. These results could contribute to the understanding of the evolution of microbial communities in the ecosystem during the remediation of anthropogenically disturbed heavy metals.

Total organic carbon concentrations in clastic cave sediments from Butler Cave, Virginia, USA: implications for contaminant fate and transport

Clastic cave deposits are representative of sediments throughout the karst aquifer and thus are an abundant and accessible resource through which to study the chemistry of karst aquifer. Clastic cave sediments are attributed to depositional facies based on cave location, sorting, and particle size. These facies settings may influence different chemical parameters of the sediments, like concentrations of total organic carbon (TOC). The TOC concentrations in clastic cave sediments have not been well constrained nor has the role of clastic sediments in contaminant fate and transport through karst systems been well described. In this study, particle size, TOC, and total nitrogen were measured in sediments representing different facies in Butler Cave, Virginia, USA. TOC concentrations ranged from 0.08 - 0.87 weight percent and C:N molar ratio ranged from 3 - 15, indicating a possible terrestrial source of organic carbon in these sediments. The diamicton facies was sandier and but had similar TOC concentrations compared to the channel facies. TOC concentrations measured in Butler Cave were within the same range as those observed in above water, eogenetic clastic cave sediments from two caves in Puerto Rico. Estimated retardation factors calculated based on the TOC concentrations in the Butler Cave sediments indicate the range of TOC in this cave could be responsible for 39 - 987% increase in retardation of selected contaminants. This study highlights the importance of measuring the ranges of TOC in clastic cave sediments across different facies and their role in contaminant fate and transport.

Paleo-Geomorphology Determines Spatial Variability of Geogenic Ammonium Concentration in Quaternary Aquifers

Naturally occurring (i.e., geogenic) ammonium in groundwater has been widely detected globally, but the major controls on its regional distribution have been poorly characterized. Here, we identified the dominant role of paleo-geomorphology driven by paleo-climate in controlling the spatial variability of geogenic ammonium in groundwater using random forest algorithm and revealed the underlying mechanisms based on borehole sediment analysis of data obtained from the Dongting Lake Plain of the central Yangtze River basins in China. In the paleo-channel (PC) area, the aquifer depth-matched sediments were deposited during the last deglaciation when warm climate resulted in rapid filling into incised valleys, and terrestrial organic matter (OM) mainly as lignin experienced less degradation prior to sedimentation and had lower humification, higher N abundance, and nominal oxidation state of carbon (NOSC). In the paleo-interfluve (PI) area, the depth-matched sediments were deposited during the last glaciation, followed by intensive erosion in the surface during the last glacial maximum, and terrestrial OM mainly as lignin had been partly degraded into aliphatics prior to sedimentation and had higher humification, lower N abundance, and NOSC. As a result, under the present anaerobic conditions, less-humic and N-rich OM with more oxidized C tends to be more intensively mineralized into ammonium in the PC area than those in the PI area. These findings highlight the importance of paleo-geomorphology with paleo-climate in controlling the enrichment of geogenic ammonium in groundwater, which has a universal significance for understanding the genesis and distribution of high N loads in the aquatic environment worldwide.

[Effects of Heavy Metal Pollution on the Structure of Microbial Communities in Different Habitats]

Heavy metal pollution seriously threatens the diversity and composition of microbial communities in various ecosystems. However, little is known about the effects of heavy metal pollution on the structure of microbial communities in the three habitats of "surface water-sediment-groundwater." Here, with help of 16S rRNA high-throughput sequencing technology, the diversity and composition of microbial communities, as well as the underlying controlling factors, were investigated and compared among the surface water, sediment, and groundwater of the Tanghe sewage reservoir. The results showed significant differences in the diversity of microbial communities among different habitats, with the highest α diversity observed in groundwater rather than surface water or sediment. Meanwhile, microbial communities also displayed distinct compositions among the three different habitats. Specifically, Pedobacter, Hydrogenophaga, Flavobacterium, and Algoriphagus were dominant in surface water; metal-tolerant bacteria such as Ornatilinea, Longilinea, Thermomarinilinea, and Bellilinea prevailedin sediment; and Arthrobacter, Gallionella, and Thiothrix were abundant in groundwater. Furthermore, physicochemical factors and metal variables jointly determined the microbial community structure in the three habitats. Among the influencing factors,pH, NO₃^--N, and Li were the main factors affecting the microbial structure in surface water; TP, NH₄⁺-N, Cr, Fe, Cu, and Zn significantly impacted microorganisms in sediment; and only pH (not metal pollutants) was weakly associated with the microbial composition in groundwater. Overall, heavy metal pollution significantly shaped the microbial community structure in sediment, followed by that in surface water and groundwater. These results provide important scientific guidance for the ecological restoration and the sustainable development of heavy metal-polluted ecosystems.

Synthetic stormwater for laboratory testing of filter materials

Synthetic stormwater was tested to determine the ageing effects on dissolved metal concentrations and used in a column experiment to determine efficiency of four different filter materials (milkweed, bark, peat, polypropylene) in removing total and dissolved metals. Synthetic stormwater was created by adding metal salts, oil and collected stormwater sediment to tap water. Two ageing experiments were performed to determine the change of synthetic stormwater quality over time. One experiment lasted for 11 days and another focused on rapid concentration changes one day after preparation. The one-day ageing experiment showed rapid decrease in dissolved concentration of certain metals, specifically Cu. To consider this change, correction coefficients for each metal were developed and used to estimate the average dissolved metal concentration in the synthetic stormwater during the experiment to determine filter treatment efficiency. During the 11-day experiment on metal concentrations, no noticeable quality changes were observed for at least six days after the preparation of synthetic stormwater. Furthermore, a column experiment was run with duplicate filter columns. Inflow and outflow samples were analysed for total and dissolved metals, turbidity, particle size distribution, and pH. High removal of total metal concentrations was noticed in all tested filter media (58-94%). Dissolved metal concentration removal varied among different filter media. In general, columns with bark and peat media were able to treat dissolved metals better than polypropylene and milkweed. The level of treatment of dissolved metals between the different filter media columns were bark > peat > milkweed > polypropylene.

Ectobacillus ponti sp. nov., a novel bacterium isolated from Pearl River Estuary

A Gram-staining-positive, aerobic, motile, and rod-shaped strain, designated SYSU M60031^T, was isolated from a Pearl River Estuary sediment sample, Guangzhou, Guangdong, China. The isolate could grow at pH 5.0-8.0 (optimum, pH 7.0), 25-37 °C (optimum, 28 °C) and in the presence of 0-1 % (w/v) NaCl (optimum, 0 %). The predominant respiratory menaquinone of SYSU M60031^T was MK-7. The cellular polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, one unidentified aminophospholipid, and one unidentified aminolipid. The major fatty acids (>10 % of total) were iso-C_14 : 0, iso-C_15 : 0, anteiso-C_15 : 0, iso-C_16 : 0, and C_16 : 0. The genomic DNA G+C content was 51.2 %. Phylogenetic analyses based on 16S rRNA gene sequences and core genes indicated that strain SYSU M60031^T belonged to the genus Ectobacillus and showed the highest sequence similarity to Ectobacillus funiculus NAF001^T (96.16%), followed by Ectobacillus antri SYSU K30001^T (95.08 %). Based on the phenotypic, genotypic, and phylogenetic data, strain SYSU M60031^T should be considered to represent a novel species of the genus Ectobacillus, for which the name Ectobacillus ponti sp. nov. is proposed. The type strain of the proposed novel isolate is SYSU M60031^T (=CGMCC 1.19243^T =NBRC 115614^T).

Pond Sediments Reveal the Increasing Importance of Road Runoff as a Source of Metal Contamination in Industrialized Urban Environments Downwind of Pittsburgh, Pennsylvania (USA)

Toxic levels of trace metals from human activities accumulate in natural environments, yet these metal mixtures are rarely characterized or quantified. Metal mixtures accumulate in historically industrial urban areas and change as economies shift. Previous research has often focused on the sources and fate of a specific element, which limits our understanding of metal contaminant interactions in our environment. Here, we reconstruct the history of metal contamination in a small pond downstream of an interstate highway and downwind of fossil fuel and metallurgical industries that have been active since the middle of the nineteenth century. Metal contamination histories were reconstructed from the sediment record using metal ratio mixing analysis to attribute the relative contributions of contamination sources. Cadmium, copper, and zinc concentrations in sediments accumulated since the construction of major road arteries in the 1930s and 40s are, respectively, 3.9, 2.4, and 6.6 times more concentrated than those during industry-dominated time periods. Shifts in elemental ratios suggest these changes in metal concentrations coincide with increased contributions from road and parking lot traffic, and to a lesser extent, from airborne sources. The metal mixture analysis demonstrates that in near-road environments, contributions from modern surface water pathways can obscure historical atmospheric industrial inputs.

[Pollution Characteristics of Organochlorine Pesticides in Water and Sediments of Huixian Karst Wetland in Guilin]

Karst wetland plays an important role in the ecological environment; however, due to the existence of karst pipeline, pollutants can threaten the underground environment through the highly developed karst pipeline. Therefore, understanding the pollution characteristics of the karst surface environment is the premise of pollution ecological risk assessment and prevention. In this study, 24 organochlorine pesticides (OCPs) were analyzed to study the concentration, composition, source, and risk of OCPs in water and surface sediments in the Huixian Wetland of Guilin. The results showed that:the concentration of OCPs in water ranged from 3.17 ng·L^-1 to 92.50 ng·L^-1, and the concentration of OCPs in sediment ranged from 1.16 ng·g^-1 to 219.52 ng·g^-1, showing the main pollution characteristics of HCHs and DDTs. The concentration of OCPs in water was higher in the wet season than that in the dry season. The concentration of OCPs in sediments was higher in the dry season than that in the wet season. The isomer ratios revealed that OCPs in the study area were mainly derived from long-term degradation residues, and some sites had new input of lindane. Based on Monte Carlo simulation, the human health risk assessment of the study area showed that the 95% quantile carcinogenic risk of OCPs in water was greater than 1×10^-6, with potential but acceptable health risk. The non-carcinogenic risk was lower than 1, which indicated that the level of OCPs residues in the water in the study area was not enough to cause non-carcinogenic risk to the human body.

[Vertical Distribution and Source Tracking Analysis of Bacteria Composition and Nitrogen Metabolism Function of a Typical Urban Inland River]

Microorganisms play an important role in the urban river nitrogen cycle. Due to the three-dimensional fluidity of river water, it is necessary to clarify the vertical distribution of community composition and nitrogen metabolism functions of microorganisms and discover how hydrodynamic factors influence microorganism sources and community composition. Based on 16S rRNA high-throughput sequencing technology, the bacteria community composition and nitrogen metabolism function of water and sediment in the North Canal at Tongzhou District Beijing City were analyzed. The effect of environmental and hydrodynamic factors on community composition and sources were studied. The results showed that the α diversity of sediment was significantly higher than that of water. Proteobacteria was the most abundant phylum, which accounted for 54.72% and 32.36% in water and sediment, respectively. Functional prediction conducted using PICRUSt2 showed that the studied North Canal had an abundance of nitrogen metabolism ability, and 47 genes related to the nitrogen cycle were obtained. Water and sediment microorganisms had a similar distribution of nitrogen metabolism functions. The copy number of genes involved with denitrification, nitrogen assimilation, and dissimilation-reduction were high, whereas the abundance of genes related to biological nitrogen fixation and nitrification were relatively low. Source tracking analysis showed that bacteria in the water that originated from upstream, neighboring sides, and sediment were 60.05%, 37.93%, and 1.05%, respectively. The amounts of bacteria in sediment that migrated from upstream, neighboring sides, and water were 50.16%, 45.55%, and 1.55%, respectively. Environmental factors, hydrodynamic conditions, and their interactions explained water bacteria community composition for 44.22%, 3.21%, and 15.60%, respectively. For sediment bacteria, the degree of explanation was 13.05%, 1.56%, and 8.51%, respectively. This indicated that environmental factors and hydrodynamic factors controlled the community composition and nitrogen cycle functions together.

Small Butt Harmful: Individual- and Population-Level Impacts of Cigarette Filter Particles on the Deposit-Feeding Polychaete Capitella teleta

In the marine environment, discarded cigarette filters (CFs) deteriorate and leach filter-associated chemicals. The study aim was to assess the effects of smoked CFs (SCFs) and non-smoked CFs (NCFs) particles on individual life-history traits in the deposit-feeding polychaete Capitella teleta and extrapolate these to possible population-level effects. C. teleta was exposed to sediment-spiked particles of NCFs and SCFs at an environmentally realistic concentration (0.1 mg particles g^-1 dw sed) and a 100-fold higher (10 mg particles g^-1 dw sed) concentration. Experimental setup incorporated 11 individual endpoints and lasted approximately 6 months. There were significant effects on all endpoints, except from adult body volume and egestion rate, in worms exposed to 10 mg SCF particles g^-1 dw sed. Although not statistically significant, there was ≥50% impact on time between reproductive events and number of eggs per female at 0.1 mg SCF particles g^-1 dw sed. None of the endpoints was significantly affected by NCFs. Results suggest that SCFs are likely to affect individual life-history traits of C. teleta, whereas the population model suggests that these effects might not transform into population-level effects. The results further indicate that chemicals associated with CFs are the main driver causing the effects rather than the CF particles.

Diverse Methylmercury (MeHg) Producers and Degraders Inhabit Acid Mine Drainage Sediments, but Few Taxa Correlate with MeHg Accumulation

Methylmercury (MeHg) is a notorious neurotoxin, and its production and degradation in the environment are mainly driven by microorganisms. A variety of microbial MeHg producers carrying the gene pair hgcAB and degraders carrying the merB gene have been separately reported in recent studies. However, surprisingly little attention has been paid to the simultaneous investigation of the diversities of microbial MeHg producers and degraders in a given habitat, and no studies have been performed to explore to what extent these two contrasting microbial groups correlate with MeHg accumulation in the habitat of interest. Here, we collected 86 acid mine drainage (AMD) sediments from an area spanning approximately 500,000 km² in southern China and profiled the sediment-borne putative MeHg producers and degraders using genome-resolved metagenomics. 46 metagenome-assembled genomes (MAGs) containing hgcAB and 93 MAGs containing merB were obtained, including those from various taxa without previously known MeHg-metabolizing microorganisms. These diverse MeHg-metabolizing MAGs were formed largely via multiple independent horizontal gene transfer (HGT) events. The putative MeHg producers from Deltaproteobacteria and Firmicutes as well as MeHg degraders from Acidithiobacillia were closely correlated with MeHg accumulation in the sediments. Furthermore, these three taxa, in combination with two abiotic factors, explained over 60% of the variance in MeHg accumulation. Most of the members of these taxa were characterized by their metabolic potential for nitrogen fixation and copper tolerance. Overall, these findings improve our understanding of the ecology of MeHg-metabolizing microorganisms and likely have implications for the development of management strategies for the reduction of MeHg accumulation in the AMD sediments. IMPORTANCE Microorganisms are the main drivers of MeHg production and degradation in the environment. However, little attention has been paid to the simultaneous investigation of the diversities of microbial MeHg producers and degraders in a given habitat. We used genome-resolved metagenomics to reveal the vast phylogenetic and metabolic diversities of putative MeHg producers and degraders in AMD sediments. Our results show that the diversity of MeHg-metabolizing microorganisms (particularly MeHg degraders) in AMD sediments is much higher than was previously recognized. Via multiple linear regression analysis, we identified both microbial and abiotic factors affecting MeHg accumulation in AMD sediments. Despite their great diversity, only a few taxa of MeHg-metabolizing microorganisms were closely correlated with MeHg accumulation. This work underscores the importance of using genome-resolved metagenomics to survey MeHg-metabolizing microorganisms and provides a framework for the illumination of the microbial basis of MeHg accumulation via the characterization of physicochemical properties, MeHg-metabolizing microorganisms, and the correlations between them.

Recent Progress on Ex Situ Remediation Technology and Resource Utilization for Heavy Metal Contaminated Sediment

Sediment is an important part of aquatic systems, which plays a vital role in transporting and storing metals. Due to its abundance, persistence, and environmental toxicity, heavy metal pollution has always been one of the hot spots in the world. In this article, the state-of-art ex situ remediation technology for metal-contaminated sediments is elaborated, including sediment washing, electrokinetic remediation (EKR), chemical extraction, biological treatment, as well as encapsulating pollutants by adding some stabilized/solidified materials. Furthermore, the progress of sustainable resource utilization methods, such as ecosystem restoration, construction materials (e.g., materials fill materials, partition blocks, and paving blocks), and agriculture use are reviewed in detail. Finally, the pros and cons of each technique are summarized. This information will provide the scientific basis for selecting the appropriate remediation technology in a particular scenario.

Solvent-Free Nonthermal Destruction of PFAS Chemicals and PFAS in Sediment by Piezoelectric Ball Milling

Studies on the destruction of solid per- and polyfluoroalkyl substances (PFAS) chemicals and PFAS-laden solid wastes significantly lag behind the urgent social demand. There is a great need to develop novel treatment processes that can destroy nonaqueous PFAS at ambient temperatures and pressures. In this study, we develop a piezoelectric-material-assisted ball milling (PZM-BM) process built on the principle that ball collisions during milling can activate PZMs to generate ∼kV potentials for PFAS destruction in the absence of solvents. Using boron nitride (BN), a typical PZM, as an example, we successfully demonstrate the complete destruction and near-quantitative (∼100%) defluorination of solid PFOS and perfluorooctanoic acid (PFOA) after a 2 h treatment. This process was also used to treat PFAS-contaminated sediment. Approximately 80% of 21 targeted PFAS were destroyed after 6 h of treatment. The reaction mechanisms were determined to be a combination of piezo-electrochemical oxidation of PFAS and fluorination of BN. The PZM-BM process demonstrates many potential advantages, as the degradation of diverse PFAS is independent of functional group and chain configurations and does not require caustic chemicals, heating, or pressurization. This pioneering study lays the groundwork for optimizing PZM-BM to treat various PFAS-laden solid wastes.

Sediment Microbiota as a Proxy of Environmental Health: Discovering Inter- and Intrakingdom Dynamics along the Eastern Mediterranean Continental Shelf

Sedimentary marine habitats are the largest ecosystem on our planet in terms of area. Marine sediment microbiota govern most of the benthic biological processes and therefore are responsible for much of the global biogeochemical activity. Sediment microbiota respond, even rapidly, to natural change in environmental conditions as well as disturbances of anthropogenic sources. The latter greatly impact the continental shelf. Characterization and monitoring of the sediment microbiota may serve as an important tool for assessing environmental health and indicate changes in the marine ecosystem. This study examined the suitability of marine sediment microbiota as a bioindicator for environmental health in the eastern Mediterranean Sea. Integration of information from Bacteria, Archaea, and Eukaryota enabled robust assessment of environmental factors controlling sediment microbiota composition: seafloor-depth (here representing sediment grain size and total organic carbon), core depth, and season (11%, 4.2%, and 2.5% of the variance, respectively). Furthermore, inter- and intrakingdom cooccurrence patterns indicate that ecological filtration as well as stochastic processes may control sediment microbiota assembly. The results show that the sediment microbiota was robust over 3 years of sampling, in terms of both representation of region (outside the model sites) and robustness of microbial markers. Furthermore, anthropogenic disturbance was reflected by significant transformations in sediment microbiota. We therefore propose sediment microbiota analysis as a sensitive approach to detect disturbances, which is applicable for long-term monitoring of marine environmental health. IMPORTANCE Analysis of data, curated over 3 years of sediment sampling, improves our understanding of microbiota assembly in marine sediment. Furthermore, we demonstrate the importance of cross-kingdom integration of information in the study of microbial community ecology. Finally, the urgent need to propose an applicable approach for environmental health monitoring is addressed here by establishment of sediment microbiota as a robust and sensitive model.

Phytoremediation Competence of Composite Heavy-Metal-Contaminated Sediments by Intercropping Myriophyllum spicatum L. with Two Species of Plants

A variety of remediation approaches have been applied to reduce the harm and diffusion of heavy metals in aquatic sediments; however, phytoremediation in co-contaminated soils is still not clear. In order to explore the phytoremediation of sediments contaminated by Cu and Pb, two submerged plants with different characteristics, Vallisneria natans and Hydrilla verticillata, were interplanted with Myriophyllum spicatum. By simulating a submerged plant ecological environment, medium-scale-simulated ecological remediation experiments were carried out. The results showed that the two planting patterns were effective in repairing the sediments in the Cu and Pb contaminated sediments. The intercropping of Myriophyllum spicatum and Vallisneria natans can be used as the plant stabilizer of Cu because of the TF > 1 and BCF < 1, and the intercropping with Hydrilla verticillata can regulate the enrichment efficiency of Myriophyllum spicatum. The removal rates of Cu and Pb in sediments reached 26.1% and 68.4%, respectively, under the two planting patterns. The risk grade of the restored sediments was RI < 150, indicating a low risk.

[Biogeographic Distribution Patterns and Ecological Mechanisms of Benthic Eukaryotic Microorganisms in Jinsha River]

Eukaryotic microbial communities play an important role in biogeochemical cycling and maintaining the health and stability of ecosystems. However, little is known about the geographical distribution patterns, key driving mechanisms, and interspecific interactions of eukaryotic microorganisms in large rivers. This study investigated the geographical distribution characteristics, influencing factors, and interspecific interactions of eukaryotic microorganisms in sediments from the Jinsha River, a cascade hydropower development river in southwest China. The results showed that the α-diversity indices of benthic eukaryotic microorganisms in the Jinsha River increased first and then decreased. The community structure and relative abundance of dominant genera of benthic eukaryotic microorganisms differed significantly among different reaches. The results of distance decay analysis showed that the community assembly of benthic eukaryotic microorganisms in the Jinsha River was influenced by environmental selection and dispersal limitation. The results of variance partitioning analysis and neutral model further demonstrated that the geographical distribution pattern was mainly driven by dispersal limitation. The co-occurrence network analysis revealed that the interspecific competition and network connectivity of the cascade dam reach were weaker than those of the upstream natural reach, indicating that the interactions of benthic eukaryotic microorganisms were stronger in the upstream natural reach. This study supplemented the lack of data on the diversity and geographical distribution of benthic eukaryotic microorganisms in the river of southwest China and provided data support for the ecological response of benthic eukaryotic microorganisms in the river of cascade hydropower development.

[Spatial Distribution and Risk Assessment of Heavy Metals in Surface Sediments from the Middle and Upper Reaches of the Yangtze River]

The hydrological regime of rivers significantly changes after dam impoundment, which in turn affects the particle composition and heavy metal fractions of the river sediments. From June to July 2019, the sediments from 26 sampling sections were collected along the main stream of the Yangtze River from Panzhihua City in the upper reaches of the Yangtze River to Hukou City in the middle reaches of the Yangtze River. The concentrations and fractions of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn were measured using the BCR three-step extraction procedure. The pollution status and potential ecological risk of heavy metals in sediments were evaluated using the geo-accumulation index, the sediment quality guideline, and the risk assessment coding method (RAC). The results showed that the average particle size of sediments in the upper reaches of the Yangtze River (Jinsha River cascade reservoir section and the Three Gorges reservoir section) decreased from upstream to downstream, the total concentrations of As and Zn increased, and the variation trend in the middle reaches was not obvious. The content of clay particles was significantly positively correlated with the acid-soluble fraction concentrations of Cd and Ni. Cd was mainly in the residual fraction (59.26%) and acid-soluble fraction (24.67%). Large parts of Cr and Ni were residual fractions accounting for 92.41% and 83.41%, respectively. As, Co, Cu, Pb, and Zn were mainly in the residual fraction and the reducible fraction. The order of decrease for the pollution degree (I_geo) of As, Cd, Co, Cr, Ni, and Zn was the Jinsha River, the middle reaches of the Yangtze River, and the Three Gorges Reservoir. The decrease order of bioavailability (RAC) of Cd, Co, Cr, Cu, Ni, and Zn was the Three Gorges Reservoir, the Jinsha River, and the middle reaches of the Yangtze River. The bioavailability of As and Pb decreased in the order of the middle reaches of the Yangtze River, the Three Gorges, and the Jinsha River. According to the classification of the RAC, Cd in the Three Gorges Reservoir area exhibited a high risk with the RAC accounting for 48.44%. Cu, Ni, and Zn showed a low or medium risk.

Plutonium Signatures in a Dated Sediment Core as a Tool to Reveal Nuclear Sources in the Baltic Sea

Plutonium distribution was studied in an undisturbed sediment core sampled from the Tvären bay in the vicinity of the Studsvik nuclear facility in Sweden. The complete analysis, including minor isotopes, of the Pu isotope composition (²³⁸Pu, ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Pu, ²⁴²Pu, and ²⁴⁴Pu) allowed us to establish the Pu origin in this area of the Baltic Sea and to reconstruct the Studsvik aquatic release history. The results show highly enriched ²³⁹Pu, probably originating from the Swedish nuclear program in the 1960s and 1970s and the handling of high burn-up nuclear fuel in the later years. In addition, the ²⁴⁴Pu/²³⁹Pu atomic ratio for the global fallout period between 1958 and 1965 is suggested to be (7.94 ± 0.31)·10^-5. In the bottom layer of the sediment, dated 1953-1957, we detected a higher average ²⁴⁴Pu/²³⁹Pu ratio of (1.51 ± 0.11)·10^-4, indicating the possible impact of the first US thermonuclear tests (1952-1958).

Biota-Sediment Accumulation Factors for Per- and Polyfluoroalkyl Substances

Per- and polyfluoroalkyl substances (PFAS) are widely used in commercial products such textiles, firefighting foams, and surface coatings across the globe and some PFAS are known to be bioaccumulative in aquatic species. The ultimate sink for numerous anthropogenic chemicals is the sediments in lakes, rivers, and oceans. To understand the relationship between sediment and aquatic species, a literature search was performed and biota-sediment accumulation factors (BSAFs) data for 17 taxonomic classes were assembled. The carbonyl and sulfonyl PFAS classes were relatively data rich whereas phosphate (no measurements), ether (one chemical), and fluorotelomer (limited number of chemicals) PFAS classes were data poor. Taxonomic classes of Teleostei and Clitellata had the largest BSAFs whereas Magnoliopsida and Bivalvia had the smallest BSAFs, and BSAF values >1 (kg-OC/kg-wet wt) were very rare. Across all studies, median (±standard deviation) whole-body Teleostei BSAFs for perfluorooctane sulfonic acid and perfluorooctanoic acid (kg-OC/kg-wet wt) were 0.0580 (±0.445, n = 60) and 0.00283 (±0.103,24), respectively. Laboratory-measured BSAFs were consistently larger than field-measured BSAFs, that is, 53 of 67 comparisons were larger (80%). Comparing BSAFs across taxonomic classes, 72% of the BSAFs were significantly different (α = 0.05). Comparing BSAFs within a taxonomic class, BSAFs were significantly different for 63% of the taxonomic classes. Elimination kinetics for benthic invertebrates suggests steady-state conditions might be reached in the 28-day uptake portion of a laboratory bioaccumulation test for some test species. The largest data gaps, beyond limited measurements, are understanding the effects of concentration and mixtures on bioaccumulation from sediments, quantifying the difference, if any, in BSAFs between freshwater and brackish/marine ecosystems, and models for predicting BSAFs based on concentrations in sediment. Environ Toxicol Chem 2023;42:277-295. © 2022 SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Effects of Bellamya purificata Cultivation at Different Stocking Densities on the Dynamics and Assembly of Bacterial Communities in Sediment

To optimize the integrated multi-trophic aquaculture (IMTA) model, improve the efficiency of resource utilization, and reduce environmental pollution, Bellamya purificata, as a potential bioremediation species, was studied to investigate the effect of B. purificata culture on the dynamics and assembly of bacterial communities in sediment. Four experimental groups were established at four different densities: 0, 234.38, 468.75, and 937.5 g/m² (represented as CON, LD, MD, and HD, respectively). Each group was with three replicates. The 16S ribosomal RNA (rRNA) high-throughput sequencing was used to evaluate the composition, function, and assembly of bacterial communities in sediment. B. purificata cultivation significantly altered the composition and function of the bacterial communities in sediment; at high stocking density, it significantly decreased anaerobic and increased aerobic organic matter decomposition, whereas at low stocking density, it decreased the number of bacteria involved in sulfate reduction and inhibited the denitrification process. B. purificata decreased direct competition and promoted collaboration or niche sharing in bacterial communities, especially at the high stocking density. Moreover, B. purificata cultivation resulted in greater changes in the environmental factors. Variations in dissolved oxygen, pH, total nitrogen, nitrate, and nitrite levels were closely related to the altered composition and function of the bacterial communities. Stochastic processes dominated the bacterial community assembly in the sediment and B. purificata cultivation had limited impacts on the bacterial community assembly. The study provided a reference for the dynamics and assembly of bacterial communities in sediment with different densities of B. purificata cultivation and we hope that the findings will provide a theoretical reference for the optimization of IMTA and improve management strategies for B. purificata polyculture.

Impacts of the Residual Trace Metals of Aquaculture in Net Cages on the Quality of Sediment

Anthropogenic pollution by trace metals in aquatic environments in semiarid zones is a critical area of investigation. The objective of this study was to investigate the concentration and spatial distribution of trace metals in surface sediments in the Rosário reservoir, which is affected by the intensive aquaculture of Tilápia-do-Nilo (Oreochromis niloticus). Sediment samples were collected in three different areas, postculture (PCTV), cultivation (CTV) and control (CTRL) in the dry season in 2019. The granulometric composition, organic matter and concentrations of Fe, Mn, Zn, Cu, Cr, Cd, Pb and Ni metals were determined. Multivariate statistics were used. Geochemical and ecotoxicological indices and a comparison with sediment quality guidelines (SQG) were used. The sediment was characterized by silty clay loam with an average organic matter of 18.76 ± 4.27. The analytical merit figures demonstrated accuracy (metal recoveries in certified standards) between 89 to 99% and high precision (RSD < 5%). The concentration ranges for the metals were Fe: 0.11-0.85 (%), Mn: 14.46-86.91, Zn: 2.6-220.56, Cu: 26.89-98.75, Cr: 60.18-76.06, Cd: 0.38-0.59, Pb: 18.13-43.13, and Ni: 34.4-46.75, all in (mg/kg^-1). The highest concentration values were found in the CTV areas (Fe: 40 ± 0.22, Mn: 66.48 ± 19.11, Zn: 114.83 ± 59.75 and Cr: 70.85 ± 2.62) and PCTV (Cd: 0.53 ± 0.04, Cu: 71.83 ± 21.20, Pb: 33.71 ± 4.34 and Ni: 44.60 ± 1.79). Pearson's correlation, hierarchical cluster analysis and principal component analysis confirmed the influence of fish farming on metals. Only Ni presented concentration values higher than the reference value established in the SQG. Thus, considering the probable geochemical and ecotoxicological effects, they comprise the two lowest levels of impact.

Investigating Environmental Matrices for Use in Avian Influenza Virus Surveillance-Surface Water, Sediments, and Avian Fecal Samples

Surveillance of avian influenza viruses (AIV) in wild water bird populations is important for early warning to protect poultry from incursions of high-pathogenicity (HP) AIV. Access to individual water birds is difficult and restricted and limits sampling depth. Here, we focused on environmental samples such as surface water, sediments, and environmentally deposited fresh avian feces as matrices for AIV detection. Enrichment of viral particles by ultrafiltration of 10-L surface water samples using Rexeed-25-A devices was validated using a bacteriophage ϕ6 internal control system, and AIV detection was attempted using real-time RT-PCR and virus isolation. While validation runs suggested an average enrichment of about 60-fold, lower values of 10 to 15 were observed for field water samples. In total 25/36 (60%) of water samples and 18/36 (50%) of corresponding sediment samples tested AIV positive. Samples were obtained from shallow water bodies in habitats with large numbers of waterfowl during an HPAIV epizootic. Although AIV RNA was detected in a substantial percentage of samples virus isolation failed. Virus loads in samples often were too low to allow further sub- and pathotyping. Similar results were obtained with environmentally deposited avian feces. Moreover, the spectrum of viruses detected by these active surveillance methods did not fully mirror an ongoing HPAIV epizootic among waterfowl as detected by passive surveillance, which, in terms of sensitivity, remains unsurpassed. IMPORTANCE Avian influenza viruses (AIV) have a wide host range in the avian metapopulation and, occasionally, transmission to humans also occurs. Surface water plays a particularly important role in the epidemiology of AIV, as the natural virus reservoir is found in aquatic wild birds. Environmental matrices comprising surface water, sediments, and avian fecal matter deposited in the environment were examined for their usefulness in AIV surveillance. Despite virus enrichment efforts, environmental samples regularly revealed very low virus loads, which hampered further sub- and pathotyping. Passive surveillance based on oral and cloacal swabs of diseased and dead wild birds remained unsurpassed with respect to sensitivity.

Arsenic and Heavy Metals in Sediments Affected by Typical Gold Mining Areas in Southwest China: Accumulation, Sources and Ecological Risks

Gold mining is associated with serious heavy metal pollution problems. However, the studies on such pollution caused by gold mining in specific geological environments and extraction processes remain insufficient. This study investigated the accumulation, fractions, sources and influencing factors of arsenic and heavy metals in the sediments from a gold mine area in Southwest China and also assessed their pollution and ecological risks. During gold mining, As, Sb, Zn, and Cd in the sediments were affected, and their accumulation and chemical activity were relatively high. Gold mining is the main source of As, Sb, Zn and Cd accumulation in sediments (over 40.6%). Some influential factors cannot be ignored, i.e., water transport, local lithology, proportion of mild acido-soluble fraction (F1) and pH value. In addition, arsenic and most tested heavy metals have different pollution and ecological risks, especially As and Sb. Compared with the other gold mining areas, the arsenic and the heavy metal sediments in the area of this study have higher pollution and ecological risks. The results of this study show that the local government must monitor potential environmental hazards from As and Sb pollution to prevent their adverse effects on human beings. This study also provides suggestions on water protection in the same type of gold-mining areas.

Metagenomics reveals biogeochemical processes carried out by sediment microbial communities in a shallow eutrophic freshwater lake

Introduction

As the largest shallow freshwater lake in the North China Plain, Baiyangdian lake is essential for maintaining ecosystem functioning in this highly populated region. Sediments are considered to record the impacts of human activities.

Methods

The abundance, diversity and metabolic pathways of microbial communities in sediments were studied by metagenomic approach to reveal patterns and mechanism of C, N, P and S cycling under the threat of lake eutrophication.

Results

Many genera, with plural genes encoding key enzymes involved in genes, belonging to Proteobacteria and Actinobacteria which were the most main phylum in bacterial community of Baiyangdian sediment were involved in C, N, S, P cycling processes, such as Nocardioides (Actinobacteria), Thiobacillus, Nitrosomonas, Rhodoplanes and Sulfuricaulis (Proteobacteria).For instance, the abundance of Nocardioides were positively correlated to TN, EC, SOC and N/P ratio in pathways of phytase, regulation of phosphate starvation, dissimilatory sulfate reduction and oxidation, assimilatory sulfate reduction, assimilatory nitrate reduction and reductive tricarboxylic acid (rTCA) cycle. Many key genes in C, N, P, S cycling were closely related to the reductive citrate cycle. A complete while weaker sulfur cycle between SO₄ ^2- and HS^- might occur in Baiyangdian lake sediments compared to C fixation and N cycling. In addition, dissimilatory nitrate reduction to ammonia was determined to co-occur with denitrification. Methanogenesis was the main pathway of methane metabolism and the reductive citrate cycle was accounted for the highest proportion of C fixation processes. The abundance of pathways of assimilatory nitrate reduction, denitrification and dissimilatory nitrate reduction of nitrogen cycling in sediments with higher TN content was higher than those with lower TN content. Besides, Nocardioides with plural genes encoding key enzymes involved in nasAB and nirBD gene were involved in these pathways.

Discussion

Nocardioides involved in the processes of assimilatory nitrate reduction, denitrification and dissimilatory nitrate reduction of nitrogen cycling may have important effects on nitrogen transformation.

Reactive Oxygen Species Promote Nitrous Oxide (N2O) Emissions from Soil/Sediment during the Anoxic-Oxic Transition

Reactive oxygen species (ROS)-induced element/pollutant geochemical processes in fluctuating anoxic-oxic areas have received increasing attention in recent years. Nitrous oxide (N₂O) is a strong greenhouse gas; however, the relationship between ROS and N₂O emissions in these areas has not been established. This work revealed the essential role of ROS in promoting N₂O emissions in soil/sediment during the anoxic-oxic transition. ROS decreased the rate of nitrate reduction by 26-31% and increased N₂O emissions by 8.8-31.3% (at 48 h). ROS-induced N₂O emission was via inhibiting the step of N₂O reduction. During the anoxic-oxic transition, the contribution of ROS to inhibit the step of N₂O reduction was higher than 52.6%, demonstrating the important role of ROS. The downregulated relative transcription of the NosZ gene demonstrated inhibition at the gene level. Hydrogen peroxide was the dominant ROS species inhibiting N₂O reduction, while the role of hydroxyl radicals was negligible, suggesting a different behavior of N₂O emission with common pollutant conversion induced by ROS during the anoxic-oxic transition. This study demonstrated an overlooked factor in promoting N₂O emission in the soil/sediment and appealed to a re-examination of the mechanism of N₂O emissions in fluctuating anoxic-oxic areas.

Applying fulvic acid for sediment metals remediation: Mechanism, factors, and prospect

Fulvic acid (FA) has been shown to play a decisive role in controlling the environmental geochemical behavior of metals. As a green and natural microbial metabolite, FA is widely used in environmental remediation because of its good adsorption complexation and redox ability. This paper introduces the reaction mechanism and properties of FA with metals, and reviews the progress of research on the remediation of metal pollutant by FA through physicochemical remediation and bioremediation. FA can control the biotoxicity and migration ability of some metals, such as Pb, Cr, Hg, Cd, and As, through adsorption complexation and redox reactions. The concentration, molecular weight, and source are the main factors that determine the remediation ability of FA. In addition, the ambient pH, temperature, metal ion concentrations, and competing components in sediment environments have significant effects on the extent and rate of a reaction between metals and FA during the remediation process. Finally, we summarize the challenges that this promising environmental remediation tool may face. The research directions of FA in the field of metals ecological remediation are also prospected. This review can provide new ideas and directions for the research of remediation of metals contaminants in sediments.

Distribution and diversity of anaerobic thermophiles and putative anaerobic nickel-dependent carbon monoxide-oxidizing thermophiles in mesothermal soils and sediments

Even though thermophiles are best known from geothermal and other heated systems, numerous studies have demonstrated that they occur ubiquitously in mesothermal and permanently cold soils and sediments. Cultivation based studies of the latter have revealed that the thermophiles within them are mostly spore-forming members of the Firmicutes. Since the geographic distribution of spores is presumably unconstrained by transport through the atmosphere, similar communities (composition and diversity) of thermophiles might be expected to emerge in mesothermal habitats after they are heated. Alternatively, thermophiles might experience environmental selection before or after heating leading to divergent communities. After demonstrating the ubiquity of anaerobic thermophiles and CO uptake in a variety of mesothermal habitats and two hot springs, we used high throughput sequencing of 16S rRNA genes to assess the composition and diversity of populations that emerged after incubation at 60°C with or without headspace CO concentrations of 25%. Anaerobic Firmicutes dominated relative abundances at most sites but anaerobic thermophilic members of the Acidobacteria and Proteobacteria were also common. Nonetheless, compositions at the amplicon sequence variant (ASV) level varied among the sites with no convergence resulting from heating or CO addition as indicated by beta diversity analyses. The distinctions among thermophilic communities paralleled patterns observed for unheated "time zero" mesothermal soils and sediments. Occupancy analyses showed that the number of ASVs occupying each of n sites decreased unimodally with increasing n; no ASV occupied all 14 sites and only one each occupied 11 and 12 sites, while 69.3% of 1873 ASVs occupied just one site. Nonetheless, considerations of distances among the sites occupied by individual ASVs along with details of their distributions indicated that taxa were not dispersal limited but rather were constrained by environmental selection. This conclusion was supported by βMNTD and βNTI analyses, which showed dispersal limitation was only a minor contributor to taxon distributions.

[Distribution Characteristics and Pollution Risk of Heavy Metals in River Sediment of Suzhou Water Network Area, China]

The average contents of the heavy metals Cd, Cu, Cr, As, Ni, Pb, and Zn in the sediment of sampling points in the Suzhou water network area were 1.4, 127.4, 83.2, 18.2, 51.7, 145.1, and 350.7 mg·kg^-1, respectively, which were 13.7, 5.7, 1.1, 1.7, 1.9, 5.5, and 5.6 times the background values, respectively. The proportions of points exceeding the risk screening values of the GB 15618-2018 standard were 100.0%, 97.3%, 38.4%, 83.6%, 97.3%, 90.4%, and 100.0%, respectively. The pollution degree of single heavy metal elements was evaluated using the improved ground accumulation index method. The pollution degree of the seven heavy metal elements in the sediment of the Suzhou water network area was in the order of Cd>Cu>Pb>Zn>As>Cr>Ni. Among them, Cd showed extremely strong pollution, Cu and Pb showed intense to extremely strong pollution, Zn showed strong pollution, As showed moderate to intense pollution, and Cr and Ni showed moderate pollution. Cd, Pb, Cu, and Zn in the sediment samples of the ancient city area, northwest area, southwest area, and east area were the heavy metal elements with high pollution contributions. The potential ecological risk degree of heavy metals was ranked as northwest>southwest>ancient city area>east. Correlation analysis and principal component analysis showed that Cd, Cu, Cr, As, Ni, Pb, and Zn may have come from anthropogenic factors such as tail gas emissions, the use of chemical fertilizers and pesticides, and the pollutant emissions of the electronic manufacturing industry.