Distribution characteristics and migration trends of hexabromocyclododecanes between seawater-sediment system in different seasons of fishing grounds along the Yellow sea and East China sea coasts.

Pollutants in the ecological environment of fishery seawater are harmful to the survival and reproduction of aquatic organisms. Hexabromocyclododecanes (HBCDs) were 42.9% detected within ND-48.89 ng/L in 177 seawater samples and 30.7% within ND-1.07 ng/g dw in 88 sediment samples of the fisheries in the Yellow Sea and East China Sea, respectively. γ-HBCD accounted for 65% of seawater and 89% of sediment samples. HBCDs in seawater in winter (ND-48.89 ng/L) were significantly higher than in summer (ND-4.99 ng/L), possibly because the re-suspension caused by winds and waves could re-migrate HBCDs from the sediment to the seawater in winter. However, seasonal differences of HBCDs in sediment were not significant. The fugacities indicated HBCDs' migrating trend from seawater to sediment due to their hydrophobic nature. There is almost no terrestrial input of HBCDs from the Yangtze and Yellow Rivers, and currently used fishery materials in marine may compose long-lasting sources of HBCDs.

Occurrence of polyhalogenated carbazoles and the combined effects with heavy metals on variation in bacterial communities in estuarine sediments.

Carbazole (CZ) and eight polyhalogenated carbazoles (PHCZs) were quantified by GC-MS in sediments of 12 estuaries, the interface linking large industrial and living areas to the Bohai Sea, China. These pollutants, heavy metals, and environmental factors caused integrated exposure to sediment bacteria. Four PHCZ congeners were detectable, with ΣPHCZs ranging from 0.56 to 15.94 ng/g dw. The dominant congeners were 3,6-dichlorocarbazole (36-CCZ) and 3-chlorocarbazole (3-CCZ), with a mean contribution of 72.6 % and 20.2 %. Significant positive correlations were found between 36-CCZ and both total organic carbon and heavy metals. Redundancy analysis of microbial variation implicated no impacts from PHCZs. Correlation analysis demonstrated an increase in abundance of Rhodocyclaceae but a decrease in Bacteroides-acidifaciens-JCM-10556 with presence of PHCZs, suggesting that these bacteria can be used as potential contamination indicators. The combined exposure of heavy metals, nutrients, and PHCZs may also increase toxicity and biological availability, adversely affecting the ecosystem and human health.

Abundance, characteristics and risk assessment of microplastics in aquatic sediments: A comparative study in the Yellow River and Yellow Sea.

The occurrence of microplastics (MPs) in aquatic ecosystems has become an increasingly serious threat to public health. Marine sediments are considered the final recipients of all microplastic pollution from inland rivers, however, whether and how the MPs differ in these two ecosystems remains poorly known due to the divergent MPs detection methods employed in previous studies. Here, we investigated the abundance, size, and types of MPs in sediment samples from the Yellow River and Yellow Sea using laser direct infrared (LDIR), and assessed their ecological risks. The abundance of MPs in the Yellow Sea is 2.9 times higher than that in the Yellow River, with an average abundance of 54813.2 ± 19355.9 and 18780.2 ± 9951.8 particles·kg-1 (dry sediment), respectively. Notably, the predominant polymer types in both sediment environments were silicone, fluororubber, and polypropylene (PP). MPs with sizes < 100 µm accounted for > 90 % of the total MPs number. Risk assessment demonstrated all the sediment environments exhibited high ecological risks. The dominance of small MPs highlighted the importance of using a method with high resolution to delineate the truthful status of MP pollution.

A strain of Vibrio alginolyticus isolated from Azumapecten farreri and its pathogenic mechanism using CRISPR-Cas9 technology.

Scallops have become an important aquaculture species in China because they contain high-quality protein, and scallops are important health food that combines multiple effects and high economic benefits. However, scallop aquaculture is perennially threatened by various pathogenic Vibrio species, leading to great economic losses. We obtained a strain of pathogenic bacteria, identified as Vibrio alginolyticus, from the diseased Azumapecten farreri in the scallop farming area of Huangdao District in 2018, and V. alginolyticus is one of the major shellfish pathogens. We showed that V. alginolyticus was isolated and identified as a pathogen in A. farreri for the first time. In this study, we evaluated its morphology and performed a phylogenetic analysis based on 16S rRNA gene sequencing. In addition, we performed a preliminary analysis of its pathogenic mechanisms. The Hfq protein in V. alginolyticus is an important RNA-binding protein in the quorum-sensing system that not only affects the sensitivity of Vibrio to environmental stress but also regulates a variety of functions, such as cell membrane formation, motility, and virulence towards the host. However, its effect on the pathogenesis of V. alginolyticus to A. farreri is unclear. To further investigate the pathogenic mechanism of the Hfq protein in V. alginolyticus to A. farreri, we used the CRISPR-Cas9 system to target and deplete the hfq gene fragment in V. alginolyticus and obtained the mutant strain V. ΔHfq-. We found that the peripheral flagellum of the mutant strain was lost, which reduced the motility of V. alginolyticus. Therefore, the deletion of target genes by the CRISPR/Cas9 genome editing system confirmed that the Hfq protein played a key role in reducing the ability of V. alginolyticus to infect A. farreri. In conclusion, our current findings provided valuable insights into the healthy culture of scallops.

Gramella oceanisediminis sp. nov., isolated from deep-sea sediment of the Indian Ocean.

A taxonomic study was carried out on strain GC03-9T, which was isolated from deep-sea sediment of the Indian Ocean. The bacterium was Gram-stain-negative, catalase-positive, oxidase-negative, rod-shaped and gliding motile. Growth was observed at salinities of 0-9 % and at temperatures of 10-42 °C. The isolate could degrade gelatin and aesculin. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain GC03-9T belonged to the genus Gramella, with the highest sequence similarity to Gramella bathymodioli JCM 33424T (97.9 %), followed by Gramella jeungdoensis KCTC 23123T (97.2 %) and other species of the genus Gramella (93.4-96.3 %). The average nucleotide identity and the digital DNA-DNA hybridization estimate values between strain GC03-9T and G. bathymodioli JCM 33424T and G. jeungdoensis KCTC 23123T were 25.1 and 18.7 % and 82.47 and 75.69 %, respectively. The principal fatty acids were iso-C15 : 0 (28.0 %), iso-C17 : 0 3OH (13.4 %), summed feature 9 (iso-C17 : 1 ω9c and/or 10-methyl C16 : 0; 13.3 %) and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c; 11.0 %). The G+C content of the chromosomal DNA was 41.17 mol%. The respiratory quinone was determined to be menaquinone-6 (100 %). Phosphatidylethanolamine, one unknown phospholipid, three unknown aminolipids and two unknown polar lipids were present. The combined genotypic and phenotypic data showed that strain GC03-9T represents a novel species within the genus Gramella, for which the name Gramella oceanisediminis sp. nov. is proposed, with the type strain GC03-9T (=MCCC M25440T=KCTC 92235T).

Identification of lower brominated bisphenol A analogs as the photooxidation products of tetrabromobisphenol A bis(2,3-dibromopropyl) ether (TBBPA-BDBPE).

The transformation products and mechanism of tetrabromobisphenol A (TBBPA) derivatives are still largely unknown compared with TBBPA. In this paper, sediment, soil and water samples (15 sites, 45 samples) collected in a river flowing through brominated flame retardant manufacturing zone were analyzed to determine TBBPA derivatives, byproducts, and transformation products. TBBPA derivatives and byproducts were detected with concentrations ranging from none detection to 1.1 × 104 ng/g dw and with detection frequencies of 0-100 % in all samples. The concentrations of TBBPA derivatives such as TBBPA bis(2,3-dibromopropyl) ether (TBBPA-BDBPE) and TBBPA bis(allyl ether) in sediment and soil samples were higher than that of TBBPA. In addition, the occurrence of various unknown bromobisphenol A allyl ether analogs in the samples was further confirmed by using 11 synthesized analogs, which might be produced during the waste treatment process of the factories. The possible transformation pathways of TBBPA-BDBPE were revealed for the first time by using UV/base/persulfate (PS) as designed photooxidation waste treatment system in the laboratory. Ether bond cleavage, debromination, and ß-scission contributed to the transformation of TBBPA-BDBPE and the occurrence of transformation products in the environment. The concentrations of the transformation products of TBBPA-BDBPE ranged from none detection to 3.4 × 102 ng/g dw. These data provide new insights into the fate of TBBPA derivatives in environmental compartments.

Abundance, diversity, and community structure of comammox cladeA in sediments of China's offshore continental shelf.

Nitrification is an important link for environmental nitrogen cycling, the appearance of comammox updates our traditional cognition about nitrification. Yet comammox has been poorly studied in marine sediments. This study explored the differences in abundance, diversity, community structure of comammox cladeA amoA in the sediments from different offshore areas of China (the Bohai Sea (BS), the Yellow Sea (YS), and the East China Sea (ECS)) and revealed the main driving factors. The abundance of comammox cladeA amoA was 8.11 × 103-4.96 × 104, 2.85 × 104-4.18 × 104, and 5.76 × 103-4.91 × 104 copies/g dry sediment in BS, YS, and ECS, respectively. The OTU (operational taxonomic units) numbers of comammox cladeA amoA in the BS, YS, and ECS were 4, 2, and 5 respectively. There were negligible differences in the abundance and diversity of comammox cladeA amoA among the sediments of the three seas. The subclade of comammox cladeA amoA, cladeA2 is the dominant comammox flora in the offshore area sediments of China. Noticeable differences in the community structure of comammox were observed among these three seas, where the relative abundance of cladeA2 in comammox was 62.98 %, 66.24 %, and 100 % in ECS, BS, and YS respectively. pH was found as the main factor affecting the abundance of comammox cladeA amoA and showed a significant positive correlation (p < 0.05). The diversity of comammox decreased with the increase of salinity (p < 0.05). NO3--N is the main factor affecting the community structure of comammox cladeA amoA.

Thin-layer chromatography coupled with HPLC-DAD/UHPLC-HRMS for target and non-target determination of emerging halogenated organic contaminants in animal-derived foods.

In this study, a simple, solvent-saving, and sensitive method was established using high-performance liquid chromatography coupled with high-resolution mass spectrometry to quantitively determine 16 emerging halogenated organic contaminants (HOCs), including polyhalogenated carbazoles, halogenated phenols, and tetrabromobisphenol-A analogs, and to qualitatively identify non-target HOCs in animal-derived food samples. The sample extracts were physically frozen to remove most lipids and further purified by thin-layer chromatography according to the targets polarity. The method detection limit and method quantification limit of 16 HOCs were in the range of 0.003-9.168 and 0.010-30.601 ng·g-1 dry weight, respectively. The recoveries were within 69.1-111.0 %, the intra/inter-day precisions were 0.1-6.1 % and 0.1-6.7 %, and the matrix effects were between -12.1 and 10.8 %, all within the acceptable range. Finally, 16 HOCs were detected in nine actual samples in range of not detected-307.22 ng·g-1 dry weight. Moreover, five bromides and two chlorides were identified by using non-target analysis in animal-derived foods.

Study of the scavenger and vector roles of microplastics for polyhalocarbazoles under simulated gastric fluid conditions.

Microplastics entering the digestive system of living organisms can serve as a carrier of hydrophobic organic pollutants (HOPs), increasing their exposure levels and the health risks they pose to both humans and animals. The desorption kinetics of six polyhalocarbazoles (PHCZs) from 5 mm and 0.15 mm polypropylene (PP) and polyvinyl chloride (PVC) microplastic particles were assessed using a combined microplastics and food system, representing the gastric system of vertebrates and invertebrates. Results showed that the chemical transfer of PHCZs is biphasic and reversible, with rapid exchange occurring within 2-48 h, followed by a period of slow transfer, which continues for weeks to months. The desorption capacity of PHCZs loaded on 0.15 mm microplastic particles was greater than that of 5 mm particles. The bioavailability percentage of PHCZ congeners for PP (24.2%-65.3%) and PVC (43.5%-57.2%) in the vertebrate fluid system were all lower than those in the invertebrate system (34.2%-70.7% for PP and 56.3%-72.7% for PVC, respectively). These findings indicate that physiological conditions, such as polarity, ingestion fluid, and microplastic affect the desorption of PHCZs from microplastics. In addition, desorption from PP was inhibited by the presence of foodstuff loaded with PHCZs due to competition, while desorption from PVC was not significantly affected by the presence of PHCZs contaminant food. Microplastics could provide a cleaning function in gastric fluid systems containing contaminated foodstuff, especially PP, which was capable of competitive adsorption of PHCZs from food. Few investigations have focused on the adverse effects of microplastic ingestion on human health, particularly in their role as vectors for HOPs, compared to other routes of exposure and transport. Therefore, these findings provide valuable insight into the health risks associated with dietary intake of microplastics and HOPs.

Determination and environmental risk assessment of organophosphorus flame retardants in sediments of the South China Sea.

As ubiquitous contaminants in the environment, organophosphorus flame retardants (OPFRs) would eventually settle in marine sediment. In this study, concentrations, spatial distributions, and ecological risks of seven OPFRs in sediment samples of the South China Sea (SCS) were investigated for the first time. Total concentration of all OPFRs ranged from 2.5 to 32.3 ng/g dry weight (dw), in which the abundance of tri-cresyl phosphates (TCPs) was the highest. OPFRs in the SCS were at a medium level compared with those from other parts of the world. The nearshore ocean current, ship transportation, and riverine inputs might influence the spatial distributions of OPFRs. The total inventory of six OPFRs in sediment was estimated to be 202.8 tons (16.7×104 km2). The hazard quotient (HQ) of OPFRs ranged from 0 to 3.2E-02, indicating the ignorable ecological risk of OPFRs in sediments of the SCS. This study provides insight into the occurrence of current-use OPFRs in the SCS which deserved long-term concern in the future due to their continuous terrigenous inputs.

Occurrence of synthetic musks in the sediment-seawater system of the Yellow Sea and East China Sea during wet and dry seasons.

Synthetic musks are aroma compounds used worldwide as substitutes for natural musks, which have become ubiquitous pollutants in the environment. The land-based input and partition behavior of synthetic musks in sediments and seawater are important for understanding their fate in the marine environment. In this study, a total of 292 seawater and sediment samples from 146 sites of the Yellow Sea and East China Sea were collected during wet and dry seasons and used to determine four synthetic musks, tonalide, galaxolide, musk xylene and musk ketone. Only tonalide was detectable in 10.6% and 17.8% of seawater samples at a concentration range of 23.7-38.2 ng/L and 19.0-24.8 ng/L in wet season and dry season, respectively. In sediments, both galaxolide and tonalide were detectable, with a sum total synthetic musks concentration ranging from 1.4 to 36.6 ng/g dry weight (dw) in wet season and 1.0 to 14.1 ng/g dw in dry season. The concentration of tonalide in seawater was significantly higher in wet season than in dry season and the concentration of synthetic musks in sediments of some coastal areas also exhibited higher concentrations in wet season than in dry season. Fugacity analysis showed that tonalide in the Yellow Sea exhibited a trend of diffusion from sediment to seawater or a state of equilibrium, while no diffusion trend was observed in the East China Sea. The hazard quotient values for tonalide and galaxolide in sediment and seawater samples were lower than 0.1, indicating that they present a low ecological risk. This research provides novel insights that help understand the pollution status, diffusion behavior and ecological risk of synthetic musks in marine environments.

Effects of emerging contaminants and heavy metals on variation in bacterial communities in estuarine sediments.

Emerging contaminants (ECs) and heavy metals (HMs) are universally present together in estuarine sediments; despite this, their effects on microbial communities have been widely studied separately, rather than in consort. In this study, the combined effects of ECs and HMs on microbial communities were investigated in sediments from 11 major river estuaries around the Bohai Sea, China. Proteobacteria, Bacteroidetes, and Firmicutes were the dominant phyla in the sediments. Using Shannon indices, total phosphorus and total organic carbon were shown to affect microbial community structure. Redundancy analysis of microbial variation implicated Cd and As as the greatest pollutants, followed by Mn, Fe, Zn and Cu; no impacts from galaxolide (HHCB) and tonalide (AHTN) were found. Correlation analysis demonstrated that the concentration of ECs increased the abundance of certain bacteria (e.g., Haliangium, Altererythrobacter, Gaiella and Erythrobacter), and therefore these can be used as potential contamination indicators. Shannon indices and Chao1 indices showed that there were differences in the richness and diversity of bacterial communities in the sediments of 11 rivers. The principal coordinate analysis displayed higher similarity of bacterial community composition in estuarine sediments in Liaoning province than other regions. The results can be used to predict changes in estuary ecosystems to maintain their ecological balance and health.

Occurrence and distribution of organophosphate flame retardants in seawater and sediment from coastal areas of the East China and Yellow Seas.

Organophosphates (OPEs) are manmade organic pollutants that are widely used as flame retardants, plasticizers, and antifoaming and hydraulic agents. In this study, seven OPEs in seawater and sediment from the Yellow Sea and East China Sea were determined to study the distribution and diffusion behavior, and to evaluate the environmental risks. The ΣOPEs in the seawater and sediments ranged from below the method detection limit (1.0, indicating high ecological risks to aquatic organisms.

Fate and ecological risks of current-use pesticides in seawater and sediment of the Yellow Sea and East China Sea.

With the frequent use of chemical pesticides, the current-use pesticides (CUPs) emerge and concentrate in the sea. The partition between the sediment and seawater is essential for understanding the environmental fate of CUPs. However, there is little research on this topic. In the present study, seventeen CUPs were screened in seawater and sediment samples collected from the Yellow Sea and East China Sea. Total concentration of 17 CUPs in surface seawater samples ranged from 9.5 to 267.3 ng/L, with 6 CUPs presenting 100% detection frequency. Carbendazim, tricyclazole, tebuconazole, atrazine and imidacloprid accounted for >80% of all CUPs, which was due to their large application in the local agriculture and fishing activities. Higher concentration sites were located near the shore and Yangtze river estuary, indicating intense human activities and riverine input that elevated the level of CUPs in marginal sea. The pesticides in seawater were mainly found in the surface followed by the bottom layer, which indicated that atmospheric deposition and re-suspension played key roles for their vertical distribution characteristics. The high fugacity fraction ratios (ff > 0.5) indicated the non-equilibrium state of pesticides that might have been transferred from sediment to seawater at most sites. These 17 detectable pesticides in seawater were at low levels, presenting ignorable or low toxic effects to aquatic organisms.

Legacy and emerging per- and polyfluoroalkyl substances (PFAS) in sediments from the East China Sea and the Yellow Sea: Occurrence, source apportionment and environmental risk assessment.

The Yellow Sea (YS), the East China Sea (ECS) and their coastal areas have undergone rapid urbanization and industrialization. These areas are important sinks for many persistent organic pollutants. In this study, the concentration of legacy and emerging per- and polyfluoroalkyl substances (PFAS) in marine sediments from the YS and ECS were investigated. Nineteen PFAS were identified, ranging in concentration from 0.21 ng/g to 4.74 ng/g (mean: 1.60 ng/g). Legacy long-chain PFAS [e.g., perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorooctane sulfonate (PFOS)] were the dominant contaminants. Alternative PFAS such as 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy) propanoic acid (HFPO-DA) were identified within the detection range of 16%-100%. HFPO-DA was measured in all sediments in equivalent levels to PFOS (0.119 ng/g and 0.139 ng/g, respectively). This is the first reported occurrence of perfluoro-1-butanesulfonamide (FBSA) and HFPO-DA in marine sediments, indicating a replacement in the production of PFAS from legacy to emerging ones along with eastern coastal cities of China. The results of the potential source identification demonstrated that metal plating plants, textile treatments, fluoropolymer products, food packaging, and the degradation of volatile precursor substances were the main sources of PFAS in the ECS and YS. The environmental risk assessment based on the risk quotient demonstrated that PFOA and PFOS in the ECS and YS may present a low to medium risk at most sampling points.

Coexistence of endonuclease and exonuclease activities in a novel RecJ from Bacillus cereus.

BACKGROUND: All RecJ proteins are known to date only perform exonuclease activity. The present study reports that a novel RecJ protein obtained from Bacillus cereus isolated from marine sediments has both endonuclease and exonuclease activities. METHODS: Analysis of the BcRecJ expression induction in E. coli BL21 revealed that the BcRecJ protein cleaved plasmids and genomic DNA in the host cell, and led to cell death and decreased the DNA content. Further, the BcRecJ protein had the ability to degrade supercoiled plasmid DNA into circular or linear forms in vitro. Meanwhile, the BcRecJ protein loaded with an S-modified guide facilitated plasmid linearization and reduced smear formation. RESULTS: The results suggested that this novel BcRecJ protein was different from any reported RecJs and had a longer C-terminus. Testing the BcRecJ mutants indicated that the endonuclease activity was affected by two residues of BcRecJ (D561, E637) after testing the BcRecJ mutants. CONCLUSION: The discovery of the type of protein is a new breakthrough for the RecJ proteins, which has both endonuclease and exonuclease activities.