Marine Environmental Samples Research Articles

Current Research Status of Azaspiracids.

The presence and impact of toxins have been detected in various regions worldwide ever since the discovery of azaspiracids (AZAs) in 1995. These toxins have had detrimental effects on marine resource utilization, marine environmental protection, and fishery production. Over the course of more than two decades of research and development, scientists from all over the world have conducted comprehensive studies on the in vivo metabolism, in vitro synthesis methods, pathogenic mechanisms, and toxicology of these toxins. This paper aims to provide a systematic introduction to the discovery, distribution, pathogenic mechanism, in vivo biosynthesis, and in vitro artificial synthesis of AZA toxins. Additionally, it will summarize various detection methods employed over the past 20 years, along with their advantages and disadvantages. This effort will contribute to the future development of rapid detection technologies and the invention of detection devices for AZAs in marine environmental samples.

Global analysis of the biosynthetic chemical space of marine prokaryotes

BackgroundMarine prokaryotes are a rich source of novel bioactive secondary metabolites for drug discovery. Recent genome mining studies have revealed their great potential to bio-synthesize novel secondary metabolites. However, the exact biosynthetic chemical space encoded by the marine prokaryotes has yet to be systematically evaluated.ResultsWe first investigated the secondary metabolic potential of marine prokaryotes by analyzing the diversity and novelty of the biosynthetic gene clusters (BGCs) in 7541 prokaryotic genomes from cultivated and single cells, along with 26,363 newly assembled medium-to-high-quality genomes from marine environmental samples. To quantitatively evaluate the unexplored biosynthetic chemical space of marine prokaryotes, the clustering thresholds for constructing the biosynthetic gene cluster and molecular networks were optimized to reach a similar level of the chemical similarity between the gene cluster family (GCF)-encoded metabolites and molecular family (MF) scaffolds using the MIBiG database. The global genome mining analysis demonstrated that the predicted 70,011 BGCs were organized into 24,536 mostly new (99.5%) GCFs, while the reported marine prokaryotic natural products were only classified into 778 MFs at the optimized clustering thresholds. The number of MF scaffolds is only 3.2% of the number of GCF-encoded scaffolds, suggesting that at least 96.8% of the secondary metabolic potential in marine prokaryotes is untapped. The unexplored biosynthetic chemical space of marine prokaryotes was illustrated by the 88 potential novel antimicrobial peptides encoded by ribosomally synthesized and post-translationally modified peptide BGCs. Furthermore, a sea-water-derived Aquimarina strain was selected to illustrate the diverse biosynthetic chemical space through untargeted metabolomics and genomics approaches, which identified the potential biosynthetic pathways of a group of novel polyketides and two known compounds (didemnilactone B and macrolactin A 15-ketone).ConclusionsThe present bioinformatics and cheminformatics analyses highlight the promising potential to explore the biosynthetic chemical diversity of marine prokaryotes and provide valuable knowledge for the targeted discovery and biosynthesis of novel marine prokaryotic natural products.8qkWfGqcrPbn_o7-XLBWPjVideo

Harmful algae diversity from a coastal upwelling system detected by high-throughput sequencing

IntroductionIn recent years, environmental DNA (eDNA) amplicon sequencing has been used to unveil plankton diversity in the field. Nevertheless, molecular methods, such as this, are rarely used in harmful algal bloom (HAB) monitoring programs, which mainly rely on morphological identification by conventional light microscopy.MethodsThe present study focused on a shallow marine environment (Ría de Vigo, Northwest Spain), where sediment and plankton samples were collected from 2016 to 2018.ResultsThe application of eDNA amplicon sequencing allowed us to simultaneously detect 25 potential harmful species (mainly diatoms and dinoflagellates) included in the IOC-UNESCO Taxonomic Reference List of Harmful Microalgae. Among these, causative agents of amnesic shellfish poisoning (Pseudo-nitzschia spp.) paralytic shellfish poisoning (Gymnodinium catenatum and Alexandrium minutum), azaspiracid producers (Azadinium poporum) and ichthyotoxic haptophytes (Chrysochromulina leadbeateri), were identified. Some toxic microalgae were better represented in sediment (e.g., Pseudo-nitzschia pungens, Gymnodinium catenatum) or planktonic fractions (e.g., Pseudo-nitzschia, Gymnodinium smaydae), confirming the importance of including both sediment and plankton fractions in eDNA monitoring studies. Despite the limitations of sequencing short amplicons, it was possible to discern in this study six Pseudo-nitzschia species and associate each of them with each seasonal peak produced in summer periods. Furthermore, several species previously unreported in Ría de Vigo (Pseudo-nitzschia turgidula, Chrysochromulina leadbeateri, Azadinium poporum) could be detected.DiscusionThese results point out the application of eDNA amplicon sequencing to expand our knowledge about harmful species in HAB monitoring programs and early warning systems for low abundant and rare taxa.

Determination of uranium isotopes in marine sediments and seawaters by SF ICP-MS after rapid chemical separation using TK200 resin.

This work provided a novel analytical procedure for rapid and precise uranium isotopic determination in marine sediment and seawater, using a new type of extraction resin, TK200 resin, in combination with microwave digestion (for marine sediments), Fe(OH)3 co-precipitation (for seawater), and single collector sector field-inductively coupled plasma mass spectrometry (SF ICP-MS) measurement. The removal ability of TK200 extraction chromatography for the interfering elements (IEs) Hg, Pb, Th, Pt, Tl, and the matrix rare earth elements (REEs) was carefully investigated. High decontamination factors (DFs) were obtained for IEs and REEs. Accurate quantification of uranium isotope ratios was accomplished based on a "double-cycle" ICP-MS measurement method. The analytical method was optimized and validated with isotopic standards (IRMM-187), matrix-containing certified reference marine sediments (IAEA-384, IAEA-385, and IAEA-412), and seawater reference material (IAEA-443). A stable chemical recovery of ~ 90% was obtained for both types of marine environmental samples, and the method showed great efficiency with a total analytical time of less than 6h. The proposed procedure was validated following ISO/IEC 17025 guidelines. The important factors affecting the isotope ratio results (instrument background, procedural blank, memory effects, peak tailing, mass discrimination, dead time, and hydride interferences) were considered in the estimation of combined uncertainties. This work provides an alternative way for the determination of trace uranium isotope ratios and can be applied in the emergency monitoring of nuclear accidents and marine environmental analysis.

Low-cost gel-filled microwell array device for screening marine microbial consortium.

In order to exploit the microbes present in the environment for their beneficial resources, effective selection and isolation of microbes from environmental samples is essential. In this study, we fabricated a gel-filled microwell array device using resin for microbial culture. The device has an integrated sealing mechanism that enables high-density isolation based on the culture of microorganisms; the device is easily manageable, facilitating observation using bright-field microscopy. This low-cost device made from polymethyl methacrylate (PMMA)/polyethylene terephthalate (PET) has 900 microwells (600 μm × 600 μm × 700 μm) filled with a microbial culture gel medium in glass slide-sized plates. It also has grooves for maintaining the moisture content in the micro-gel. The partition wall between the wells has a highly hydrophobic coating to inhibit microbial migration to neighboring wells and to prevent exchange of liquid substances. After being hermetically sealed, the device can maintain moisture in the agarose gels for 7 days. In the bacterial culture experiment using this device, environmental bacteria were isolated and cultured in individual wells after 3 days. Moreover, the isolated bacteria were then picked up from wells and re-cultured. This device is effective for the first screening of microorganisms from marine environmental samples.

Novel electrochemical sensor modified with molecularly imprinted polymers for determination of enrofloxacin in marine environment.

Molecularly imprinted polymers were synthesized by gel-sol method with multi-walled carbon nanotubes as support and enrofloxacin as a template and further modified on the surface of glassy carbon electrode to construct a molecularly imprinted electrochemical sensor. The performance of the imprinted electrochemical sensor was thoroughly investigated by using cyclic voltammetry and differential pulse voltammetry. The influence of imprinted polymers amount, electrolyte pH, and incubation time on the sensor performance was investigated for the detection of enrofloxacin. Under the optimal experimental conditions in a three-electrode system with the modified electrode as the working electrode the differential pulse voltammetry response current of the sensor had a good linear relationship at 0.2V (vs. saturated calomel reference electrode) with the enrofloxacin concentration within 2.8pM-28μM and the limit of detection of the method was 0.9pM. The competitive interference experiment showed that theimprinted electrochemical sensor could selectively recognize enrofloxacin. The method was applied to analyze spiked natural seawater, fish, and shrimp samples. The recovery was 96.4%-102%, and RSD was less than 4.3% (n = 3), indicating that the proposed imprinted electrochemical sensor was suitable for the determination of trace enrofloxacin in marine environment samples.

Intelligent Image Monitoring Technology of Marine Environmental Pollution Information

Chen, H.; Li, W., and Xie, X., 2020. Intelligent image monitoring technology of marine environmental pollution information. In: Li, L. and Huang, X. (eds.), Sustainable Development in Coastal Regions: A Perspective of Environment, Economy, and Technology. Journal of Coastal Research, Special Issue No. 112, pp. 1-4. Coconut Creek (Florida), ISSN 0749-0208.With the increasing shortage of land resources, countries around the world gradually develop and use marine resources. Therefore, the marine economy has gradually become an important pillar of our national economy, which will gradually expand the scale of marine resources development. With the increase of sea related projects, the probability of marine environmental pollution events is increasing, which has seriously affected the marine ecological environment. Therefore, we need to monitor the degree of marine pollution, which can better protect the marine environment. There are many problems in traditional marine environmental pollution monitoring technology, such as short monitoring range, low monitoring accuracy, long monitoring time, etc., which cannot meet the development needs of modern industrial technology. Based on the digital remote sensing technology, this paper establishes the intelligent image monitoring technology of marine environmental pollution information, which can monitor the marine water quality in multiple dimensions. Through big data analysis, we can calculate and process the collected data, which will better complete the monitoring and analysis of marine environmental pollution. Through the intelligent image monitoring technology, we can achieve the full coverage of high-precision marine pollution monitoring, which will improve the information of marine environmental pollution samples.

Origin, geochemical characteristics and filling pathways in the Shadegan oil field, Dezful Embayment, SW Iran

The Shadegan oil field is one of the fields in the central part of the Dezful Embayment. Little or no geochemical studies have been performed previously in this field. This paper provides valuable information to answer most of the geochemistry ambiguities and issues in this field. Different techniques were used to investigate the genetic types of Asmari and Bangestan reservoirs. Structural characteristics of asphaltenes, biomarker fingerprints, and V/Ni ratio indicates that all oils in the Shadegan field have similar source rock(s) and belong to one oil family. The homologous series of normal alkanes distribution and the absence of 17α(H) 25-hopane reveals that biodegradation has not affected oil samples and planktons/algal or higher plants are dominating organic matters, proved by hopanes/steranes ratio. The Pr/Ph < 1, 0.49 < V/(V + Ni) < 0.81, and homohopanes distribution implied an anoxic condition during source rock deposition. The DBT/Ph, C24/C23 tricyclic terpanes, C22/C21 tricyclic terpanes, C29/C30 hopane, diasterane/sterane ratios suggest that the contribution of clay to source rock was insignificant and source rock has composed of a mix shale and carbonate. Steranes show C29 > C27 > C28 pattern, and the ternary diagram of steranes confirmed that the source rock deposited in the open marine environment and oil samples originated from marine organic matters. All samples have been sourced from a source rock(s) older than the Upper Cretaceous, as shown by the oleanane ratio. The Kazhdumi Formation is the primary source rock in this field, and some contributions from other source rocks might have occurred. In general, samples indicate maturity before the peak of the oil window in which the Bangestan samples have lower maturity regarding the Asmari samples based on aromatic and saturate maturity parameters. The tracing of oil filling pathways by isopleth maps of 4-/1-MDBT and C29 sterane 20S/(20S + 20R) ratios revealed that each reservoir had been charged from several directions. Although the Upper Asmari and Bangestan reservoirs have been charged laterally, the Lower Asmari has been charged vertically and laterally.

Environmental DNA from multiple pathogens is elevated near active Atlantic salmon farms

The spread of infection from reservoir host populations is a key mechanism for disease emergence and extinction risk and is a management concern for salmon aquaculture and fisheries. Using a quantitative environmental DNA methodology, we assessed pathogen environmental DNA in relation to salmon farms in coastal British Columbia, Canada, by testing for 39 species of salmon pathogens (viral, bacterial, and eukaryotic) in 134 marine environmental samples at 58 salmon farm sites (both active and inactive) over 3 years. Environmental DNA from 22 pathogen species was detected 496 times and species varied in their occurrence among years and sites, likely reflecting variation in environmental factors, other native host species, and strength of association with domesticated Atlantic salmon. Overall, we found that the probability of detecting pathogen environmental DNA (eDNA) was 2.72 (95% CI: 1.48, 5.02) times higher at active versus inactive salmon farm sites and 1.76 (95% CI: 1.28, 2.42) times higher per standard deviation increase in domesticated Atlantic salmon eDNA concentration at a site. If the distribution of pathogen eDNA accurately reflects the distribution of viable pathogens, our findings suggest that salmon farms serve as a potential reservoir for a number of infectious agents; thereby elevating the risk of exposure for wild salmon and other fish species that share the marine environment.

Comparison of the distribution and diversity of antimicrobial resistance genes between wild and commercially available Atlantic Mackerel

The global uncontrolled rise of antimicrobial resistance (AMR) is a major societal threat and it is well documented that AMR is already negatively affecting healthcare and intensive livestock farming systems. Nonetheless, capture fisheries are still essential to the global food supply providing over 50% of the world’s aquatic organism production. To facilitate improved management, it is therefore imperative that we better understand reservoirs of AMR and how gene transmission occurs in the aquatic environment. In order to discern which AMR bacteria and genes are present in the marine environment, sediment and seawater samples were collected and Atlantic Mackerel were captured at the beginning of summer and autumn in the Solent Strait (Portsmouth, U.K). In addition, commercially available Atlantic mackerel were purchased at a local fish market. Using culture-dependent techniques we obtained more than 700 bacterial and 20 fungal isolates from skin, intestinal lining, and intestinal content. Ten different cefotaxime-resistant Pseudomonas spp. were isolated from the seawater and market fish skin samples, and one cefotaxime-resistant Rhanella sp. was isolated from wild fish digesta. Results from ongoing whole-genome shotgun metagenomics analysis will be discussed, as well as the connection between AMR bacteria and AMR gene presence within the marine coastal environment and the local fish markets, which are the last link between capture fisheries and consumers.

Analyses of environmental sequences and two regions of chloroplast genomes revealed the presence of new clades of photosynthetic euglenids in marine environments.

Euglenophyceae are unicellular algae with the majority of their diversity known from small freshwater reservoirs. Only two dozen species have been described to occur in marine habitats, but their abundance and diversity remain unexplored. Phylogenetic studies revealed marine prasinophyte green alga, Pyramimonas parkeae, as the closest extant relative of the euglenophytes' plastid, but similarly to euglenophytes, our knowledge about the diversity of Pyramimonadales is limited. Here we explored Euglenophyceae and Pyramimonadales phylogenetic diversity in marine environmental samples. We yielded 18S rDNA and plastid 16S rDNA sequences deposited in public repositories and reconstructed Euglenophyceae reference trees. We searched high-throughput environmental sequences from the TARA Oceans expedition and Ocean Sampling Day initiative for 18S rDNA and 16S rDNA, placed them in the phylogenetic context and estimated their relative abundances. To avoid polymerase chain reaction (PCR) bias, we also exploited metagenomic data from the TARA Oceans expedition for the presence of rRNA sequences from these groups. Finally, we targeted these protists in coastal samples by specific PCR amplification of two parts of the plastid genome uniquely shared between euglenids and Pyramimonadales. All approaches revealed previously undetected, but relatively low-abundant lineages of marine Euglenophyceae. Surprisingly, some of those lineages are branching within the freshwater or brackish genera.

A new method for analyzing microplastic particle size distribution in marine environmental samples

Microplastics (MPs) are recognized as a global emerging threat to aquatic ecosystems and biodiversity worldwide. Though the number of publications and interest to the MP research have been increased rapidly, it is still hamper to compare the obtained data due to the usage of different methodologies in MP assay. Thus, there is an urgent need for a standardized approach to the procedures of MP quantification in order to produce comparative assessments. In this pilot study, the conventional NOAA protocol of MP extraction from seawater was combined with a simple and inexpensive method for analyzing shape and size spectrum of all MP particles making up the sample. A common flatbed scanner equipped with slide adapter was applied for image acquisition while MP dispersive properties (particle abundance, shape and size spectrum) were quantified using ImageJ software. Feret’s diameter and circularity (or roundness) appeared to be the most efficient shape descriptors for the particle analysis. The total silhouette area of MP particles was shown to produce a confident approximation of the MP overall mass. The first reliable estimates of MP concentrations in the Black Sea coastal waters (Sevastopol Bay) accounted for 0.6 to 7 items m-3 and 6 to750 µg m-3 in terms of abundance and mass, respectively. No steady-state gradients have been revealed in MP distribution along the transect from the mouth of the bay to its corner. Inflow of MP to the bay waters and their transport along the bay seemed to be controlled by a complex combination of factors including rainfalls, wind regimes, currents and the Black river discharge.

An improved rapid analytical method for the arsenic speciation analysis of marine environmental samples using high-performance liquid chromatography/inductively coupled plasma mass spectrometry.

Arsenic contamination in marine environments is a serious issue because some arsenicals are very toxic, increasing the health risks associated with the consumption of marine products. This study describes the development of an improved rapid method for the quantification of arsenic species, including arsenite (AsIII), arsenate (AsV), arsenocholine (AsC), arsenobetaine (AsB), dimethylarsinic acid (DMA), and monomethyl arsonic acid (MMA), in seaweed, sediment, and seawater samples using high-performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS). ICP-MS based on dynamic reaction cells was used to eliminate spectral interference. Ammonium nitrate- and phosphate-based eluents were used as the mobile phases for HPLC analysis, leading to shorter overall retention time (6 min) and improved peak separation. Arsenicals were extracted with a 1% HNO3 solution that required no clean-up process and exhibited reasonable sensitivity and peak resolution. The optimized method was verified by applying it to hijiki seaweed certified reference material (CRM, NMIJ 7405-a) and to spiked blank samples of sediment and seawater. The proposed method measured the concentration of AsV in the CRM as 9.6 ± 0.6 μg/kg dry weight (dw), which is close to the certified concentration (10.1 ± 0.5 μg/kg dw). The recovery of the six arsenicals was 87-113% for the sediment and 99-101% for the seawater. In the analysis of real samples, AsV was the most abundant arsenical in hijiki and gulfweed, whereas AsB was dominant in other seaweed species. The two inorganic arsenicals (AsIII and AsV) and AsV were the most dominant in the sediment and seawater samples, respectively.

Global distribution of Trebouxiophyceae diversity explored by high-throughput sequencing and phylogenetic approaches.

Trebouxiophyceae are a ubiquitous class of Chlorophyta encountered in aquatic and terrestrial environments. Most taxa are photosynthetic, and many acts as photobionts in symbiotic relationships, while others are free-living. Trebouxiophyceae have also been widely investigated for their use for biotechnological applications. In this work, we aimed at obtaining a comprehensive image of their diversity by compiling the information of 435 freshwater, soil and marine environmental DNA samples surveyed with Illumina sequencing technology in order to search for the most relevant environments for bioprospecting. Freshwater and soil were most diverse and shared more than half of all operational taxonomic units (OTUs), however, their communities were significantly distinct. Oceans hosted the highest genetic novelty, and did not share any OTUs with the other environments; also, marine samples host more diversity in warm waters. Symbiotic genera usually found in lichens such as Trebouxia, Myrmecia and Symbiochloris were also abundantly detected in the ocean, suggesting either free-living lifestyles or unknown symbiotic relationships with marine planktonic organisms. Altogether, our study opens the way to new prospection for trebouxiophycean strains, especially in understudied environments like the ocean.

Cold vapour matrix-independent generation and isotope dilution inductively coupled plasma mass spectrometry for reference measurements of Hg in marine environmental samples.

The analytical procedure for reference measurements of Hg in marine environmental samples based on cold vapour generation (CVG) inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) and isotope dilution calibration strategy (ID) is described in the present study. The procedure was applied on different matrices and varying mass fractions for mercury in oyster, marine sediment and costal seawater samples. The use of CVG for sample introduction resulted in sensitivity enhancement, reduction of blank levels, minimization of matrix interferences and the elimination of memory effects. The entire measurement process was described by mathematical equations, and all factors influencing the final results were systematically investigated. The expanded uncertainty on results was estimated following the ISO/Guide to the Expression of Uncertainty in Measurement guidelines, and all major contributions were identified. Modelling of the entire measurement process and the use of primary method of measurements ID ICP-MS related obtained values for total mercury in different types of marine matrices to the international system of units SI. Obtained results for mercury mass fractions in biota and marine sediments were used as the International Atomic Energy Agency's contribution in the certification campaigns for marine reference materials and were in excellent agreement with the assigned reference values.

Diversity of salt-tolerant tellurate-reducing bacteria in a marine environment.

Tellurium (Te) has been increasingly used as a semiconductor material in copious amounts, with a concomitant increase in its discharge from industrial effluents and mining wastewater into the environment. However, soluble Te, such as tellurate (VI) and tellurite (IV), is toxic to organisms. Thus, highly efficient technologies need to be developed for a double-benefit detoxification and recovery of soluble Te from industrial and mining wastewater. Since industrial wastewater contains high concentrations of salt, salt-tolerant microorganisms that metabolize rare metals such as Te have been the subject of focus for the effective detoxification and recovery of Te. In the present study, a total of 52 salt-tolerant tellurate-reducing microorganisms were isolated from marine environmental samples. Of these, 18 strains achieved greater than, or equal to, 50% removal of water-soluble Te from a medium containing 0.4 mM tellurate after 72 h incubation. The 18 isolated strains belonged to 13 species of the following 9 genera: Sulfitobacter, Ruegeria, Hoeflea, Alteromonas, Marinobacter, Pseudoalteromonas, Shewanella, Idiomarina, and Vibrio. No microorganism has been reported to reduce tellurate and tellurite from six of the aforementioned genera, namely, Sulfitobacter, Ruegeria, Alteromonas, Marinobacter, Idiomarina, and Vibrio. Especially, one of the isolates Sulfitobacter sp. strain TK39B, removed 82% (w/w) of soluble Te with a 4% NaCl tolerance. These results showed that salt-tolerant tellurate-reducing bacteria that can be used in the detoxification and recovery of Te are widely present in the marine environment.

Integrated disperser freezing purification with extraction using fatty acid-based solidification of floating organic-droplet (IDFP-EFA-SFO) for triclosan and methyltriclosan determination in seawater, sediment and seafood

A microextraction method for the determination of triclosan and methyltriclosan in marine environmental samples was developed. The disperser was first serves as a preliminary extractant for analytes, then as a frozen solvent to remove impurities at −20 °C, and finally as a disperser agent in the microextraction procedure. With the extractants solidified and float on the surface of the aqueous phase at low temperature, a separation was achieved to avoided use of specialized laboratory instruments. The method was optimized using Plackett-Burman design and central composite design as follows: 146 μL octanoic acid as extractant, 793 μL acetoneas disperser, 3.0 min centrifugation and 1.1 min vortex time. The limits of detection were 0.022–0.060 μg L−1 or μg kg−1 and recoveries were 83.3–103.5% for TCS and MTCS in seawater, sediments and seafood. The method has excellent prospects for sample pre-treatment and trace-level analysis of triclosan and methyltriclosan in marine environmental samples.

A High-Throughput Method (ASE-GC/MS/MS/MRM) for Quantification of Multiple Hydrocarbon Compounds in Marine Environmental Samples

AbstractA high-throughput method was applied in small and complex environmental samples for targeting multiple organic fractions (polar, nonpolar). The analytical method consists of a single-step lipid extraction and purification procedure (accelerated solvent extraction [ASE] system) coupled with a single-run step using gas chromatography with tandem mass spectrometry, operated in multiple reaction monitoring mode (GC/MS/MS/MRM). Successful application of this method is summarized for multiple chemical groups (aliphatics, terpanes, steranes, triaromatic steroids, polycyclic aromatic hydrocarbons, and oxidation products).

Draft Genome Sequence of "Candidatus Moanabacter tarae," Representing a Novel Marine Verrucomicrobial Lineage.

The Tara Oceans Consortium has published various metagenomes of marine environmental samples. Here, we report a contig of 2.6 Mbp from the assembly of a sample collected near the Marquesas Islands in the Pacific Ocean, covering a nearly complete novel verrucomicrobial genome. We propose the name "Candidatus Moanabacter tarae" for the corresponding bacterium.

Distribution, accumulation, and potential risk of polybrominated diphenyl ethers in the marine environment receiving effluents from a sewage treatment plant

We investigated the effect of sewage treatment plant effluent on the distribution and accumulation of polybrominated diphenyl ethers (PBDEs) in the marine environment. PBDEs concentrations in seawater and surface sediments were within the ranges 1.58–6.94 ng/L and 2.18–307 ng/g dw, respectively. PBDE concentrations in sediments gradually decreased with increasing distance from inner bay including the sewage outfall. The contribution of effluent to PBDE distributions was very limited. The concentrations of PBDEs in sediment core decreased exponentially with increasing depth. PBDE concentrations in oysters were 4.7–37 ng/g lw. BDE-209 was the dominant congener in marine environmental samples receiving effluent. Estimated dietary exposures of PBDEs by seafood were 0.01–0.08 ng/kg body weight/day, which were more than six orders of magnitude lower than the reported levels of PBDEs with the no observable adverse effects. Hazard quotients demonstrated that, at present, PBDEs posed no potential risk to benthic organisms in the study area.