Comparative study of trace metals distribution in the surface sediment of Sundarban mangrove ecosystem in India and Bangladesh is one of the primary baseline study done so far. Trace metal distribution assessment covering lower salinity zone to higher salinity zone was done along Matla River (tidal river) in Indian side and freshwater zone to higher salinity zone along Passur River in Bangladesh side of Sundarban; representing anthropogenic influenced area, agricultural area, tourist site and pristine area. Trace metals distribution in the surface sediments of Sundarban mangrove ecosystem shows relatively higher value of trace metals, Co, Cr, Cu, Fe, Ni, Pb and Zn in Indian part when compared to Bangladesh. Enrichment factor shows the highest enrichment of Pb in both parts of Sundarban mangroves. Co, Cr, Cu, Pb and Zn show EF>1 indicates sediment contamination from anthropogenic activities. Cr, Ni and Pb were found to have moderate accumulation in geoaccumulation index with Fe showing high accumulation. Normalized data of trace metals shows 87.5% from Indian site and 80% of Bangladesh site as outlier, indicating anthropogenic influence. Out of total sampling site 50% of Indian and 40% of Bangladesh site show trace metal values enriched more than predicted value of trace metals indicating Indian part have more polluted sites than Bangladesh side of Sundarban, which is also confirmed by enrichment factor, I-geo and normalization values in both the sides.

Surface water samples from the environmental continuum spanning rivers (Petrohue, Cochamo, Puelo), fjord (Reloncaví), and the inner sea of Chiloé in Chilean Patagonia were analyzed to estimate concentration and distribution of dissolved Organochlorine pesticides (OCPs). High concentrations of HCHs, DDTs and endosulfan found in surface waters from rivers suggest that rivers are the major source of dissolved OCPs to coastal marine ecosystems. We interpret variations in the distribution and concentration as an apparent oscillation between rain and snow-scavenging processes that might determine the type of OCPs that can be preferentially deposited on mountains, glaciers, rivers, estuaries, and finally transferred to the marine realm. Predominance of α-HCH, γ-HCH, p,p′-DDE and α-endosulfan compounds suggest that the main deposition mechanism of OCPs to the Chilean Patagonia is rain scavenging. Snow and rain can be additional sources of OCPs that must be considered for future studies in fjord systems in Chilean Patagonia.

The aim of this study was to determine the activity concentrations and radiological hazard parameters of 137Cs and 40K in soft tissue samples of sea snails (Rapana venosa) collected from 12 different stations in the East Black Sea coastal area of Turkey. The values in soft tissues of sea snail samples with three different sizes were between 0.31 and 1.79 Bq kg−1 for 137Cs and 163.9 and 269.4 Bq kg−1 for 40K. The mean activity concentrations of 137Cs and 40K in tissues of small-sized sea snails were determined to be higher than those of 137Cs and 40K in soft tissues of the other sizes. The determined activity concentration values were lower than the concentrations reported in similar studies. Radiological hazard parameters such as the daily intake (Dint) of 137Cs and 40K, annual committed effective dose (Eeff), and lifetime cancer risk (LCR) were calculated and compared with the international recommended values.

Oil spills in the marine environment can have serious environmental, social and economic impacts. These impacts may be of transnational nature, and this makes the oil spill problem an international issue. Therefore, it is necessary to develop a common structured methodology for oil spill risk assessment. In this research, a general framework is presented for probabilistic risk assessment of oil spill from offshore oil wells. A case study is also performed in Persian Gulf to quantify the risk posed by 357 offshore wells to the near-shore receptors. First, thousands of hypothetical spill scenarios of different volumes are defined and simulated using a Lagrangian particle tracking model. Then, the result of the simulations is statistically processed to generate the risk networks and risk maps. The result of this research shed light on the importance of the pattern of environmental forcing elements and the frequency of spills in oil spill risk assessment.

Total contents and chemical speciation of Co, Ni, Cu, Ga, Mo, Cd, In, Sn, Sb, V, W, Tl, Bi and U in size-fractionated (<32, 32–63 and >63μm) core sediments from Jiaozhou Bay were investigated to reveal their responses to anthropogenic activities. Metal contents showed a decreasing trend with increasing grain sizes. However, the loadings of metal fraction on <32, 32–63 and >63μm grain sizes were 16%, 47% and 37%, respectively. Anthropogenic fluxes and enrichment factors of metals in >63μm fraction were closely linked to anthropogenic activities, with an obvious increase in upper 27cm (1998–2015) and a slight decrease in 2009year. Metals (especially for Cd, Co, Cu and Ni) in >63μm fraction were more easily released, with the highest percentage of acid soluble form and lowest residual form. Thus, the size fraction of >63μm cannot be ignored.

Poor microbial water quality jeopardizes the health and safety of food produced by aquaculture farms. Three fish farms and transect sites in Singapore were assessed for microbial water quality and antimicrobial resistance determinants. Of the 33 multidrug resistant E. coli isolated from surface waters of the Johor Straits, 81.8% were ESBL producers. The relative abundance of sul1, qnrA and intI1 genes were higher in sediments than surface waters. Among the surface water samples, higher concentrations (10−1−101) of beta-lactamases (blaSHV, blaOXA, blaCTX-M) were detected in the transect sites. This study highlights a potential antimicrobial resistance transmission chain from environmental waters, to animal carriers and humans.

The effects of two plastic-derived chemicals: Bisphenol A (BPA) and di-2-ethylhexyl phthalate (DEHP) were assessed on abundance and physiological responses of the marine toxic dinoflagellate Alexandrim pacificum. During 7days experiment, A. pacificum was exposed to different levels of BPA and DEHP (separately and in mixture). The responses were evaluated and compared with controls. Results showed that A. pacificum was highly sensitive to this contaminants comparing to other phytoplankton species. BPA and DEHP caused the decrease of the biomass (1.2 to 50 times lower relative to the controls), as well as the perturbation of the photosystem and the photosynthetic activity. Nevertheless, our results show a recovery of contaminated cells activity depending on exposure time and BPA and DEHP contamination. This could be related to an adaptation to induced stress or a degradation of BPA and DEHP in the medium.

Non-indigenous species (NIS) can cause substantial change in ecosystems and as marine invasives they can become a major threat to coastal and subtidal habitats. In September 2017 previously unknown and apparently NIS soft corals were detected on a shallow subtidal tropical rocky reef at Ilha Grande Bay, southeast Brazil. The present study aims to identify the species, quantify their distribution, abundance, and their interactions with native species. The most abundant NIS belonged to the recently described genus Sansibia (family Xeniidae) and the less common species was identified as Clavularia cf. viridis (family Clavulariidae). They were found along 170 m of shoreline at all depths where hard substrate was available. Sansibia sp. dominated deeper communities, associated positively with some macroalgal and negatively with the zoantharian Palythoa caribaeorum, which probably provided greater biotic resistance to invasion. Both species are of Indo-Pacific origin and typical of those ornamentals found in the aquarium trade.

Microplastics (<5 mm) exhibit intrinsic features such as density, hydrophobic surface, or high surface/volume ratio, that are known to promote microbial colonization and biofilm formation in marine ecosystems. Yet, a relatively low number of studies have investigated the nature of microplastic associated bacterial communities in coastal ecosystems and the potential factors influencing their composition and structure. Here, we characterized microplastics collected in the Bay of Brest by manual sorting followed by Raman spectroscopy and studied their associated bacterial assemblages using 16S amplicon high-throughput sequencing. Our methodology allowed discriminating polymer type (polyethylene, polypropylene and polystyrene) within small size ranges (0.3–1 vs. 1–2 vs. 2–5 mm) of microplastics collected. Data showed high species richness and diversity on microplastics compared to surrounding seawater samples encompassing both free living and particle attached bacteria. Even though a high proportion of operational taxonomic units (OTU; 94 ± 4%) was shared among all plastic polymers, polystyrene fragments exhibited distinct bacterial assemblages as compared to polyethylene and polypropylene samples. No effect of microplastic size was revealed regardless of polymer type, site and date of collection. The Vibrio genus was commonly detected in the microplastic fraction and specific PCR were performed to determine the presence of potentially pathogenic Vibrio strains (namely V. aestuarianus and the V. splendidus polyphyletic group). V. splendidus related species harboring putative oyster pathogens were detected on most microplastic pools (77%) emphasizing the need of further research to understand the role of microplastics on pathogen population transport and ultimate disease emergence.

This study provides contamination levels, distributions and source apportionment of PAHs in surface sediments in the mid-Adriatic and along the Croatian coast. Median summed concentrations of parent and alkyl-PAHs are circa 10 times lower in the off-shore transect stations of the mid-Adriatic (22.3 and 18.2 μg.kg−1 d.w.) than the ranges determined at the coastal stations, including those of Kaštela bay (227–331 and 11.7–197 μg.kg−1 d.w., respectively). The highest levels, circa 20 times higher, were found in Šibenik bay (median 6603 and 3051 μg.kg−1). The overall range of PAH concentrations spans more than 2000 times between the lowest and the highest contamination level. The geographical distributions reflect the presence of strong gradients at local and regional scales. A major factor influencing sedimentary PAH distributions at local scale appears to be the distance from their known continental and coastal upstream emission sites (urban, industrial, harbour …), whereas at regional scale, this distribution depends more on the routes of entry of PAHs into the study area. Two combustion and one petroleum model source profiles of PAHs were determined by alternative least square analysis. Benzo[b+j]fluoranthenes and fluoranthene/pyrene are compounds characterizing two pyrogenic sources respectively, while signatures of alkyl-substituted homologues (phenanthrenes/anthracenes, fluranthenes/pyrenes, chrysenes and dibenzothiophenes) delineate a petrogenic source profile. The quantitative apportionment of source contributions shows significant geographical differences, with a dominant petrogenic source found along the mid-Adriatic transect (approximately 74%) and in Kaštela bay (61%). In the coastal sediments about a fifty-fifty contamination mix is assigned to a petrogenic/pyrogenic source of PAHs (47% and 53% respectively), whereas in Šibenik bay a strong predominance is apportioned to the combustion compounds (81%).