The global presence and prevalence of microplastic have moved microplastic from an emerging pollutant to a persistent contaminant. Microplastic prevails in almost all spheres of the environment viz. terrestrial, marine and atmosphere the globe abundantly. The prevalence and toxic effects on marine organisms have been studied around the world but the studies are limited to the coastal regime of the Andaman and Nicobar Islands (ANI). This study aims to record microplastic prevalence on the tourist beaches of Port Blair, ANI. Three coastal stations namely Cove beach, Quarry beach and Wandoor beach were examined in detail in this regard. Microplastics in the form of lines, fragments, pellets, foams and fibres were found at the sampled sites. Wandoor beach recorded the highest microplastic particles ranging from 105–475 particles kg⁻¹ of sediment with the mean value of 249.82 ± 105.78 particles kg⁻¹. Quarry beach near the municipal waste dumpsite showed the lowest of 72.5–222.5 particles kg⁻¹ with a mean value of 135.625 ± 62.83 particles kg⁻¹. The polymeric forms found were High-density polyethylene (HDPE), polystyrene (PS), polypropylene (PP) and polyethylene terephthalate (PET). This study revealed microplastic input from municipal dump waste near the beach. Fourier Transform Infrared spectroscopy (FTIR) revealed the presence of a new type of polymer namely plasta zinc in the beach sediment, which possibly could be a nanoplastic. Its presence reveals the biological enzymatic degradation of microplastic occurring in the marine environment. Further investigations are required to determine the factors influencing the prevalence of microplastic, its toxic effects on marine habitat and microplastic degradation mechanisms in the marine habitat.

Spatial distribution and ecological risk levels of toxic metals (Cu, Pb, Zn, Ni, Co, As, Sr, V, and La) in sediments from the southern Black Sea coastal (Türkiye) were evaluated. The sediment samples were taken in April and May 2019 from thirty-one stations, from depths ranged between 16 and 65 m. The average metal concentrations (in dry weight) varied from 59.4 ± 4.8 to 102.5 ± 12.3 for Cu, 39.3 ± 4,1 to 46.1 ± 2.9 for Pb, 104.5 ± 4.7 to 126 ± 6.9 for Zn, 21.2 ± 1.8 to 24.9 ± 1.4 for Ni, 9.8 ± 0.4 to 16.6 ± 1.5 for As, 16.7 ± 0.5 to 18.2 ± 0.9 for Co, 68.2 ± 11.4 to 123.3 ± 13.5 for Sr, 82.7 ± 13.1 to 97.3 ± 4.3 for V, and 16.2 ± 1.8 to 23.6 ± 1.8 μg g⁻¹ for La. Geoaccumulation index (IGEO), Sediment enrichment factor (SEF), and pollution load index (PLI) indicated that Cu and Pb are above the pollution limits. Thus, continuous pollution monitoring programs should be established. Moreover, measures should be implemented more effectively to prevent pollution.

Considering the phasing-out of polybrominated diphenyl ethers (PBDEs), environmental concerns of PBDE alternatives and dechlorane plus (DP) are rising. Accordingly, this study investigates occurrence and ecological risks of PBDEs, PBDE alternatives and DPs in sediments of two littoral regions, the Pearl River Estuary (PRE) and Daya Bay (DYB), in southern China. Total PBDEs concentrations in surface sediments of the PRE and DYB were in the range (mean) of 0.30–28.7 (8.71) and 0.29–43.4 (6.05) ng/g dw, respectively. DP levels in surface sediments of the PRE (0.004–0.27 ng/g dw) were significantly higher than those in the DYB (0.005–0.24 ng/g dw) (p < 0.05). BDE 209 was the predominant component, followed by DBDPE, exhibiting regional variations in BFRs usage. Vertical profiles of BFRs and DP in the PRE and DYB sediment cores exhibited clear anthropogenic influences. Risk quotients suggest critical ecological risks of tetra-, penta- and deca-BDE congeners in all the surface sediments.

Measurement of particle motion from an offshore piling event in the North was conducted to determine noise levels. For this purpose, a bespoken sensor was developed that was both autonomous and sensitive up to 2 kHz. The measurement was undertaken both for unmitigated and mitigated piling. Three different types of mitigation techniques were employed. The acceleration zero-to-peak values and the acceleration exposure levels were determined. The results show that inferred mitigation techniques reduce the levels significantly as well as decreases the power content of higher frequencies. These results suggest that mitigation has an effect and will reduce the effect ranges of impact on marine species.

Properties and stability of water-in-oil emulsions influence oil behavior and response decisions. Closed-system lab protocols that assess emulsion stability cannot fully represent oil behavior in the open sea. We developed a novel test system that allows emulsions to spread over a laboratory flat pan. Nine highly weathered oils were studied and seven formed very stable emulsions in a closed-system. Results from our tests show that these oils underwent significant spreading unless the testing temperature were well below the oils' pour point. These findings indicate that emulsions may be less stable than laboratory tests indicate under some at-sea conditions (e.g. offshore in either high-energy or low-energy seas). Oil thinning due to spreading causes emulsions to break and the resulting thin oil film would be more susceptible to natural dispersion. Additional carefully designed laboratory and controlled field tests are needed to determine the operational relevance of our findings.

Comparative toxicological assessment studies on the effects of petroleum- and cellulose-based microfibers on aquatic plants are limited. Therefore, we evaluated the acute and 10-generational toxicological effects of two types of petroleum- and cellulose-based microfibers on the duckweed Lemna minor. Plant growth and photosynthesis parameters were monitored as bioindicators. The multigenerational test revealed the following ranking of the microfibers according to the severity of their effects on L. minor: polypropylene > lyocell > viscose > polyethylene terephthalate. The acute tests revealed a significant increase in the energy required to initiate photosynthesis, although the growth of L. minor was not adversely affected by any microfiber. Both petroleum- and cellulose-based microfibers induced adverse effects on the growth and photosynthesis of L. minor in multigenerational tests. The results of the generational tests contribute to the understanding of the long-term adverse effects of microfibers on aquatic plants.

Baseline polycyclic aromatic hydrocarbons (PAHs), total petroleum hydrocarbons (TPH) and organochlorine pesticides (OCPs) in surface sediments were measured in Gorgan Bay, Iran. Total PAHs, TPH, and OCPs concentrations ranged between 13.70 and 23.68 ng g⁻¹, 2.97 to 11.51 μg g⁻¹ dry weight, and below detection to 1.41 ng g⁻¹, respectively. Benzo [k] fluoranthene and anthracene had the highest (BkF; 19.77 ± 0.08 ng g⁻¹), and lowest (Ant; 4.38 ± 1.72 ng g⁻¹) individual PAH concentrations, respectively. The most abundant OCPs were β-Endosulfan, followed by methoxychlor and endrin. PAH isomeric ratios in sediments revealed that contamination originated from mixed sources, with a strong indication of pyrogenic sources. Ecological risk assessments based on sediment quality guidelines (SQGs) suggested that individual PAHs and OCPs posed low ecological risks in Gorgan Bay.

Outlet infrastructure and hypersaline discharge from large-scale desalination operations have the potential to impact marine environments. Here, we present the results of a six-year M-BACI assessment of the impacts of desalination discharge outlet construction and hypersaline effluent on the cover of habitat-forming species on temperate reefs. The construction of the desalination outlet caused a decrease in the cover of Ecklonia radiata (kelp) and an increase in the cover of algal turfs up to 55 m from the outlet. Following the commencement of discharging of hypersaline brine, the impact to E. radiata and algal turfs persisted, but decreased in spatial extent to be less than 25 m from the outlet. Hypersaline discharge was also associated with a significant decline in the cover of sponges in outlet compared to reference sites. Overall, our results demonstrate that the water security benefits from large-scale desalination may sometimes be appropriately balanced against the associated ecological consequences.

Plastic comprises of variety of polymers and has many applications, but the waste generated by plastic pose threat to environment and marine life. Plastic can be classified into two types: thermoplastics and thermosetting and are divided into 7 different categories: (Polyethylene Terephthalate [PETE], High-Density Polyethylene [HDPE], Polyvinyl Chloride [PVC], Low-Density Polyethylene [LDPE], Polypropylene [PP], Polystyrene or Styrofoam [PS] & Polycarbonate or ABS [others]). To curb the deleterious effects of plastic waste various methods have been devised and utilized that include chemical, physical and biological treatments. One of the aspects primarily focused by the researchers is the phenomenon of biodegradation and there are many microorganisms (bacteria) that have the ability to carry out this particular process. These bacteria assist biodegradation by production of several enzymes like PETases and MHETases. There are few microorganisms that have been listed which cannot be applied for industrial use due to its low biodegradation capacity. To overcome this problem, PHA is one of the alternatives to replace the synthetic plastic due to its high degrading capacity.

China is one of the largest waste importers and producers in the world, with land-based discharges mainly from domestic sewage and industrial wastes being the main source of marine debris (MD) including three distributional types as stranding on the beach (BMD), floating on the water surface (FMD), and submerging into sediments (SMD). Fishery-related activities are also one of the main sources of marine debris: intensive aquaculture, fishing, and related household activities. Marine debris, showing different ways of leaching, degradation and fragmentation, can be ingested, incorporated and accumulated by marine organisms through the food chain, and ultimately pose risks to the ecological environment, economic benefits and human health. Comprehensive countermeasures, from awareness to practices and from the government to the public, are now being implemented in China and have achieved remarkable results especially in domestic waste incineration, but greater commitment and stronger execution are urgently required.