Lipid peroxidation level (LPO), shell biometry, shape, elemental content, and microstructure were studied in three populations of Siphonaria pectinata in the complex lagoon-channel of Bizerte across a coastal pollution gradient (northern Tunisia). LPO was found in higher concentrations in harbour populations, and shells had centred apex and were flattened. Shells were also thicker, particularly in the inner layer, with many fibrous inter-beds formed. Difference in crystallization pattern was observed in numerous shells from all three populations, being more common in harbours. From the control station to the contaminated stations, shell elemental changes were observed, with a decrease in Ca, P, Sr, and S and an increase in Cl, Cd, Cu, Fe, and K. All of these findings suggested that shell alterations could be used as a good biomarker for coastal contamination.

Knowing the polycyclic aromatic hydrocarbons (PAHs) pollution properties in ocean is highly needed to protect the open sea. In July to August of 2020, twenty surface water samples were obtained from the East China Sea to the Philippine Sea. The ranges of Σ₁₅PAHs concentrations were 3.188–5.29 ng L⁻¹ in dissolved phase, 0.455–1.305 ng L⁻¹ in particulate phase in the Philippine Sea. 3, 4-Ring PAHs were the most abundant PAHs. Their spatial differences in dissolved phase were mainly caused by human activities, the summer monsoon from the Philippine Islands and the Northern Equatorial Current, and the Kuroshio Current and Subtropical Countercurrent. The source analysis showed that PAHs in surface water in the Philippine Sea may come from coal combustion. It is the first time to analyze the occurrence and distribution of PAHs in the Philippine Sea.

To evaluate the heavy metal contamination and groundwater quality in southern Saudi Arabia, 105 groundwater samples were analyzed for EC, pH, TDS, major ions (NO₃⁻, Cl⁻, HCO₃⁻, SO₄²⁻, F⁻, Ca²⁺, Mg²⁺, Na⁺, and K⁺), and heavy metals (Fe, Li, As, B, Al, Cr, Cu, Mo, Ni, Se, Sr, V, Zn, and Mn). Groundwater quality index (GWQI), degree of contamination (Cd), heavy metal pollution index (HPI), ecological risks of heavy metals (ERI), salinity hazard (EC), sodium adsorption ratio (SAR), sodium percentage (Na%), and Kelly's ratio (KR) were calculated and compared, and multivariate statistical techniques were applied. The results revealed that the major cations and anions followed the orders of Na⁺ > Ca²⁺ > Mg²⁺ > K⁺ and Cl⁻ > SO₄²⁻ > HCO₃⁻ > NO₃⁻ > F⁻, respectively. The maximum values of As, Mn, Cr, Ni, Se, and Zn were above the permissible limits for drinking water purposes. Pollution indices indicated that 20 to 52% of the groundwater samples were suitable for agricultural and domestic purposes. The unsuitable samples were distributed mostly in the western part along the Red Sea coast. Multivariate statistical analyses revealed that the dissolution of halite and gypsum (in sabkha deposits), carbonates, and the agricultural activities were the possible sources of the major cations and anions, and heavy metals in the study area.

In 2010, Indonesia estimated as the second-largest country in the world that donates plastic to the sea. This study aims to investigate the spatial and temporal distribution of microplastics in tropical estuaries. The sampling was carried out in Benoa Bay with four repetitions representing the wet and dry seasons. Spatially it was found that the highest microplastic abundance around the Suwung landfill, while the lowest at Badung River Estuary, middle, and an inlet of the Benoa Bay. The highest percentage to the lowest microplastic based on the size was 500–1000 μm (37.9%), >1000 μm (35.7%), 300–500 μm (22.1%), and <300 μm (4.3%), while based on the shape were fragments (73.19%), foam (17.02%), fiber (6.38%), and granule (3.40%). No significant differences were found between the wet and dry seasons based on the abundance, but significantly varied based on size and shape. Polymers of microplastics were dominated by polystyrene, polypropylene, and polyethylene.

Plastic is one of the most commonly found residues in the marine environment, which can cause several impacts. This study evaluated the interaction of marine litter with surf-zone trammel nets in Southern Brazil. Fifty fishing operations were sampled, where 4213 items were captured: 1500 discarded fish, 1384 fragments of marine litter, and 1329 utilized fishes. Plastics were the most abundant items (n = 1363), representing 98.4% of the registered marine litter, especially plastic bags (n = 1191). 94.5% of registered marine litter is considered as single-use waste. The interaction with marine litter can cause negative impacts to small-scale fisheries (e.g. economic and damage to fishing nets). We highlight the urgency in implementing actions for urban solid waste management and public policies to reduce single-use plastics and educational campaigns on the environmental theme.

Stranded marine debris (MD) has become a hot topic on Bali Island because it threatens coastal tourism sustainability. This study aims to investigate the spatiotemporal abundance and characteristics of MD on 14 touristic beaches in Bali Island. Sampling is carried out twice every season by adapting methods from NOAA's MD program. We found that the average MD abundance and weight were 0.356 ± 0.366 items/m² and 4.057 ± 3.892 g/m², respectively. Plastic dominated the MD based on abundance (86.9%) and weight (40.1%). Plastic bags, straws, and plastic cups are the most common items among plastics. The MD is originated from Indonesia and is dominated by land-based sources. The beaches are categorized as dirty in the rainy seasons and clean in the dry seasons. Statistically, the MD based on abundance, weight, category, source, and level of cleanliness varied significantly between seasons.

Coastal systems are highly productive areas for primary productivity and ecosystem services and host a large number of human activities. Since industrialization, metal micronutrients in these regions have increased. Phytoplankton use metals as micronutrients in metabolic processes, but in excess, had deleterious effects. In coastal systems, picoeukaryotes represent a diverse and abundant group with widespread distribution and fundamental roles in biogeochemical cycling. We combined different approaches to explore picoeukaryotes seasonal variability in a chronically metal polluted coastal area at the south-eastern Pacific Ocean. Through remote and field measurements to monitor environmental conditions and 18S rRNA gene sequencing for taxonomic profiling, we determined metal chronic effect on picoeukaryote community's structure. Our results revealed a stable richness and a variable distribution of the relative abundance, despite the physicochemical seasonal variations. These results suggest that chronic metal contamination influences temporal heterogeneity of picoeukaryote communities, with a decoupling between abiotic and biotic patterns.

This baseline intends to report on littering related to single-use plastic straws, contextualized on two touristic beaches on the Northern shores of Crete (Greece). While beached straws were found to be mainly depending on local drivers, the study further highlighted an additional source of pollution related to plastic straws: the clear wrap in which single-use items can be offered to users. Over the summer months, a number of discarded straw wraps was in fact found, significantly related to both beach width and the presence of colorful straws. Wraps are different in shape, material, as well as likelihood of being dispersed and broken down in the environment, and easily escape estimates from non-targeted sampling. The ban on single use items seems then to be the most effective approach to avoid straws and, indirectly, straw wraps litter or spills.

Microplastics pollution is progressively threatening natural parks across the world. In the framework of monitoring this concerning trend, the present study focuses on the occurrence and identification of mesoplastics (MEPs) and microplastics (MPs) in sand samples collected before and after the summer season from the beach of the Nature Park of Migliarino San Rossore Massaciuccoli (Pisa, Italy). Meso- and microplastics were identified using Fourier transform infrared spectroscopy 2D Imaging, and detected in all samples with average concentrations of 207 ± 30 MPs/kg d.w., and 100 ± 44 MEPs/kg d.w., respectively. Seasonal changes of flow of the Arno River, industrial activities, and urban footprint were considered as the major sources of plastic pollution. Our results showed the occurrence of both natural and synthetic polymers including cellulose, polyethylene, polypropylene, polyamides, polyethylene terephthalate, and acrylonitrile.

This study deals with the toxicity assessment of crude and bunker oils representative of prospective oil spill threats in Arctic and Sub-Arctic seas (NNA: Naphthenic North-Atlantic crude oil; MGO: Marine Gas Oil; IFO: Intermediate Fuel Oil 180), alone or in combination with a third-generation dispersant (Finasol OSR52®). Early life stages of sea urchin, Paracentrotus lividus, were selected for toxicity testing of oil low-energy water accommodated fractions. A multi-index approach, including larval size increase and malformation, and developmental disruption as endpoints, was sensitive to discriminate from slight to severe toxicity caused by the tested aqueous fractions. IFO (heavy bunker oil) was more toxic than NNA (light crude oil), with MGO (light bunker oil) in between. The dispersant was toxic and further on it enhanced oil toxicity. Toxic units revealed that identified PAHs were not the main cause for toxicity, most likely exerted by individual or combined toxic action of non-measured compounds.