Nutrient and heavy metal concentrations in porewater/overlying water and their benthic fluxes were investigated to study their accumulation and transport at the sediment−water interface and the influences of sediment in the Pearl River Estuary, China. Results revealed that distribution of nutrients and metals reflected the effects of terrestrial inputs and some physicochemical processes. Benthic fluxes also suggested that nutrients and heavy metals Pb, Zn and Cd diffused from sediment to overlying water, but not for As, Co, Cr, Fe, Mn and Ni. Exchange capacities showed that 10⁶–10⁸ mol nutrients and 10⁵–10⁷ g Pb, Zn and Cd released from sediment to overlying water annually, indicating their potential ecological threat. However, 10⁵–10⁹ g metals As, Co, Cr, Fe, Mn and Ni were deposited annually, which may reduce the pollution pressure caused by anthropogenic activities. This study will provide references for the potential influence of benthic fluxes on estuarine environment globally.

Microplastic transfer between horseshoe crabs (Limulus polyphemus) and migratory shorebirds through consumption of crab eggs was examined in Jamaica Bay, New York. Fertilized and unfertilized crab eggs, shorebird fecal pellets, beach sand, and bay water were processed with a hydrogen peroxide solution to remove organic material, then stained with a Nile Red to identify microplastics using fluorescence microscopy. Microplastics were present in all samples and ranged from approximately26–1300 μm. Unfertilized and fertilized eggs contained significantly higher numbers of microplastic particles per gram than shorebird fecal pellets, beach sand, and bay water. The presence of microplastics in unfertilized egg samples indicates that microplastics undergo maternal transfer during oogenesis. We estimated that 1 g of horseshoe crab eggs could contain approximately 426 to 840 microplastic particles, suggesting that shorebirds feeding on this resource could be ingesting a substantial burden of microplastics during their migratory stopover, much of which appears to be retained by shorebirds, rather than being eliminated in their fecal pellets.

A literature assessment was conducted to determine the current state of microplastics research in ASEAN countries focusing on 1) microplastics in water, sediment, and water organisms; 2) microplastics' sources and dispersion; and 3) microplastics' environmental consequences, including human toxicity. ASEAN countries contributed only about 5 % of the global scholarly papers on microplastics, with Indonesia contributing the most followed by Malaysia and Thailand. The lack of standard harmonized sampling and processing methodologies made comparisons between research difficult. ASEAN contributes the most to plastic trash ending up in the ocean, indicating a need for more work in this region to prevent plastic pollution. Microplastics are found in every environmental compartment; however, their distribution and environmental consequences have not been sufficiently investigated. There are very few studies on microplastics in the human blood system as well as respiratory organs like the lungs, indicating that more research is needed.

Anthropogenic sedimentation is a major contributor to the worldwide decline in coral cover. Resuspension of benthic material can exacerbate the threat to corals, but evidence of vertical sediment gradients is limited. Here, we installed sediment traps at 10, 20, 30, 40, and 50 cm above the substrate at three equatorial reef sites for three months and determined the dry mass, particle size, and biogeochemical composition of the material collected. As the trap mouth height increased from 10 to 50 cm, dry mass decreased as sediments became finer, poorer in carbonate, and richer in silicate. Despite among-site differences in collected sediment, this vertical gradient was present in all trap arrays, likely driven by resuspension mechanisms on seabed sediments. These results have implications for coral vertical ecology and underline the importance of standardising sediment collection protocols.

Understanding the distribution of trace elements in Ocellated icefish (Chionodraco rastrospinosus), one of fish species with lacking hemoglobin from the family Channichthyidae and distributes in a very limited area at the south Scotia Sea, will help understand their physiological composition and conserve this vulnerable population; however, information on this topic is extremely limited. This study examines trace elements (two essential elements, copper [Cu] and zinc [Zn], and two non-essential elements, cadmium [Cd] and lead [Pb]) in C. rastrospinosus and provides for the first time baseline data on elemental distribution in four tissues of C. rastrospinosus in the northern Antarctic Peninsula (NAP). The element concentrations showed the following trends: Zn > Cu > Pb > Cd in muscle and stomach and Zn > Cu > Cd > Pb in intestine and liver. Among all tissues, muscle had the lowest element concentrations. The average Zn level is 70.81 ± 28.91 μg g⁻¹ dry weight (DW) in C. rastrospinosus muscle, which is higher significantly than average levels of Cu (0.56 ± 0.41 μg g⁻¹ DW), Pb (0.29 ± 0.33 μg g⁻¹ DW) and Cd (0.12 ± 0.05 μg g⁻¹ DW). Zn and Cd concentrations in the stomach and intestines were significantly positively correlated. C. rastrospinosus could be a useful bioindicator for monitoring variability in trace elements dynamics in NAP and the environmental variability in this region.

Global shipping facilitates the introduction of invasive species and parasites via ballast water and hull fouling. Regional management of invasives may be strengthened by identifying the major routes in a network, to allow for targeted ship inspections. This study used cargo shipping records to establish the connectivity of shipping routes between ports in Ireland and other nations. 9291 records were analysed, investigating vessel residence and journey times. On average, vessels spent up to five days in port and less than five days at sea. However, there was strong variation, with general cargo ships recording up to 13 days in port. A horizon scan for species likely to invade in Ireland was incorporated for five species and their associated parasites: American razor clam, Asian shore crab, Brush clawed shore crab, Chinese mitten crab and American slipper limpet. Routes of concern are highlighted and a general framework for effective management is outlined.

This study evaluated the impacts of the mining tailings after the rupture of the Fundão dam on fish communities on the Atlantic Ocean southeast coast. Four sample collections were carried out over two years (2018–2020), in seasonal periods. Omnivorous/herbivorous and carnivorous fish were collected for analysis of metal bioaccumulation, multibiomarkers of environmental contamination and histopathology. Metal bioaccumulation was stronger correlated in carnivorous fish in the dry-2018 collection, besides higher activity of antioxidant enzymes, energy metabolism and higher morphological damage; however, there was less oxidative damage and less metallothioneins induction, and these variables were strongly associated with the wet-2020 collection. In a temporal view, it was possible to observe a reduction in metal levels in fish, except in the mouth of the Doce River. These events can be explained by seasonal natural events, which tend the resuspension and boost metal levels, mainly in the mouth region during the rainy season.

From 2006 to 2020, groundwater investigations were conducted in the Korba coastal aquifer in northern Tunisia along two flow paths (transects S1 and S2), perpendicular to the shoreline. Groundwater sampling, hydrodynamic monitoring, and electrical tomography imaging were performed in situ. Geochemical analysis (Ionic ratios, ionic deltas, conventional diagrams, and stable isotopes) and modelling using PHREEQC, and multivariate statistical analysis were applied. The objective was to identify the potential origin of groundwater salinization (i.e., high TDS and NO₃) and to study associated processes. The groundwater flow inversion was corroborated by the piezometric survey in transect S1, where a piezometric depression of 5 m was detected at 4000 m from the seashore. Seawater intrusion and agricultural contamination, mainly through N-fertilizers, both contribute to groundwater mineralization and consequently salinization, according to PCA analysis. The impacted geochemical area of seawater intrusion was estimated to be 4000 and 1500 m, respectively, along transect S1 and transect S2. Inversely, agricultural contamination acts in internal areas beginning at 2000 m and 1500 m from the shoreline for S1 and S2, respectively. Results of different scenarios of inverse geochemical modelling along flow paths indicated that mixing, ion exchange, dissolution of gypsum, and precipitation of dolomite and calcite are the main processes controlling the groundwater composition in the coastal study area.

Strong stratification has formed in Lake Abashiri, a typical meromictic lake in Hokkaido, in the subarctic zone in Japan. When the anoxic water of the lower layer is upwelled to the surface by a strong wind, fish and corbicula clams die due to a lack of dissolved oxygen. This event is called as blue tide. It was observed that the dissolved methane in the lake decreased more than 100 t after the blue tide which occurred in 2008. This is the discovery of the phenomenon that a large quantity of methane diffuses to the atmosphere caused by upwelling of anoxic water which contains dissolved methane. We named the event as “methane burst”. It is also the first report that the wind-driven upwelling is reproduced using a numerical analysis code and the methane burst is analyzed. During this blue tide, the methane flux was approximately 170 times greater than usual.

We examined microplastics (MP) in two commercially important dried fish, Bombay duck (Harpadon nehereus) and ribbon fish (Trichiurus lepturus), collected from two sites on the Bay of Bengal (Cox's Bazar and Kuakata). The number of MP found in dried Bombay duck and ribbon fish from Kuakata was significantly higher (41.33 g⁻¹ and 46.00 g⁻¹, respectively) than the MP present in samples collected from Cox's Bazar (28.54 g⁻¹ and 34.17 g⁻¹, respectively). Fibers were the most common type of MP identified in all samples (41–64%), followed by fragments (22–34%), microbeads (9–16%), films (3–4%), foams (1–4%), and pellets (0–2%). ATR-FTIR analysis revealed three different types of MP polymer - polyethylene (35–45%), polystyrene (20–30%) and polyamide (30–45%) in the dried fish samples. The study confirms the presence of high MP loads in dried fish from the Bay of Bengal, with high potential of trophic transfer of MP to the human body.