Estuaries are ecologically valuable ecosystems that process nutrients through complex biogeochemical processes. Here we identify drivers and inhibitors of nitrogen removal in unvegetated intertidal sandflats at six sites in Manukau Harbour (37° 2.00′S 174° 42.00′E) to quantify the exchange of solutes across the sediment-water interface, with nitrogen removal rates (NRR) measured at two contrasting sites (PI and CB) near and far, respectively, from an historical wastewater treatment plant. Solute fluxes were paired with sediment and macrofauna community data to identify drivers of ecosystem function. Fluxes of oxygen, nitrogen and phosphorous were found to vary among sites, with differences attributed to variation in sediment characteristics (grain size, chlorophyll a, organic content) and macrofauna community structure. Mean NRR was found to vary between sites (PI = 32.2 vs CB = 217.9 μmol N₂/m²/h), with bioturbating macrofauna (bivalves Austrovenus stutchburyi and Macomona liliana), microphytobenthic biomass, and exposure to nutrients likely key contributing drivers.

This study compared the ability of Sargassum fusiforme to accumulate As, Cd, Cr, Cu, Ni, Pb and Zn in its five tissues (main branch, lateral branch, leaf, receptacles and pneumathode). The concentrations of these trace elements in seawater, surface sediments and different tissues of S. fusiforme were analyzed in different areas in Dongtong County (Wenzhou City, China). The presence of receptacle at all sites indicated that S. fusiforme had entered the mature stage. However, the proportion of each tissue in S. fusiforme in different sites was varied, indicating subtle differences in growth. S. fusiforme has a great capacity to accumulate trace elements, showing relatively high levels of As (28.2–64.2 mg kg⁻¹) and Zn (19.9–80.8 mg kg⁻¹). The elements are mainly stored in leaf, receptacles and pneumathode. Compared to element concentrations in the surrounding environment, the seaweed exhibited stronger bioconcentration capacity for As and Cd than for other elements. According to our health risk assessment results, the hazard index and carcinogenic risk were below the limit, suggesting that the S. fusiforme ingestion would not pose any health risk and the potential risk of intake branches was even lower than that of other tissues.

The number of studies on microplastic accumulation in marine organisms has increased precipitously recently, though information is geographically-skewed and limited in terms of local effects. We characterized microplastic accumulation in oysters (Saccostrea cucullata) along a Bornean coastline, focusing on spatial variation. Comparisons were made between locally-polluted (Brunei Estuarine System, BES) and relatively pristine, open-shore (South China Sea, SCS) coastlines. Sixteen coloured microplastic types were characterized into three shapes (fragments, fibres, pellets). Fragments (74.9%), especially smaller polypropylene black fragments predominated in the samples (<50 μm, 31.7%). Site-specific levels of microplastic accumulation varied from 0.43 to 7.20 particles/g oyster tissue. BES and SCS sites differed qualitatively, indicating limited interaction. In the BES, accumulation was greatest near the predicted source (Bandar) and declined strongly seawards, implying current flow, environmental sequestration (local sinks) and seawater dilution effects. Such local-scale variation in microplastic loading in estuaries cautions against extrapolating from limited sampling.

Heavy metal-contaminated wastes can threaten mangrove forests, one of the most biodiverse ecosystems in the world. The study evaluated the geospatial distribution of heavy metals concentrations in soils, the ecological and human health risks, and metal contents in soil fractions and mangrove organisms in the Botafogo estuary, Brazil, one of the most environmentally impacted estuaries in the country. The metal concentrations exceeded by up to 2.6-fold the geochemical background; 91%, 59%, 64%, 31%, and 82% of the soils were contaminated with Cr, Zn, Pb, Cu, and Ni, respectively. Adverse effects to the biota may occur due to Cr, Cu, Ni and Pb exposures. Contents of clay and organic matter were the main factors governing the distribution of metals in soil, contributing to up to 63% of the total variability. However, the geospatial modeling showed that the predictive ability of these variables varied spatially with the metal and location. The ecological and human health risks assessments indicated that the metal concentrations in soils are safe for the environment and human beings. There was a low transfer of metals from the soil to the biota, with values of sediment-biota accumulation factor (SBAF) and biological accumulation coefficients (BAC) lower than 1.0, except for Zn (SBAF = 13.1). The high Zn bioaccumulation by Crassostrea rhizophorae may be associated with the concentrations of Zn in the bioavailable fractions.

Ingestion of microplastics has been documented across marine species, but exposure remains sparsely described in many seabird species. We assess microplastic (between 0.2 and 5.0 mm) ingestion in two Northwestern Atantic - breeding species for which exposure to microplastics is entirely or largely undescribed: Common Terns (Sterna hirundo) and Roseate Terns (S. dougallii). Common Tern microplastic load did not vary between life stages (p = 0.590); microplastic load did differ in Common Tern adults breeding at two of three colonies explored (p = 0.002), with no other regional differences observed. Roseate Terns ingested significantly more microplastics than Common Terns (p = 0.007). Our results show that microplastic ingestion by terns varies regionally and interspecifically, but not by life stage, trends potentially explained by dietary differences. We provide the first quantification of microplastic fiber ingestion by terns in the Northwestern Atlantic and identify trophic dynamics related to microplastic ingestion, representing an important step toward understanding the risk of the pollutant to terns across regions, as well as toward the use of terns as potential bioindicators of microplastics.

Blue swimming crab (BSC) Portunus pelagicus from the Bali Strait had the lowest Cu, Zn, Cr, Pb, Cd and Hg concentrations compared to those from the Java Sea and the Madura Strait. The order of metal concentrations in BSC was Cu > Zn > Cr > Pb > Cd > Hg. The levels of six metals in BSC from all stations were less than the maximum allowable limits. However, Cr levels in BSC from the Java Sea and the Madura Strait exceeded the provisional tolerable weekly intake. All of the hazardous index values reported were greater than one, indicating that consumption of this crab from these locations appears to be hazardous to human health. Furthermore, because the Cr and Cd target cancer risk values were higher than 10⁻⁴, people who consume this crab from these locations may develop cancer after a lifespan of consumption.

Anthropogenic fibres are an emerging pollutant worldwide. The Can Gio mangrove area is located downstream of the Saigon River, and is characterised by high level of anthropogenic fibres originating from domestic and industrial textile and apparel manufacturing. In this area, biota is thus subjected to a high potential risk of anthropogenic fibre contamination. This study aims to characterise the accumulation of anthropogenic fibres in different tissues, i.e. gills, digestive systems, and remaining tissues, of white clams (Meretrix lyrata) cultivated in the Can Gio beach sand, during a seven-month sampling period. The results showed an average concentration of 3.6 ± 2.1 fibres individual⁻¹ or 2.7 ± 2.4 fibres g⁻¹ ww. Higher fibre accumulation was observed in remaining tissues than in gills and digestive systems, and no temporal variation was observed in all clam tissues. The intake of fibres by humans consuming clams was estimated to be 324 fibres inhabitant⁻¹ yr⁻¹.

The establishment of water quality criteria (WQC) for copper (Cu) was used as the basis for an ecological risk assessment of marine Cu pollution in Liaodong Bay, China. Published ecotoxicity data for Cu were obtained and supplemented with the results of acute Cu toxicity tests. The marine WQC for Cu in Liaodong Bay was developed using a species sensitivity distribution method with a safety factor of 2.0 and the USEPA acute-to-chronic ratio method. The ecological risk of Cu in Liaodong Bay was assessed by comparing the seawater Cu concentrations with the developed WQC. The results of this study showed that the acute and chronic Cu concentrations in Liaodong Bay were 3.31 and 2.18 μg/L, respectively. Comparison of the WQC to Cu concentrations in the bay resulted in risk quotients slightly >1.0 and typically ≤2.0. These data suggest that certain organisms in Liaodong Bay are at risk. These results can assist in the development of a pollution control management approach for the bay.

PURPOSE OF REVIEW: Microcystins (MCs) are refractory cyclic heptapeptides which mainly due to the release of bloom-forming cyanobacteria and is a problem of emerging environmental concern. The presence of MCs in water poses a severe challenge to the health of human beings. This review is aimed to summarize the recent progress in removing MCs, and to serve the development of theories and technologies for eliminating MCs in the future. RECENT FINDINGS: The traditional methods such as membrane filtration, chemical reagent, and biological enzyme suffer from high cost or second pollution in the process of removing MCs. The magnetic adsorption nanomaterial is regarded as an efficient treatment technology for the removal of MCs due to its easy separation and low cost. The carbon-based photocatalysis possesses a broader prospect for application in eliminating MCs, which could degrade MCs with high efficiency and lower energy consumption. This article reviews the physical, biological, and chemical methods of eliminating MCs. The mechanism of various methods for the removal of MCs was proposed. Additionally, the magnetic adsorption nanomaterial and carbon-based photocatalysis for removing MCs are also discussed. Finally, based on the drawbacks of current research, prospects for future research were discussed. This review is expected to provide a reference for future environmental pollutants remediation particularly within the domain of eliminating MCs.

One of the aims of this study is the development of a pretreatment method for additives, plasticizers and other components of micro-litter (APFs), and small microplastics (SMPs <100 μm) in the gastrointestinal tract (GIT) of five of the most widely distributed and consumed commercial fish species, Engraulis encrasiculos, Sardina pilchardus, Mullus surmuletus, Solea solea, and Sparus aurata. The second aim was to develop a simultaneous quantification and identification method via Micro-FTIR of APFs and SMPs ingested by these commercial fish species. The distribution of SMPs and APFs is characteristically different for each species investigated. E. encrasiculos and S. pilchardus had a higher weight of SMPs than the other species investigated. Regarding APFs, the highest abundance was observed in E. encrasiculos. This study highlights the importance of studying additives and plasticizers that can be used as efficient proxies of microplastics, as shown by the presence of vulcanizing agents such as Vanax®.