Finfish cage culture is the most predominant form of mariculture. The rapid expansion of fish cage culture systems has raised concerns about their environmental impact, such as nutrient release. In this study, for the first time, we estimated the release of nitrogen (N) and phosphorus (P) from fish cage culture in Daya Bay, southern China, by constructing N and P budget models based on a mass balance principle. In addition, the contribution and importance of nutrients from fish culture and other nutrient sources, including submarine groundwater discharge, benthic sediments, local rivers, and atmospheric deposition were assessed. The annual amount of N and P released from fish cage culture was 205.6 metric tons (hereafter tons) of N and 39.2 tons of P, including 142.7 tons of dissolved inorganic nitrogen (DIN) and 15.1 tons of dissolved inorganic phosphorus (DIP). Among the analyzed nutrient sources, the contributions of DIN and DIP from fish culture were 7.0% and 2.7%, respectively. For cages consuming conventional trash fish, 142 kg of N and 26 kg of P were released into the environment per ton of fish products, much higher than the values (72 kg N and 17.3 kg P) for cages using formulated feed. In fish culture, the dissolved nutrients were more N rich, but the particulate nutrients were more P rich. The ratio of cage-derived N and P was 21.1, higher than the ratio of coastal seawater (27.1), indicating that cage culture may also impact the local nutrient forms around farming regions. Oyster cultivation and harvest removed 126.3 tons of N and 35.1 tons of P from of the bay. Replacing trash fish with formulated feed and co-culturing of nutrient extractive species (e.g., bivalves, macroalgae) and deposit-feeding species (e.g., sea cucumber) in fish culture zones can be efficient nutrient mitigation strategies.

The concentrations and distributions of polycyclic aromatic hydrocarbons (PAHs) were examined from 2008 to 2014 in the surface waters of the Japan Sea region. PAH concentrations decreased in the Japan Sea and Tsushima Strait; consistent with improvements in atmospheric pollution from Japan. There were no changes in the Korean Strait, suggesting a continual influx of contamination separate from the Japan Sea. At all sites, PAHs in the dissolved phase were greater than in the particulate phase. A separate survey in 2011 studied whether contamination in the Kuroshio current accounted for the contamination in the Tsushima strait and Japan Sea. PAH concentrations increased as waters moved into the Tsushima strait and the Japan Sea, suggesting inputs were local and not from the Kuroshio current. This was however confounded by the greater influence of particulate phase PAHs, which are likely deposited by seasonal desert storms.

With the status as the world's top contributor of marine plastic debris, Indonesia has committed to reduce marine plastic debris up to 70% in 2025 by establishing the National Action Plan (NAP) on Marine Debris. The high amount of marine plastic debris as a result of transport and accumulation become a complex issue in Indonesia due to its ocean-atmospheric circulation, high population of coastal communities, and marine activities. Based on our findings, there are gap of publications related to marine debris in Indonesia that had been already published. Marine debris is ubiquitous and transboundary, as they were found in marine environment and transported by currents to various direction including uninhabited islands, thus, we propose more comprehensive future research about the impact of marine debris on ecosystem (e.g. biological impact of organisms in the water column, ecological alteration in distribution pattern, and invasive species), human health, and economic loss.

In this study, the fate of residual oils was investigated during remediation activities for a year after the Wu Yi San oil spill. Microscope observations showed that relatively large amounts of oil-suspended particulate matter aggregate (OSA) were formed. Negatively buoyant OSA was the dominant form (>95%), followed by neutrally (~5%) and positively buoyant (<1%) forms. To elucidate the dominance of negative buoyancy OSA, physicochemical properties of the mineral and residual oils were identified. Chemical analysis showed that the weathering percentage of residual oils was 43.7 ± 2.59%, which was the driving factor for sedimentation of OSA. As the density of oil increased with weathering stages, the density of OSA also increased simultaneously. These results showed that, during mechanical remediation activities, resurfaced residual oils can form negative buoyancy OSA which tends to sink and transfers oil contaminants from intertidal to benthic environments.

Research on marine microplastics continues to increase in popularity, with a large number of studies being published every year. However, with this plethora of research comes the need for a standardised approach to quantification and analysis procedures in order to produce comparative assessments. Using data collected from neuston nets in 2016, parameters for quantifying microplastics were compared. Surface area was the most accurate parameter to describe plastic size and should be used to describe plastic quantity (per km2 or m3), alongside abundance. Of the two most commonly used methods for calculating plastic concentration (flowmeter and ship's log), ship's log provided consistently smaller abundances, with the exception of one sample, calling for a standardisation in the techniques and measurements used to quantify floating microplastics.

As the main fluorescent substances in oils, polycyclic aromatic hydrocarbons (PAHs) are the basis of ultraviolet (UV)-induced fluorescence spectroscopy methods to detect oil films on the sea surface. The relative contents of PAHs in six crude oil samples and their effects on ultraviolet fluorescence spectra were studied. The PAHs were divided into four categories according to their fluorescence characteristics. Naphthalene series dominated the fluorescence spectra, which led to a main peak at 320–350 nm, but this showed no relationship with PAH content. The six oil samples could not be distinguished by differences in the fluorescence spectra in this range, but could be distinguished by the fluorescence spectra in the 350–380 nm band. The relative contents of dibenzothiophene and phenanthrene series showed significant positive correlations (R² = 0.96) with fluorescence intensity. Fluorescence spectroscopy combined with GC–MS can be used to distinguish and identify crude oils.

Microplastics (MPs) contamination has been recognized as one of major threats to coastal marine environments. Although studies evidenced severe MPs contaminations to the Pacific Ocean, environmental implications of MPs concentrations, distributions, and characteristics have not been evaluated in sufficient detail. Here, we report on the distribution, abundance, and characteristics of MPs at the surface of the Northwestern Pacific Ocean, from which environmental implications are assessed. A manta trawl with a mesh size of ~330 μm and a rectangular net opening of 0.45 × 1 m was used to collect MPs samples on May 11–June 3, 2018. The MPs samples were sequentially isolated, digested, filtered, and characterized using an optical microscope, micro-Raman spectroscopy, and scanning electron microscopy. The results indicate the heterogeneity in abundance, shapes, color, and sizes of MPs. The study provides strong environmental implications such as sources, environmental degradation, residence time, transportation routes, and biological interactions.

Seabirds have been widely used to monitor marine debris by the analysis of plastic ingestion. With the aim of obtaining the first data on ingestion of plastics by different seabird species in the Bay of Biscay and evaluating their suitability as biomonitors of plastic pollution in this area, a total of 159 seabirds of fifteen species were analyzed. Plastics were found in 26 birds (16% of the individuals) of nine species (60% of the species). Frequency of occurrence of plastics varied between 0% (Razorbill) and 100% (species of the family Procellariidae). Considering several criteria to assess their suitability as biomonitors of plastic pollution (frequency of occurrence of plastic ingestion, species abundances and stranding occurrence in the Bay of Biscay), the Common Guillemot and the Atlantic Puffin seem the most promising candidates. This study provides the first data on plastic ingestion in seabirds of the Bay of Biscay.

Hydrocarbonoclastic bacterial consortium that utilizes crude oil as carbon and energy source was isolated from marine sediment collected at a depth of 2100 m. Molecular characterization by 16S rRNA gene sequences confirmed that these isolates as Oceanobacillus sp., Nesiotobacter sp., Ruegeria sp., Photobacterium sp., Enterobacter sp., Haererehalobacter sp., Exiguobacterium sp., Acinetobacter sp. and Pseudoalteromonas sp. Self-immobilized consortium degraded more than 85% of total hydrocarbons after 10 days of incubation with 1% (v/v) of crude oil and 0.05% (v/v) of Tween 80 (non-ionic surfactant) at 28 ± 2 °C. The addition of nitrogen and phosphorus sources separately i.e. 0.1% (v/v) of CO (NH₂)₂ or K₂HPO₄ enhanced the hydrocarbon utilization percentage. The pathways of microbial degradation of hydrocarbons were confirmed by FTIR, GC–MS, ¹H and ¹³C NMR spectroscopy analyses. These results demonstrated a novel approach using hydrocarbonoclastic self-immobilized deep sea bacterial consortium for eco-friendly bioremediation.

Anthropogenic contamination of beaches in the south of Brazil was assessed by detection of Escherichia coli, human mastadenovirus species C (HAdV-C) and F (HAdV-F) and hepatitis E virus (HEV). Sampling was carried out in October (2016), and in January, April and July (2017). Water, sediment, sea surface microlayer (SML), bivalves, and air sentinel samples were evaluated. Quantitative microbiological risk assessment (QMRA) was used to estimate the probability of swimmer infection. HAdV-C was present in 26% of the samples, for both qPCR and viral isolation. The highest rates of detection in genomic copies (GC) were in water (2.42E+10 GC/L), SML (2.08E+10 GC/L), sediment (3.82E+08 GC/g) and bivalves (3.91E+07 GC/g). QMRA estimated daily and annual risks with a maximum value (9.99E-01) in almost all of the samples. Viable HAdV-C was often detected in the SML, pointing that this is a source of infection for people bathing in these waters.