Nutrients distribution and influencing factors in three seamount areas named Y3, M2 and C4 of the Tropical Western Pacific Ocean (TWPO) were investigated. Nutrients showed obvious uplifts around the three seamounts, consistent with the uplifts of isotherms and isohalines, indicating the existence of a bottom-up process of nutrients. Meanwhile, compared with the stations away from seamount and the reference stations in the TWPO, nutrients concentrations around seamount were much higher. Among the three seamounts, the average nutrients concentrations were highest in Y3, while they were lowest in C4. Moreover, compared with the obvious nitrogen limitation in Y3 and M2, the N:P (13.5:1) and Si:N (6.1:1) were closed to the Redfield ratio. The current-seamount interaction was the determining influencing factor on nutrients distribution, causing the hydrology dynamic changes such as uplifts and Taylor column. Meanwhile, T and S also affected nutrients distribution, especially nutrients and T showed significant negative correlations.

Limited experimental and field data are available describing oil droplet formation from subsea releases at high pressure. There are also analytical challenges quantifying oil droplets over a wide size and concentrations range at high pressure. This study quantified oil droplets released from an orifice in seawater at low and high pressure (5 m and 1750 m depth). Oil droplet sizes were quantified using a newly developed sensor (Silhouette camera or SilCam).The droplet sizes measured during experiments at low and high pressure, using the same release conditions, showed no significant difference as a function of pressure. This lack of a pressure effect on oil droplet sizes was observed for both untreated oil and for droplet formation during subsea dispersant injection or SSDI. This strongly indicates that the effectiveness of SSDI is not influenced by water depth or pressure, at least for simulated subsea releases of oil alone (no gas).

Planktonic sea-urchin larvae actively ingest polyethylene microplastics (MP) that accumulate in the larval stomach and can be distinguished from natural food using polarized light microscopy. MP filtering rates were similar to those of natural particles (microalgae) of the same size range; 0.30 to 0.35 mL min⁻¹. However, the ingestion of MP did not increase the toxicity of a hydrophobic organic chemical, the 4‑n‑nonylphenol (NP), either in microalgae-fed or starved larvae. The 48 h EC₅₀ of NP was more than two fold higher in fed (158.8 to 190.9 μg L⁻¹) compared to starved larvae (64.3 to 83.7 μg L⁻¹), disregarding the presence and amount of MP, which did not significantly affect larval growth. Therefore, MP did not act as vectors of a hydrophobic chemical such as NP to these planktonic organisms. These results challenge the hypothetical role of MP as vectors of organic contaminants to marine food webs.

The widespread use of antibiotics in aquaculture can potentially lead to the emergence of antibiotic resistance genes (ARGs) and threaten human health by entering the food chain. To assess the environmental risk posed by antibiotics in China, the spatial-temporal distribution and correlation of 8 antibiotics based on the abundance of 11 ARGs in water sources, pond water, and sediment in 8 ponds were determined. The results indicated that sul1 was the predominant ARG in water sources and pond water, and tetC was the most in the sediment. A trend of increasing abundance of ARGs was observed with increased rearing density and pond age. Compared to monoculture, shrimp culture integrated with different trophic levels of fish farming could influence the abundance of ARGs. There was also a significant correlation between the abundance of ARGs and antibiotic concentration in the sediment, while no correlation was observed in water sources and pond water.

Plastics constitute an important part of our life for many decades. All the wastes produced from human activities finally enters into the aquatic ecosystem. Microbial degradation of plastic is a promising eco-friendly strategy which represents a great opportunity to manage waste plastic materials with minimum adverse impacts. In this present study, totally 248 bacterial isolates were isolated from the plastic waste dumped sites in the coastal region districts of Tamil Nadu, India and screened for HDPE degradation. Based on the results obtained from the weight loss, viability and FT-IR, 10 bacterial isolates were considered to be potent HDPE degraders. The identification of efficient HDPE degrading isolates confirms that most of the bacterial isolates belong to the genus Bacillus spp. and Pseudomonas spp. The present study suggests that the isolated efficient bacterial strains can be used as cost-effective, eco-friendly and safe approach for the elimination of plastic wastes from the environment.

Large yellow croaker (Larimichthys crocea) purchased from five different farming sites in Zhoushan Archipelago and Xiangshan Harbor in the East China Sea, China were analyzed for polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Concentrations of PAHs and PCBs in the edible muscle of L. crocea ranged from 83.14 to 174.68 ng/g wet weight (or 266.89 to 695.24 ng/g dry weight) and 3.89 to 17.40 ng/g wet weight (or 15.50 to 54.25 ng/g dry weight), respectively. Incremental lifetime cancer risk (ILCR) associated with the dietary intake of PAHs and PCBs in L. crocea was assessed. Results showed that levels of PAHs in L. crocea were high enough to cause potential carcinogenic risks for human consumption, while, levels of PCBs in fish samples were of low significant carcinogenic risk.

The bioaccumulation and the main source of total Hg (THg) and methylmercury (MMHg) in the deposit-feeding polychaete Neanthes japonica collected in Jinzhou Bay, China, were investigated. Compared with the historical data, THg bioaccumulation in polychaetes collected in sediment of Jinzhou Bay was distinctly higher due to higher sediment THg concentration, but MMHg bioaccumulation was significantly lower. THg accumulation in polychaetes mainly derived from its accumulation in sediment. However, MMHg bioaccumulation in polychaetes did not correlate with Hg concentration in sediment. Besides sediment ingestion, MMHg accumulation in polychaetes may partially source from the process of in vivo transformation. The in vivo Hg methylation may take place in polychaetes, according to the excellent correlation between MMHg concentration and THg and inorganic Hg concentration in polychaetes. The biochemical characters in polychaete body, the oxidation-reduction environment and the microbial activity in polychaete gut may be beneficial to in vivo Hg methylation.

The aim of this research was to assess the impact of hydrotechnical works within the riverbed and riparian zone on the mobility of mercury in soil and its outflow to the river and the sea. Deepening and reconstruction of the riverbed or the cutting of reeds, influenced the fate of mercury in the river system. However, only activitis that disturbed the riperian zone increased mobilization of Hg in soils. Hg transformations in these places were controled by inflow of fresh organic matter in soil and sediments as well as by oxidation-reduction potential. In areas where reducing conditions occurred, mercury released from the soil was incorporated into the sediment. However, in areas where oxidizing conditions prevailed in the sediment, mercury flowing out of the soil occurred mainly in dissolved form and most of it was transported downstream from where it could reach the sea.

Due to the effects of heightened warming in the Arctic, there has been an urgency to develop methods for detecting oil in (or under) sea ice, owing to increasing potential for oil exploration and ship traffic in the more accessible Arctic regions. To test the potential for radar utilizing the normalized radar cross section (NRCS) of the sea ice, an oil-in-ice mesocosm experiment was performed. Throughout the experiment, corn oil was used as a surrogate for medium crude oil, to assess oil movement tendencies in sea ice, and the resultant impact on the complex permittivity through measurement and modelling techniques. We performed a modelling study to establish the effects of corn oil on the NRCS of sea ice. The oil presence in the sea ice increased the temperature and reduced the salinity of the sea ice, thereby lowering its complex permittivity and modeled NRCS when compared to control sea ice.

This study aims to examine the composition and the spatial/tidal changes of marine debris caught with a fishing net during a fishery survey in two different areas of a sand beach at the northeast of Brazil. Samples were conducted weekly, at each moon phase, for two months using a beach seine net in the surf zone. Abundance of debris were estimate by swept area (items·km⁻¹ and g·km⁻¹). A total of 12 categories of debris were recorded. Plastic – both hard and soft types - was the most abundant debris category. Most fragments were classified as macro (20–100 mm) and mega debris (>100 mm). Significant differences (P < 0.05) between areas and tides were registered for plastic, metal and cloth. Spring tides were responsible for the high rates of marine debris found in the surf zone of Miramar beach. The results demonstrate the occurrence and abundance of litter in this fish nursery area and reinforce the need and importance of environmental protection and educational programs.Marine debris caught by a fishing net in the surf zone of Brazilian beach.