Oceanographic processes are examined and used to assess their effect on the movement and dilution of wastewater discharged from Sydney's three deepwater ocean outfalls. Such processes link wastewater discharges with observed changes in biological communities and the accumulation of contaminants in the sediments. The East Australian Current, coastal trapped waves and local winds contribute 40%, 20% and 10% respectively to the total spectral energy in the along-shore currents off Sydney. Median dilutions at the edge of the initial dilution zone range between 185:1 and 347:1. Plumes remain submerged 95% of the time, surfacing only in the middle of winter and during large storms. Negatively buoyant particles sink from the plumes and first reach the ocean floor within 10 km of the discharge location. Resuspension of the sediments due to currents occurs 2.5% of the time and due to waves 1%–4% of the time.

Zooplankton were studied in the largest scale investigation in the South Yellow Sea in spring 2007 by using large plankton net when the green tide hasn't yet occurred. Ninety-six zooplankton species were identified. Copepods, pelagic larvae and hydromedusae were comprised of the largest number of species; Calanus sinicus, Paracalanus parvus, Aidanosagitta crassa, Euphausiidae larvae, Oithona plumifera and Corycaeus affinis were dominant species and their abundance comprised 81.65% of total abundance. Three high abundance areas contained with an average of 224.31 ± 247.93 individual/m³, with an average total biomass of 674.33 ± 1696.92 mg/m³; The average of Shannon-Wiener diversity, Pielou evenness and Margalef richness was 1.96 ± 0.61, 0.50 ± 0.14 and 2.31 ± 0.95, respectively. The Shannon-Wiener diversity and Pielou evenness showed positive correlation with bottom temperature, while Shannon-Wiener diversity and Margalef richness were positively correlated with bottom salinity. Additionally, Pielou evenness and Margalef richness showed negative correlation with total abundance which indicated that sampling efforts might affect the findings.

This is the first study on polychlorinated biphenyls (PCBs) in fish from the Cau Hai lagoon, a part of the largest coastal lagoon in Southeast Asia. Seven selected PCB congeners and organochlorine pesticides in sediments and edible fish tissues were quantified by GC–MS. The sum of ICES-7 PCB and DDTs concentrations in fish species consumed regularly and of economic value were in ranges 26–43 ng g−1 lw and 182–277 ng g−1 lw, respectively. The ratio between the parent DDT compound and the sum of metabolites, DDE and DDD, was most of the time smaller than 1, suggesting primarily an historical contamination of the lagoon. An agglomerative hierarchical clustering indicates sites located in the north-western part of the Cau Hai lagoon were characterized by above-average concentrations of DDE and DDT. Comparing to previous data, a large decrease in ∑DDT residues can be seen over the past 20 years.

A new tool was developed for microplastics (MPs) investigation in the water column. It can collect several cubic meters of water from predefined water layers down to 100 m. The tool was tested in the Baltic Sea during the period of spring thermocline formation. Strong MPs stratification was observed at all of the sampled stations. On coastal stations (~30 m deep), stratification with high fibers content was associated with the proximity of terrestrial sources and estuarine discharges, while on off-shore stations the variability of MPs was related to vertical thermohaline structure. Mean MPs content was the 32.2 (SD 50.4) pcs/m³. Elevated MPs concentrations were observed in subsurface, near-bottom and thermohaline layers compared with intermediate layers. The heterogeneity of MPs distribution suggests that MPs particles can be retained above the density-gradient layers in coastal seas and the World Ocean.

The northeastern Arabian Sea (NEAS) experiences convective mixing during winter, but this mixing does not reach up to the silicicline, resulting in the limited supply of silicate (Si) compared to nitrate (N) and phosphate (P) to the mixed layer (ML) and formation of non-diatom blooms. The poleward advection of waters of low surface salinity by the West India Coastal Current (WICC) to the NEAS weakens the vertical mixing and reduces the Si input to the mixed layer, resulting in occurrence of Noctiluca scintillans blooms. The saturation of dissolved oxygen in the NEAS varied between 88 and 98%, suggesting N. scintillans blooms occur in oxic conditions. Enhanced cell abundance of N. scintillans was observed in the bloom region in the upper 10 m. Phytoplankton pigments data revealed higher contribution of Chlorophytes, Prasinophytes, Prymnesiophytes and Prochlorophytes in the bloom than non-bloom region. The isotopic composition of nitrogen and carbon of particulate organic matter indicated that natural and in situ processes contributed to both nutrients and organic carbon pool in the NEAS in supporting the massive occurrence of N. scintillans blooms than hitherto hypothesized to anthropogenic sources. This study further suggests that the effect of anthropogenic pollutants released into the NEAS from the mega-cities is limited to the neighbourhood of these cities and does not affect the open ocean.

The establishment of water quality criteria (WQC) for oil pollutants is the basis for ecological risk assessment of marine oil pollution. Ecotoxicity data of oil pollutants to marine organisms in China were collected and toxicity test of oil to nine Chinese marine organisms were performed. Based on the WQC guidelines of the United States, the sea WQC of oil pollutants in China were studied. Then, the ecological risk of oil in 7 sea areas of China was assessed. Results showed that the long-term and short-term criteria of oil pollutants in China are 7.3 μg/L and 36 μg/L, respectively. Except for Qinhuangdao and Xiamen sea areas, the highest oil concentration in the other five sea areas exceeded the long-term WQC by >10 times, and the highest oil concentration in the Pearl River Estuary exceeded the long-term WQC by >100 times, indicating serious ecological risk.

Stable isotopes and geochemical proxies (TOC/TN and Chla/TOC) in sediments can be used to distinguish organic matter sources (anthropogenic, terrestrial, or marine). This study aims to characterize organic matter (OM) in superficial sediments from three sectors of central Chile (33°S) that are highly influenced by urban and industrial development. Our results show that a substantial fraction of these OM in Quintero Bay is anthropogenic, from industrial and domestic wastewater sources. In contrast, a mixture of terrestrial and anthropogenic OM dominates the isotopic signal of surface sediments from Concón, derived from non-point industrial and agriculture sources associated with the Aconcagua River basin, while Ritoque exhibited a mixture of different OM sources. However, deposition of allochthonous OM in our study area depends on coastal topography, which influences the local currents and well-ventilated waters, promoting the dispersion and assimilation of OM and thus providing an environment with a high capacity for natural remediation.

We used manually spawned, field-deployed embryos of a common marine fish species, Pacific herring (Clupea pallasii), to evaluate accumulation of polycyclic aromatic hydrocarbons (PAHs) associated with an incomplete creosote-treated piling (CTP) removal project. Embryos near undisturbed 100-year-old CTPs (before removal) accumulated higher PAHs and exhibited higher cyp1a gene expression than embryos from reference areas. Embryos incubated close to CTP debris after CTP removal showed PAHs 90 times higher than reference areas up to a year after CTP removal. cyp1a fold-induction correlated with total embryo PAHs in all three years. Patterns of individual PAH chemicals differed slightly between embryos, wood sampled from CTPs, and passive samplers. This study illustrates the importance of using appropriate techniques and procedures to remove CTPs in aquatic environments to prevent release of toxic chemicals. Of particular concern is that incomplete CTP removal could expose sensitive life stages of fishes to chemicals that may reduce their survival.

In this study, we examined radioactivity simultaneously in surface marine sediments and coral skeletons collected from 12 locations of the fringing and atoll reefs in the South China Sea. Radioactive level declined from the fringing reefs to atoll reefs because of input of terrigenous minerals in the fringing reefs. Radioactivity was higher in coral skeletons than in marine sediments because of the high ²²⁸Ra activity in coral skeletons. Additionally, an abnormally low ²²⁶Ra/²³⁸U activity ratio (<0.1) of marine sediments in coral reefs was attributed to the biological process of active uptake of ²²⁶Ra and ²³⁸U from seawater by coral polyps rather than the ingrowth process in the ²³⁸U-²³⁰Th-²²⁶Ra decay chain. Several radiological indices were evaluated in coral reefs and significantly lower than recommended values. Particularly, the average Raₑq in the atoll reefs was <5% of the world's average of Raₑq. Our results displayed typically radioactive status in coral reefs without close-in fallout of anthropogenic radionuclides.