The crude oil drilling and extraction operations are aimed to maximize the production may be counterbalanced by the huge production of contaminated produced water (PW). PW is conventionally treated through different physical, chemical, and biological technologies. The efficiency of suggested hybrid electrobiochemical (EBC) methods for the simultaneous removal of total petroleum hydrocarbon (TPH) and sulfate from PW generated by petroleum industry is studied. Also, the factors that affect the stability of PW quality are investigated. The results indicated that the effect of biological treatment is very important to keep control of the electrochemical by-products and more TPH removal in the EBC system. The maximum TPH and sulfate removal efficiency was achieved 75% and 25.3%, respectively when the detention time was about 5.1min and the energy consumption was 32.6mA/cm2. However, a slight increasing in total bacterial count was observed when the EBC compact unit worked at a flow rate of average 20L/h. Pseudo steady state was achieved after 30min of current application in the solution. Also, the results of the study indicate that when the current intensity was increased above optimum level, no significant results occurred due to the release of gases.

The distribution, seasonal variations and ecological risk assessment of polycyclic aromatic hydrocarbons (PAHs) in water from three estuaries in Hai River Basin of China, which has been suffering from different anthropogenic pressures, were investigated. In three estuaries, the average concentration of ΣPAHs was the lowest in Luan River estuary, followed by Hai River estuary, and the highest in Zhangweixin River estuary. There were significant seasonal variations in ΣPAHs, the concentrations of ΣPAHs were higher in November than in May and August. The composition profiles of PAHs in different sites were significantly different, and illustrated seasonal variations. Generally, 2-ring (Nap) and 3-ring PAHs (Acp, Fl and Phe) were the most abundant components at most sampling sites in three estuaries. The PAHs in three estuaries were mainly originated from pyrogenic sources. A method based on toxic equivalency factors (TEFs) and risk quotient (RQ) was proposed to assess the ecological risk of ΣPAHs, with the ecological risk of individual PAHs being considered separately. The results showed that the ecological risks caused by ΣPAHs were high in Hai River estuary and Zhangweixin River estuary, and moderate in Luan River estuary. The mean values of ecological risk in August were lower than those in November. The contributions of individual PAHs to ecological risk were different in May, August and November. 3-ring and 4-ring PAHs accounted for much more ecological risk than 2-ring, 5-ring and 6-ring, although the contributions of 5-ring and 6-ring to ecological risk were higher than these to PAHs concentrations.

In this study, PAH analyses have been conducted on indigenous mussels. Mussel samples (Mytilus galloprovincialis) have been collected from seven stations of Prince Islands during September 2015. Concentrations of total determined PAHs (sum of 16 compounds) ranged between 664 and 9083ngg−1. The origin of PAHs has been found to be pyrolytic according to the PHE/ANT and FA/PYR ratios in Büyükada. For other islands, PAH origins have been observed as pyrolytic and petrogenic together according to the PHE/ANT, FA/PYR and BaA/CHR ratios.

European maritime companies have adopted programs to limit operational impacts on the environment. For maritime companies in North America, the Green Marine Environmental Program (GMEP) offers a framework to establish and reduce environmental footprints. Green Marine (GM) participants demonstrate annual improvements of specific environmental performance indicators (e.g., reductions in air pollution emissions) to maintain certification. Participants complete annual self-evaluations with results determining rankings for performance indicators on a 1-to-5 scale. Self-evaluations are independently verified every two years to ensure rigor and individual results are made publicly available annually to achieve transparency. GM benefits the marine industry across North America by encouraging sustainable development initiatives. GM's credibility is reflected through a diverse network of environmental groups and government agencies that endorse and help shape the program. Merits of this relatively new maritime certification (not previously described in the academic literature), are discussed.

An exploration of historical data suggested that eutrophication patterns might drive long-term fluctuations in Cystoseira populations along the west Istrian Coast (northern Adriatic Sea, Croatia). The regimes of northern Italian rivers, which flow approximately 100km west of the study area, mainly modulate the eutrophication levels of the northern Adriatic Sea. A regression of Cystoseira populations from the 1970s through the 1990s corresponded to increased levels of eutrophication in the study area. During the late 1990s, the density of sea urchins, which are efficacious macroalgal predators, decreased, likely due to an intense formation of pelagic mucilage aggregates that resulted in mass mortality episodes of macrozoobenthic species. During the 2000–2013 period, an oligotrophication of the northern Adriatic formed the basis for the recovery of Cystoseira taxa, whose abundances from 2009 to 2013 were similar to those characterising the most flourishing Mediterranean Cystoseira assemblages.

Oil slicks were detected using satellite Synthetic Aperture Radar (SAR) images in 2011. We investigated potential origins and regional and seasonal features of oil slick in the Bohai Sea. Distance between oil slicks and potential origins (ships, seaports, and oil exploitation platforms) and the angle at which oil slicks move relative to potential driving forces were evaluated. Most oil slicks were detected along main ship routes rather than around seaports and oil exploitation platforms. Few oil slicks were detected within 20km of seaports. Directions of oil slicks movement were much more strongly correlated with directions of ship routes than with directions of winds and currents. These findings support the premise that oil slicks in the Bohai Sea most likely originate from illegal disposal of oil-polluted wastes from ships. Seasonal variation of oil slicks followed an annual cycle, with a peak in August and a trough in December.

Simplified physical models and geometrical considerations reveal general physical and dynamical properties of microplastic particles (0.5–5mm) of different density, shape and size in marine environment. Windage of extremely light foamed particles, surface area and fouling rate of slightly positively buoyant microplastic spheres, films and fibres and settling velocities of negatively buoyant particles are analysed. For the Baltic Sea dimensions and under the considered idealised external conditions, (i) only one day is required for a foamed polystyrene particle to cross the sea (ca. 250km); (ii) polyethylene fibres should spend about 6–8months in the euphotic zone before sinking due to bio-fouling, whilst spherical particles can be retained on the surface up to 10–15years; (iii) for heavy microplastic particles, the time of settling through the water column in the central Gotland basin (ca. 250m) is less than 18h. Proper physical setting of the problem of microplastics transport and developing of physically-based parameterisations are seen as applications.

The molecular composition and distribution of sterols were investigated in the East China Sea to identify the origins of suspended particulate matter (SPM) in offshore waters influenced by Changjiang River Diluted Water (CRDW). Total sterol concentrations ranged from 3200 to 31,900pgL−1 and 663 to 5690pgL−1 in the particulate and dissolved phases, respectively. Marine sterols dominated representing 71% and 66% in the particulate and dissolved phases, respectively. Typical sewage markers, such as coprostanol, were usually absent at ~250km offshore. However, sterols from allochthonous terrestrial plants were still detected at these sites. A negative relationship was observed between salinity and concentrations of terrestrial sterols in SPM, suggesting that significant amounts of terrestrial particulate matter traveled long distance offshore in the East China Sea, and the Changjiang River Diluted Water (CRDW) was an effective carrier of land-derived particulate organic matter to the offshore East China Sea.

In Maui, Hawai'i, wastewater reclamation facilities (WWRFs) dispose of partially treated effluent into injection wells connected to the nearshore environment. Hawai'i State Department of Health data from 2004–2015 were assessed for qualitative trends in nutrient, turbidity, and Chlorophyll a water quality (WQ) impairments for fourteen marine sites on Maui Island. We introduce a novel method, the Qualitative Impact Percentage (QIP), to facilitate a qualitative comparison of disparate factors contributing to WQ impairment. Sites near the Lahaina WWRF in West Maui, which was found in violation of the Clean Water Act in 2014, had fewer exceedances and lower geometric means compared to sites near the Kihei WWRF. Our results suggest that WQ impairments may be a greater concern in Kihei than previously acknowledged. This paper attempts to raise the awareness of policymakers and the public and to encourage further research assessing the effects of the Kihei WWRF on the marine environment.

The Japanese Government is seeking an appropriate level of nutrient load from the land to maintain the highest possible estuarine fishery production and water transparency simultaneously. To provide a scientific basis for the governmental inquiry, we conducted sensitivity analyses using an ecosystem model of Hiroshima Bay in order to assess the ecosystem’s responses to phosphorus and nitrogen inputs. Load levels of phosphorus (Case P), nitrogen (Case N) and both phosphorus and nitrogen (Case NP) that were different from the average loading recorded during 1991–2000 (±25%, ±50%, and ±75%) were applied. The results showed that phosphorus had a significantly greater impact on the primary production of the bay than nitrogen. Case P+25 increased the primary production but led to N-limitation. However, it was found that Case NP at the levels over +25% could bring the Hiroshima Bay ecosystem back to its eutrophic state of 30years ago.