A phytoremediation experiment was carried out in mesocosms to investigate the performance of Rhizophora mangle in the remediation of polycyclic aromatic hydrocarbons (PAHs) in mangrove sediment contaminated with crude oil. The water pH of the experiments (phytoremediation and natural attenuation) ranged from 4.9 to 8.4 at 0 and 90 days, respectively. The oxy-reduction potential (Eh) ranged from oxidising (108.0 mV, time 0) to reducing (approximately −110.0 mV, time 90) environments. Dissolved oxygen (DO) ranged from 5.7 mg L⁻¹ (time 0) to 4.5 mg L⁻¹ and 3.6 mg L⁻¹ (time 90) in phytoremediation and natural attenuation, respectively. The sediments had silty texture and an average concentration of 5% organic matter (OM). Phytoremediation (60.76%) showed better efficiency in the remediation of the 16 PAHs compared to natural attenuation (49.57%). Principal component analyses showed a correlation between the concentrations of PAHs with pH, Eh, OM and DO in both experiments.

Millions of recreational boats and ~ 65,000 ocean-going merchant ships anchor routinely. Anchor and chain scour associated with these vessels mechanically disturb the seabed having implications for marine environments globally. Our review summarises the scientific literature that examines the response of biota to anchor scour across five habitats; unvegetated sediments; seagrass; rhodolith beds; coral and rocky reefs. Forty-one studies met our criteria with >85% of articles targeting recreational-based disturbances, mostly focussed on seagrass. Investigations of anchor scour from ships comes almost exclusively from cruise ships anchoring on coral reef. All research examined reported biota responding negatively to anchor scour, either directly or indirectly. Effects to biota were dependent on the spatio-temporal scale of the perturbation or the life-histories of the organisms impacted. We highlight several key knowledge gaps requiring urgent investigation and suggest a range of management strategies to work towards sustainable anchoring practices and the preservation of valuable seabed environments.

OSPAR, Rake and Flood accumulation zone methods were applied at 29 beaches of the German and Lithuanian Baltic Sea coast (2011–2018) to monitor cigarette butt pollution. Also, butt pollution prevention measure - ballot bin, was tested.The number of cigarette butts was significantly higher in Germany than in Lithuania, but the percent of butts from total litter items was similar. Rake method turned out to be suitable for cigarette butt assessment, while the OSPAR method underestimates the butt pollution.The visitor number on the beach had a significant effect on the cigarette butt number: in remote beaches, without visitors, usually, no butts were observed, while the highest number and the percent of butts were observed in beaches with the highest number of visitors.The ballot bin campaign may have increased the public awareness about pollution, but turned out to be in-efficient in reducing it.

Hydrodynamics play a critical role in determining the trajectory of an oil spill. Currents, stratification and mesoscale processes all contribute to how a spill behaves. Using an industry‑leading oil spill model, we compare forecasts of oil dispersion when forced with two different hydrodynamic models of the North-West European Shelf (7 km and 1.5 km horizontal resolution). This demonstrates how the trajectory of a deep water (>1000 m) release in the central Faroe-Shetland Channel is influenced by explicitly resolving mesoscale processes. The finer resolution hydrodynamic model dramatically enhances the horizontal dispersion of oil and transports pollutant further afield. This is a consequence of higher mesoscale variability. Stratification influences the depth of subsurface plume trapping and subsequently the far-field transport of oil. These results demonstrate that the choice of hydrodynamic model resolution is crucial when designing particle tracking or tracer release experiments.

Triphenyltin chloride (TPTCL) is a well-known marine pollutant that may constitute major environmental threats to seaweed mariculture. In the present study, the toxic effects of TPTCL on physiology and ultrastructure of cultivated sporophytes of Undaria pinnatifida were investigated under different TPTCL concentrations ranging from 0 to 100 μg L⁻¹. Significant negative effects of increased TPTCL concentration were detected in the relative growth rates, survival percentages and chlorophyll a contents of young and adult sporophytes. Low TPTCL concentrations could significantly stimulate the activities of enzymes related to nitrogen metabolism. The chloroplast, mitochondria and nucleus inside cells were greatly damaged by TPTCL. Meanwhile, significant increases of electron dense deposits and physodes were found. Additionally, young sporophytes exhibited greater tolerance to TPTCL stress than adult sporophytes. The results of this study indicate that coastal TPTCL pollution could reduce the productivity and quality of cultivated U. pinnatifida.

Microplastics (MPs) pollution has been increasingly investigated in marine and freshwater environments, even in atmosphere in China. Current literatures show that MPs contamination is highly related to human activities and geomorphology. Higher MPs occurrences were detected in freshwaters than those in seawaters in China. Furthermore, the abundance of MPs was influenced by many factors, including sampling method, unit of measurement, characteristics of sampling area, and others. Currently, investigating the condition of MPs occurrences and distribution on a broader scale and developing standardized protocol, along with basic toxicological research, will help to address crucial knowledge gaps regarding MPs pollution, their interaction with other pollutants and ecological consequences on individual, population or ecosystem levels in the environment. Meanwhile, this review calls for more efforts to be made for better and scientifically sound risk management for mitigation of MPs pollution in China.

Plastics pollution is ubiquitous. Microplastics (<5 mm in diameter) and mesoplastics (5–20 mm in diameter) are emerging as the most common plastic particulates found in the marine environment. In this study, the occurrence of microplastics and mesoplastics in the gastrointestinal tract (GI) of some commercially important fish collected from Chennai and Nagapattinam of Tamil Nadu, Southeast coast of Bay of Bengal was assessed. A new and improved alkaline digestion method, using alcoholic potassium hydroxide (KOH) was carried out to destroy the organic matter. Following this method, twenty plastic particulates were isolated from the GI tract of 17 individual fish. Fourier Transform Infrared Radiation analysis (FTIR) showed that polymers found in GI tracts were of Polyethylene, Polyamide and Polyester types. Given the dry fish is India's biggest market and popular delicacy, the presence of microplastics in the fish gut is a potential serious human health concern, as they are directly consumed.

Chemical-surveys of sediments are source of information about historical-pollution in aquatic-ecosystems, because ecological/human-health risks may arise from polycyclic-aromatic-hydrocarbons (PAHs) and nitrogen-PAHs presence in aquatic-environments, particularly sediments, where they partition. Despite this, sediment-PAHs/N-PAHs have not been reported in the Niger Delta. This study investigated vertical-profiles of PAHs/N-PAHs in 2 cm-intervals-segments from Bonny Estuary, Niger Delta. Analysis showed that ƩPAHs/ƩN-PAHs in segments ranged from 8699 to 22,528 μg/kg and 503 to 2020 μg/kg, respectively. Abundant-PAH/N-PAH are 2,6-dimethyl-naphthalene and benzo[a]acridine. PAHs/N-PAHs in the samples appeared to be from petrogenic and pyrogenic-sources. Petrogenic-PAHs/N-PAHs were predominated by 2-, 3-rings, alkylated-substituents, while, pyrogenic-PAHs/N-PAHs were dominated by 4-, 5-, 6-rings. Surface-sediments were dominated by petrogenic-PAHs/N-PAHs while, deeper-cores were heavily-contaminated with pyrogenic-PAHs/N-PAHs. ƩPAHs exceeded the ISQGs and PELs of CSQGs. Ʃ-quinoline/Ʃ-acridine exceeded the guidelines for protection of aquatic-life. Furthermore, there are concerns over toxic-ratios >70% in the estuary. Such surveys may be helpful in future sediment-management-decisions for contaminated-systems and long-term-monitoring of sediments to assess remediation/recovery.Distinct sources of PAHs and N-PAHs exist in the Niger Delta ecosystem and, there are concerns over toxic ratios >70% in the oil rich region and the potential for adverse biological effects.

The dinoflagellate Karlodinium veneficum has worldwide distribution and is associated with harmful algal blooms through the production of karlotoxins. We investigated the allelopathy and toxicity to explore the potential ecological implications. Prorocentrum donghaiense was inhibited significantly when grown either in co-cultures or in culture filtrate of K. veneficum. In addition, the effect of the co-occurring microalga species (P. donghaiense) on the hemolytic activity of K. veneficum was also evaluated. P. donghaiense did not inhibit the growth of K. veneficum but increased the hemolytic activity. The culture of K. veneficum was loaded onto an RP-C18 column and eluted with different percentages of aqueous methanol solution. 80% methanol fraction not only inhibited the growth of P. donghaiense by allelopathy but also exhibited strong hemolytic activity, indicating that the allelochemicals and toxins of K. veneficum might be the same components. Furthermore, KmTx 3 (C₆₈H₁₂₄O₂₄) was identified using HPLC-HRMS from this fraction.

Intensification of lateritic nickel mining in Southeast Asia and Melanesia potentially threatens coastal ecosystems from increased exposure to nickel and suspended sediment. This study investigated the response of Acropora muricata when exposed to either dissolved nickel, clean suspended sediment or nickel-contaminated suspended sediment for 7 days, followed by a 7-d recovery period. Significant bleaching and accumulation of nickel in coral tissue was observed only after exposure to high dissolved nickel concentrations and nickel-spiked suspended sediment. No effect on A. muricata was observed from exposure to a particulate-bound nickel concentration of 60 mg/kg acid-extractable nickel at a suspended sediment concentration of 30 mg/L TSS. This study demonstrates that bioavailability of nickel associated with suspended sediment exposure plays a key role in influencing nickel toxicity to corals. These findings assist in assessments of risk posed by increasing nickel mining activities on tropical marine ecosystems.