Most marine mammal species and populations are listed as endangered, threatened, or depleted under the Endangered Species Act and the Marine Mammal Protection Act. Organic contaminants such as polycyclic aromatic hydrocarbons from anthropogenic activities are part of the threat to marine mammals. The evaluation of the potential bioaccumulation of these compounds by marine mammals is a tool for adoption of policies to reduce polycyclic aromatic hydrocarbons discharges to the marine environment, where important players such as the oil and gas industries, maritime transport and sewage companies operate. This review seeks to present a bibliographic survey covering all published peer reviewed works of the contents of polycyclic aromatic hydrocarbons in biological tissues of marine mammals. It intended to compare the sampling protocols, procedures for preservation of the tissues, and the analytical method applied to quantify the polycyclic aromatic hydrocarbons, no to criticize any of them but to review the data and discuss how they can be compared.

Chlorophyll a fluorescence is increasingly being used as a rapid, non-invasive, sensitive and convenient indicator of photosynthetic performance in marine autotrophs. This review presents the methodology, applications and limitations of chlorophyll fluorescence in marine studies. The various chlorophyll fluorescence tools such as Pulse-Amplitude-Modulated (PAM) and Fast Repetition Rate (FRR) fluorometry used in marine scientific studies are discussed. Various commonly employed chlorophyll fluorescence parameters are elaborated. The application of chlorophyll fluorescence in measuring natural variations, stress, stress tolerance and acclimation/adaptation to changing environment in primary producers such as microalgae, macroalgae, seagrasses and mangroves, and marine symbiotic invertebrates, namely symbiotic sponges, hard corals and sea anemones, kleptoplastic sea slugs and giant clams is critically assessed. Stressors include environmental, biological, physical and chemical ones. The strengths, limitations and future perspectives of the use of chlorophyll fluorescence technique as an assessment tool in symbiotic marine organisms and seaplants are discussed.

Polyvinyl chloride (PVC) is the third one after polyethylene and polypropylene in the production demand. It intends to grow further, causing an increase in the risk of health and ecological problems due to environmental accumulation and incineration. In the present study, we determined the biodegradative abilities of marine bacteria for PVC. Three potential marine bacterial isolates, T-1.3, BP-4.3 and S-237 (Vibrio, Altermonas and Cobetia, respectively) were identified after preliminary screening. They led to active biofilm formation, viability and protein formation on the PVC surface. The highest weight loss (1.76%) of PVC films was exhibited by BP-4.3 isolate after 60 days of incubation. Remineralization of PVC film was confirmed by CO₂ assimilation assay. Change in surface topography was confirmed by field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The functional group peak intensity was decreased for the terminal chlorine group at the region 1000–1300 cm⁻¹, which indicated the dechlorination. Thermogravimetric, tensile strength and contact angle analysis showed a decline in the mechanical properties and a rise in PVC film's hydrophilic nature after biodegradation. These results demonstrated promising evidence of PVC degradation by marine bacteria.

Coral Ba/Ca is a proxy for seawater barium concentration that varies with upwelling, terrigenous input, and marine productivity whereas coral Sr/Ca varies with temperature. We examine monthly coral Ba/Ca and Sr/Ca before and during offshore oil exploration in a Siderastrea siderea coral from West Flower Garden Bank located on the continental shelf edge in the Gulf of Mexico. Coral Ba/Ca variations lack pulses driven by upwelling or river outflow and are not in sync with coral Sr/Ca that exhibit a different seasonal pattern. Seasonal variations in chlorophyll-a concentration negatively correlate with coral Ba/Ca explaining 25% of that variability. A significant increase in mean coral Ba/Ca of 1.76 μmol/mol between 1931–1944 and 1976–2004 corresponds to the increase in the United States barite production and consumption primarily used in offshore oil drilling, which escalated in the 1970s, suggesting oil drilling operations are increasing seawater Ba concentration in the Gulf of Mexico.

Total concentrations of Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, V, Zn, and As together with Sr and Pb isotopic compositions of seabed sediments from the worldwide famous tourist destination of Acapulco Bay, Guerrero (southern Mexico) were determined to reveal the origin of detritus and toxic elements (TEs), their potential natural and anthropogenic sources, elemental distribution and their ecological risk. Sediments derive entirely from the nearby Acapulco Granite and their concentrations of TEs are variable and rather low, although, several are above the Local Geochemical Baseline in some sites of the bay. The enrichment factor (EF) and Pb isotopes indicate that TEs derive from the Acapulco Granite with contributions of an anthropogenic source represented, very likely, by ship-bottom paints. Wastewaters are a significant source of Pb and Cu. The ecological risk of TEs is low and only Cu represents a moderate ecological risk in a few sites.

The heavy metals (HMs) concentration range, the metal/Al and metal/Fe value were determined in the sediment in order to evaluate the correlation coefficient of HMs at the regions of South East Mediterranean Sea, Cyprus. The results showed that the mean concentrations of the HMs in the sediment samples followed the order Al > Fe > Mn > Cr > Ni > Zn > Cu > Pb > As>Hg, respectively. The pollution indices of contamination factor (CF), geoaccumulation index (Igeo), enrichment factor (EF), and soil pollution index (SPI) were calculated. The Igeo, CF and EF values for Cu were obtained moderately to strongly polluted, moderate contamination and moderately severe enrichment, respectively. The remaining elements indicated unpolluted or low contamination results. Also, SPI indicated a low level of contamination for the all of the metals. The cluster analysis of data set indicates that the HMs are separated with 50% similarity in two categories of Al category (As, Pb, Cr, Ni) and Fe category (Mn, Zn, Cu, Hg).

Accumulation of microplastics (MPs) data on a global scale is key to supporting plastic waste management for protecting ecosystems. To respond this call, a sampling campaign was conducted in the summer and winter seasons of 2018 to collect beach and mangrove sediment samples from 32 sites along the coastline of South China. The MPs concentrations in the intertidal zone along the coast of South China were comparable to those in other regions around the world. Polystyrene foams and fibers were the most abundant debris in the 0.2–5 mm and 0.02–2 mm MPs, respectively. Principal component and correlation analyses indicated that the abundances of MPs were related to wind direction, wastewater discharge amount, and tourist and fishing activities. Risk assessments suggested that potential ecological risks induced by MPs on beaches and mangrove forest along the coast of South China should not be overlooked.

Plastic pollution is ubiquitous and not even remote protected islands are safe from it. Floating debris can adsorb toxic compounds that concentrate on their surface, being available to the animals that ingest them. For this reason, a baseline study of plastic pollution was conducted in the remote Revillagigedo Archipelago, in the Mexican Pacific Ocean. In 47 manta net samples an average of 4.8 plastics/1000m² was found, 73% of the pieces being <5 mm. Polyethylene and polypropylene were the most common polymers found. The chemical analysis of organic pollutants revealed that organochlorine pesticides, polycyclic aromatic hydrocarbons and polychlorinated biphenyls are adsorbed on the plastics collected in the area. Filter feeding megafauna such as humpback whales, manta rays and whale sharks could ingest contaminated micro and macroplastics. Plastics were found also on the beach, where they are available to the ingestion by terrestrial animals, including endemic species endangered to extinction.

Marine protection is one of the main Sustainable Development Goals designed by the United Nations. Specifically, Goal 6.3 – Clean Water and Sanitation – defends that the spill of dangerous and pollutant substances must be eliminated. This principle is inherent in Maritime law since maritime salvage concerns not only vessels and cargo but also the marine environment. Since the Torrey Canyon accident in 1967, spilt crude has become the centre of attention of the International Maritime Organization (IMO). Nowadays, IMO has extended its scope of application to new threats, such as pollutant gas emissions. Its last approved strategy is IMO 2020, focused on the reduction of sulphur emissions by vessels. It came into force on the 1st of January 2020, becoming one effective measure to minimize the sulphur emissions to the atmosphere and to improve the environmental conditions, not only at the sea but also in the coastal and inland areas.

Jakarta is the capital of Indonesia with a high population density, which affects the amount of waste generated. The waste that ends up in Jakarta Bay has become an environmental problem. Understanding the pathway of marine debris in the ocean is important to identify the mitigation strategies. Before this study, the pathways and sources of marine debris in Jakarta Bay were unknown. By using virtual floating marine debris particles in a high-resolution ocean model, the fate of marine debris based on the pathways of particles released in Jakarta Bay in both forward and backward tracking experiments was analyzed. It was found that most of the particles from Jakarta Bay flow toward the Indian Ocean in all seasons. They flow off through the Sunda Strait and reach the open Indian Ocean after a few weeks. With regard to the source location, most particles that end up in Jakarta Bay come from the north of Java Island locally and from the Gulf of Thailand, Sumatra, and Kalimantan coasts. The particles do not appear to vary significantly across all seasons and identifying the pathway of marine debris might be useful in pollution reduction.