Surface microplastics were sampled monthly in four tropical bays (Manzanillo, Santiago, Navidad and Cuastecomates) of the central Mexican Pacific during March 2017 to February 2018. Microplastic concentrations ranged between 0.01 and 1.05 particles/m² with a median per bay ranging between 0.26 and 0.40 particles/m². Raman spectroscopy registered polypropylene (40%), polyethylene (40%) and polyester (20%) polymers. Fibers dominated all samples, except for Manzanillo where fragments numerically dominated during the rainy season (Jun-Oct). Fiber concentration was not significantly different among bays or seasons, likely associated with continuous wastewater discharge. Fragment concentrations were significantly higher in Bahía Manzanillo and Santiago than the other two bays. Non-metric multidimensional scaling showed distinct distribution of Manzanillo samples (which has important port activities) as compared to Santiago, Navidad, Cuastecomates (where tourism economic activities predominate). This first direct comparison of sea surface microplastic concentration among four bays in Mexico provides a baseline to study impacts on marine zooplankton in this tropical ecosystem.

Very Low Sulfur Fuel Oils (VSLFO, <0.5% S) are a new class of marine fuel oils, introduced to meet recent International Maritime Organization regulations. The MV Wakashio was reported to have released 1000 t of VLSFO when it grounded on a reef in Mauritius on 25th July 2020. A field sample of oily residue contaminating the Mauritian coast was collected on 16th August 2020 and compared with the Wakashio fuel oil. Both oils were analyzed for organic and elemental content, and stable isotope ratios δ¹³C and δ²H measured. Comprehensive two-dimensional gas chromatography with high-resolution mass spectrometry was used to identify and compare biomarkers resistant to weathering. The aromatic content in the VLSFO was relatively low suggesting that the potential for ecosystem harm arising from exposure to toxic components may be less than with traditional fuel oil spills. The Wakashio oil spill is, to our knowledge, the first documented spill involving VLSFO.

A two-dimensional hydrodynamic model that couples hydrology and water quality processes was developed to simulate the concentrations of PAH in water phase and sedimentation rates of PAHs in marine environment. The kinetic processes of the model included atmospheric exchange, transportation, deposition, etc. Taking Liaodong Bay as an example, the pollution level, spatial distribution of PAHs in sediments were analyzed and the transport, transformation and sedimentation processes of PAHs were simulated. The results show that PAHs concentrations in sediments are at a “moderate risk” level, and the distribution has a conspicuous spatial variation. According to the results of simulation, the PAHs in sediments are easily accumulated with weak hydrodynamic conditions. Thus, hydrodynamic is one of the important factors affecting the spatial distribution characteristics of PAHs in the sediments. The PAHs numerical calculation model established in this paper and its evaluation results have important research value for PAHs pollution prevention and control.

Marine debris is a global issue with adverse impacts on marine organisms, ecological processes, aesthetics, and economies of nations. Several studies have been conducted to quantify the plastic debris along Indian beaches. This baseline study describes the results of a survey conducted on the types of plastic litters and their quantification during January to March 2020 along Mandvi beach in Gujarat. A quadrate having 10 × 10 m size was used for sampling the plastic litter on the shoreline. A total of 10 quadrates along the shore was considered for quantification of the plastic materials based on their density, color, and weight. The plastic material observed includes gutkha pouches, food wrappers, and fragments, along with plastic straws, cutleries, and fragments of various dimensions and thickness. The major contributing factors for the debris abundance in Mandvi beach are land-based sources and recreational activities. The results suggest that similar long-term projects covering extensive areas should be undertaken for accurate quantification of available debris and their impacts on coastal habitats of Gujarat.

Understanding of the pre-development, baseline denudation rates that deliver sediment to the Great Barrier Reef (GBR) has been elusive. Cosmogenic ¹⁰Be in sediment is a useful integrator of denudation rates and sediment yields averaged over large spatial and temporal scales. This study presents ¹⁰Be data from 71 sites across 11 catchments draining to the GBR: representing 80% of the GBR catchment area and provide background sediment yields for the region. Modern, short-term, sediment yields derived from suspended load concentrations are compared to the ¹⁰Be data to calculate an Accelerated Erosion Factor (AEF) that highlights denudation “hot-spots” where sediment yields have increased over the long-term background values. The AEF results show that 58% basins have higher modern sediment yields than long-term yields. The AEF is considered a useful approach to help prioritise on-ground investments in remediation and the additional measured empirical data in this paper will help support future predictive models.

Time series were compiled of terrestrial nitrogen, phosphorus, carbon, iron, and silica fluxes to the Southern California Bight (SCB), a U.S. West Coast embayment (Sutula et al., 2021). Monitoring data and model output were used to construct a baseline of inputs from direct point source (PS) discharges of wastewater treatment (WWT) effluent (via ocean outfalls) and PS, non-point and natural sources from coastal rivers. The baseline covers 1971—2017 for large WWT plants discharging >50 million gallons per day (MGD) and 1997–2017 for small WWT plants and rivers. PS are the dominant nitrogen source, with contributions of 70% of the total annual freshwater discharge and 95% of nitrogen loads. WWT upgrades have reduced organic nitrogen loads by 73% since 1971. Inorganic nitrogen loads have generally held constant (35–40 Gg y⁻¹) for the large WWT plants. This baseline represents a period prior to extensive wastewater and stormwater recycling that is increasing in the region.

This study focuses on estimating CO₂ emissions and analysing energy efficiencies using the Energy Efficiency Operational Index (EEOI) for ferries sailing within an urban port of Taiwan and passenger-ships operating on island routes surrounding Taiwan. A comparative analysis of energy efficiency parameters showed that hybrid diesel-electric ferries had a 12% improved efficiency compared to the traditional full-diesel ferries, while high-speed passenger ships had up to 79% lower efficiency than medium-speed passenger ships. Some potential policies for reducing CO₂ emissions from in-port ferries and island passenger-ships are presented based on these results. The estimated CO₂ emissions from in-port ferries sailing within the urban port could be reduced by 10% when employing hybrid diesel-electric ferries instead of traditional full-diesel ferries. Emissions from island passenger-ships operating on island routes could be reduced by 11–26% through utilising small medium-speed passenger ships instead of small high-speed passenger ships and large passenger ships.

The United Arab Emirates (UAE) host valuable coastal and marine biodiversity that is subjected to multiple pressures under extreme conditions. To mitigate impacts on marine ecosystems, the UAE protects almost 12% of its Exclusive Economic Zone. This study mapped and validated the distribution of key coastal and marine habitats, species and critical areas for their life cycle in the Gulf area of the UAE. We identified gaps in the current protection of these ecological features and assessed the quality of the data used. The overall dataset showed good data quality, but deficiencies in information for the coastline of the north-western emirates. The existing protected areas are inadequate to safeguard key ecological features such as mangroves and coastal lagoons. This study offers a solid basis to understand the spatial distribution and protection of marine biodiversity in the UAE. This information should be considered for implementing effective conservation planning and ecosystem-based management.

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.

Ocean plastic pollution is a global problem that causes ecosystem degradation. Crucial knowledge gaps exist concerning patterns in microfiber abundance across regions and ecosystems, as well as the role of these pollutants within the environment. Here, we quantified the abundance of microfibers in coral samples collected from the Belize Mesoamerican Barrier Reef System (MBRS) using a polarized light microscope and identified a subsample of these to the polymer level using an Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy microscope. Microfibers were found in all coral samples with rayon being identified as the most common microfiber, comprising 85% of quantified pollutants. We found a greater average abundance of microfibers in coral samples from the Sapodilla Cayes (296 ± SE 89) than in samples from the Drowned Cayes (75 ± SE 14), indicating spatial variation in microfiber abundance within coral tissue along the MBRS. These results demonstrate that corals on the Belize MBRS interact with microfibers and that microfiber abundance on reefs varies spatially due to point sources of pollution and local oceanography. As rayon from clothing typically enters the ocean through wastewater effluent, alterations to waste water infrastructure may prove useful in decreasing rayon pollution in coastal waters.