The production of rare earth elements, REE, has significantly increased over the past years, in parallel with the latest advances in nanotechnologies and representing a new group of emerging contaminants. They find application in construction, transport, agriculture, electronics, catalysis, and biomedicine. Their extraordinary intrinsic characteristics are fundamental for overcoming current technological challenges. The accumulation of REE is consistent in near-shore waters being affected by runoff, wastewater discharge, and proximity to built-up areas. Bioavailability in water, sediments, and accumulation in marine biota as well their endocrine disruptor effect is mostly unknown. There is a significant gap of knowledge on the ecotoxicological behaviour of REE in marine areas. The existing investigations have been performed inside well-mixed estuarine systems, due to complex hydrodynamics and multiple sediment transport situations. This hampers the definition of regulatory thresholds for REE concentrations and emissions. The review summarizes the existing information on REE geochemistry and physicochemical conditions influencing dissolution, surface complexation reactions, and distribution at the continent–ocean interface, as well as their speciation, bioavailability, and detrimental effects on living organisms. Strategies for reducing REE usage and inputs are also discussed.

This review is a follow-up to a previous review published in Journal of Marine Science and Engineeringon the issues of accumulation, transport, and the effects of microplastics (MPs) in the oceans. The review brings together experimental laboratory, mathematical, and field data on the dual role of MPs as accumulators of hydrophobic persistent organic compounds (POPs), and their release-effect in the marine ecosystem. It also examines the carrier role, besides POPs, of new emerging categories of pollutants, such as pharmaceuticals and personal care products (PPCPs). This role becomes increasingly important and significant as polymers age and surfaces become hydrophilic, increasing toxicity and effects of the new polymer-pollutant associations on marine food webs. It was not the intention to provide too many detailed examples of carriers and co-contaminants, exposed marine species, and effects. Instead, the views of two different schools of thought are reported and summarized: one that emphasizes the risks of transport, exposure, and risk beyond critical thresholds, and another that downplays this view.

One of the major concerns regarding the presence of plastics in ocean environments are the effects on marine biota. Plastics can be distinguished in macro- (≥25 mm), meso- (<25 mm–5 mm) micro- (<5 mm–1 µm), and nano-plastic (<1 µm) and are practically omnipresent in aquatic habitats and subject to long-range transport. The purpose of this review is to report the last findings on the release, transfer, accumulation, and effects of micro-plastics, MPs, in the oceans. MPs have the chance to adsorb different kind of organisms and compounds on their outer surface, including bacteria, viruses, algae, and abiotic substances. In this way, they can cause sever hazard once they enter the food chain. Their harm to higher organisms is discussed as well as main routes of MPs–organism interactions, i.e., ventilation, and ingestion. Potential effects on populations, communities, and ecosystems and uptake routes and transition into tissues are discussed. In consideration of the potential threats of plastic particles to ecological functions and human health risks, we recommend specific directions of future research approaches.

Coastal erosion affects several beaches worldwide in association with natural and human pressures. In recent decades, the coastland located on the Paraíba do Sul River mouth has been recognized as one of the main areas that suffer from this geomorphological dynamic. Furthermore, the scientific literature, even if scarce, has pointed out that these dynamics are causing negative socio-environmental responses and making the area less resilient. In the last few decades, hundreds of homes and other urban structures have become debris due to erosion caused by sea ingression, triggered by the coupling of environmental processes and dynamics occurring at different spatial and temporal scales. Thus, the present research aimed to analyze how the anthropic changes carried out in the Paraíba do Sul hydrographic basin are related to the intense coastal erosion at the mouth. Variations in fluvial–marine hydrosedimentary dynamics triggered this due to the construction of dams to supply large cities and for agricultural purposes. Water and sediment samples were collected and analyzed in different sectors of the main channel and on the adjacent coast, mapping land use in the basin area and surveying socioeconomic data. The results suggest that human pressures on the hydrographic basin during the last century are directly associated with the imbalance of the environmental system and, consequently, the progression of coastal erosion on the Paraíba do Sul delta shoreline.

In the last decade, metal engineered nanomaterials (ENMs) have seen an exponential use in many critical technologies and products, as well an increasing release into the environment. Coastal ecosystems worldwide may receive ENM-polluted waters and wastes, with a consequent alteration of habitats and contamination of aquatic biota. There is a scarcity of data regarding the fate of these emerging contaminants in such environments. Open issues include the determination of the sources, the quantification of the interactions with marine sediments, the bioaccumulation pathways, the ecotoxicology on marine fauna and the identification of the principal biotic and abiotic factors that may alter metal ENMs toxicity. Little is known about their potential transference into the food web, as well toxicity features and co-stressors of single or multiple ENMs under laboratory and real environmental conditions for various taxonomic phyla. This review reports current knowledge on the ecological impact of ENMs under the complex environmental conditions of estuary systems, identifies gaps in current knowledge and provides directions for future research.

A multidisciplinary survey was carried out on the quality of water and sediments of the estuary of the Sele river, an important tributary of the Tyrrhenian Sea, to assess anthropogenic pressures and natural variability. Nine sediment sites were monitored and analyzed for granulometry, morphoscopy, benthic foraminifera and ostracod assemblages, heavy metals, and polycyclic aromatic hydrocarbons. Surface water was assayed for ionic composition and phytoplankton biomass. Total organic carbon (TOC) and total nitrogen (TN) in sediments were higher in the inner part of the estuary (IE), up to 12.7 and 0.7% because of anthropic influence. In waters, N-NH₄, N-NO₃, and P_tot. were high, with loads of P_tot in IE exceeding ~fourfold the limit. Here, it was also observed that the highest primary production was Chl-a, 95.70 µg/L, with cryptophytes, 37.6%, and diatoms, 33.8%, being the main phytoplanktonic groups. The hierarchical analysis split the estuary into two areas, with marked differences in anthropic pollution. Waters were classified as poor–bad level with respect to the content of nutrients. Sedimentological assay reveals littoral erosion and poor supply of river sandy sediments. The erosion environment is confirmed by the presence of meiobenthic recent marine forms intrusion inside the river. All these data reveal the fragility of the estuary and the need of urgent remediation actions.