Microplastics (MPs) are toxic pollutants, which are found ubiquitously in the marine environment. The present study aimed to assess the level of MP contamination in Vellar estuary, southeast coast of India. MP abundance in surface water and sediments ranged from 1.15 ± 0.01 to 5.14 ± 0.04 items/m³ and 24.8 ± 0.75 to 43.4 ± 0.98 particles/kg d.w., respectively. Fiber, fragment, film, pellet and glitter were present in the study area. In total, ten colors of MPs were found in the study, of which black was the most abundant. Seven polymers in sediments and four polymers in water were characterized from the study area, among which LDPE was the most dominant. Sediment texture results showed that clay particles were able to retain a greater number of MPs. This study shows that the Vellar estuary is contaminated with MPs; however, further investigation is required to classify the estuary as polluted.

The present study was carried out to determine the characteristics, distribution, and abundance of plastic debris in 25 sediment samples collected from the Poompuhar beach, southeast coast of India. The result reveals that the mean plastic debris abundance was 42 ± 27 particles/m² dry weight (dw) (1 SD, n = 25) with higher concentrations in the river mouth. The dominant shapes in the study area were fragment (70.7%), followed by fiber (20.7%), and pellet-shaped (8.6%). The dominant colors of the plastic debris were: white-colored (47%) followed by blue (28%) and green (14%). The study further reveals that the dominant polymer type was polyethylene (PE, 63.4%), followed by nylon (PA, 16.9), polyvinyl chloride (PVC, 15.5%), polypropylene (PP, 3.1%), and polystyrene (PS, 1.1%). In the study area, the main source of plastic debris was from land-based fishing and tourism activities, and rainwater runoff from the Cauvery River.

Excessive discharge of N and P pollutants results in deterioration of marine environment quality and reduction of sustainability and safety of marine ecology. Spatiotemporal variations characteristics and sources of N and P pollutants were determined based on the long-term monitoring data in Liaodong Bay. Results indicated that an evident spatiotemporal variation was investigated for nutrients. The highest concentrations of NH₃-N, NO₂-N, NO₃-N and PO₄-P were in spring (25.32 μg/L), summer (20.67 μg/L) and autumn (222.07 μg/L, 11.08 μg/L), respectively. The hot-spots of pollutants were mainly concentrated in estuarine and aquaculture areas. The hot spot of PO₄-P gradually extended to the middle of Liaodong Bay in autumn. In addition, pollution sources in each marine functional zone were different, the main pollution source was aquaculture wastewater, river input, domestic sewage. This study provided reasonable suggestions for effectively reducing N and P pollution in Liaodong Bay, and elsewhere.

The ‘taxonomic sufficiency’ (TS) approach has been applied to algae, protists, invertebrates, and vertebrates, generally by aggregating species-level abundance data to a higher taxonomic level, where genus-level data are often highly correlated with species-level data and are a valid proxy level. The TS approach offers the possibility of a comparison of data from different geographical areas and highlights the effects of contaminants. The TS approach is stable in the face of different researchers and in the comparison of long-term biological survey data. The effectiveness of the TS approach may increase with increasing environmental gradients or spatial area. The TS approach should be avoided when the spatial area is small and small differences in species-level data are considered important, so as not to cancel out the distribution patterns specific to the local environment of the biological taxa.

Polycyclic aromatic hydrocarbons (PAHs) most likely derived from natural sources were observed in two sediment cores covering the last 100 years in an Amazon estuarine region. A considerable change in the PAHs main source was observed in the 1960s. Before the 1960s, the sources of PAHs seem to be related to biogenic and/or early-diagenetic processes. Concentrations of perylene were higher before the 1960s and suggest that its primary source to the sediments in the Amazon region is linked to a short-term diagenetic transformation of their biogenic precursors. The natural formation of alkylated PAHs in sediments was linked to the methylation of the parental aromatic hydrocarbons due to sediment maturation processes and the dehydrogenation of sterols in the sediments. The relatively rapid reaction occurring in recent sediments of the Amazon region suggests the importance of the microbial community in the transformation of biogenic precursors to alkylated-PAHs in the sediments.

Coastal zones, which are strategic points of considerable importance to the tourism industry, are among the environments most affected by anthropogenic debris. Thus, it is crucial to monitor and implement management programs to provide immediate solutions. Here, we aimed to evaluate anthropogenic litter along 21 macrotidal sandy beaches in the Amazon region. Indices and multivariate statistical analyses were used to identify spatial patterns of pollution, as well as sources and lifetime of the items. A total of 20,286 items were collected, with an average density of 0.19 items/m² and a predominance of plastics. Litter was associated with tourist and recreational activities. The lifetime of most items was <1 year. All beaches had intermediate levels of pollution. The analyses identified varying patterns of anthropogenic litter related to the cleaning frequency and waste item typologies. In conclusion, pollution of macrotidal beaches in the Amazon region is an emerging problem that requires measures to prevent and mitigate the impacts on this ecosystem and to reconsider the form of production and consumption of plastic waste.

In the present study Web of Science, Scopus, and PubMed as electronic databases were used to find work published up to October 27, 2020 about microplastics evaluation in conventional wastewater treatment plants. In total, 407 publications were found, of which 77 were eligible for meta-analysis. A comprehensive meta-analysis was undertaken to evaluate the relevant publications regarding microplastics abundance. The average microplastics abundance was within the 1–31,400, 0.2–12,580, 0.002–7863, and 0.003–447 items range per liter wastewater for influent, primary, secondary, and tertiary treatment steps, respectively. The difference between the abundance of microplastics characterization for the different treatment steps was analyzed using ANOVA or Kruskal-Wallis test (depending on the data distribution). According to the pooled data, the average microplastics abundance was 124.04, 20.67, 5.62, and 1.97 (items/l) for influent, primary, secondary, and tertiary treatment. The results of Egger's test (t = 7.49, P ≤ 0.0001) were statistically significant, suggesting the existence of publication bias.

This review summarizes the current state of knowledge regarding the risk assessment of plastic-associated residual additives, i.e. residual monomers, degradation products and additives, in the marine environment, also considering effects of weathering and bioavailability. Experimental studies have found a number of organic and metal additive compounds in leachates from plastics, and the analysis of weathered plastic particles, such as polyethylene, polypropylene and polystyrene particles sampled on beaches and shorelines, has identified residual additives, such as flame retardants, plasticizers, UV stabilizers and antioxidants. While the transfer of e.g. PBDEs to organisms upon ingestion has been demonstrated, studies on uptake and bioaccumulation of plastic-associated chemicals are inconclusive. Studies on hazard and risk assessments are few, and focus on monomers and/or a limited number of high concentration additives, such as phthalates and flame retardants. The risk assessment results vary between low, moderate and high risks of specific additives, and are not necessarily consistent for the same compound. Given the large number of chemicals potentially introduced into the marine environment with plastic particles and the challenges associated with the correct quantification of exposure concentrations and toxicity thresholds, the question arises whether new risk assessment concepts may be needed.

The study aimed to understand beach litter status at some of the world-famous beaches of Goa, West India, to comprehend the impact of the Covid-19 lockdown. We characterize litter in six categories (Nylon+Rubber, Plastics, Footwear, Glass, Metal, and Thermocol) for eight sampled beaches in the north and south Goa. All beaches show increased glass and decreased plastics (significant litter) during the lockdown period compared to the unlock period that marked the high tourist inflow. Beaches were classified and graded with colour codes using litter density exhibit light blue-green colour coding during the lockdown or unlock period, suggests clean maintenance. The Miramar beach located in the heart of the capital city showed relatively more litter density (yellow code) due to the combination of local people and tourist inflow. Morjim, Palolem, Velsao were littered the least during both periods.

The association and statistical correlation of anthropogenically important trace metals (TM) Cd, Cu, Pb, Zn and degraded marine microplastic (MP) extracted from the bulk debris samples at two locations from two marine systems, estuarine and coastal, in the Croatian Adriatic coastal area were assessed. The abundance of MP particles at both sites were primarily defined by local wave climate, with the open coastal site containing 9-fold more microplastic particles (>4 mm) as compared to the semi-closed estuarine, or twice as much considering bulk plastics. Generally, the higher abundance of adsorbed metal on MP were observed in the more anthropogenically influenced estuary than in the open coastal site and followed the order: polystyrene > polypropylene > low density polyethylene. The amounts of adsorbed zinc were the highest on all types of plastics at both sites, while the affinity of polystyrene for metals followed: Zn > Pb ≈ Cu > Cd.