Microplastic pollution in sediments of tropical shallow lakes.

Forty-eight tropical shallow lakes (depth ≤ 4 m) across a climatic gradient were assessed for microplastic (MPs; <5 mm) pollution based on MPs concentrations in archive samples from lake shore sediments. The MPs were classified by type (fragments or fibres), colour (yellow, black, red, green, blue, white, and transparent), size (0.55 to 4.93 mm), and polymer (polyester, polyethylene, chlorinated polyethylene, and polyamide). Sediments were predominantly medium sand, and all samples (144) contained MPs, consisting of 24 % fragments (6.3 ± 11.3 MPs·300 g-1) and 76 % fibres (21.25 ± 12.7 MPs·300 g-1). The lake climate (humid, transitional, or semi-arid), type of surrounding land use (urban, semi-arid, or rural), and distance from the shoreline (0, 5 or 10 m) did not explain the differences in MPs concentrations, partially refuting the initial hypothesis. The only significant difference was between the sample medians for the number of fragments based on the region (H = 7.586; p = 0.0481). The number of fragments in the lakes in the humid region was greater than that in the semi-arid region (p < 0.05). Poor sanitation, sewage effluents, and solid wastes reaching and accumulating in the lakes may be the primary and transversal conditioning factors for this small difference among diverse environments. Freshwater lakes are investigated in all continents, and the present study contributes to the first record of MPs in shallow lake sediments in eastern South America. The 48 shallow lakes assessed showed a relatively low concentration of MPs compared to other lake contaminants reported in the international literature. This information coincides with public policies issued, regarding the control and reduction of plastics and MPs in Brazil, and the study region.

Temporal analysis of environmental quality of Ponta Negra beach (Natal-RN) related to coastal erosion: what has changed in 10 years?

Ponta Negra beach is one of the main tourist destinations in the state of Rio Grande do Norte (Brazil), which is used by many tourists. This study aimed to perform a temporal analysis of the environmental quality of the beach related to coastal erosion, considering environmental and anthropic parameters at two different times, 10 years apart. The total length of the beach (3 km) was subdivided into 10 sections of approximately 300 m numbered 1-10, from south to north. Eight parameters were assessed based on an attribute scale ranging from the worst to the best possible quality (1-4) found in each section. The sum of the parameters was used to determine the final score. To determine the level of environmental quality, four conditions were considered (excellent, good, regular, and bad). Compared with the first sampling period, the results indicated that 50% of the beach showed reduction in environmental quality. The "excellent" condition, obtained in the first sampling period for two of the sections, was not repeated in the second period. Two situations were responsible for the decrease in beach quality over time: the erosive process that took place after 2012 and consequent reduction in vegetation cover and width of the beach environment. The current state of the beach and its gradual loss of quality over the years indicate an unpromising trend towards recovery. The methodology used in this study can be easily repeated in other locations with similar problems, generating data that can help in understanding local conditions.

Microplastics ingestion by a common tropical freshwater fishing resource.

Microplastics pollution is widespread in marine ecosystems and a major threat to biodiversity. Nevertheless, our knowledge of the impacts of microplastics in freshwater environments and biota is still very limited. The interaction of microplastics with freshwater organisms and the risks associated with the human consumption of organisms that ingested microplastics remain major knowledge gaps. In this study, we assessed the ingestion of microplastics by Hoplosternum littorale, a common freshwater fish heavily consumed by humans in semi-arid regions of South America. We assessed the abundance and diversity of both plastic debris and other food items found in the gut of fishes caught by local fishermen. We observed that 83% of the fish had plastic debris inside the gut, the highest frequency reported for a fish species so far. Most of the plastic debris (88.6%) recovered from the guts of fish were microplastics (<5 mm), fibres being the most frequent type (46.6%). We observed that fish consumed more microplastics at the urbanized sections of the river, and that the ingestion of microplastics was negatively correlated with the diversity of other food items in the gut of individual fish. Nevertheless, microplastics ingestion appears to have a limited impact on H. littorale, and the consequences of human consumption of this fish were not assessed. Our results suggest freshwater biota are vulnerable to microplastics pollution and that urbanization is a major factor contributing to the pollution of freshwater environments with microplastics. We suggest the gut content of fish could be used as a tool for the qualitative assessment of microplastics pollution in freshwater ecosystems. Further research is needed to determine the processes responsible for the high incidence of microplastics ingestion by H. littorale, and to evaluate the risk posed to humans by the consumption of freshwater fish that ingested microplastics.

Plastic litter on an urban beach---a case study in Brazil.

Beaches are subject to solid waste contamination at the strandline. Litter depositional dynamics is influenced by specific beach morphology and sources of solid wastes. The amount of items on the strandline of Boa Viagem beach (Recife, Brazil) was evaluated during dry and rainy seasons of 2005 to characterize their sources and depositional patterns. The strandline was surveyed once a month to count and classify all visible solid waste items within a belt-transect. Plastics were used for detailed analysis of the wastes accumulated. There were quantitative, but not qualitative, differences in litter accumulation during the year and parts of the beach. The main source of debris was land-based. In general, the beach was low-polluted in the dry season and medium-polluted during the rainy season. The method is a low-cost and highly efficient characterization of solid wastes contamination of urban beaches.