Hidrocarbonetos Policíclicos Aromáticos em Microplásticos de Praias do Litoral Brasileiro

Abstract

When introduced on the environment, plastic materials might have many destinies, and one of them is the fragmentation. The continue degradation and fragmentation of the plastic materials originates the called microplastics (MP), particles with sizes between 5 mm and 1 μm of a great potential of dispersion. When in polluted environments microplastics tend to become adsorption superficies for hydrophobic pollutants more efficiently than natural solid particles, as Polycyclic Aromatic Hydrocarbons (PAH). PAH are organic pollutants that might have its origin from natural and anthropic processes. In the same way as microplastics, PAH are highly persistent in the environment, and for presenting mutagenic and potential carcinogenic properties when absorbed by human and aquatic organisms metabolisms they are extremely dangerous. Due to its toxic and harmful properties to environment and human health, sixteen PAH are defined as priorities in environmental studies by the United States Environmental Protection Agency (US EPA). Several studies have evaluated the occurrence of microplastics and PAH individually in environmental matrices, but still are few that investigated the association of these two pollutants. In this way, especially in Brazil, there is a need of expansion of research about this theme. The present study has the aim of investigate the occurrence and concentration of PAH in microplastics in beach sediments from eight Brazilian coastal states, to verify its composition and possible sources of the compounds to MP in the studied areas, to relate the accumulation of MP and PAH considering the land use and social-environment factors of each region, and to evaluate the toxic potential and of contamination of PAH from MP to aquatic organisms. Sediment samples were taken from the high tide mark from potentially polluted locals from the beaches of Ver-o-Rio and Farol (PA), Iracema (CE), Boa Viagem (PE), Porto da Barra (BA), Curva da Jurema (ES), Arpoador and Botafogo (RJ), Praia Grande, Santos and São Vicente (SP), and Praia Grande (RS). On the laboratory using a hypersaline solution and a filtration system, MP were separated from the sediments. PAH were extracted using three types of microplastics, 0,2-0,3 g of fragments and pellets, and 0,02 g of EPS (foam), and were analyzed in Gas Chromatography Tandem Mass Spectrometry (GC/MS/MS). It was possible to detect fourteen of the sixteen studied PAH, where the total concentration of PAH (Σ-PAH) varied between 0,25 to 71,60 ng g-1 on the samples and types of MP. On the North and Northeast regions, the low concentration (0,31 to 71,60 ng g-1) of PAH in MP appears to be related to the intense hydrodynamic processes. The concentration of Naphthalene on the foam samples were above the Threshold Effect Level (TEL > 35) on the samples from Pernambuco and Bahia, e near of TEL at Ceará (70,15, 36,97 and 33,28 ng g-1, respectively); so, effects in the organisms might occur due to this compound. The Southeast and South regions are the only that presented previous studies of PAH in MP, so it was possible to make a better comparison and discussion of the obtained data from the present study. The sources of PAH for the environment and consequently for MP were attributed to the anthropogenic contribution (petrogenic and pyrogenic). The highest concentration of PAH was found in the foam samples, suggesting that this type of MP might have a considerable contribution in the dispersion of these contaminants, especially in more polluted locals. Lastly, its concluded that PAH are present on all the Brazilian states studied and its occurrence were evidenced by its adsorption in MP sampled in beach environments. The organic contaminants originate both from petrogenic and pyrogenic processes, and the principal sources of these compounds to the evaluated locals were industrial and port activities, the inadequate disposal of effluents, and the urban runoff by pluvial waters.