Characterization and abundance of macroplastics and microplastics in biotic and abiotic matrices in Concepción Bay, Chile

In the last decade, increasing concern has been raised to protect the marine environment from plastic pollution. Plastic has the potential to break down into microscope and nanoscope particles (secondary microplastics). Among them, microplastics (MPs) (also known as emergent pollutants=EC) are fragments of grain size lower than 5 mm. The characteristics of plastics such as colour, heat resistance, etc., change thanks to the adhesion of chemical substances, called additives. In some cases, the additive ingredients constitute up to 50% of the proportion of the plastic product. Phthalate esters, bisphenol A (BPA), brominated flame retardants (BFRs) are among many other plastic additives known as toxic compounds to organisms when released to the environment. Also, because of their properties, plastics sorbed a complex mixture of chemical contaminants present in the surrounding environment. It is estimated that of the total annual plastic consumption in Chile, only 8.5% is recycled. However, this includes both post-industrial waste and household solid waste. If only the recycling of household plastic waste is measured, the recycling percentage is only 1.4% of the total plastic consumed each year in Chile. This study evaluated the state of contamination by plastics (micro and macroplastics) on the coasts of the province of Concepción, Chile, specifically in Coliumo Bay, Concepción Bay and on the adjacent beach at the mouth of the Biobío River. The main results of this study were to conduct the first information of POPs sorbed in macroplastics collected on beaches of coastal areas in Chile and characterization and abundance of microplastics collected in the sand and fish. Identification/characterization of polymer types in plastics was done using Fourier-transform infrared (FT-IR) spectroscopy and an optical microscope with an integrated camera. This is essential because it allows an assumption on the source of the plastic pollutants and governs its origin from the break down of macro, larger or extra-large plastic components or nearby recreational and industrial activities. In the coast of central Chile, fragment and fibres account for 100% of the collected MP particles, indicating the presence of secondary MPs in Concepcion Bay and the most frequent plastics identified were polystyrene foam beads (46% in sand) and Polyethylene (PE) (75% in fish). Black fragments were the most abundant microplastics both in the biotic and abiotic samples of Concepción Bay. The abundance of microplastics in the sand was 0.035 ± 0.04 items/g and 1 item/individual in fish (Trachurus murphyi (Chilean jack mackerel) and Merluccius gayi (Hake)). Regarding macroplastics, the average abundance was 2 items/m2 less than in other studies. The highest abundance of macroplastic types were the fragments and the most frequent plastics identified were polypropylene (PP) (38%), mostly white. Also, to determine the chemical load, such as persistent organic pollutants (POPs) found in plastic waste, they were analysed using ultrasonic extraction and gas chromatography–mass spectrometry (GC-MS) for POPs determination. Screened compounds were PBDEs (n = 10), PCBs (n = 7), and OCPs (n = 13). High concentrations of PBDEs were found ranging from 2.1 to 1300 ng/g in the spring of 2017 and 392 to 3177 ng/g in the summer of 2018. Σ7PCBs ranged from 0.9 to 93 ng/g during the spring of 2017 and 0.3 to 4.5 ng/g for the summer of 2018. The concentrations of OCPs (DDX and HCHs) were low and were only detected in the summer of 2018. The plastics found in this study are commonly used in commercial, fishing, and household activities. These findings reinforce the need to improve effective sustainable management actions of solid waste treatment and disposal in the Coastal cities of Chile, also taking into account the chemical burden associated with plastic waste.