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Browsing by Author "Rodrigues, Beatriz Isabel Martins"

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  • The use of microplastics to reconstruct dated sedimentary archives: the showcase of Mondego estuary (Portugal)
    Publication . Rodrigues, Beatriz Isabel Martins; Teixeira, Margarida Ribau; Bessa, Ana Filipa da Silva
    Microplastics (plastics < 5 mm), have become a defining feature of the Anthropocene epoch, representing humanity's profound impact on the planet. Envisioned as "techno-fossils" they provide detailed records of deposition history with dating resolutions from years to decades. This study used the Mondego estuary as a case study to assess whether microplastics can be used as a marker of the Anthropocene. Sediment corers were used to collect 50cm replicates longitudinally. In total, 885 particles were extracted using a saturated NaCl (1.2. g.cm-3) solution and characterised according to type, colour and shape. The polymer of 14 particles were ascertained using FTIR analysis. The sediments retrieved, dated approximately from 1947 to 2019, presented potential microplastics in all layers. The abundance of these particles fluctuated over the years, without a clear pattern, even though, the highest concentration of potential microplastics corresponded to the sediment layer (37) of 1973, where the first Polyethylene terephthalate beverage bottles were introduced and produced in mass. This study also supported the trend of high abundances of fibres, with a total value of 93% of total samples, which is often the most predominant type of microplastics found in aquatic environments and can be linked to point sources in transitional ecosystems and estuaries, such as wastewater treatment plants (WWTPs). This is a preliminary study evaluating the way microplastics tend to accumulate in sediments and how this data can be integrated. During this present work, it was clear that the main amount of potential microplastics present is fibres (93% of the total sample), followed by fragments (6%), and then by films (1%). In these particles, the most predominant colour is blue, with a total of 397 potential microplastics (45%) in a sample of 885 potential microplastics.
    2023-11-23Master thesis Open access Show more