abstract
Microplastic contamination of aquatic environments has become an increasingly alarming problem. These, defined as particles <5 mm, are mostly formed due to the cracking and embrittlement of larger plastic particles. Recent reports show that the increasing presence of microplastics in the environment could have significant deleterious consequences over the health of marine organisms, but also across the food chain. Herein, we have studied the effects of artificial seawater on polyethylene (PE)-based beads by exposing them up to eight weeks to saltwater in stirred batch reactors in the dark and examined the structural and morphological changes these endured. Electron microscopy observations showed that artificial seawater induces severe microcracking of the pellets' surfaces. Additionally, Fourier transform infrared spectroscopy (FTIR) analyses evidenced the formation of oxidized groups whenever these particles were exposed to water and an increase in organic matter content of the waters in which the pellets were kept was evidenced by Raman spectroscopy. There were also noticeable consequences in the thermal stability of the polyethylene pellets, as determined by thermogravimetric studies (TGA). Furthermore, the parallel exposure of polyethylene pellets to UV radiation yielded less pronounced effects, thus underscoring its lower preponderance in the degradation of this material. These results highlight the importance of determining the mechanisms of degradation of microplastics in marine settings and what the implications may be for the environment. Overall, the herein presented results show that a relatively short period of time of accelerated exposure can yield quantifiable chemical and physical impacts on the structural and morphological characteristics of PE pellets.
keywords
LOW-DENSITY POLYETHYLENE; PRINCIPAL COMPONENT ANALYSIS; THERMAL-DEGRADATION; PLASTIC SCRUBBERS; MARINE POLLUTION; FTIR; BIODEGRADATION; RAMAN; IDENTIFICATION; SPECTROSCOPY
subject category
Engineering; Environmental Sciences & Ecology
authors
Da Costa, JP; Nunes, AR; Santos, PSM; Girao, AV; Duarte, AC; Rocha-Santos, T
our authors
Ana Violeta Girão
Junior Researcher
João Miguel Martins Novaes Pinto da Costa
Research Fellowshipacknowledgements
This work was funded by national funds through FCT/MEC (PIDDAC) under project IF/00407/2013/CP1162/CT0023 and by FCT under project UID/AMB/50017/2013. The FCT fellowships given to P.S.M. Santos (Ref. SFRH/BPD/102452/2014) and Joao Pinto da Costa (scholarship SFRH/BPD/122538/2016) are also acknowledged.