engleski

Nanoplastics in the marine environment: effect of microalgal extracellular polymers studied by AFM

The stability of plastic nanoparticles - nanoplastics in the marine environment plays an important role in determining their environmental implication and potential risk to marine biota and eventually to human health. In order to understand the behavior of nanoplastics in the marine environment, it is important to understand possible mechanisms involved in nanoplastics interaction with the naturally occurring seawater components, particularly natural organic matter including algal extracellular polymers (EPS). We studied the role of diatom extracellular polysaccharides in scavenging and stabilizing amine-modified polystyrene nanoparticles in the marine environment. Atomic force microscopy (AFM) revealed that EPS biopolymers displayed strong interaction with NPs and the incorporation of nanoparticles into the polymer network was visualized. NPs dispersed in seawater without presence of EPS showed enhanced aggregation of NPs that was visualized by AFM and confirmed by dynamic light scattering measurements. Our results indicate that the presence of EPS biopolymers changes the fate of NPs in the marine environment. By scavenging nanoplastics, EPS could prolong their presence in water column and make them available to higher organisms. This study shows that the presence of natural organic matter including extracellular polysaccharides should be accounted for in future research evaluating impact of nanoplastics in the marine environment. This is the way how polystyrene nanoparticles (and most likely other plastic nanoparticles) can persist in water column, in spite the fact that NPs quickly aggregate in seawater. Furthermore, EPS polymers are an important source of food for phytoplankton grazers and higher trophic levels and the incorporation of NPs in EPS may have significant impact on marine biota.

Nanoplastics ; Marine environment ; Microalgal extracellular polymers ; Atomic force microscopy (AFM)

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