EGU General Assembly 2020
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Degradation of nanoplastics in aquatic environments: reactivity and impact on dissolved organic carbon

Angelica Bianco1, Fabrizio Sordello2, Mikael Ehn1, Davide Vione2, and Monica Passananti1,2
Angelica Bianco et al.
  • 1University of Helsinki, INAR – Institute for Atmospheric and Earth System Research, Helsinki, Finland (
  • 2Dipartimento di Chimica, Università di Torino, Via Pietro Giuria 5, 10125, Torino, Italy.

The large production of plastic material (PlasticsEurope, 2019), together with the mishandling of plastic waste, has resulted in ubiquitous plastic pollution, which now reaches even the most remote areas of the Earth (Allen et al., 2019; Bergmann et al., 2019). Plastics undergo a slow process of erosion in the environment that decreases their size: microplastics (MPs) and nanoplastics (NPs) have diameters between 1 µm and 5 mm and lower than 1 µm, respectively (Frias and Nash, 2019).

The occurrence, transformation and fate of MPs and NPs in the environment are still unclear. Therefore, the objective of this work is to better understand the reactivity of NPs using an aqueous suspension of polystyrene NPs (PS-NPs) as a proxy, in the presence of sunlight and chemicals oxidants. The results obtained are relevant to both the atmospheric aqueous phase, such as cloud and fog droplets, and surface waters. We investigated the reactivity of PS-NPs with light and with two important oxidants in the environment: ozone (O3) and hydroxyl radicals (OH). The adsorption of ozone (O3) on PS-NPs is investigated, showing a significant O3 uptake. Moreover, for the first time, a reactivity constant with OH is determined. We found a linear correlation between the kinetic constants measured for three different sizes of PS-NPs and the surface exposed by the particles. Degradation products (short chain carboxylic acids and aromatic compounds), obtained by direct and OH-mediated photolysis of PS-NPs suspensions, are identified by high-resolution mass spectrometry. Irradiation of a PS-NPs suspension under natural sunlight for 1 year has shown the formation of formic acid and organic compounds similar to those found in riverine and cloud dissolved organic matter.

This work is crucial to assess the impact of NPs abiotic degradation in atmospheric and surface waters; indeed, the reactivity constant and the degradation products can be implemented in environmental models to estimate the contribution of NPs degradation to the natural dissolved organic matter in the aqueous phase. A preliminary simulation using APEX (Aqueous Photochemistry of Environmentally occurring Xenobiotics) (Bodrato and Vione, 2014) model shows that in NPs-polluted environments (109 particles mL-1) there is potential for NPs to significantly scavenge OH, if the content of natural organic matter is not too high, as observed for surface and cloud water.

Allen, S., et al., 2019.  Nat. Geosci. 12, 339–344.
Bergmann, et al., 2019.  Sci. Adv. 5, eaax1157.
Bodrato, M., Vione, D., 2014. Environ. Sci.: Processes Impacts 16, 732–740.
Frias, J., Nash, R., 2019. Mar. Pollut. Bull. 138, 145–147.

How to cite: Bianco, A., Sordello, F., Ehn, M., Vione, D., and Passananti, M.: Degradation of nanoplastics in aquatic environments: reactivity and impact on dissolved organic carbon, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5308,, 2020

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