The Montreal Protocol and the fate of environmental plastic debris
Citation:
Jansen, M., P. Barnes, J. Bornman, K. Rose, S. Madronich, C. White, R. Zepp, AND A. Andrady. The Montreal Protocol and the fate of environmental plastic debris. PHOTOCHEMICAL AND PHOTOBIOLOGICAL SCIENCES. Royal Society of Chemistry, Cambridge, Uk, 22(5):1203-1211, (2023). https://doi.org/10.1007/s43630-023-00372-x
Impact/Purpose:
The impact of plastics in the environment is tightly linked to UV-driven weathering, which is followed by subsequent fragmentation that can lead to a decrease in plastic macro-debris in the environment, yet increase the concentration of microplastics (MPs). The purpose of this section is to provide an assessment of efforts to integrate existing surface UV irradiation data with better knowledge of the distribution of plastics across various environmental niches: this could provide is an opportunity to generate quantitative predictions of plastic persistence at a global scale. Insights from this effort can inform the design of more environmentally friendly plastics. Key data needed for this approach, however, are better knowledge of action spectra and dose-response relationships of UV driven oxidation of common compounded plastics, which include intentionally added chemicals such as nanomaterials, plasticisers, dyes, antioxidants, flame retardants and/or UV stabilisers. Moreover, quantitative predictions of plastic persistence will be subject to interactions of plastic photooxidation with climate change, which may affect processes as diverse as UV penetration into the water column, sedimentation rates and/or air movements. Furthermore, the chemical or toxicological properties of MPs, and thus their hazards and risks, are affected by UV irradiation. Therefore, there is an urgent need to better understand the interactions between plastics in the environment, climate change, and UV radiation.
Description:
Microplastics (MPs) are an emerging class of pollutants in air, soil, and, especially, in all aquatic environments. Secondary MPs are generated in the environment during fragmentation of especially photo-oxidized plastic litter. Photo-oxidation is mediated primarily by solar UV radiation. The implementation of the Montreal Protocol and its Amendments, which have resulted in controlling tropospheric UV-B (280-315 nm) radiation, is therefore pertinent to the fate of environmental plastic debris. Due to the Montreal Protocol high amounts of solar UV-B radiation at the Earth's surface have been avoided,retarding the oxidative fragmentation of plastic debris, leading to a slower generation and accumulation of MPs in the environment. Quantifying the impact of the Montreal Protocol in reducing the abundance of MPs in the environment, however, is complicated as the role of potential mechanical fragmentation of plastics under environmental mechanical stresses is poorly understood.
