Office of Research and Development Publications

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

Citation:

Neale, R., P. Barnes, T. Robson, P. Neale, C. Williamson, R. Zepp, S. Wilson, S. Madronich, A. Andrady, A. Heikkilä, G. Bernhard, A. Bais, P. Aucamp, A. Banaszak, J. Bornman, L. Bruckman, S. Byrne, B. Foereid, D. Häder, L. Hollestein, W. Hou, S. Hylander, M. Jansen, A. Klekociuk, J. Liley, J. Longstreth, R. Lucas, J. Martinez-Abaigar, K. McNeill, C. Olsen, K. Pandey, L. Rhodes, S. Robinson, K. Rose, T. Schikowski, K. Solomon, B. Sulzberger, J. Ukpebor, Q. Wang, S. Wängberg, C. White, S. Yazar, A. Young, P. Young, L. Zhu, AND M. Zhu. Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020. PHOTOCHEMICAL AND PHOTOBIOLOGICAL SCIENCES. Royal Society of Chemistry, Cambridge, Uk, 20:1-67, (2021). https://doi.org/10.1007/s43630-020-00001-x

Impact/Purpose:

In this section we update the current understanding of photodegradation of natural organic matter in terrestrial and aquatic ecosystems. Photodegradation produces carbon dioxide (CO2) as well as biologically-labile photoproducts that can be more easily degraded by decomposer organisms (bacteria and fungi) in a process known as photo-facilitation. Research on the cryosphere has continued to quantify the permafrost carbon feedback that releases the greenhouse gases, CO2, methane and nitrous oxide, from thawing permafrost in the Arctic. New data and models are assessed on the photochemical decomposition of controlled substances and other contaminants. Finally, we assess the sunlight photoinactivation of biological contaminants, including pathogens and their indicator organisms.

Description:

Changes in solar UV radiation and climate have direct and indirect effects on the way in which cycling of elements (e.g., carbon, nitrogen and sulfur cycles) and the fate of contaminants occur in aquatic and terrestrial ecosystems. It is well established that a wide range of synthetic chemicals such as pesticides, pharmaceuticals and other controlled substances are intentionally or accidentally released into the environment by human activities. Solar radiation contributes to the degradation of many of these contaminants and plays a significant role in reducing their concentrations in the environment. Direct photodegradation of these contaminants is mainly driven by UV radiation. Both UV (UV-B and UV-A) and visible radiation are responsible for driving indirect photodegradation processes, with UV radiation being the more important of the two. Climate change, which influences temperature and precipitation levels, also leads to changes in the chemical composition of surface waters, namely dissolved organic matter and oxygen concentrations, which in turn will affect indirect photochemical processes.