Hydroxyl radicals in natural waters: Light/dark mechanisms, changes and scavenging effects

Hydroxyl radicals (center dot OH) are the most active, aggressive and oxidative reactive oxygen species. In the natural aquatic environment, center dot OH plays an important role in the biogeochemistry cycle, biotransformation, and pollution removal. This paper reviewed the distribution and formation mechanism of center dot OH in aquatic environments, including natural wa- ters, colloidal substances, sediments, and organisms. Furthermore, factors affecting the formation and consumption of center dot OH were thoroughly discussed, and the mechanisms of center dot OH generation and scavenging were summarized. In partic- ular, the effects of climate change and artificial work on center dot OH in the largest natural aquatic environment, i.e., marine environment was analyzed with the help of bibliometrics. Moreover, Fenton reactions make the center dot OH variation more complicated and should not be neglected, especially in those areas with suspended particles and sediments. Regarding the center dot OH variation in the natural aquatic environment, more attention should be given to global change and human activities.

Automated summary

This paper reviews the distribution and formation mechanism of hydroxyl radicals (center dot OH) in aquatic environments, as well as the factors affecting their formation and consumption. The mechanisms of center dot OH generation and scavenging are summarized. Climate change and human activities in marine environment have significant effects on center dot OH.