Generation Mechanism and Fate Behaviors of Environmental Persistent Free Radicals

Environmental persistent free radicals (EPFRs) can persist in environment for hours to days, and have potential environmental and public health impacts, which has attracted more and more attention in recent years. Environmental persistent free radicals are found to exist in a variety of environmental media, such as combustion particles and organic contaminated soil, and they are considered to be an emerging pollutant recently. Compared with transient free radicals, environmental persistent free radicals have received relatively less attention, and the generating mechanisms and environmental impacts remain unclear. Meanwhile, environmental persistent free radicals are widely distributed in the environment, which makes them more complex in their research. This review highlights EPFRs from the following aspects: detection methods, generating mechanisms, speciation types, environmental characteristics (persistence, stability, and reactivity), the harm to the environment and the elimination method. By studying the fate behaviors of environmental persistent free radicals, this article proposes a possible migration pathway in environment. The purpose of this review is to have a more comprehensive understanding of the EPFRs, especially to help reduce the harm to the human and environment, and provide scientific basis for researchers to have a deeper study on it.