Occurrence and potential harms of organochlorine pesticides (OCPs) in environment and their removal by periphyton

Organochlorine pesticides (OCPs) have been widely used around the world due to their high-efficiency and broad-spectrum insecticidal effects. However, they pose a severe threat to ecosystems and human health due to their easy bioaccumulation and high toxicity. Periphyton is ubiquitous in the submerged substrates surface. It plays a crucial role in carbon, nutrients elements cycling and contaminants transformation in environment. Periphyton can remove OCPs through bioadsorption, bioaccumulation and biodegradation, which alters the fate of OCPs in environment. This review presents a comprehensive summary of OCPs occurrence, global cycle, potential harm in environment, and their removal by periphyton. The OCPs residual have been detected frequently in different environmental medias such as water, soil, atmosphere, sediment, and organisms. Their harm is depending on their physicochemical properties and the exposure route. The main compositions and functions of periphyton have been summarized. Moreover, the artificial cultivation methods of periphyton in laboratory and in-situ field are compared. In addition, the mechanisms of periphyton-mediated OCPs removal and the main factors impacting OCPs removal are also discussed. Periphyton could self-regulate its biological communities to adapt to the OCPs and environment, and then regenerate new species to degrade OCPs. Finally, the prospect of OCPs removal by periphyton and future studies are also proposed. This review provides a systematic introduction on current knowledge of OCPs occurrence, cycle, potential harm in environment, and their removal by periphyton.