Spatio-temporal characteristics of genotoxicity in the Yangtze River under the background of COVID-19 pandemic

The global spread of viruses can lead to the release of large amounts of disinfectants or antiviral drugs into the water environment. The resulting disinfection byproducts (DBPs) and residual antiviral drugs, acting as genotoxic substances or their precursors, may pose risks to aquatic animals and drinking water sources; however, to date, no studies have analyzed the changes in genotoxicity in the Yangtze River before and after the epidemic. In the present study, water and sediment samples from the Yangtze River were collected during different seasons, just before and after the outbreak of COVID-19, and were assessed using the SOS/umu test (with and without liver S9). The results indicated that water samples exhibited more pronounced genotoxicity than did sediments, with direct genotoxicity being the primary factor. Additionally, there were significant regional differences, with notably greater genotoxicity observed in the upper Yangtze River than in the lower reaches before the COVID-19 epidemic. However, this trend was reversed six to ten months later, suggesting the accumulation of DBPs or antiviral drugs after the COVID-19 pandemic. Moreover, the risk quotient indicated that 65% of the water samples posed a high risk for Paramecium caudatum, whereas 71% of the samples posed a medium risk for Danio rerio, thereby representing a potential threat to the ecological security of the Yangtze River. In conclusion, this study, at the basin scale, revealed the impacts of COVID-19 on the Yangtze River, highlighting the need to prevent DBPs and pharmaceutical pollution during similar events in the future.