Occurrence of Antiviral drugs in the urban rivers of Xi'an, a megacity of northwest China: Analytical methods, distribution characteristics, and ecological risk

In the post-pandemic era, the continuous input and ecological effects of antiviral drugs (ATVs) in environmental waters are of increasing concern. Here we report a comprehensive investigation into the environmental spatial distribution and ecological risk of ATVs in river waters and sediments from Xi'an, a megacity in northwest China. A rapid analytical method for 8 ATVs was developed using solid-phase extraction and HPLC-MS/MS. The method validation showed that the detection limits of ATVs in water and sediment were 0.009 – 1.356 ng L -1 and 0.003 – 1.543 ng g -1 , respectively, and the method quantification limits were 0.030 – 4.520 ng L -1 and 0.008 – 5.143 ng g -1 , respectively. Furthermore, the contamination of ATVs was investigated across nine urban rivers, revealing widespread presence of amantadine (AMT), acyclovir (ACV), nevirapine (NVP), tenofovir (TDF) and efavirenz (EFV). Their concentrations ranged from 0.06 to 202.26 ng L -1 in waters and from 0.3 to 9.74 ng g -1 in sediments, respectively, which were significantly lower compared to other regions worldwide. The spatial distribution of ATVs exhibited a distinct point-source pattern, and was influenced by regional consumption and human activities. Ecological risk assessment indicated that seven target ATVs posed low risk ( RQ < 0.01), while AMT presented medium risk at almost half of the sampling sites. These findings highlight the need to better manage the emerging contaminants in densely populated urban centers like Xi'an, where the risks associated with ATVs are intricately linked to urbanization and human activity.