ABSTRACT
Abstract To fight against the coronavirus infectious disease-2019 (COVID-19), chlorine-based disinfectants are extensively or even over used for water, surface and personal care decontamination. The risks of disinfection by-products (DBPs) have been alerted to cause serious secondary pollution; however, there is still lack of evidence. This study collected 110 water samples from nine lakes and two rivers in Wuhan during the COVID-19 pandemic and comprehensively analyzed the occurrence of eighteen DBPs. Trihalomethanes, halonitromethanes, halogen acetonitriles and nitrosamines had a high detection frequency and were 0.99-14.26, ND-4.62, ND-1.09 and 0.0414-0.0861 μg/L, respectively, all lower than the maximum contamination level (MCL) suggested by China and USA. Haloacetic acids were detected in all lakes and Yangtze River and ranged from 33.8 to 856.1 μg/L, much higher than the MCL. Haloacetic acids and halogen acetonitriles accounted for 74.2-95.1% of the total cytotoxicity (0.38-3.62×105); halonitromethanes (94.0-98.7%) contributed to the majority of genotoxicity (0.52-5.17×104). Dichloroacetic acid exhibited significant ecological risks to green algae in two lakes and Yangtze River (risk quotient >10), and all the other DBPs showed negligible risks (risk quotient <0.01) to fish, daphnid or green algae. Correlation and redundancy analysis identified strong correlations between total organic carbon, conductivity, NH3-N, turbidity and DBPs. DBP composition and the fluorescence indices of dissolved organic matters together categorized all lakes into two types. Type-I lakes contained all DBP categories, driven by total organic carbon and secondarily formed by residual active chlorine with natural organic matters; Type-II lakes and Yangtze River only had high levels of haloacetic acids and small amounts of trihalomethanes, explained by the primary formation of DBPs in sewage. Our findings for the first time uncovered the significant accumulation and risks of DBPs in lakes and rivers of Wuhan during the COVID-19, provided the evidence of secondary pollution from intensive disinfection activities with chlorine-based disinfectants, evaluated the potential the ecological risks of DBPs in Wuhan and along Yangtze River, and raised our re-consideration of disinfection strategy in the pandemics and post-COVID-19 era.
Subject(s)
COVID-19ABSTRACT
The outbreak of coronavirus infectious disease-2019 (COVID-19) pandemic has rapidly spread throughout over 200 countries, posing a global threat to human health. Till 15th May 2020, there are over 4.5 million confirmed cases, with roughly 300,000 death1. To date, most studies focus on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in indoor environment owing to its main transmission routes via human respiratory droplets and direct contact2,3. It remains unclear whether SARS-CoV-2 can spill over and impose transmission risks to outdoor environments despite potential threats to people and communities. Here, we investigated the presence of SARS-CoV-2 by measuring viral RNA in 73 samples from outdoor environment of three hospitals in Wuhan. We detected SARS-CoV-2 in soils (205-550 copies/g), aerosols (285-1,130 copies/m3) and wastewaters (255 to 18,744 copies/L) in locations close to hospital departments receiving COVID-19 patients or in wastewater treatment sectors. These findings reveal significant viral spillover in hospital outdoor environments that was possibly caused by respiratory droplets from patients or aerosolized particles from wastewater containing SARS-CoV-2. In contrast, SARS-CoV-2 was not detected in other areas or on surfaces with regular disinfection implemented. Soils may behave as viral warehouse through deposition and serve as a secondary source spreading SARS-CoV-2 for a prolonged time. For the first time, our findings demonstrate that there are high-risk areas in hospital outdoor environments to spread SARS-CoV-2, calling for sealing of wastewater treatment unit and complete sanitation to prevent COVID-19 transmission risks.