Citation:

Ahmed, W., A. Korajkic, M. Gabrewold, S. Payyappat, M. Cassidy, N. Harrison, AND C. Besley. Assessing the nucleic acid decay of human wastewater markers and enteric viruses in estuarine waters in Sydney, Australia. SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, Netherlands, 926:171389, (2024). https://doi.org/10.1016/j.scitotenv.2024.171389

Impact/Purpose:

This study describes decay rates of microbial source trackin markers, viral surrogates and pathogens in estuarine waters under in situ conditions and in light vs dark conditions.

Description:

This research investigated the in-situ decay rates of four human wastewater-associated markers (Bacteroides HF183 (HF183), Lechnospiraceae Lachno3 (Lachno3), cross-assembling phage (crAssphage), pepper mild mottle virus (PMMoV) and three enteric viruses (human adenovirus 40/41 (HAdV 40/41), enterovirus (EV) and human norovirus GII (HNoV GII) in estuarine water environments in temperate Sydney, NSW, Australia, employing qPCR and RT-qPCR assays. The study also aimed to compare decay rates observed in mesocosms with previously published laboratory microcosms, providing insights into the persistence of markers and viruses in diverse environments. Results indicated varying decay rates between Davidson Park (DP) and Hen & Chicken Bay (HCB) mesocosms, with HF183 consistently exhibiting faster decay, and crAssphage showing differential decay rates in sunlight and dark conditions. In DP mesocosms, HF183 decayed the fastest, contrasting with PMMoV, which exhibited the slowest decay. Sunlight induced higher decay rates for all markers and viruses. Similarly, HCB mesocosms displayed differential decay rates, with HF183 exhibiting the fastest decay in sunlight. Sunlight exposure significantly accelerated decay in both mesocosms, impacting HF183, Lachno3, and EV in DP mesocosms. HF183 consistently decayed faster than other targets, and enteric viruses showed faster decay than PMMoV and crAssphage. Comparisons with laboratory microcosms revealed faster decay than the mesocosms, except for crAssphage in sunlight and EV. The study concludes that decay rates vary between mesocosms, emphasizing the impact of sunlight exposure, which was potentially influenced by the elevated turbidity at HCB. HF183 consistently exhibited faster decay, and distinct patterns are observed among targets. The generated decay rates contribute valuable insights for establishing site-specific risk-based thresholds of human wastewater-associated marker genes.

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