Viral genetic diversity in surface and groundwater at a non-operational dumpsite and its surrounding neighborhood.

Inappropriate municipal solid waste disposal areas lack waterproof base liners, drainage systems, treatment of waste degradation by-products, mass coverages, and vector control. Leachate is a by-product derived from water percolation through solid waste disposal sites, comprising an environmental and health contamination source when not adequately collected and treated. This study aimed to describe surface and groundwater viral diversity in a dumpsite area non-operational for over a decade and its surrounding neighborhood in the metropolitan Rio de Janeiro region employing shotgun metagenomic analysis. Between May 2021 and March 2023, 100 leachate samples (2 L each) were collected from 21 sampling points and subsequently organized into five pooled samples. Nucleic acids were extracted employing the Biopur Nucleo-mag Virus kit, followed by purification with AMpure XP beads and quantification via Qubit 4.0, Next-Generation Sequencing was performed on a NextSeq 2000 sequencer (Illumina, USA). Sequencing analysis identified 578 operational taxonomic units, of which 312 (54 %) were classified into 46 viral families, while 266 (46 %) remained unclassified, the Microviridae family was the most abundant. Viral sequences linked to pathogenic hosts were detected, including canine circovirus. Comparable viral family profiles were observed between the dumpsite and the residential area suggesting that some of the shared viral families may be influenced by groundwater flow originating from the closed dumpsite. Although irregular land use hinders precise attribution of contamination sources, the detection of potentially pathogenic viruses in waters intended for human use raises significant public health concerns. These findings support long-term virome-based surveillance of groundwater near closed dumpsite.