Phylogenetic distribution of ARGs based on taxonomy of contigs carrying ARGs. a The phylogenetic distribution and abundances of ARGs (outer heatmaps) and total genes (inner heatmaps) across bacterial families based on the taxonomic classification of metagenome contigs from the samples taken in May 2016. The phylogenetic tree was reconstructed using the maximum-likelihood method based on 16S rRNA gene sequences representative of bacterial families. Heatmaps were generated using the Interactive Tree of Life online tool (http://itol.embl.de). Each circular track in the heatmap represents a sample. b The abundance profiles of human-related ARGs, river-specific ARGs, total genes, and genes in plasmid-like contigs in the selected bacterial taxa (marked as 1–6 in Fig. 5a).