Riverine mixing at the molecular scale – An ultrahigh-resolution mass spectrometry study on dissolved organic matter and selected metals in the Amazon confluence zone (Manaus, Brazil)

•Molecular dynamics of DOM in Amazon confluence studied by FT-ICRMS.•DOM mainly conservative even if natural particles >0.2 µm are present.•Aromatics and small, moderately saturated formulae distinguish river endmembers.•Aromatics and N-containing saturated formulae display non-conservative behavior.•Cu release by particles related to potential ligands and DOM complexation properties.