Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes

Abstract This paper compares the structural characteristics of aquatic humic substances (AHS) with humic substances from peat (HSP) through different analytical techniques, including elemental analysis, solid state 13C cross polarization/magic-angle-spinning nuclear magnetic resonance spectroscopy (13C CP-MAS NMR), ultraviolet/visible (UV/Vis) spectroscopy and Fourier transform infrared (FTIR) spectroscopy and total organic carbon (TOC). The AHS were extracted from water collected in a tributary of the Itapanhaú River (Bertioga/SP) using XAD 8 resin, and the HSP were extracted from peat collected in the Mogi Guaçu River bank (Luis Antonio/SP) with a KOH solution. After dialysis, both AHS and HSP extracts were filtered in membrane of 0.45 µm pore size (Fraction F1: