Tracking changes and sources of sedimentary humic substances in Itupararanga Reservoir (Brazil)

The investigation related to these data aimed to track sources, molecular composition, and structural information of sedimentary fulvic (FA) and humic (HA) acids across a subtropical reservoir. This data set includes results from 13C nuclear magnetic resonance (13C NMR, raw spectra files), Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), organic carbon distribution (from fractionation using ultrafiltration), fluorescence and UV/VIS spectrometry. These techniques were used to investigate the origin and characteristics of FA and HA extracted from surface sediments from seven sampling sites (P1-P7) in Itupararanga Reservoir (Brazil). The results showed that samples from the upstream part of the reservoir (P1-P2) have more aromatic, oxygen-poor (O/C ratio < 0.5) and unsaturated compounds (H/C ratio < 1.1). Near-dam samples (P5-P7) have oxygen-rich (O/C > 0.5) and partly more unsaturated compounds for FA as well as oxygen-poor and saturated compounds with H/C > 1.1 for HA. Many oxygen-poor molecules were present in HA samples but in none of the FA samples.