Fig. 5
From: The synergistic effect of calcium on organic carbon sequestration to ferrihydrite
ATR-FTIR spectra for DOM-bearing 2-line ferrihydrite with and without calcium addition: background corrected and normalized FTIR spectra for DOM (a and b) or citric acid-bearing (c) 2-line ferrihydrite in the presence or absence of Ca at either pH 6 or 9. Samples with Ca at pH 9 were observed to have increased peak area and a broader peak compared to those without Ca, which indicates increased association of 2-line ferrihydrite with COO− functional moieties