Molecular Signatures of Humic Acids from Different Sources as Revealed by Ultrahigh Resolution Mass Spectrometry

<div>Van Krevelen diagrams of molecular formulas (a) common among all humic acid samples, (b) identified only in humic acids from Jiufeng forest soil, (c) identified only in humic acids from Suwannee River, and (d) identified only in humic acids from leonardite. Formulas include CHO (blue), CHOS<sub>1</sub> (green), CHON<sub>1</sub> (red), and CHON<sub>2</sub> (orange).</div>

Journal of Chemistry

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Figure 4

Figure 4: Molecular Signatures of Humic Acids from Different Sources as Revealed by Ultrahigh Resolution Mass Spectrometry 