¹³C NMR and ESR Characterization of Humic Substances Isolated from Soils of Two Siberian Arctic Islands

Table 1

Carbon species and chemical shifts via ¹³C NMR.

Chemical shift, ppm	Molecular fragments: carbon species
0–47	Unsubstituted saturated alkyl carbons (C)
47–60	Alkyl C substituted by oxygen and nitrogen atoms
60–110	Alkyl C singly bonded to one oxygen atom (such as ring C in carbohydrates) and alkyl C bonded to two oxygen atoms (such as anomeric C of carbohydrates)
110–144	Proton- and alkyl-substituted aromatic C
144–164	Oxygen-substituted aromatic C
164–183	Carboxyl, ester, and amide C
183–190	Quinone C