Electron paramagnetic resonance evidence that copper is complexed in humic acid by the nitrogen of porphyrin groups.
D003300:Copper / Q000032:analysis*; D006812:Humic Substances / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D009584:Nitrogen / Q000032:analysis; D011166:Porphyrins / Q000032:analysis; D012987:Soil / Q000032:analysis*
D006812:Humic Substances; D011166:Porphyrins; D012987:Soil; D003300:Copper; D009584:Nitrogen