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Biological Activity of Humic Substances Is Related to Their Chemical Structure

Dipartimento di Gestione dei Sistemi Agrari, e Forestali, Università degli Studi Mediterranea, Feo di Vito, 89060 Reggio Calabria, Italy

Ornella Francioso

Dipartimento di Scienze e Tecnologie, Agroambientali, Università di Bologna, Via Fanin 40, 40127 Bologna, Italy

Vitaliano Tugnoli

Dipartimento di Biochimica, Università di Bologna, Via Belmeloro 8/2, 40126 Bologna, Italy

Serenella Nardi

Dipartimento di Biotecnologie Agrarie, Facoltà di Agraria, Agripolis, Strada Romea 16–35020, Legnaro, Padova, Italy

View larger version (25K): [in this window] [in a new window]   Fig. 1. The 1H nuclear magnetic resonance spectra (8.0–0.6 ppm) of grass humic substance separated into fractions corresponding to high (HMWG) and low (LMWG) relative molecular mass. The peaks are attributed according to Fan (1996).

View larger version (22K): [in this window] [in a new window]   Fig. 2. Region of 1H nuclear magnetic resonance spectra (4.0–2.0 ppm range) of a forest humic substance. The humic substance was separated into fractions with high (HMWF) and low (LMWF) relative molecular mass. The peaks are attributed according to Fan (1996).

View larger version (18K): [in this window] [in a new window]   Fig. 3. Region of 1H nuclear magnetic resonance spectra (2.0–0.6 ppm range) of high (HMWF) and low (LMWF) relative molecular mass fractions. The peaks are attributed according to Fan (1996).

View larger version (26K): [in this window] [in a new window]   Fig. 4. Diffuse reflectance infrared Fourier-transform spectra of a humic substance separated in high (HMW) and low (LMW) relative molecular mass fractions. Humic substances (top) from grass are LMWG and HMWG and (bottom) from forest land are LMWF and HMWF.