Hydrophobic and hydrophilic properties of humic acids from soils under shelterbelts of different ages

Abstract

A comparative investigation of the hydrophobic–hydrophilic properties of humic acids (HA) extracted with 0.1 M Na₄P₂O₇ at pH 7 from soils under shelterbelts of different ages 14 years old (young) and 200 years old (old) and adjoining cultivated fields was carried out with the application of ¹³C NMR spectroscopy and hydrophobic interaction chromatography (HIC). The results determined using both methods were in line with the chemical composition of HA. Shelterbelt age was shown to be the principal factor affecting the composition and hydrophobic–hydrophilic properties of HA. HA from soil under the young shelterbelt was found to be less chemically mature and more hydrophilic than HA from the soil of the adjoining cultivated field. By contrast, HA from soil under the old shelterbelt was considerably more chemically mature and hydrophobic than that of the corresponding cultivated field and HA from the soil under the young shelterbelt.

Keywords:

• shelterbelt
• humic acid
• hydrophobic–hydrophilic properties
• ¹³C NMR
• hydrophobic interaction chromatography