Assessing the Complexing Properties of Soil Organic Matter by IMAC (Case Study of Copper Ions)

摘要

Immobilized metal affinity chromatography (IMAC) has been used to fractionate organic compounds in alkaline extracts from forest soils of the Komi Republic by their ability to form complexes with copper ions. An algorithm for chromatographic fractionation of substances into the groups of homogeneous molecular compounds is proposed by selecting the separation conditions; this algorithm comprises sequential change in pH and ionic strength of the eluent. As is shown, the alkaline extract contains three fractions, the components of which differ in their ability to form complexes with copper. The humic substances of iron-illuvial podzol (Albic Podzol), podzolic (Glossic Retisol), and peaty-podzolic gleyic (Histic Retisol) soils are shown to differ in their relative contents of ligand-forming organic compounds. The maximum content (according to C-org) of copper complexones is recorded in the organic matter of forest litters of the examined soils (14-21 g/kg). The corresponding values of the organic matter content in the eluvial horizons are 0.5-1.5 g/kg. The highest content of the carbon compounds able to bind copper ions is characteristic of podzolic soils, while the organic matter components of podzols and peaty-podzolic gleyic soil display somewhat lower affinity for copper. The proposed algorithm can be used to assess the soil vulnerability to heavy metal pollution.