Fractionation of total water soluble aluminium in extracts from peat and sand soil samples by ion‐exchange method followed by GF AAS

Abstract

This study attempted the use ion‐exchange resins in order to fractionate total water soluble aluminium in extracts collected over acidic peat and alkaline sand soils. Extraction was performed in neutral and acidic conditions in order to imitate the behaviour of natural or acid rains. The total aluminium content in soil extracts and fractions was determined by graphite furnace atomic absorption spectrometry (GF AAS). In order to retain aqua Al3+ and hydroxycomplexes of aluminium Chelex 100 was used. It was found that fractionation of the aluminium in extracts depends strictly on the type of soil. When neutral spring water was used for the extraction the content of water soluble aluminium was found to be over two times higher in case of peat soil when compared with sand soil extract. Acidification of water by addition of HNO3 and H2SO4 (2:1) pronounced in much extend the extraction efficiency of aluminium only form sand soils (over 10 times) but did not change proportion in fractionation of the particular aluminium species. Admittedly in the case of peat soils no significant increase in total aluminium content was observed but the concentration of cationic forms in acidic extract increased twofold when compared with the neutral extract.