Use of a sequential extraction scheme with data normalisation to assess the metal distribution in agricultural soils irrigated by lake water

Multi-element analysis was performed in a sandy loam and a loam agricultura l soil irrigated with water from a relatively polluted lake applying a sequ ential extraction procedure. Extracts were analyzed for: Al, As, Ba, Cd, Co , Cr, Cu, Fe, Mn, Ni, Pb, V and Zn. The concept of data normalisation is in troduced, yielding interesting information on the relative intrinsic affini ty of some of the metals for the separate phases of the soil system. The re sults indicated a low percentage of easily exchangeable and carbonate bound metals. For certain elements, the study revealed new information for the s eparate extracted phases as regards the relative retention behaviour of the se metals. The majority of the metals extracted were found in the oxidizabl e (organically bound + sulphides) and reducible (Fe-Mn oxyhydroxides) fract ions. These fractions are considered as the most efficient scavengers for t he studied metals. Total metal analysis showed an enrichment of some elemen ts in the surface soils as a result of agricultural and anthropogenic activ ities. The depth variation of heavy metals in the core soils in connection with extractability by EDTA suggests a relatively high mobility of Pb, Cu, Co and Mn. The results of this study present both an issue of local interes t and the interpretation of the trend of the binding metals in the phases o f soil systems using a simple normalization method. (C) 1999 Elsevier Scien ce B.V. All rights reserved.