Some Experiments on Extraction of Heavy Metals Present in Soil

Copper and zinc present in a soil before and after addition of a sewage sludge were extracted using several reagents either with sequential or parallel procedures. The order of extracting reagents had a great influence on the amounts of heavy metals supposed to correspond to different soils fractions (exchangeable, associated with carbonates, oxides, organic matter and silicates). Further, for a given fraction, the nature of the extracting reagent also had an effect on amounts of metals extracted. Results were discussed on the basis of the possible states of heavy metals in the soil. It was concluded that: no extraction procedure was able to give unequivocally the distribution of heavy metals between several soil fractions. for a given soil fraction, the meaning of results was not straightforward.