Reactivite Chimique des Metaux-Traces de Deux Sols Pollues en Presence D'un Reactif Reducteur Chemical Reactivity of Trace Metals in Two Polluted Soils as Affected by a Reducing Compound

• Published in: Environmental technology Vol. 18; no. 2; pp. 139 - 149
• Main Authors: Yousfi, I., Bermond, A.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 01.02.1997
• Subjects: hydroxylamine hydrochloride; metal readsorption; reuction compound; sequential extraction; trace metals
• DOI: 10.1080/09593330.1997.9618480
• ISSN: 0959-3330

Two soil samples polluted by sewage sludge or atmospheric deposition were mixed with hydroxylamine hydrochloride as reducing agent, in order to simulate anoxic conditions able to occur in natural medium, thus evaluating the reactivity of trace metals. Metal extractability in reducing conditions was studied as a function of time and pH. Although the effect of the reducing reagent is more pronounced in acidic medium, one must keep in mind the extracting effect of proton. The calculated difference between reducing medium and acidity effects shows that, for instance, zinc is not mobile, due to reducing conditions. The monitoring of trace metals during hydroxylamine extraction does not reveal refixation phenomena. However, in a second part of the study, readsorption phenomena able to occur during leaching were investigated using a second chemical reagent (Baryum perchlorate). It was shown that refixation of Copper and Lead effectively occurs. Such processes constitute a serious limitation in the interpretation of speciation found using sequential extraction procedures with hydroxylamine.