A comparison of extraction techniques for the determination of metals in soil

Abstract

A growing issue in groundwater studies concerns the distinction between anthropological and geological metal contaminants in soil. Current extraction methods, such as hot acid extraction, result in the digestion of the sample matrix which may obscure the origin of the contaminant. Since metals from anthropological sources are most often adsorbed to the surface of the soil sediment, the dissolution of the geological matrix is not necessary to release the contaminat metals. The resolution to this problem may lie in the use of chelating agents, where the adsorbed metals can be removed from the sediments without disrupting the geological matrix. This would allow the surface bound metal contaminants to be differentiated from the geological metals which are a natural part of the soil's composition. The basis of this study is a comparison of a hot acid extraction method vs. a chelation extraction method for the determination of metals in soils. Statistical comparisons on the precision and accuracy of the these methods on a reference soil, salt amended soil, and sewage sludge amended soil is discussed.