Sequential extraction Sewage sludge

Chemometrics can also be used to overcome some of the intrinsic deficiencies of sequential extraction, such as non-specificity. Barona and Romero (1996a) used principal components analysis (PCA) to establish relationships between the amounts of metals released at each stage of a sequential extraction procedure and bulk soil properties, and demonstrated that carbonates played a dominant role in governing metal partitioning in the soil studied. The same workers employed multiple regression analysis to study soil remediation (see Section 10.11.1.1). Zufiaurre et al. (1998) also used PCA to confirm their interpretation of phase association and hence potential bioavailability of heavy metals in sewage sludge. 

Forstner, U.W., Calmano, K., Conrad, H., Jaksch, H., Schimkus, C. and Schoer J. (1981) Chemical speciation of heavy metals in solid waste materials (sewage sludge, mining waste, dredged materials polluted sediments) by sequential extraction. In Proceedings of the International Conference on Heavy Metals in the Environment. WHO/EED, pp. 698-704. 

Nyamangara, J. (1998) Use of sequential extraction to evaluate zinc and copper in a soil amended with sewage sludge and inorganic metal salts. Agric. Ecosyst. Environ., 69, 135-141. 

Perez-Cid, B., Lavilla, I. and Bendicho, C. (1996) Analytical assessment of two sequential extraction schemes for metal partitioning in sewage sludges. Analyst, 121, 1479-1484. 

Fuentes, A., Liorens, M., Saez, J., Soler, A., Aguilar, I., Orturio, J. F., and Meseguer, V. F. (2004). Simple and sequential extractions of heavy metals from different sewage sludges. Chemosphere 54, 1039-1047. 

Kim, B., and McBride, M. B. (2006). A test of sequential extractions for determining metal speciation in sewage sludge-amended soils. Environ. Pollut. 144, 475—482. 

Metal contamination of soils is primarily due to the application of sewage sludge, manure, phosphate fertilizers, atmospheric deposition, and traffic emissions. The most common heavy metal ions found in soils are Zn, Cu, Ni, Pb, Cr, and Cd. As mentioned earlier (see Section 6.3.1.4), sequential extraction techniques can differentiate among the metal forms in a soil, typically the acid soluble fraction (e.g., carbonates), the reducible fraction (e.g., iron/manganese oxides), and the ox-idizable fraction (i.e., metals in low oxidation states). 

Rauret, G., Ldpez-Sanchez, J. F., Sahuquillo, A., Barahona, E., Lachica, M., Ure, A., Davidson, C. M., Gomez, A., Luck. D., Bacon, J., Yli-Halla, M., Muntau H., and Quevauviller, Ph. (2000). Application of a modified BCR sequential extraction (three-step) procedure for the determination of extractable trace metal contents in a sewage sludge amended soil reference material (CRM 483), complemented by a three-year stability study of acetic acid and EDTA extractable metal content. J. Environ. Monit. 2, 228-233. 

Rgure 3 Sequential extraction scheme for various soil zinc fractions. (From Penreen Z et al. (1994) Redistribution of zinc from sewage-sludge applied to a range of contrasting soils. Science of the Total Environment 55 161-171.)... 

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