Heavy Metal Contents of Sludge-Treated Soils as Determined by Three Extraction Procedures1
- Hong-Fa Cao,
- A. C. Chang and
- A. L. Page2
The extraction efficiency of three soil metal extraction procedures (4M HNO3 extraction, HClO4 digestion, and HF decomposition) were compared by determining Cd, Cr, Cu, Ni, Pb, and Zn contents of two sewage sludge-treated soils. In soils not treated with sludges, approximately 50 and 75% of total metals (HF-decomposed) were recovered by 4M HNO3 extraction and HClO4 digestion, respectively. For sludge-treated soils, between 70 and 80% of soil metals were recovered by 4M HNO3 extraction. The increase in extraction efficiency indicated that sludge-borne heavy metals in soils were more extractable with 4M HNO3 than metals indigenous to soils. Amounts of Cd, Cr, Cu, and Zn recovered from sludge-treated soils by HClO4 were not significantly different from those recovered by HF decomposition. Recoveries of Ni and Pb by HClO4 digestion, however, were less complete. It appeared that sludge-borne Ni and Pb were either associated with silicate minerals or converted into silicate-containing solid phase minerals after land application.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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