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This article in JEQ

  1. Vol. 30 No. 5, p. 1667-1674
    Received: May 26, 2000

    * Corresponding author(s): mlthomps@iastate.edu


Distribution and Movement of Sludge-Derived Trace Metals in Selected Nigerian Soils

  1. Monday O. Mbilaa,
  2. Michael L. Thompson *a,
  3. Joe S. C. Mbagwub and
  4. David A. Lairdc
  1. a Agronomy Dep., Iowa State Univ., Ames, IA 50011-1010
    b Univ. of Nigeria at Nsukka, Nsukka, Nigeria
    c USDA-ARS, National Soil Tilth Lab., Ames, IA 50011


Use of metal-rich sewage sludge as soil fertilizer may result in trace-metal contamination of soils. This study was conducted to evaluate the effects of long-term sludge application on trace-metal (Zn, Cu, Pb, and Ni) distribution and potential bioavailability in Nigerian soils under a tropical wet–dry climate. Total metal analyses, sequential chemical fractionation, and DTPA extractions were carried out on samples of control and sludge-amended pedons in Nigeria (a Rhodic Kandiustult and two Rhodic Kandiustalfs from Nigeria, respectively). The sewage sludge applied to the soils contained higher levels of Zn and Cu than Pb and Ni. The control pedon contained low levels of all four metals. Soil enrichment factors (EF) were calculated for each metal in the sludge-amended pedons. Compared with the control soil, the sludge-amended pedons showed elevated levels of Zn and Cu, reflecting the trace-metal composition of the sewage sludge. Zinc and Cu in the sludge-amended soils were strongly enriched at all depths in the profile, indicating that they had moved below the zone of sludge application. The sequential extraction and DTPA analyses indicated that the sludge-amended soils contained more readily extractable and bioavailable metal ions than the unamended soil.

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Copyright © 2001. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyPublished in J. Environ. Qual.30:1667–1674.