Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 30, 1995
Publication Date: N/A
Technical Abstract: Concerns exist over the long-term availability of trace metals in soils amended with sewage sludge. The objective of this study was to determine approximate geochemical forms and bioavailability of trace metals in continuously cultivated soils following multiple annual sewage sludge applications. Trace metals in surface soils from two sludge amended sites were speciated into increasingly stable geochemical fractions using a series of sequential extractions. Lettuce was grown on the soils to determine heavy metal bioavailability. In general, a positive correlation was found between heavy metal loading rates on the soils and the concentration of metals in the sequential extractions. However, the distribution of trace metals among the geochemical fractions was similar in control and sludge-amended soils. Greater than 75 percent of Cr, Cu, Ni, Pb, and Zn were found in the relatively stable oxide, organic and residual fractions of control and sludge-amended soils. Sludge-amended soils contained a greater fraction of these metals in the oxide fraction than control soils. In both control and sludge-amended soils, 40-50 percent of Cd was found in plant available or potentially available forms. Correlations are presented of the relationship between trace metal concentrations in lettuce and the various geochemical fractions.