Transport of Heavy Metals in a Sludge-Treated Forested Area
1977
Sidle, R. C. | Kardos, Louis T.
Plots in a mixed hardwood forest received two separate applications of anaerobically digested sewage sludge (0.102–3.094% solids) in fall 1974 and spring 1975. Total solids loading in the low and high treatments were 12.71 and 26.96 metric tons/ha, respectively. Copper, Zn, and Cd loadings in the high treatment were 24.50, 28.49, and 0.253 kg/ha, respectively. Calculated amounts of percolate Cu, Zn, and Cd moving out of the 120-cm depth in the high treatment were 0.3, 3.2, and 6.6% of the total applied levels, respectively, indicating the order of relative mobility in soil as Cd > Zn > Cu. Relative levels of 0.1/V HCl extractable vs. total soil Cu, Zn, and Cd sampled before and after sludge applications indicated that Cu applied in the sewage sludge was more extractable than the native soil Cu, Zn was only slightly more extractable, and Cd was less extractable. Of the other heavy metals (Cr, Pb, Co, and Ni) analyzed in 0.1/V HCl soil extracts, only Cr and Ni increased in the 0- to 7.5-cm depth following sludge applications.
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