A sludge was conducted to attain the chemical extractability and mobility of Ni63 in
soil and sludge. The results of this sludge showed a variation in extractable Ni63
activity with different incubation times. The extractions from the spread columns
within increase in time showed, the amount of water soluble Ni63 in the soil, sludge
and soil mixtures decreased significantly. The percentage removal of organically
bound Ni63 by DTPA varied during the eight weeks, while EDTA showed a higher
percentage of removal with a correlation with plant uptake. In some cases water
decreased the solubility of Ni63 with increasing time in soil, sludge and mixture
columns. Organic matter also decreased the Ni63 concentrations in all mixtures.
Nitric acid digestion was used as a method of total recovery of Ni63 from all columns
and 86-94% of the initial Ni63 was recovered in leachates from the soil and
soil/sludge mixtures a greater proportion of cationic species of Ni63 than non cationic
special were present, but in the sludge only leachates the reverse was true after 8
weeks. Organic matter content of soil increased by incorporation of sewage sludge
may help to reduce the mobility of nickel.