Extractability of Cu in Alkaline Biosolids-Amended Soilsas Influenced by γ-Irradiation

An incubation experiment was conducted to investigate the microbial biomass associated Cu in four contrasting soils to which an alkaline stabilised sewage sludge cake was applied. The organisms of sludge- amended and control soils were killed using ry-irradiation technique, and the aqueous and acid-extractable Cu concentrations were determined. Addition of the sludge product increased significantly the concentration of both the aqueous and dilute HOAc-extractable Cu in all the irradiated soils compared to the non-sterilised sludge/soil mixtures, but the increase was more pronounced in the dilute acid-extractable Cu, indicating that the Cu rendered extractable in water and dilute acetic acid by 7-irradiation existed in the both soil liquid and solid phases. The additional increase in extractable Cu following the biocidal treatment is likely to be due to release of Cu from the same fraction of soil microbial biomass.