Separating the direct effects of a metal from the effects of
other soil physicochemical properties on soil processes in
metal-contaminated soil states a strong argument for the
operation of PICT in a community. Kelly et al. (1999), for
example, showed the development of Zn resistance in microbial
communities inZn-contaminated soil (4,660 mg kg-1 dw)
but not in control treatments or in pH-control treatments.