High concentrations of contaminants can be toxic, in which case degradation of the contaminants may occur only at the fringe of the contaminated matric where the concentration of the contaminants is sufficiently low to avoid toxicity.
High concentrations of contaminants can be toxic, in which case degradation of the contaminants may occur only at the fringe of the contaminated matric where the concentration of the contaminants is sufficiently low to avoid toxicity.