Degradation of phthalate esters (PAEs) in soil and the effects of PAEs on soil microcosm activity

BACKGROUND: Phthalate esters (PAEs), a class of refractory and toxic organic compounds, are becoming one of the most widespread contaminants in the environment. Degradation of PAEs in soil has been investigated, but limited to one or a few kinds of PAEs. Microorganisms could be regarded as a sensitive bio-indicator for soil contaminants. Therefore, four commonly used PAEs were chosen to investigate their degradation patterns and potential impacts on soil microbial activity with a series of bioassays. RESULT: PAEs in sterile soils changed slightly, while degradation of PAEs in non-sterile soil followed a single first-order kinetic. Higher concentrations of PAEs led to lower beta-glucosidase activity and higher protease activity, with smooth changes of phosphatase and urease activities. PAEs decreased average well color development (AWCD), while Shannon index (H) showed a tendency to increase after a decrease. Carbon utilization profile was affected significantly by PAEs, especially at 10 mg kg(-1) soil. CONCLUSION: Degradation of PAEs was driven mainly by microbial mediated processes. PAEs affected carbon, nitrogen and phosphorus cycles variously, and had temporal effects on metabolic diversity, owing to the adaptation of microbes. Carbon substrates utilization changed from easily degradable sugars and carboxylic acids to recalcitrant compounds during the simulation. (C) 2010 Society of Chemical Industry