Phthalic acid and benzo[a]pyrene in soil–plant–water systems amended with contaminated sewage sludge

We studied the fate of ¹⁴C-labelled phthalic acid and benzo[a]pyrene applied to the soil by the way of contaminated sewage sludge in model ecosystems allowing the simultaneous assessment of physicochemical and biological descriptors. Here we show that the mineralisation of phthalic acid is higher than 30% after 90 days in the situation of direct soil contamination, amendment with contaminated digested or composted sludge. It is reduced to 10% in the presence of the raw sludge. In that case, the values of phospholipidic fatty acids and dehydrogenase activity are the highest. By contrast, benzo[a]pyrene is recalcitrant to biodegradation whatever the type of soil contamination. We show also that the chemicals present in the sludge are poorly transferred to soil leachates and plant seedlings.