Polycyclic aromatic hydrocarbons and phthalic acid esters in the soil–radish ( Raphanus sativus) system with sewage sludge and compost application

Abstract

We studied the accumulation of polycyclic aromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs) in a latosolic red soil and radish ( Raphanus sativus) with application of sewage sludge at rates of 10, 20 and 40 g kg −1 soil or compost at rate of 10 g kg −1 soil. In radish the concentrations of individual PAHs and PAEs varied from non-detectable to 803 μg kg −1 dry weight (d.w.) and from non-detectable to 2048 μg kg −1 d.w., respectively. Compared to the control, higher application rates of sewage sludge resulted in pronounced increases in shoot, root and soil concentrations of PAHs and PAEs. PAE concentrations in radish grown in soil spiked with sludge compost were higher while the PAH concentrations were comparable to those receiving 10 g kg −1 of sewage sludge. However, the root biomass of radish in soil amended with compost was significantly higher and the shoot-to-root ratio was significantly lower than in the other treatments. The bioconcentration factors (BCFs, the ratio of contaminant concentration in plant tissue to the soil concentration) of di- n-butyl phthalate and di(2-ethylhexyl) phthalate in both shoots and roots and of total PAH concentrations in roots were less than 1.0, but some BCFs for individual PAHs were high with a maximum value of 80.