The uptake of polynuclear aromatic hydrocarbons (PAHs) from sewage sludge-amended soils by carrots (Daucus carota) was investigated. Carrots were grown in control soils and soils amended with three sludge application rates, 15, 55, and 180 t/ha. Applied sludge contained 17.2 mg ~PAH/kg, a concentration typical for a sludge derived from a rural area. Carrot foliage, root peels and root cores were analyzed for 15 PAH compounds. Carrots foliage PAIl concentrations were unaffected by sludge applications (PAR Ioadings), but root peel PAR concentrations increased to a plateau concentration with increasing soil PAR levels. Low molecular weight PAR compounds dominated individual components of the SPAH load in the root tissues. The PAR concentrations detected in the root peels were all significantly lower than in the foliage, which receives PAR inputs from the atmosphere. Carrot core ]~PAR concentrations were unaffected by sludge application, implying little or no transfer of PARs from the peels to the core. About 70% of the PAR burden found in carrots was associated with the peels. Fresh weight carrot core concentrations were all <4.2 p.g/kg. Overall, this investigation suggests that the risks posed to human health by PARs applied in sewage sludge to arable soils are minimal.
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