Polynuclear Aromatic Hydrocarbon Uptake by Carrots Grown in Sludge‐Amended Soil

Abstract

AbstractThe 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 ΣPAH/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 PAH concentrations were unaffected by sludge applications (PAH loadings), but root peel PAH concentrations increased to a plateau concentration with increasing soil PAH levels. Low molecular weight PAH compounds dominated individual components of the ΣPAH load in the root tissues. The PAH concentrations detected in the root peels were all significantly lower than in the foliage, which receives PAH inputs from the atmosphere. Carrot core ΣPAR concentrations were unaffected by sludge application, implying little or no transfer of PAHs from the peels to the core. About 70% of the PAH burden found in carrots was associated with the peels. Fresh weight carrot core concentrations were all <4.2 µg/kg. Overall, this investigation suggests that the risks posed to human health by PAHs applied in sewage sludge to arable soils are minimal.