Field study on the uptake, accumulation, translocation and risk assessment of PAHs in a soil-wheat system with amendments of sewage sludge

Field experiments were conducted to explore the uptake and translocation of polycyclic aromatic hydrocarbons (PAHs) by wheat plants following sewage sludge application. Two types of application methods (single or annual application) and four application rates (5, 10, 20, and 40 t/ha/year) were investigated. The contents of 16 PAHs in soils, wheat roots and straws increased as the rate of sewage sludge application increased and were in the range of 20.7 to 241, 166 to 700, and 110 to 260 ng/g dry weight (dw), respectively. Meanwhile, for the PAH contents in grains (81.2-95.2 ng/g dw), no statistically significant differences were observed among different treatments. A single application of a large quantity of sewage sludge would likely increase the accumulation of PAHs in soil as well as their subsequent uptake and translocation by wheat. Profile analysis indicated that the transfer and accumulation of lower weight PAHs in wheat plants were greater. Regarding PAHs, sewage sludge application at 40 t/ha/year for 6 years did not significantly increase the risks of intake by wheat grain grown on sludge-amended soils. (C) 2016 Elsevier B.V. All rights reserved.