Concentration of Polycyclic Aromatic Hydrocarbons in Sewage Sludge‐Amended Soil

Abstract

The objective of this research was to estimate the content of polycyclic aromatic hydrocarbons (PAHs) in sandy soil fertilized with various doses of sewage sludge. The experiment consisted of six plots to which the following doses of sewage sludge were added: 30, 75, 150, 300, and 600 t/ha. Sixteen PAHs from the United States Environmental Protection Agency list were determined by means of a high‐performance liquid chromatography (HPLC) with UV detection after preliminary ultrasonic extraction. Content of PAHs in the control soil was 46 µg/kg. The application of sewage sludge caused an increase in the PAH sum in relation to the dose applied. In soil amended with 30, 75, 150, 300, and 600 t/ha of sewage sludge, the increase of PAH content to 74, 177, 430, 883, and 1004 µg/kg, respectively, was observed (in the 0‐ to 20‐cm horizon). After 2 days from the introduction of the sludge, an increase of the PAH content in the 20‐ to 40‐cm horizon was also noted. The composition of the PAH group also changed. A decrease in the share of 3‐ring PAHs at the expense of the 4‐ and 5‐ring PAHs took place. The addition of sewage sludge to sandy soil in an amount up to 300 t/ha did not cause an increase in the PAH content in the soil to a level that could pose a danger of these compounds migrating into the human food chain. However, an increase in PAH content in the 20‐ to 40‐cm soil horizon shows the danger relating to PAH migration into the deeper horizon with the possibility of contaminating groundwater.