Persistence of polycyclic aromatic hydrocarbons (PAHs) in biochar-amended soil

• PAH contents in biochar-amended soil were investigated in field experiment.
• The addition of biochar to the soil caused an increase in the PAH contents.
• A rapid loss of 3- and 4-ring PAHs from the biochar-amended soil was observed.

In the present study the persistence of polycyclic aromatic hydrocarbons (PAHs) applied with biochar to acidic soil (loamy sand) was studied in two and half year field experiment. An experiment was carried out in three experimental plots (15 m2 each). The biochar was introduced in the following doses: soil without fertilization – control (C-BC00), soil with 30 t ha−1 (B-BC30) and soil with 45 t ha−1 (A-BC45) of biochar. Biochar addition to soils resulted in an increase in the PAHs content from 0.239 μg g−1 in control soil to 0.526 μg g−1 and 1.310 μg g−1 in 30 and 45 t ha−1 biochar-amended soil respectively. However during the experimental period the PAHs content decreased to a level characteristic for the control soil. The highest losses of PAHs were observed during the first 105 days of the experiment. Three and four rings PAHs were the most susceptible for degradation and leaching. Migration of PAHs from 0-10 cm to 10–20 cm soil horizon was also observed.

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