Dosage- and site-dependent retention of black carbon and polycyclic aromatic hydrocarbons in farmland soils via long-term biochar addition

The supplementary material contains descriptions of the methods and relevant parameters of health risk assessment about polycyclic aromatic hydrocarbons, elemental composition of soil and biochar, contents of benzene polycarboxylic acid (BPCA) species and polycyclic aromatic hydrocarbon (PAH) species in the soil and biochar, scanning electron microscopy (SEM) image of fresh biochar, ontents of black carbon (BCBPCA), benzene polycarboxylic acid (BPCA) species, 18 polycyclic aromatic hydrocarbons (18PAHs) and polycyclic aromatic hydrocarbon (PAH) species in biochar.