Degradation of Emerging Organic Contaminants in an Agricultural Soil: Decoupling Biotic and Abiotic Processes

Although there is a growing interest in emerging organic contaminants (EOCs), most research is focused on wastewater treatment, the occurrence of EOCs, and their fate in the aquatic environment. There is limited information about their behavior in agricultural soils, where they can be introduced via irrigation with treated wastewater (TWW). In this study, the degradation in an agricultural soil of eight EOCs (bisphenol A, carbamazepine, diethyl phthalate, ethyl paraben, 5-methyl-1H-benzotriazole, primidone, Surfynol 104, and tris(2-chloroethyl) phosphate) with a broad range of physical-chemical properties was monitored for 40 days. Two types of soil treatments were performed: non-sterilization and sterilization. In the non-sterilized soil, by the end of the incubation period, degradation was greater than 70% for all the target compounds except carbamazepine, Surfynol 104, and primidone (<50%). In contrast, in the sterilized soil, the degradation of most of the compounds was less than 50%, except ethyl paraben, 5-methyl-1H-benzotriazole, and diethyl phthalate (>70%). These findings indicate that soil sterilization reduces overall degradation rates, which suggests that microbial activity plays an important role in the degradation of most of the EOCs studied in soil.