Influence of manure application on electrokinetic remediation of arsenic- antibiotic co-contaminated paddy soils

It is a new challenge to simultaneously remove heavy metals and antibiotic resistance from farmland soils. This study investigated the synergistic effects of electrokinetic remediation (EKR) on arsenic (As) and antibiotic resistance and explored the microbial response mechanisms in co-contaminated paddy soils. During the 7-d EKR, the comparison between treatments with (EKR-PD) and without pig manure dissolved organic matter (PD), EKR-PD had better removal efficiency. EKR-PD has a stronger current density, and more effective removal of As by regulating the release and transformation of soil As, especially the removal rate of available As can reach 25.2-41.4%. Electric field action contributed to 33.9% of antibiotic degradation. Antibiotic resistance genes (ARGs) with ribosomal protection and enzymatic deactivation were easier to remove, with removal rate of 37.8-41.6%. Brevundimonas was the species with the most significant differences between treatments. Bacillus and Clostridium_sensu_stricto_1 were potential host bacteria of ARGs in electric field soils. PICRUSt functional predictions suggest that amino acid metabolism and membrane transport may be effective strategies for microorganisms to respond to the stress of electric fields and co-contaminated environments. PD application enhanced the positive response of soil microbes to the electric field.