Manure application facilitated electrokinetic remediation of antibiotic-arsenic co-contaminated paddy soil

The co-existence of antibiotics and heavy metals in soil with manure application poses high risk to both envi-ronment and human health, and thus effective remediation methods are in urgent need. This study investigated the synergistic effects of electrokinetic remediation (EKR) on antibiotic resistance and arsenic (As) in co -contaminated paddy soils. EKR treatments in soil amended with pig manure (EKR-PD) showed better remedia-tion efficiency compared with that without pig manure. In detail, the content of available As and the abundance of antibiotic-resistant bacteria (ARB) decreased by 25.2 %-41.4 % and 9.5 %-21.1 % after 7-d remediation, respectively, due to a relatively higher current density for EKR-PD. The role of the electric field contributed to 33.9 % of antibiotic degradation. Antibiotic resistance genes (ARGs) with ribosomal-protection and enzymatic -deactivation types were easier to remove, with the removal ratio of 37.8 %-41.6 % in EKR-PD. Brevundimonas was the most significantly different species during remediation. Bacillus and Clostridium_ sensu_stricto_1 were potential host bacteria of ARGs in the electric field. Membrane transport might be an effective strategy for microorganisms to respond to the stress of both electric field and co-contaminated environments. This study supports the potential role of EKR in the co-contamination of heavy metals and antibiotic resistance under manure application.

Automated summary

This study investigated the synergistic effects of electrokinetic remediation (EKR) on antibiotic resistance and arsenic (As) contamination in paddy soils. The study found that EKR treatments with pig manure amendment showed better remediation efficiency, reducing the content of available As and the abundance of antibiotic-resistant bacteria. The electric field played a significant role in antibiotic degradation and certain types of antibiotic resistance genes were easier to remove. Brevundimonas was found to be the most significantly different species during remediation, and Bacillus and Clostridium_ sensu_stricto_1 were potential host bacteria for antibiotic resistance genes in the electric field. Membrane transport was identified as an effective strategy for microorganisms to respond to the stress of electric field and co-contamination.