Effects of degradable and non-degradable microplastics and oxytetracycline co-exposure on soil N2O and CO2 emissions.

Microplastics and antibiotics are emerging contaminants that can elicit considerable adverse effects on carbon and nitrogen cycles and greenhouse gas emissions. The effect of the combined occurrence of antibiotics and different types of microplastics on soil ecosystem is poorly understood. We investigated the effects of oxytetracycline (OTC), polylactic acid (PLA) microplastics, and polyethylene (PE) microplastics alone and in combination on plant root growth traits, soil extracellular enzymatic activity, and nitrous oxide (N 2 O) and carbon dioxide (CO 2) emissions from the soil. Plant root growth traits including root area, root surface area, root volume and root branches were negatively affected by all treatments; soil extracellular enzymatic activity was also negatively affected by all treatments expect for the cellobiohydrolase. The results showed that CO 2 emission increased in all treatments, with a maximum increase of 505 % in the PLA treatment; however, N 2 O emissions increased in the OTC treatment by 44 % but decreased in all other treatments as compared to the control. Furthermore, partial least squares path modeling analysis suggested that soil extracellular enzymes significantly influenced soil N 2 O and CO 2 emissions (P < 0.05) and had a strong correlation with root growth traits (P < 0.05). We thus concluded that changes in soil extracellular enzymatic activities and plant root growth traits, which were affected by different microplastic and antibiotic treatments, influenced soil CO 2 and N 2 O gas emissions. • Antibiotic enhanced but microplastics in soil reduced the N 2 O gas emission. • Degradable microplastics enhanced more CO 2 emission as compared to other treatments. • Antibiotic and microplastics negatively affect plant root growth and soil enzymes. [ABSTRACT FROM AUTHOR]