Effect of Microplastic Coexistence Conditions on the Environmental Behavior of Atrazine on Soil

The objective of this study was to explore the environmental impact of microplastics on the coexisting contaminant atrazine in soil.The highest adsorption of atrazine under PE coexistence circumstances was 66.18 mg/kg and 67.85 mg/kg for black and black calcium soils, which were 1.21fold and 0.83-fold greater respectively than the control soil.The Freundlich isothermal adsorption equation better described the isothermal adsorption characteristics of black and black calcium soils with added microplastics to the co-existing pollutant atrazine, and their adsorption capacities Kf in descending order were: black calcium soil + 2%PE > black soil + 2%PE > black calcium soil > black soil.The black clay + 2%PE adsorption constant Kf was 14.513 L/kg, which was 2.11 times higher than the control black clay adsorption constant Kf, and the black calcium clay + 2%PE adsorption constant Kf was 15.926 L/kg, which was 1.01 times higher than the control black calcium clay adsorption constant Kf.The adsorption free energy ΔG θ < 40 kJ/mol and the thermodynamic fitting parameter ΔH θ < 40 kJ/mol show that the adsorption is physical and that it is an exothermic, spontaneous reaction.The thermodynamic parameter value ΔS θ < 0 shows that adsorption confusion gradually reduces.The adsorption capacity of atrazine in both soils containing PE decreased as the Ca 2+ concentration in the solution increased.Under sterilized conditions, the half-life time of black soil and black calcium soil was increased by 23.43% and 10.53%, respectively.As 2%PE polyethylene microplastics were introduced to the two unsterilized soils, the degradation rate dropped by 27.78% and 20%, respectively, as compared to the control soils.