Microplastics' impact on soil health and quality: Effect of incubation time and soil properties in soil fertility and pollution extent under the circular economy concept.

The aim of the present study is to highlight the effect of two commonly used plastics, polyethylene (PE) and polyethylene terephthalate (PET), on the quality and health indices of soil. To this end, a pot experiment was carried out using two soils, one acidic and one alkaline. The soil samples were collected from rural areas of central and Northern Greece and had similar particle size composition and almost equal copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) concentrations. PE and PET microplastics (MPs) were added into the soil samples in two ratios (2% and 4% v/v) and remained in the soils for 20, 60 and 120 days. Then, the changes in the properties, nutrients, potentially toxic elements and health indicators of the soil samples were measured. PE addition at 4% v/v caused the maximum increase in trace element availability when it remained in the soil sample for 120 days. In contrast, PET addition caused a maximum decrease in the DTPA-extractable concentration of toxic elements (Cd and Pb), after 120 days of incubation in acid and alkaline soil. The present work provides a fresh perspective evaluating MPs from unwanted waste to materials with potential positive benefits, enhancing the circular economy approach to soil systems. Knowledge of the MPs present in soils, along with physicochemical soil properties, including their nutrient and toxic element content, are critical aspects that need to be addressed to ensure that soil quality and health are not adversely affected.