Soil Contamination by Microplastics in Relation to Local Agricultural Development as Revealed by FTIR, ICP-MS and Pyrolysis-GC/MS

Applying sewage sludge to improve soil, irrigated with wastewater, and grew crops inside polyethylene greenhouses in Tunisia, could introduce potential sources of microplastic pollution. To the best of knowledge, there is no data about the occurrence of microplastics in Tunisian farm soils which led to the study of the role of agricultural activities on microplastic pollution (MPs). The present study examined agricultural practices as a source of microplastics by sampling in a typical agricultural province named Moknine located in the center of Tunisia and characterized by intensive use of plastics mulches and extensive greenhouse coverage for growing vegetables and fruits. This study aims to investigate the MPs distribution and characteristics in the agriculture soil of Moknine farmlands. The evidence that agricultural soil is contaminated by MPs was evaluated by determining the total amount of MPs particles in soil at 16 sampling points. The total concentration of targeted MPs was 50-880 items/kg. White/transparent fibers and small sized particles (<0.3 mm) predominate in the studied area. SEM images of MPs surfaces revealed multiple features related to environmental exposures. Pyrolysis-GC-MS method enables us to a rapid identification of MPs incorporated in soil micro- and macro-aggregates based on spectral and mass spectrometry markers. ICP-MS technique analysis of soil samples revealed a broad range of metals. Trace metals are mainly adsorbed on the surface of MPs, inferring that MPs in the soil can be vectors for transporting trace metals which represent a risk to ecosystems and human health.