Microplastic Pollution in EU Farmland Soils: Preliminary Findings from Agricultural Soils (Southwestern Poland)

Abstract

Agricultural soils are considered as “hot-spots” of plastic particles; however, due to a lack of standardized method of microplastic determination in soils, as well as no legal regulations requiring the monitoring of the soil environment in the context of microplastic contamination, the data on MP abundance and occurrence in European soils are very limited. In this first study of MPs pollution in agricultural soils in Poland, we developed a method of microplastic extraction from soil samples with different properties (particle size distribution, clay and organic matter content) and used optical microscopy for MP determination and quantification. In this study, we analyzed 44 soil samples from five sampling site locations with differing soil type, agricultural activity, including farmland soils on floodplains and past records of sewage sludge and compost applications. We found evidence that 93% of cultivated soils in the SW part of Poland contained MPs. The content of MP varied between soil types and present/former use of the land. Loamy and clay soils contained more MPs, 1540 ± 912 particles per kg soil and 933 ± 682 particles per kg, respectively, compared with sandy soils at 383 ± 188 particles per kg of soil. The highest MP concentrations were determined in soils amended with sewage sludge, wastewaters and green-waste composts (up to 4050 ± 2831 particles per kg of soil). The wide distribution of MPs with a dominance of plastic fibers (up to 60% of determined MP types) can be associated with agricultural sources such as soil mulching, the use of organic fertilizers, seed coating or unintentional waste dumping and air deposition.