Methodologies for Microplastics Recovery and Identification in Heterogeneous Solid Matrices: A Review

The missing link in plastic mass balance between mismanaged plastic waste worldwide and plastic waste effectively detected in marine environments has recently risen the attention on microplastics. In fact, beside primary sources of microplastics such as cosmetic products and textile fires, there are secondary microplastics generated from plastic items due to weathering agents and biological degradation. While the marine and fresh water environments are actually of great concern, ground environments, and matrices related to it, have been less considered in the last years research about microplastics detection. Major attention should be reserved to solid heterogeneous matrices, such as soil, compost, sediments and sludges. Worldwide regulations about compost, which is used as amendant in agricultural fields, have a threshold ranging from 2 to 15 mm for the requirements related to plastic impurities. Microplastics which pass through the mesh of the threshold sieve are considered assimilable to compost. One of the main lacks that prevents the improvement of these regulation, is a standard protocol for microplastics detection in solid heterogeneous matrices. To this purpose, the current review proposes an outline of methods tested in previous research for microplastics recovery and identification in the matrices of our interest.