Microplastics in soil: Current status and evaluation of the greenness of various analytical methods of identification

Abstract

• Terrestrial environments can be considered as potential sinks of Microplastics (MPs). • Both primary and secondary sources of MPs contribute to a significant amount of MPs in soil. • The greenness of analytical methods can be evaluated using AGREE software. • The electrostatic separation method of MPs can be considered as green quantification method. Microplastics (MPs) have received increasing attention because of their ubiquitous and persisting nature and high degree of resistance to degradation, and bioaccumulation. There has been growing evidence of their direct and indirect impacts on the ecosystem's health. Although the extensive research has been carried out to assess the impact of MPs on aquatic environment, terrestrial environment is a significant research hotspot that needs to be focused more as it is highly polluted by anthropic plastic usage. The overarching aim of this study was to assess the current research trends on MPs analysis and the evaluation of the greenness of existing quantification methods, particularly in soil samples. In the last three years the trend in the quantification of MPs in soil media is found to be exponential and few studies have reported significant concentration of MPs of about 85,000 particles per kg dry weight of soil samples, raising an alarm to the policy makers to implement stringent policies. It has been observed that the existing quantification methodologies are not following the sustainable principles of green analytical chemistry due to their low score obtained from AGREE method. In this context, the electrostatic method of separation of MPs can be considered green, while the magnetic and Olive oil-based separation methods are classified as worse based on the greenness parameter. This paper attempts to provide some new information on the implementation of sustainable methods of MP quantification.