Continents of plastics: An estimate of the stock of microplastics in agricultural soils

While there are estimates of the stock of microplastics in the marine environment, there are no estimates for soils. The main objective of this work is to estimate the total mass of microplastics in global agricultural soils. Microplastic abundance data from 442 sampling sites were collected from 43 articles. From these, the median of the abundance values, as well as the abundance profile of microplastics in soils were calculated. Thus, 1.5 to 6.6 Mt of microplastics would be present in soils on a global scale, i.e. one to two orders of magnitude higher than the estimated ocean surface microplastic stock. However, many limitations exist to accurately calculate these stocks. This work should therefore be considered as a first step in addressing this question. In the long term, in order to better assess this stock, it seems important to obtain more diversified data, e.g. better representing certain countries, or certain land uses.