How Many Soil Samples Do We Need to Take to Determine Concentrations of Micro- and Nanoplastics in Terrestrial Systems?

Plastics pollution of terrestrial environments is a global problem, and plastics have been observed even in remote areas. However, how much plastic is present in terrestrial ecosystems is not well known. Here, we present a theoretical framework for representative sampling of randomly distributed plastic particles in soils or sediments. Based on geostatistical analysis, we determined optimal sampling strategies to quantify micro- and nanoplastics in soils or sediments. We used numerical simulations to test the sampling of randomly distributed plastic particles, and determined the sampling support (number of cores or sampling area) needed to obtain plastic concentrations within a specific error. Plastic pollution in the field was numerically simulated by placing plastic particles randomly in two dimensional space. We then took soil samples with differently sized cores, and determined plastic concentration as a function of number of cores taken. We will show how many cores are needed to determine the plastic concentrations within a given error.