Assessing microplastic contamination in Icelandic soils: Insights from pristine, agricultural, and urban environments

In recent years, there has been increasing attention on microplastic in the atmosphere. It is generally assumed that microplastics disperse into the air, potentially travelling long distances before being deposited into remote soil. However, there is limited literature on whether microplastics accumulate in such pristine soil, as most studies focus on daily deposition rates rather than soil analysis. This study aims to investigate microplastic abundance in pristine soil samples collected from Icelandic highlands in terms of count and estimated mass. Urban and agricultural samples were also collected and used as reference points. In addition, it was also explored whether specific soil characteristics, such as water and organic matter content, influence microplastic accumulation in pristine soils. Microplastics were extracted from the soil using state-of-the-art sample preparation and analytical methods, including pre-oxidation, sieving, density separation, and chemical treatment, to enable analysis with µ-FTIR imaging. Data were processed using the freeware siMPle to obtain information on count, type, size, and estimated mass. Microplastics were detected in all 15 investigated samples, with urban samples showing the highest average count (26206 (±25345) counts per kg) and pristine samples the lowest (857 (±561) counts per kg), indicating the influence of anthropogenic activity on microplastic accumulation. When investigating the microplastics' type, size, and shape, it was observed that medium-sized lightweight fragments primarily accumulated in pristine soil. Additionally, correlation analysis between different soil parameters revealed that the only significant correlation observed was between organic matter content and microplastic count, showing a slight positive correlation. These findings underscore the impact of human activity on microplastic distribution and highlight the transfer of microplastics to remote regions of the world, where they eventually will accumulate in the soil. Also see: https://micro2024.sciencesconf.org/558690/document