Microplastics are found in the atmosphere- even in remote areas like mountaintops and Antarctica- indicating aeolian transport of microplastics is partially driving their distribution in the environment. Microplastic concentration is expected to be several orders of magnitude in urban air which is inhaled by billions of urban dwellers; this poses a potentially significant health risk. Thus, it is critical to estimate the atmospheric concentration of microplastics. In this study, we evaluate the potential of leaves to serve as natural passive samplers to determine microplastic accumulation in the environment by atmospheric transport. Leaves were collected from 21 sites all over Los Angeles to analyze the effect of their type, position above ground, and land use category: residential, natural, commercial, roadside, on the concentration of microplastics. Our results show that the type of leaf significantly affects the accumulation of microplastics on it. In particular, palm leaves contained higher numbers of microplastics than oak leaves. Contact angle measurements revealed that palm leaves have a higher contact angle, a traditional indicator of surface hydrophobicity, than other leaves. Atomic force microscopy and SEM image analysis of leaves further helped link microplastic concentration on leaves to their surface features such as roughness and leaf hairs. Unexpectedly, the height of leaves above ground and the type of land use in the area of leaf collection appear to have no correlation with the concentration of microplastics. The results are useful for developing a standard method to estimate the extent of microplastic deposition from the atmosphere so that inhalation risks can be assessed in future studies.

Leaves act as passive samplers for quantifying atmospheric deposition of microplastics

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.