Project Specifics

Microplastic research has increased in the past decade, primarily focusing on aquatic environments. Recently, there has been a shift in focus toward understanding microplastic impacts in terrestrial environments, including agricultural land. There have been limited studies of how microplastics move through the soil; how they affect soil properties and biota; and their potential consequences for seed germination, plant growth, and fruit production. Of the published studies, researchers have found that microplastics in soil can affect seed germination rates, be absorbed by plants, and be transported from the roots to other parts of the plant. The results of these studies could impact multiple industries, including agriculture and industrial wastewater.

Geosyntec Scope of Services

The team was awarded a Proof of Concept grant from Geosyntec’s Technology Advisory Council to evaluate the impact of microplastics on seed germination and plant growth. The objective of this project was to develop a deeper understanding of the effects of microplastics on soil function, seed germination, and plant growth by completing a critical review of the currently available literature.

The technical literature review was conducted by searching for peer-reviewed publications. The team organized studies based on the following factors: size, type, and source of microplastics; plant species or soil function being studied; and findings on microplastics and their impacts on soil function, plant growth, or both.

Notable Accomplishments

The key findings of this literature review were as follows:

• Microplastics in agriculture come from multiple sources, including those introduced in agricultural practices.
• Microplastics can modify soil properties.
• Microplastics can enter and translocate in certain plants and hinder seed germination and plant growth.
• It remains unclear whether microplastics’ adverse effects occur at ecologically significant levels.

It is also unknown if weathered microplastics can affect toxicity since most studies used virgin microplastics that do not reflect actual conditions found in the environment.

Geosyntec researchers identified significant gaps in research regarding microplastics, including the following:

• The lack of a standardized procedure for quantifying microplastics in soil samples
• Difficulty finding control sites with no plastics
• The fact that current toxicity studies use concentrations that may not be environmentally relevant
• The fact that such studies are limited in what species, polymer, sizes, and endpoints evaluated

What is a Quick Qual?