How to take representative samples to quantify microplastic particles in soil?

Area of Science:

• Environmental Science
• Ecotoxicology
• Soil Science

Background:

• Accurate quantification of plastic particles in terrestrial ecosystems is hindered by sampling challenges.
• Existing literature on plastic concentrations may have errors due to non-representative sampling methods.

Purpose of the Study:

• To numerically simulate and determine optimal methods for collecting representative terrestrial samples for plastic particle quantification.
• To evaluate the accuracy of reported plastic concentrations in the scientific literature based on sampling strategies.

Main Methods:

• Numerical simulation of terrestrial fields with randomly distributed plastic particles (uniform and clustered).
• Determination of the representative elementary volume (REV) and the required number of samples for various plastic concentrations and error tolerances.
• Evaluation of sampling strategies including sample size and replication.

Main Results:

• The representative elementary volume (REV) and the number of required samples decrease hyperbolically with increasing plastic particle concentration.
• Hundreds to thousands of small soil cores are needed for low concentrations (10^2 particles/m^2), while few large samples suffice for high concentrations (10^5 particles/m^2).
• Accurate measurements require total sample surface area to meet or exceed the REV.

Conclusions:

• Sampling strategies must adapt to plastic particle concentration for accurate terrestrial plastic quantification.
• Larger, replicated samples are recommended over numerous small cores, utilizing methods like quartering to reduce soil volume.
• This research provides a framework for improving the reliability of data on terrestrial plastic pollution.