The Impact of Plastic Pollution on The Soil

The effect of microplastics on soil ciliates remains unknown and generally untested. This experiment explores the effect of the microplastic polypropylene, found in bailing twine, on Tetrahymena Pyriformis. An experiment was preformed using Tetrahymena grown in polypropylene and Protease-peptone-tryptone media for two days. Cell count, direction change, and spin time assays were performed on the control and treatment groups. The author hypothesized that the microplastics would inhibit reproduction and reduce direction change and spin time. But, the results suggest that there is no significant statistical significance to reject the null hypothesis. The only results which showed statistical significance was difference in spin time. While the green twine did not seem to influence the Tetrahymena more research needs to be performed on the effects of microplastics on soil ciliates.

The effect of microplastics on the environment are not known. There are more than 300 million tons of plastic produced each year and over 268940 tons are in the oceans. Little to no research had been performed on the effect of microplastic pollution in terrestrial environments. A study conducted in Shanghai, China suggests that the majority of microplastic pollution on farmlands is in the topsoil and polypropylene and polyethylene. This study focuses on polypropylene found in hay baling twine. Because of the twines exposure to sunlight and high heat, the twine fragments into microplastics which contaminate the soil. Tetrahymena and other microorganisms, would be among the first to be affected by the microplastics because of their low trophic levels and location in the top-soil. Tetrahymena are used as a model organism because of the ciliate fast reproduction rate and observable behaviors.

It is important that soil ciliates, particularly Tetrahymena, are studied because they act as transport vehicles of microplastics to the soil food web. In the ocean, biomagnification occurs in phytoplankton taking up mercury in concentrations that are thousands of times greater than surrounding seawater. Animals consuming the predators of phytoplankton contain mercury levels more than 50 times higher than the initial consumers. Mesozooplankton are also known to ingest microplastics and have transferred the contamination up the food web to Mysid shrimp. The same process could happen in terrestrial environments.

To begin the soil food web, plants decompose to organic matter which is then consumed by bacteria and in turn hunted by protozoa. Predator nematodes then consume the ciliates while still future up the web birds consume the nematodes. Because of biomagnification, animals that consume Tetrahymena would have a higher concentration of microplastics. It is vital that scientist continue to research microplastics effect on soil ciliates to avoid major issues caused by biomagnification in the future.

Cite this page