Microplastic Contamination in Soils: A Review from Geotechnical Engineering View

Abstract

Microplastic contamination is a growing threat to marine and freshwater ecosystems, agricultural production, groundwater, plant growth and even human and animal health. Disintegration of plastic products due to mainly biochemical or physical activities leads to the formation and existence of microplastics in significant amounts, not only in marine and freshwater environments but also in soils. There are several valuable studies on microplastics in soils, which have typically focused on environmental, chemical, agricultural and health aspects. However, there is also a need for the geotechnical engineering perspective on microplastic contamination in soils. In this review paper, first, degradation, existence and persistence of microplastics in soils are assessed by considering various studies. Then, the potential role of solid waste disposal facilities as a source for microplastics is discussed by considering their geotechnical design and addressing the risk for the migration of microplastics from landfills to soils and other environments. Even though landfills are considered as one of the main geotechnical structures that contribute to the formation of considerably high amounts of microplastics and their contamination in soils, some other geotechnical engineering applications (i.e., soil improvement with tirechips, forming engineering fills with dredged sediments, soil improvement with synthetic polymer-based fibers, polystyrene based lightweight fill applications), as potential local source for microplastics, are also mentioned. Finally, the importance of geotechnical engineering as a mitigation tool for microplastics is emphasized and several important research topics involving geotechnical engineering are suggested.

Microplastic Pollution: An Emerging Threat to Terrestrial Plants and Insights into Its Remediation Strategies

“…Besides, MPs are well-known for their long-term persistence in soils. In this context, some studies demonstrated that after burying the plastics in the forms of pro-oxidant mulching films in soil for 8.5 years and when analyzing the degradation of LDPE film in laboratory conditions for 10 years there was no degradation, because all the plastics were recovered in their original forms [25]. Likewise, in another study, the biodegradation after 32 years was recorded for different polymers that were buried in soil, and the results revealed that there was no degradation at all [26].…”

Microplastic pollution in landfill soil: Emerging threats the environmental and public health

“…Plastic waste that is not recycled, whether illegally dumped or disposed of in landfills, can pollute the environment, including soil and water, through macro, micro, and nano-plastics. Approximately 75 % of the plastic waste disposed of in landfills has the potential to threaten the soil and other environments through microplastic contamination [ 33 , 34 ]. Microplastics in landfills can originate from various sources, including household waste, industry, and transportation.…”

Correlation of contamination/pollution from microplastics with physical properties of inceptisols

“…Degradation mechanisms might be chemical, physical, biological, or a mix of these activities. Polymer degradation activities that contribute to microplastic breakdown through thermal, mechanochemical, ozone, biological, photolysis, and catalytic degradation mechanisms can all have an influence on the toxicity of MPs to the environment [6]. MPs breakdown via ozone induction, biodegradation, and photo-oxidative reactions all contribute significantly to the decomposition of "macro" and "meso" plastics, and hence to the creation of microplastics in the soil [7].…”