Impact of microplastic pollution in terrestrial ecosystem on index and engineering properties of sandy soil: An experimental investigation

Sandy soils cover a major portion of various natural and managed ecosystems. Soil health plays a key role in achieving sustainable development goals 2, 3,11,12,13 and 15. The engineering properties of soil are crucial in determining the stability and safety of structures. The increasing microplastic contamination in the soil ecosystem creates a need to study the effect of terrestrial microplastic contamination on the strength and stability of soil and therefore on the index properties and engineering properties of the soil. The present paper investigates, the effects of varying concentrations (2 %,4 %,6 % (w/w)) of Low-density polyethylene (LDPE), Polyvinyl chloride (PVC), and High-density polyethylene (HDPE) microplastics on the index properties and engineering properties of sandy soil for varying observation days. The moisture content, specific gravity, shear strength, compaction characteristics and permeability are found to be significantly altered by changing the concentrations of microplastics but, insignificant changes are observed with respect to observation days. The shear strength value of non-contaminated sandy soil is 1.74 kg/cm2 which reduces after 5th observation days as 0.85 kg/cm2, 0.90 kg/cm2, and 0.91 kg/cm2 for 2 %, 4 %, and 6 % LDPE microplastic contamination respectively. Similar trends are observed for PVC and HDPE microplastic contamination. It is also observed that although the shear strength value decreases, the cohesion value increases for the microplasticscontaminated sandy soil. The coefficient of permeability for non-contaminated sample is 0.0004 m/s which reduces for 2 % LDPE microplastic contamination to 0.000319 m/s, for 4 % to 0.000217 m/s, and 6 % to 0.000208 m/s respectively. Similar trends of are observed for the PVC and HDPE microplastic contamination. The soil strength and structural stability are affected due to alterations in soil index and engineering properties. The paper provides detailed experimental evidence of the impact of microplastic pollution on index properties and engineering properties of sandy soil.

Automated summary

Sandy soils are prevalent in natural and managed ecosystems, and their health is crucial for achieving sustainable development goals. This study investigates the effects of varying concentrations of microplastics on the index and engineering properties of sandy soil. The results show significant alterations in moisture content, specific gravity, shear strength, compaction characteristics, and permeability with changing microplastic concentrations. The study provides experimental evidence of the impact of microplastic pollution on soil properties and stability.