engleski

Microplastics in Lumbricus terrestris middens/casts and surrounding urban soil

Continuous accumulation and low degradation rates of plastic waste in the environment indicate the cumulative effect that microplastics particles could have on the environment. The impact of microplastics pollution on terrestrial ecosystems, relative to aquatic ecosystems, has been poorly investigated. Also, the impact of soil microplastics on soil-dwelling organisms is not well understood. Therefore, the main objective of this study was to investigate whether Lumbricus terrestris concentrates the microplastics with its behaviour. To investigate the interaction of microplastics and L. terrestris, topsoil samples and earthworm casts/middens samples were collected at different locations that included agricultural land and green urban areas. Microplastics from soil and cast samples were extracted by density separation using aqueous zinc (II) chloride solution (5M). Isolated particles were counted, and their surface areas and diameters were analyzed and quantified using ImageJ 1.5. Mean microplastics count in soil was 977.76 ± 726.39 particles kg soil-1 and in earthworm casts 655.89 ± 265.11 particles kg cast.-1 . Mean surface area of microplastics isolated from soil samples was 0.482 ± 0.765 mm 2 and from earthworm casts 0.529 ± 0.660 mm 2 . On average, diameter of microplastic particles was 1.102 ± 0.703 mm in particles isolated from soil and 1.205 ± 0.705 mm in particles from earthworm casts. Previous studies have shown that earthworms can accelerate biodegradation of microplastics in the soil by ingestion. Therefore, it was expected that the count of microplastics in earthworm casts would exceed the count of microplastics in soil samples. Also, it was expected that dimensions of microplastics would be smaller in size in earthworm casts compared to microplastics in soil. However, this research has shown the opposite, which could be explained by the preferential retention of smaller microplastics within the earthworm organism.

soil microplastics ; earthworm cast ; biodegradation ; Lumbricus terrestris

nije evidentirano