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Microplastic accumulation and transport in agricultural soils with long-term sewage sludge amendments

Journal of Hazardous Materials 2024 25 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count. Score: 55 ? 0–100 AI score estimating relevance to the microplastics field. Papers below 30 are filtered from public browse.

Weimin Zhou, Weimin Zhou, Bomin Fu, Jiukai Xu, Yang Wu, Yang Wu, Yang Wu, Weimin Zhou, Jiukai Xu, Weimin Zhou, Bomin Fu, Yang Wu, Yang Wu, Kai Zhang, Juanjuan Han, Jiejing Kong, Yibing Ma Yibing Ma Yibing Ma Yibing Ma

Summary

This study examined farmland that received sewage sludge applications for 16 years and found that microplastic levels in the topsoil were about five times higher than in untreated fields. Microplastics also migrated deeper into the soil over time, with migration rates 20 times greater in sludge-treated areas. The findings demonstrate that long-term use of sewage sludge as fertilizer is a significant pathway for microplastic accumulation in agricultural soils.

Land application of sewage sludge brings microplastic contamination to soil. However, studies regarding the occurrence and mobility of sludge-borne microplastics in soil are insufficient. In the present study, based on an experimental field, the effects of sludge application amount on the accumulation and migration of microplastics in 0-20 (upper) and 20-40 cm (lower) soil layers were evaluated. After 16 years of continuous sludge application (36 t/ha per year), the microplastic content and migration ratio in upper soil reached 6811 particles/kg and 148 %, which was about 5 and 20 times, respectively, higher than that of the control soil without sludge. The microplastics in upper and lower soil layers, were mainly 0.2-0.5 mm in size, mostly fibrous in shape, primarily transparent in color, and predominantly rayon in composition. Microplastic surfaces may persistently adsorb clay minerals and iron/titanium oxides from soil, posing potential environmental risks. Sludge application had a significant positive correlation with soil microplastic abundance, resulting in a good fit of predictive model constructed for microplastic accumulation in sludge-amended soils. These findings help to improve the knowledge on environmental behavior of microplastics in sludge-amended soil, and can provide a scientific basis for the regulation of microplastic pollution during sludge land application.

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