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Effect of Different Microplastics on Phosphorus Availability in an Alkaline Paddy Soil

Water Air & Soil Pollution 2023 19 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Zihan Zhang, Xiangmei Lai, Congli Xiao, Yaying Li, Yongxiang Yu, Huaiying Yao

Summary

Researchers found that both biodegradable and conventional microplastics in paddy soil reduced phosphorus availability for crops by suppressing key soil enzymes and microbial genes — suggesting that microplastic contamination of agricultural soils could impair nutrient cycling and potentially reduce food crop yields.

Microplastics (MPs) can affect phosphorus (P) cycling in paddy fields by changing soil properties and microbial community function, but their impact on soil P availability remains unclear. A laboratory incubation experiment was applied to explore the effect of different MPs on the soil available P content. Amendment with nonbiodegradable MPs significantly (p < 0.05) reduced soil P availability, whereas the available P content decreased with increasing biodegradable MP content from 0.1 to 1.0% (except in the 1.0% poly(lactic acid) treatment). The presence of MPs inhibited soil alkaline phosphatase activity and reduced the copy numbers of microbial functional genes involved in organic P mineralization (phoD and phoX) and inorganic phosphate solubilization (ppk and pqqC). There were positive linear relationships of the soil available P content with phosphatase activity and the phoX and pqqC genes. Partial least squares path modeling indicated that nonbiodegradable MPs indirectly reduced the soil available P content by controlling the abundance of microbial functional genes involved in organic P mineralization, whereas amendment with biodegradable MPs did not significantly affect soil P availability directly or indirectly. Our results provide evidence that MPs have the potential to reduce the available P substrate in soils, and management practices should be established to improve P availability in MP-polluted paddy fields.

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