Effect of LDPE microplastics on chemical properties and microbial communities in soil

Abstract

The accumulation of plastics in the soil ecosystem poses an increasing environmental concern worldwide. However, little is known about the effect of plastic concentrations on soil properties and soil biota. In this study, we investigated the effect of low‐density polyethylene (LDPE) microplastics (MPs) on the chemical and microbial properties of agricultural soil using a set of microcosm experiments. The soil was incubated for 100 days with LDPE at concentrations of 0%, 0.1%, 1%, 3%, 5%, and 7% at 25°C with 70% water‐holding capacity. Along with soil chemical analysis, we conducted an analysis of soil microbial properties on the first day and again after 100 days of incubation. LDPE concentrations of ≥1% significantly (p < .05) decreased the pH but increased the electrical conductivity of the soil in comparison with the control (0% LDPE at 100 days). Increasing the LDPE concentration did not affect the soil exchangeable cation content or the available Pb concentration. Firmicutes were the most abundant phyla in the soil on the first day, whereas Proteobacteria, Firmicutes and Actinobacteria became dominant in all treatments after 100 days. An increasing LDPE concentration increased the abundance of Actinobacteria and decreased Proteobacteria. Principal component analysis demonstrated that only 7% LDPE was positively correlated with Actinobacteria, indicating that higher concentrations of LDPE contributed to the growth of this phylum. The findings of this study imply that MP contamination could affect soil chemical properties and microbial activity and that these effects primarily depend on MP concentrations in soil.

Potential effect of key soil bacterial taxa on the increase of rice yield under milk vetch rotation

“…Related studies show that lower soil pH led to higher Firmicutes abundance ( Li Y. Z. et al, 2022 ; Palansooriya et al, 2022 ), which contrasts with our study in which Firmicutes was enriched in NPKGM at higher pH. Firmicutes can also benefit from a high source-availability environment, whose content increases with abundance of nutrients ( Vanwonterghem et al, 2016 ; Zhou et al, 2021 ); in our study, Firmicutes may have responded more to nutrients than pH.…”

Do Added Microplastics, Native Soil Properties, and Prevailing Climatic Conditions Have Consequences for Carbon and Nitrogen Contents in Soil? A Global Data Synthesis of Pot and Greenhouse Studies

“…In MPcontaminated soils, pH reduction can occur via (1) the release of organic acids during decomposition of organic compounds 64,65 and (2) the increased abundance of actinobacteria, which acidify soil to outcompete other bacterial species. 63,66 It is highly possible that these mechanisms were responsible for decreased soil pH: (1) because we have observed a depletion of C and N stocks that produce organic acids to lower pH and (2) because under polluted conditions, the soil microbial community will often shift, resulting in altered pH. 67,68 In contrast, a recent study found that MPs did not affect soil pH after only 30 days of exposure.…”

Soil health and ecosystem services

“…Biochar derived from biological waste can be used to reduce the bioavailability of soil heavy metals (Ayaz et al, 2022). The use of plastic in agriculture and accumulation of microplastics/nanoplastics may affect soil microbial community and plant health (Palansooriya et al, 2022; Wang et al, 2023; Zhou et al, 2023). Biochar was also found to be effective in mitigating soil pollution caused by microplastics (Dissanayake et al, 2022).…”