Microplastics mineralization accelerates soil organic carbon decomposition by positive priming effects: A meta-analysis

Abstract

Microplastics (MPs), as a novel global pollutant, are abundant in agricultural soils due to their recalcitrant nature. However, the key drivers regulating MPs mineralization and their impact on soil organic carbon (SOC) decomposition remain unclear. Here, we conducted a meta-analysis to estimate the mineralization rate of MPs in soil and their priming effect (PE) on SOC decomposition. We found that MPs mineralization rate was 0.114% per day, mainly mediated by MPs characteristics (chemical composition and particle size) and soil pH. MPs input simultaneously induced a significant positive PE, accelerating SOC decomposition by 33.6% on average. This process was primarily regulated by soil carbon (C):nitrogen (N) ratio and pH, and there was a significant correlation between MPs mineralization and PE. Furthermore, dissolved organic C and microbial biomass C and N in soil increased after MPs input, while nitrate decreased. These results indicated that the positive PE induced by MPs may be driven by soil microbial co-metabolism and N mining. Collectively, our findings emphasize the crucial role of MPs in terrestrial biogeochemical cycles and provide an improved assessment of SOC turnover under the global MPs crisis.

Graphical abstract

Keywords

microplastics mineralization / soil organic carbon / priming effect / meta-analysis

Highlight

	● MPs mineralization rate was mainly regulated by MPs characteristics and soil pH.
	● MPs addition induced a significant positive PE (34%) on SOC decomposition.
	● The MPs-induced PE was primarily controlled by soil C:N ratio and pH.
	● Soil microbial co-metabolism and N mining were key drivers for the PE.

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