Silver Nanoparticles Altered Soil Microbial Activity and Carbon Dynamics: Unraveling Microbial Sensitivities and Ecosystem Responses

Abstract

Silver nanoparticles (AgNPs) are popular for their antimicrobial properties but their effects on soil carbon cycles remain unclear. This study explored AgNPs' impact on soil carbon dynamics and related microbial structures. Topsoil samples were treated with varying AgNPs concentrations (1, 10, 100, 500, and 1000 mg kg-1) over 56 days. We assessed carbon mineralization, dissolved organic carbon (DOC), microbial biomass carbon (MBC), metabolic quotient (qCO2), and enzymatic activities of β-glucosidase, β-xylosidase, and cellobiohydrolase. Using 13C-labeled DOC, microbial carbon use efficiency (CUE) was evaluated, and 13C-phospholipid fatty acid assays traced carbon assimilation by soil microbes. Higher AgNPs levels significantly increased CO2 emissions, while soil DOC and qCO2 were influenced by AgNPs dose and exposure time. Enzyme activities varied with AgNPs concentration, and the highest dose showed a 49.7% CUE rise by day 56. AgNPs altered microbial biomass and shifted microbial populations, favoring Gram-negative bacteria. Collectively, these findings underscore the ecological implications of AgNPs on soil health and shed light on their role in disrupting soil microbial networks and carbon flow dynamics.

Keywords: Silver nanoparticles, Microbial activity, Carbon use efficiency, Soil carbon cycle, 13C-PLFA