F. Eivazi;Zahra Afrasiabi;Elizabeth Jos

Department of Agriculture and Environmental Sciences, Lincoln University, Jefferson City MO 65101 (USA);Department of Physiology and Cell Biology, The Ohio State University, Columbus OH 43210 (USA;Department of Environmental Studies, Soka University, Aliso Viejo CA 92656 (USA)

agnp;agnps;month;soil enzymes;soil samples;wee

Soils are continuously exposed to large amounts of engineered nanoparticles, especially silver nanoparticles (AgNPs), which can affect the activity, stability, and specificity of microbial enzymes. Therefore, the measurement of specific enzyme activity can be used to identify major changes in soil environments. Accordingly, the aim of the present study was to investigate the effects of AgNPs on soil enzymes that play critical roles in mineralizing carbon and nutrients in soil. Soil samples (silt loam and sandy loam) were collected from the surface layer (0-15 cm) of a field at the George Washington Carver Farm, Lincoln University of Missouri, USA. The soils were then treated with AgNP solutions at 0, 1600, or 3 200 mu g Ag kg(-1) dry soil, using either 10- or 50-nm AgNPs and a randomized complete block design, with three replicates per treatment. The AgNP-treated soil samples were homogenized and incubated for one month, and soil acid phosphatase, beta-glucosaminidase, beta-glucosidase, and arylsulfatase activities were measured after one hour, one week, and one month of incubation. The activities of all four enzymes were reduced by AgNP treatment after one hour and one week. However, AgNP size had no effect. After one month of incubation, the AgNP treatments had mixed effects, which suggests that soil enzymes are only affected on a short-term basis. Further studies are required to determine the mechanisms by which AgNPs reduce soil enzyme activity.