Comparative assessment of polymeric and other nanoparticles impacts on soil microbial and biochemical properties

Interest has been generated in nanotechnology application in agricultural and food systems and understanding ecotoxicity of nanoparticles (NPs) is imperative for ecosystem health and food safety. This study compared the dose-effects of newly synthesized polysuccinimide NPs (PSI-NPs) with mull-walled carbon nanotubes (MWCNTs), nano-Ag and nano-TiO2, on soil microbiological and biochemical processes. The effects of NPs varied largely with the type and dose of NPs as well as soil properties. Of the tested NPs, PSI-NPs had no significant perturbance, while the rest of NPs decreased microbial biomass C and N (MBC and MBN), stimulated the microbial metabolic quotient (MMQ), and inhibited dehydrogenase (DA), urease (UA), and phosphatase (PA) activities. Significant dose-effects of MWCNTs, nano-Ag and nano-TiO2 occurred, and the influences were more intensive at higher application rate (500 ppm). Irrespective of NP type and dose, the effects were severer in Spodosol soil than Alfisol soil. Principle component analysis (PCA) also confirmed that most of the measured indicators were not affected by PSI-NPs, partly affected by MWCNTs, but intensively influenced by nano-Ag and nano-TiO2. These results highlight the advantages of PSI-NPs over the other NPs for agricultural applications and could facilitate the development of guidelines in regulating NPs application in agroecosystems.