Dissolution of Ag Nanoparticles in Agricultural Soils and Effects on Soil Exoenzyme Activities


To assess environmental risks related to the mobility and toxicity of AgNPs, the chemical availability of AgNPs and polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) in three agricultural soils was quantified in a pot experiment. Porewater collection and soil extractions with 0.01 M CaCl2, 0.4 M Glycine (pH 1.5) and 0.05 M NH4-EDTA were performed. The effect on soil exoenzyme activities was also assessed. Porewater concentration was low (<0.4% and <0.04% of dosed Ag, for AgNPs and PVP-AgNPs, respectively) and only detected in acidic soils (pH 4.4 and 4.9). The PVP-coating reduced the downward mobility of AgNPs in soil and possibly also their dissolution rate (and subsequent release of dissolved Ag+ ions into porewater). The effect of variation in organic matter on soil enzymatic activity was larger than that of AgNPs, as no significant additional inhibitory effect from Ag could be observed. Only at low pH and in the presence of complexing ligands that form very stable Ag complexes (0.4 M Glycine extraction at pH 1.5) up to 58% of the Ag added to soil was released (independently of PVP coating). An extraction with glycine is proposed as a useful indicator of potentially available Ag in soils.



subject category

Environmental Sciences


Cruz, NC; Farto, M; Mourinha, C; Tavares, D; Duarte, AC; Trindade, T; Pereira, E; Romkens, PFAM; Alvarenga, P; Rodrigues, SM

our authors


S.M.R. acknowledges the financial support from the Portuguese Foundation for Science and Technology (FCT) (Project IF/01637/2013/CP1162/CT0020). Thanks are due to CESAM and to FCT/MCTES for the financial support to (UIDP/50017/2020+UIDB/50017/2020), through national funds. This work was supported by the project AgriTarget (POCI-01-0145-FEDER-029258 and PTDC/BAA-AGR/29258/2017) and project NanoFertil (POCI-01-0145-FEDER-016749-PTDC/AGR-PRO/6262/2014), funded by FEDER, through COMPETE2020-Programa Operacional Competitividade e Internacionalizacao (POCI), by LEAF (Linking Landscape, Environment, Agriculture and Food Research Unit), funded by FCT (UID/AGR/04129/2020) and by national funds (OE), through FCT/MCTES.

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