Effect of copper or silver engineered nanoparticles on phosphorus availability in volcanic soils
Engineered nanoparticles (ENPs) present in consumer products are being released into the agricultural systems. There is little information about the direct effect of ENPs on phosphorus (P) availability, which is an essential nutrient for crop growth naturally occurring in agricultural soils. Conside...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2021 |
| País: | Chile |
| OAI Identifier: | oai:repositorio.anid.cl:10533/253089 |
| Acceso en línea: | https://hdl.handle.net/10533/253089 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciencias Naturales Ciencias Químicas Otras Especialidades de la Química |
| Sumario: | Engineered nanoparticles (ENPs) present in consumer products are being released into the agricultural systems. There is little information about the direct effect of ENPs on phosphorus (P) availability, which is an essential nutrient for crop growth naturally occurring in agricultural soils. Considering this situation, this study evaluated the effect of different doses of Cu or Ag ENPs produced by synthesis on the availability of P in a volcanic soil and the role played by natural soil organic matter (SOM) on this soil characteristic. The adsorption studies showed that when the Cu or Ag ENPs doses were increased, the pH value decreased and phosphate adsorption on soil with total organic matter (T-OM) and with partial removal of organic matter (R-OM) increased and was higher with Cu than with Ag ENPs. The Pseudo-second-order (PSO) and Elovich kinetics models for both soil samples in the presence and absence of Cu or Ag ENPs showed a good fit to the experimental data, suggesting that phosphate adsorption is chemical and occurs in a heterogeneous surface. The Freundlich model showed a good fit to the experimental data of the adsorption isotherms without both ENPs; on the contrary, with both ENPs the Langmuir model fitted better to the isotherm data. Phosphate desorbed was lower in R-OM sample than in T-OM soil sample and it increased with increasing doses of Ag or Cu ENPs. In addition, clay size fraction (<2 μm) had higher phosphate adsorption than sand/coarse silt (2000-32 μm), fine silt (32-2 μm) and in the presence of both ENPs phosphate adsorption increased in relation to systems without ENPs and was higher with Cu than with Ag ENPs. The Elovich model, which was used to interpret the kinetic data, revealed that Cu ENPs in the three soil fractions promoted the formation of adsorption sites for phosphate at initial adsorption times, whereas Ag ENPs can generate adsorption sites for phosphate or/and generate a blockage of them. The Langmuir-Freundlich isotherm model showed an excellent fit for all experimental data, suggesting that phosphate adsorption occurs on heterogeneous fraction surfaces through chemical interactions. In the absence of ENPs, the phosphate desorption was lower for clay size fraction than for sand/coarse silt and fine silt fractions and it decreased with increasing in both ENPs content. The main conclusion of our study is that the incorporation of Cu or Ag ENPs suspensions into an Andisol generated a decrease in the pH values and thus increased P adsorption, leading to lower P availability. A lower P availability in agricultural soils may affect agricultural crop production. |
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