The effect of pH and ageing on the fate of CuO and ZnO nanoparticles in soils

Izabela Jośko; Joanna Dobrzyńska; Ryszard Dobrowolski; Magdalena Kusiak; Konrad Terpiłowski

doi:10.1016/j.scitotenv.2020.137771

The effect of pH and ageing on the fate of CuO and ZnO nanoparticles in soils

Sci Total Environ. 2020 Jun 15:721:137771. doi: 10.1016/j.scitotenv.2020.137771. Epub 2020 Mar 9.

Authors

Izabela Jośko¹, Joanna Dobrzyńska², Ryszard Dobrowolski², Magdalena Kusiak³, Konrad Terpiłowski⁴

Affiliations

¹ Institute of Plant Genetics, Breeding and Biotechnology, Faculty of Agrobioengineering, University of Life Sciences, Lublin, Poland; Department of Radiochemistry and Environmental Chemistry, Faculty of Chemistry, Maria Curie-Skłodowska University, Lublin, Poland. Electronic address: izabela.josko@up.lublin.pl.
² Department of Analytical Chemistry, Faculty of Chemistry, Maria Curie-Skłodowska University, Lublin, Poland.
³ Institute of Plant Genetics, Breeding and Biotechnology, Faculty of Agrobioengineering, University of Life Sciences, Lublin, Poland.
⁴ Department of Interfacial Phenomena, Faculty of Chemistry, Maria Curie Skłodowska University, Lublin, Poland.

PMID: 32197287
DOI: 10.1016/j.scitotenv.2020.137771

Abstract

The objective of this study was to evaluate the fractionation of ZnO and CuO engineered nanoparticles (ENPs) in soils with a pH adjusted to 4.0, 6.5, and 9.0 after 1 day and 30 days of incubation. Based on the multi-stage extraction, 5 fractions of metals were determined. Moreover, the effect of ENPs on the activity of acid, neutral and alkaline phosphatase was determined. The results of the study revealed that pH had a dominant effect on the metal participation in soils. The levels of those fractions of metals differed between nano-ZnO and nano-CuO, which could have resulted from differences in the dissolution of the ENPs. After 1 day, the concentration of Zn²⁺ (0.02-7.4 mg L^-1) was 10 times higher than that of Cu²⁺. The metal fractionation in soil treated with ENPs and metal salts may also confirm the role of ENP dissolution. The concentration of potentially bioavailable fraction of Zn increased with a drop in pH. At a 4 pH concentration of Zn in the treatment with nano-ZnO and ZnCl₂ was at a similar level (42.1-45 mg kg^-1), whereas the addition of nano-CuO resulted in a lower content of Cu (24.7 mg kg^-1) than CuCl₂ (36.5 mg kg^-1). On the other hand, the concentration of fraction exchangeable of both metals in the alkaline soil did not exceed the level of 5.0 mg kg^-1. Sample incubation time was especially important for metal participation in samples with a pH of 6.5. The greatest differentiation of metal fractionation between the soils was also noted at a pH of 6.5, which could also have been a result of other properties of the soils. The strong effect of pH on the lability of ENPs in soils confirmed a need to trace the fate of ENPs in extreme soil conditions as well as in changing environment.

Keywords: Metal participation; Nanoparticles; Phosphatase activity; Soils; pH.