Partitioning and stability of ionic, nano- and microsized zinc in natural soil suspensions

Martin Šebesta; Lucia Nemček; Martin Urík; Marek Kolenčík; Marek Bujdoš; Ivo Vávra; Edmund Dobročka; Peter Matúš

doi:10.1016/j.scitotenv.2019.134445

Partitioning and stability of ionic, nano- and microsized zinc in natural soil suspensions

Sci Total Environ. 2020 Jan 15:700:134445. doi: 10.1016/j.scitotenv.2019.134445. Epub 2019 Sep 13.

Authors

Martin Šebesta¹, Lucia Nemček², Martin Urík², Marek Kolenčík³, Marek Bujdoš², Ivo Vávra⁴, Edmund Dobročka⁴, Peter Matúš²

Affiliations

¹ Institute of Laboratory Research on Geomaterials, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15 Bratislava, Slovakia. Electronic address: martin.sebesta@uniba.sk.
² Institute of Laboratory Research on Geomaterials, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15 Bratislava, Slovakia.
³ Department of Soil Science and Geology, Faculty of Agrobiology and Food Resources, Slovak University of Agriculture in Nitra, Trieda A. Hlinku 2, 949 76 Nitra, Slovakia; Nanotechnology Centre, VŠB Technical University of Ostrava, 17. listopadu 15/2172, 708 33 Ostrava, Czech Republic.
⁴ Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.

PMID: 31629258
DOI: 10.1016/j.scitotenv.2019.134445

Abstract

Batch experiments aimed at solid-liquid distribution of 40 nm engineered zinc oxide nanoparticles (ZnO-NP), microparticles (bulk ZnO), and ionic Zn in ZnSO₄ solution were conducted on eight field soil samples of different characteristics to identify how the form of Zn affects its distribution in soil. The concentration of Zn in different size fractions present in supernatant solutions obtained from centrifuged soil suspensions was also measured. The distribution between a liquid and a solid was different for the ionic Zn (ZnSO₄) and particulate Zn (ZnO-NP and bulk ZnO). In acidic soil solutions, the partitioning coefficient (K_dA) of the ionic Zn was in range of 14.7-15.9 compared to 133.4-194.1 for ZnO-NP and bulk ZnO. The situation was reversed under alkaline conditions resulting in a decreased retention of particulate forms of Zn by the solids, with ZnO-NP showing K_dA of 8.5-23.4 compared to 160.0-760.1 of ionic Zn. Soil pH thus appears to be the predominant factor influencing the solid-liquid distribution of Zn in different forms. Even the distribution of Zn in different size fractions is heavily affected by the soil pH, causing dissolution of ZnO-NP and bulk ZnO in acidic soils. In alkaline soils, applied ionic Zn (ZnSO₄) remained dissolved. This study shows that ZnO-NP are the most mobile of the three tested forms of Zn in alkaline soils. This may affect the spatial distribution of Zn in soil and potentially increase the effectivity of the application of Zn fertilizer when in nanoparticle form.

Keywords: Environmental fate; Nanoparticle; Partitioning; Soil; Stability; Zinc.