Insight in transformations of nano-metallic and ionic platinum forms in different soil types in the context of Pt immobilization

Joanna Kowalska ¹, Paulina Brusik ¹, Monika Sadowska ¹

⁰Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, Warsaw, 02-093, Poland.

Scientific Reports +

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December 17, 2025

View abstract on PubMed

Summary

Platinum nanoparticles (Pt-NPs) from vehicle emissions transform in soil. Mobility varies by soil type, with sandy and transformed soils showing higher platinum mobility than clay and peat soils.

Area Of Science

Environmental Science
Environmental Chemistry
Soil Science

Background

Road traffic is a significant source of platinum emissions, primarily as metallic nanoparticles (Pt-NPs).
Platinum nanoparticles interact with soil components, potentially undergoing chemical transformations and dissolution.
Understanding platinum's behavior in soil is crucial for assessing its environmental fate and impact.

Purpose Of The Study

To investigate the influence of soil type on the mobility of platinum (Pt) in various soil matrices.
To assess the transformation of metallic Pt-NPs into ionic forms within different soil environments.
To evaluate the effect of citrates, mimicking rhizosphere activity, on Pt mobility.

Main Methods

Studied platinum mobility in peat, sandy, chalk loam, and transformed roadside soils.
Utilized solid-liquid extractions with modified BCR protocols to determine mobile and organic Pt fractions.
Employed voltammetry and ICP-MS for platinum quantification and cross-comparison to identify Pt transformations.

Main Results

Platinum mobility was significantly higher in transformed and sandy soils (approx. 10% extractability) compared to clay (4-5%) and peat soils (0.4-0.8%).
Metallic Pt-NPs, especially smaller ones, can transform into ionic forms, with significant proportions found in mobile (30-50%) and oxidizable (75-80%) fractions.
Citrate incubation increased Pt mobility, not by transforming Pt-NPs to ionic forms, but by reducing NP-soil matrix interactions.

Conclusions

Soil type is a critical factor controlling platinum mobility and transformation.
Small metallic Pt-NPs are prone to transformation into more mobile ionic forms in certain soil conditions.
Rhizosphere activity, simulated by citrates, can enhance Pt mobility through altered nanoparticle-soil interactions.

Keywords:

Fractionation Platinum mobility Platinum nanoparticles Rhizosphere activity Soil type effect Ultrasound assisted extraction Voltammetry