Insight in transformations of nanometallic and ionic platinum forms in different soil types in the context of Pt immobilization

Sep 30, 2026

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Platinum emitted from road traffic undergoes soil-driven chemical transformation that can increase dissolution and alter mobility. This study evaluates how soil type affects platinum mobility in soils enriched with metallic and ionic platinum forms, comparing peat, sandy, chalk loam, and road-adjacent transformed soil, with citrate addition to mimic rhizosphere activity. Modified BCR-based solid-liquid extractions and platinum quantification by voltammetry and ICP-MS show transformation of Pt-NPs into Pt(II), with mobility highest in transformed and sandy soils and strongly reduced mobility in peat soil; citrate increases mobility via limited nanoparticle–matrix interaction.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Introduction

Soil type, rhizosphere activity, and platinum transformation

Extraction and analytical methods

[www. nature.com/scientificreports](www. nature.com/scientificreports) OPEN Insight in transformations of nanometallic and ionic platinum forms in different soil types in the context of Pt immobilization Joanna Kowalska, Paulina Brusik, Monika Sadowska, Katarzyna Kińska & Beata Krasnodębska-Ostręga􀀍 Platinum is emitted by road traffic mainly in the form of metallic particles. Interaction of Pt-NPs with soil causes their chemical transformation that may result in dissolution. Investigation of soil – Pt-NPs interactions presented in this study focuses on assessing the influence of soil type on Pt mobility in soil enriched in its metallic and ionic forms. Studied soil types included peat soil (high content of organic matter), sandy soil, chalk loam soil and transformed soil collected next to a road with high traffic (Zabrze, Poland), to which citrates were added to mimic the rhizosphere activity. Solid-liquid extractions based on modified BCR protocols were applied to establish mobile and organic fractions, and Pt was determined with both voltammetry and ICP-MS. Cross-comparison of the results of these two techniques allows to conclude about Pt-NPs transformation into Pt(II). The mobility of Ptin transformed soil and sandy soil (about 10% extractability with CH3COOH) is significantly higher than in clay (4–5%) and peat soil (0.4–0.8%) . Metallic Pt-NPs with small diameters can be effectively transformed into ionic forms. Their content in mobile fraction reaches 30–50%, and in oxidizable fraction – even 75–80%. Higher mobility of Pt was observed after incubation in the presence of citrates, however it is not due to a transition of Pt-NPs into ionic forms but results from limited interaction of small NPs with the soil matrix. Keywords Platinum nanoparticles, Platinum mobility, Soil type effect, Rhizosphere activity, Fractionation, Ultrasound assisted extraction, Voltammetry Platinum is one of the technologically critical elements (TCEs), exploited due to its physical and chemical properties, such as high melting point, high corrosion resistance, mechanical strength and ductility. It has a high economic value and many different applications-in catalytic converters, electronics, drugs and as a catalyst in chemical industry. The consequence of increasing use of that metal is the increasing release of platinum into the natural environment, and thus there is growing interest in its fate in soil ecosystems1. Undoubtedly, the main source of environment contamination are catalytic car converters. It was confirmed by calculating the platinum group elements’ (PGEs) ratios in samples of roadside soils and grasses, and comparing them with the ratios in car converters, which are defined as Pt/Pd from 1 to 2.5, Pd/Rh from 4 to 9 and Pt/Rh from 5 to 162. It is well documented that PGEs concentration in soil decreases with the distance from the road and with the depth1. Still, information about geochemical behavior of Pt in soils is very limited. Although the emission strongly depends on car age, engine type and driving conditions, platinum is emitted mainly (up to 99%) in a form of metallic nano-particles (NPs), and deposited in the vicinity of the road3. However, other studies revealed that also soluble Pt forms can be emitted, which are much more mobile in the soil, and that fraction comprised even 10% of total city traffic emission4. In a simulated experiment, PtCl2 was introduced in three soil types contrasting in properties and resistance to metal contamination (slightly alkaline heavy loamy soil, acidic heavy loamy soil, and neutral sandy loamy soil), and the results show that contamination with Pt(II) leads to a decrease in the biological indicators ofthe soil condition and impairments ofthe ecosystem functions of all studied soil types5. So to understand the environmental fate of platinum, studies devoted to identification of particulate platinum forms – metallic and soluble ones – seem to be crucial. Moreover, the assessment

FAQs

How does soil type influence platinum mobility in the enriched soils?

Mobility varies markedly by soil type: transformed and sandy soils show higher extractability than clay and peat soils, indicating strong soil-dependent immobilization and transformation behavior.

What role do citrates play in the experiment?

Citrate addition increases observed platinum mobility, but the effect is attributed to reduced interaction of small nanoparticles with the soil matrix rather than a direct Pt-NP-to-ionic-form transition.

Which analytical techniques were used to determine platinum forms and mobility?

The study uses modified BCR solid-liquid extraction to separate mobile and organic fractions, followed by quantification with voltammetry and ICP-MS, enabling cross-comparison of transformation trends into Pt(II).

Sep 30, 2026

Upload by Jacob