ORIGINAL RESEARCH article
Front. Soil Sci.
Sec. Soil Pollution & Remediation
Comparative indexation of potentially toxic elements for soil pollution monitoring using ICP-OES and FTIR spectroscopy in Central Morocco
Provisionally accepted
- 1AgroBioSciences Program, College of Agriculture and Environmental Sciences, Mohammed VI Polytechnic University, Ben Guerir, Morocco
- 2Universite Cadi Ayyad, Marrakesh, Morocco
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The accumulation of potentially toxic elements (PTEs) in agricultural soils poses significant risks to food safety and ecosystem health, necessitating rapid and cost-effective monitoring approaches. While inductively coupled plasma optical emission spectroscopy (ICP-OES) provides accurate PTE quantification, its high cost, time requirements, and chemical reagent necessitate the search for green, fast, robust, and cost-effective alternatives. This study aims to evaluate the suitability of mid-infrared Fourier transform infrared (MIR-FTIR) spectroscopy combined with partial least squares regression (PLSR) as an alternative rapid method for predicting PTE concentrations and calculating pollution indices in semi-arid agricultural soils of central Morocco. A total of 67 surface soil samples (0-20 cm) were collected from three distinct soil types: Lithic Calciustolls (n=23), Typic Haplusterts (n=23), and Typic Calciustolls (n=21). Ten PTEs (As, Ba, Cd, Cu, Mn, Pb, Se, Sr, Ti, and Zn) were measured by ICP-OES and predicted using MIR-FTIR (4000-400 cm⁻¹) coupled with PLSR. Mean PTE concentrations varied substantially across soil types, with Cd ranging from 0.95 to 3.91 mg·kg⁻¹, Sr from 56.25 to 535.14 mg·kg⁻¹, and Zn from 38.23 to 59.63 mg·kg⁻¹. PTE Pollution Index (PI) was calculated using both datasets for comparative pollution assessment. Results demonstrated strong to excellent predictive performance (R² = 0.82-0.95) with the highest correlations for Ba, Zn, and Sr. PI calculations showed exceptional concordance between methods (mean PI: 1.54 for both), with all samples classified as low pollution. FTIR spectroscopy maintains the same geochemical relationships as ICP-OES (correlation differences <0.083), confirming method equivalence for soil pollution indexation. This approach offers significant advantages for large-scale monitoring programs while maintaining classification accuracy for environmental risk assessment.
Keywords: Chemometric method, FTIR Mid-infrared spectroscopy, icp-oes, Morocco, Potentially toxic elements, PTE Pollution Index
Received: 22 Dec 2025; Accepted: 04 Feb 2026.
Copyright: © 2026 AIT MANSOUR, TAJEDDINE, Boularbah and Kebede. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Laila AIT MANSOUR
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