## 2 Materials and Methods
### Soil and Plant Analysis
For comparison, a control sample was also prepared using the same reagent mixture. The digestion vessels were placed in the Berghof microwave oven, and a four-step digestion program was used as follows: Step 1--140 \({}^{\circ}\)C, time 10\({}^{\prime}\), power 90%; Step 2--180 \({}^{\circ}\)C, time 15\({}^{\prime}\), power 90%; Step 3--100 \({}^{\circ}\)C, time 15\({}^{\prime}\), power 90%; and Step 4--85 \({}^{\circ}\)C, time 5\({}^{\prime}\), power 90%. After cooling at room temperature, the digested samples were transferred to 50 mL volumetric flasks and then diluted with 0.5% HNO\({}_{3}\). A ContrAA 700 Analytik Jena spectrometer was used to investigate the concentration of HMs in soil and plants employing both flame and graphite oven methods. The results were expressed in mg kg\({}^{-1}\) d.w. (dry weight). The mineralogical compositions of soil and chemical groups in plant structures were analyzed using the ATR-FTIR method, with assistance from a Bruker Tensor 27 FTIR spectrometer that featured an ATR unit coupled with a diamond crystal. Soil and plant samples, prepared as described, were put as a thin layer onto the ATR device. Background correction was performed, and spectra were recorded as an average of 32 scans per analyzed sample within the range of 4000-400 cm\({}^{-1}\) and at a resolution of 4 cm\({}^{-1}\). Separation of the overlapping bands found into the complex 1250-850 cm\({}^{-1}\) absorption band was obtained by deconvolution using OriginPro 2016 (version 9.3.226) software. Curve fitting was performed by setting the number of component bands found by second derivative analysis and Lorentzian profile. The Scanning Electron Microscopy (SEM) method was used to analyze soil and plant samples to study their microstructure and surface morphology. The SEM images were captured using an SEM microscope, model FEI QUANTA 200, Thermo Fisher Scientific,Hillsboro, OR, USA. During imaging investigations, the electron beam was accelerated to an accelerating voltage of 20 kV, which was sufficient to obtain a secondary electron signal resulting from the excitation of as many constituent chemical elements as possible. The vacuum pressure was set to 60 Pa (medium vacuum), and the working distance was 10 mm. SEM images were taken at various magnifications, ranging from 250X (overview) to 5000X (structural details). For the SEM analysis, the samples were mounted on an aluminum support using double-adhesive carbon tape, following the protocol described by [26]. After the samples were dried, finely mortared, and pastilled, they were covered with a thin layer of gold before the microscopic analysis. The surface metallization step was performed using SPI Sputter Coater Module equipment (SPI Supplies, West Chester, PA, USA) at a pressure of 6 mbar and a plasma current intensity of 18 mA, resulting in a metal layer with a thickness of 10 nm. The SEM micrographs were complemented by the X-ray spectra through a semi-quantitative elemental analysis of the samples using the Energy-Dispersive X-ray Spectroscopy (EDX) method. This required the use of a Si (Li) detector, coupled to the SEM microscope. Four different micro areas were randomly selected and analyzed on a surface with an area of 60 um\({}^{2}\), calculating the average value of the percentage concentration of the elements. EDX spectra were recorded at a magnification of 5000X, and the measurement time was 100 s. To eliminate the matrix effect, the ZAF correction algorithm was applied (correction by atomic number (Z), absorbance (A), and fluorescence (F)), as suggested by [26]. The algorithm converted the apparent concentrations (raw spectral line intensity) into semi-quantitative concentrations. The PIGE technique used a proton beam with an energy of 3 MeV to irradiate environmental samples in a multi-target reaction chamber under vacuum (10\({}^{-5}\) mbar). An Ortec HPGe Gamma-ray detector (GEM10 PA-70) with a relative efficiency of 10% and a resolution of 1.75 keV at 1332 keV (60 Co) was used in the experimental setup.