Caracterização da contaminação por bisfenol A e microplásticos em solos de área urbana de Francisco Beltrão e seu entorno

Abstract

Contamination by bisphenol A (BPA) and microplastics in aquatic and terrestrial matrices has intensified in recent decades, becoming an emerging issue of environmental and public health relevance. At five sampling points in the municipality of Francisco Beltrão, state of Paraná, selected based on land use and anthropogenic influence criteria (rural area with heavy traffic, peripheral industrial region, surroundings of a recycling station, proximity to a highway and health unit, and consolidated industrial area), 700 g of soil were collected at a depth of 10-20 cm, using representative subsamples. The samples were subjected to granulometric analyses, which revealed textures ranging from sandy (P1: 22.5% sand) to predominantly clayey (P3: 81% clay; P5: 79% clay), and chemical analyses that showed organic matter contents between 0.402% (P4) and 3.753% (P2), acidic to slightly acidic pH (4.8 to 5.8), and cation exchange capacity (CEC) ranging from 8.72 to 67.69 cmolc kg⁻¹. Fourier transform infrared spectroscopy (FTIR) identified characteristic bands of clay minerals, organic matter, and silicate impurities, with a specific band at 1100 cm⁻¹ in sample P3, suggesting the presence of synthetic organic materials. For BPA extraction, 5 g of previously homogenized soil was used, employing HPLC-grade solvents: methanol and ultrapure water solution (80:20 v/v), and 0.1 mol L⁻¹ NaOH solution to promote the desorption of BPA adsorbed to the soil. The resulting solution was subjected to ultrasonic agitation for 20 minutes and centrifuged at 4000 rpm for 30 minutes. The supernatant was analyzed by liquid chromatography coupled with mass spectrometry (LC-MS/MS), conducted on a Biphenyl column (2.1×100 mm, 3 μm) at 40 °C, using a mobile phase consisting of water and methanol, with a flow rate of 0.3 mL min⁻¹ and an injection volume of 5 μL. The analytical method demonstrated satisfactory performance, with a detection limit (LOD) of 3.39 μg kg⁻¹, a quantification limit (LOQ) of 10.27 μg kg⁻¹, a coefficient of variation of less than 7%, and accuracy between 83% and 101%. The results showed the ubiquitous presence of BPA in all samples, with concentrations ranging from 1.256 μg kg⁻¹ (P1) and 234.557 μg kg⁻¹ (P5), the latter being approximately 60 times higher than the concentration of P3 and 8,000 times higher than the averages reported in agricultural soils globally, indicating critical contamination in the consolidated industrial area. The integrated analysis revealed that BPA distribution is modulated by soil texture, organic matter content, pH, and, above all, the intensity of local anthropogenic activities, with clay soils demonstrating greater retention capacity in the surface layers and sandy soils showing greater susceptibility to vertical leaching. The objective of this study was to investigate the occurrence of Bisphenol A in urban and peri-urban soil samples, providing unprecedented data for the southwestern region of Paraná that highlight the need for systematic monitoring in terrestrial environments, the establishment of regional guideline values, the assessment of ecotoxicological risks, and the elucidation of exposure routes related to this emerging contaminant.