Physicochemical-mineralogical characterization of automobile garage soils with identification of potentially toxic elements (trace metal elements, total petroleum hydrocarbons) and principal component analysis.

Petroleum spills are increasingly reported in tropical regions, particularly at non-compliant automobile garages. Consequently, this study aimed to characterize soils contaminated by petroleum products from automobile garage sites and to assess their potential environmental impacts. To achieve this, soil physicochemical properties, trace metal elements (TMEs), mineralogical composition, total solvent extractable materials (TSEM), and total petroleum hydrocarbons (TPH) were analyzed using standard analytical techniques. Results indicated that control soils (CS) were alkaline (pH 9.05) with trace metal elements concentrations below detection limits, whereas garage floor soils (GFS) exhibited decreased pH (6.818.47) and elevated levels of Cr (902050 mg/kg), Ni (50750 mg/kg), Cu (7001000 mg/kg), Zn (90320 mg/kg), and Pb (110340 mg/kg). Quartz was identified as the dominant mineral phase in all soils, and corresponded to petroleum-derived functional groups including mercaptans, aromatics, and esters, which were detected in GFS. TSEM concentrations were high across the studied sites: GFS1 (4.53 ± 0.48%), GFS2 (4.00 ± 0.14%), GFS3 (8.67 ± 0.64%), and GFS4 (5.57 ± 0.08%). Moreover, characterization of TPH revealed detectable hydrocarbons, including n-alkanes, polycyclic aromatic hydrocarbons (PAHs), and petroleum biomarkers (pristane and phytane). In addition, principal component analysis (PCA) further showed that the first two components, Dim1 and Dim2, explained 73.4% of the total variance, reflecting the combined influence of physicochemical, mineralogical, and contamination parameters. Overall, the co-occurrence of hydrocarbons and trace metal elements in garage soils represents significant environmental and ecotoxicological risks, with potential implications for human health.