Assessment of heavy metal contamination (Pb, Ni, Cr, and Cd) in automotive fuels from Central India

The presence of toxic heavy metals such as lead (Pb), nickel (Ni), chromium (Cr), and cadmium (Cd) in fossil fuels remains a growing environmental and public-health concern due to their persistence, bioaccumulation, and potential release during fuel combustion. This study assessed the concentrations of these metals in petrol and diesel samples collected from fuel stations across Central India. Over 200 fuel samples were collected, from which 30 representative sub-samples were analyzed using microwave-assisted digestion followed by Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES). All four metals were detected in both fuel types. In diesel, average concentrations were 0.028 ppm (Pb), 0.049 ppm (Cr), 0.0012 ppm (Cd), and 0.032 ppm (Ni), while petrol samples exhibited 0.015 ppm (Pb), 0.043 ppm (Cr), 0.0011 ppm (Cd), and 0.034 ppm (Ni). Diesel contained 90%, 14%, and 9% higher concentrations of Pb, Cr, and Cd, respectively, compared to petrol, whereas Ni was marginally lower. Statistical analyses revealed a significant difference only for Pb (p < 0.05). A moderate positive correlation between Ni and Cr in petrol was also observed. These findings provide crucial baseline data regarding heavy-metal contamination in automotive fuels in Central India and highlight the potential emission of toxic metals into the environment. The results underscore the need for regulatory attention, improved monitoring, and further research to understand the implications of metal-contaminated fuels on air quality and human health.