Assessment of chemical content of base oil blends used as alternative diesel fuel for environmental safety

• A study of chemical characterization of base oil blends used as diesel substitute.
• Spatial heterogeneity of pollutant levels suggests poor control measures.
• Enrichment of Zn, Mo, Cl indicates blending with used motor oil.
• Estimated emission rates were far beyond the industrial sources.

Increases in crude oil prices have led the transportation sector drivers to seek alternative cheaper fuels for diesel engines. A blend of virgin and/or non-standard base oils with diesel fuel called Number 10 lube (NTL) has been widely used for such purposes in public buses or trucks all over Turkey. This study was conducted as a first step to assess the occurrence, spatial distribution, and potential sources of Ag, As, Ba, Bi, Cd, Cl, Co, Cr, Fe, Li, Mn, Mo, Ni, Pb, Rb, Se, Sr, Tl, V, and Zn in this generic oil to make further evaluation of environmental and public health. A microwave-assisted combustion procedure was applied for the determination of metals and metalloids in NTL samples by inductively coupled plasma-mass spectrometry while a field test method was used for Cl. The range of total metallic/metalloid elements and chlorine concentration was between 0.04 and 189 μg/g, and from below detection to 825 μg/g, respectively. Unexpectedly, samples varied in types and levels of constituents between the western and eastern parts of the country. The enrichment of Zn, Mo, and Cl in NTL samples suggests that some sort of waste oils, lubricating oils, chlorinated solvents, or transformer oils were mixed with base oils. The metal emission rates derived from the annual consumption of NTLs were far beyond the estimations for diesel vehicles and industrial sources. Therefore, the problem, which leads to financial, environmental, and health concerns in Turkey, could probably be experienced in other countries and, thus, should be managed properly.