Molecular composition of water soluble fraction of petroleum products and crude oils: Insights into groundwater contamination potential and environmental forensics

Petroleum leakage is a major groundwater contamination source, with chemical composition of water soluble fractions (WSFs) from diverse oil sources significantly impacting groundwater quality and source identification. The aim of this study was to assess impact of 15 diverse oils on groundwater quality and environmental forensics based on oil-water equilibrium experiments. Our results indicate that contamination of groundwater by gasoline and naphtha is primarily attributed to volatile hydrocarbons, while pollution from diesel, kerosene, and crude oil is predominantly from non-hydrocarbons. Rapid determination of the extent of non-hydrocarbon pollution in WSFs was achieved through a new quantitative index. Gasoline and naphtha exhibited the highest groundwater contamination potential while kerosene and light crude oils were also likely to cause groundwater contamination. Although volatile hydrocarbons in the WSFs of diesel and jet fuel do not easily exceed current regulatory standards, unregulated non-hydrocarbons may pose a more severe contamination risk to groundwater. Notably, the presence of significant benzene and toluene, hydrogenation and alkylation products (e.g., C4-C5 alkylbenzenes, alkylindenes, alkyltetralins, and dihydro-indenes), cycloalkanes in WSFs can effectively be utilized for preliminary source identification of light distillates, middle distillates, and crude oils, respectively.