Isotopic topology hierarchy decoupling (ITHD): A new method for high-resolution gasoline source attribution and...

The escalating environmental contamination and regulatory breaches stemming from illicit and substandard gasoline urgently demand high-resolution source attribution. Current provenancing methods are severely limited by the complex interplay of intrinsic crude oil geochemistry and anthropogenic refining-induced isotopic fractionation, rendering precise source identification elusive. Addressing this critical analytical bottleneck in environmental forensics, we introduce the Isotopic Topology Hierarchy Decoupling (ITHD) framework. The ITHD refers to the spatial and hierarchical structuring of isotopic signals that arise from both natural geographical factors and anthropogenic refining processes. Leveraging compound-specific carbon stable isotope ratios from extensive Chinese refinery gasoline samples, ITHD uniquely disentangles these convoluted signals, providing mechanistic interpretability into both regional crude oil origins and manufacturer-specific refining process variations. ITHD achieves robust high-accuracy regional provenance (97.8 %). Crucially, it identifies distinct manufacturer-specific isotopic fingerprints through orthogonal signal processing, enabling definitive tracing to individual refineries. Furthermore, a novel topological network analysis quantifies subtle inter-source similarities, effectively resolving ambiguities in challenging forensic scenarios. Successfully applied to 9 real-world illicit gasoline cases across diverse regions in China, the ITHD framework consistently delivered conclusive and validated source attribution, providing actionable and defensible evidence. This pioneering framework not only significantly advances environmental forensics by setting a new paradigm for high-resolution fuel provenance but also provides a critical tool for strengthening environmental governance and combating illicit trade, generating actionable and defensible evidence.