Geochemical analysis of surface natural seepages and hydrocarbon fields of technogenic origin in the Amga River Basin (Siberian platform)

Abstract

The presence of substantial accumulations of bitumen is critically significant as they serve as direct indicators of oilbearing regions. However, in the context of environmental studies, their existence complicates the assessment of technogenic soil contamination by oil and petroleum products. The objective of this research was to identify informative geochemical parameters that would facilitate the differentiation between natural surface seepages and technogenic hydrocarbon fields resulting from commercial oil spills. This study examined natural surface oil seepages in the Amga River Basin and technogenic oil contamination near the Amga Oil Depot. Employing classical bituminology, Fourier transform infrared spectroscopy, gas chromatography, and mass spectrometry, a comparative analysis of their compositional characteristics was conducted. Notably, significant differences in geochemical parameters, such as the concentrations of hydrocarbons, resins, asphaltenes, and oxygen-containing compounds, were observed when comparing oil pollution to natural surface seepages for the first time. Furthermore, it was demonstrated that genetic parameters for diagnosing soil contamination by oil, based on biomarker composition, could include the presence of 12- and 13-methylalkanes in the hydrocarbon profile of the pollutant. These compounds are recognized as distinctive biological markers of Cambrian and Early Paleozoic oils from the Nepsko-Botuobinsk oil and gas region. Conversely, these biomarkers were absent in the natural surface oil seepages of Amga. The findings of this research may prove valuable in environmental studies, particularly in monitoring efforts aimed at identifying technogenic oil contamination in soils that are not associated with natural oil seeps.