Geophysicochemical characterization of soil contaminated with hydrocarbons in the northern of Veracruz

Purpose

In this study, a methodology is developed that involves geochemical and geophysical prospecting methods to identify the type and concentration of hydrocarbons, soil and water resistivity-salinity, and the delineation of hydrocarbon migration in the subsurface within an agricultural region in the northern part of the state of Veracruz, Mexico, where a landfill resulting from hydrocarbon exploitation is the contamination source.

Materials and methods

The methodology involves hydrocarbon fractionation by packed open column liquid chromatography (SARA: Saturates, Aromatics, Resins, and Asphaltenes), textural analysis by sieving, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM–EDX), salinity concentration, total petroleum hydrocarbon concentration in water (TPH), water resistivity, and salinity determination using a laboratory geo-electrical method and Electrical Resistivity Tomography (ERT).

Results and discussions

The hydrocarbon exhibited a stable colloidal stability, and the soil composition is of the general type, classified as clay-sandy with high concentrations of iron and strong salinity. The water showed TPH concentrations, and the resistivity and salinity exceeded the permissible limits set by Mexican standards. Electrical Resistivity Tomography delineated both recent and mature contamination.

Conclusions

With this methodology, it was determined that the region exhibits active contamination directly related to the exploration, exploitation, and pipeline leakage of hydrocarbons. The most affected area was the agricultural zone (low-lying area) due to the overflow of contaminated water from the landfill.