In order to investigate the contamination and attenuation of BTEX compounds from fuel tank leaks into the Basin of Lucaia’s river aquifer, Salvador, Bahia (Brazil), it was determined in samples of groundwater concentrations of volatile aromatics benzene, toluene, ethylbenzene and xylenes (BTEX), sulfate, nitrate and iron (II) in two distinct periods. The concentrations of compounds were compared to ascertain the yield reduction of BTEX in the sampling points up to 82%. Isotenor curves were generated by observing the behavior of composites and the relation of Eh and nitrate consumption with natural attenuation of BTEX, verifying that it does not occur in a wide spread critical levels and dangerous for the population
