Biological Recovery of Soil Impacted by 30,000 ppm of Gasoline

Abstract

Gasoline is a mixture of low and high molecular weight hydrocarbons, which spilled on the soil due to fuel theft, causes environmental pollution. In consequence the Mexican standard, called NOM-138- SEMARNAT/SSA1-2012, establishes a maximum allowed limit of 4,400 ppm gasoline in soil. Therefore, the objectives of this research were i) biological recovery of the soil impacted by 30,000 ppm of gasoline, by biostimulation with commercial detergent 123® plus a mineral solution ii) phytoremediation with Phaseolus vulgaris plus, Methylobacterium symbioticum and Xanthobacter autotrophicus, to decrease the concentration of gasoline to a value lower, than the maximum value of the NOM-138-SEMARNAT/SSA1-2012. Based in response variables after biostimulation: as well as: measurement of total hydrocarbons for the decrease in gasoline concentration. While during phytoremediation for the remaining gasoline: in P. vulgaris seeds, the days of emergence and germination percentage; in phenology and biomass in seedling stage, the final concentration of gasoline. The experimental data were analyzed by ANOVA/Tukey p<0.05%. The results indicated that in 35 days the biostimulation of the soil impacted by gasoline with 123® detergent and 50% mineral solution decreased it to 20,000 ppm. While 15 days after gemination the phytoremediation by P. vulgaris with M. symbioticum and X. autotrophicus seedling, healthy growth of the legume was observed, that improved 35 days after sowing to seedling stage; when P. vulgaris with M. symbioticum and X. autotrophicus grew healthy, that coincided with the decrease, in the gasoline concentration at 1000 ppm, lower than the maximum of NOM-138-SEMARNAT/SSA1-2012. This supports that the integration of biostimulation and phytoremediation, is an effective option for relatively, low concentrations of 30,000 ppm. In the reuse of this soil, with not risk to human and/or animal health.