Leachability of volatile fuel compounds from contaminated soils and the effect of plant exudates: A comparison of column and batch leaching tests

• Published in: Journal of hazardous materials 2016-03, Vol.304, p.481-489
• Main Authors: Balseiro-Romero, María, Kidd, Petra S., Monterroso, Carmen
• Format: Article
• Language: English
• Subjects: Adsorption; Batch; Benzene Derivatives - chemistry; Ethyl Ethers - chemistry; Holcus; Leaching potential; Methyl Ethers - chemistry; Packed-columns; Plant Exudates - chemistry; Plant root exudates; Soil - chemistry; Soil Pollutants - chemistry; Volatile fuel contaminants
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.11.017

•Contaminant leachability was influenced by soil composition.•Soil organic matter hindered leaching of the most hydrophobic contaminants.•Soil inorganic components hindered leaching of the least hydrophobic contaminants.•Batch shaking favoured contaminant desorption and annulled differential sorption.•Plant exudates influence soil-contaminant interactions. Volatile fuel compounds such as fuel oxygenates (FO) (MTBE and ETBE) and BTEX (benzene, toluene, ethylbenzene and xylene) are some of the most soluble components of fuel. Characterizing the leaching potential of these compounds is essential for predicting their mobility through the soil profile and assessing the risk of groundwater contamination. Plant root exudates can play an important role in the modification of contaminant mobility in soil–plant systems, and such effects should also be considered in leaching studies. Artificially spiked samples of A and B horizons from an alumi-umbric Cambisol were leached in packed-columns and batch experiments using Milli-Q water and plant root exudates as leaching agents. The leaching potential and rate were strongly influenced by soil-contaminant interactions and by the presence of root exudates. Organic matter in A horizon preferably sorbed the most non-polar contaminants, lowering their leaching potential, and this effect was enhanced by the presence of root exudates. On the other hand, the inorganic components of the B horizon, showed a greater affinity for polar molecules, and the presence of root exudates enhanced the desorption of the contaminants. Column experiments resulted in a more realistic protocol than batch tests for predicting the leaching potential of volatile organic compounds in dissimilar soils.