“Humic Coverage Index” as a Determining Factor Governing Strain-Specific Hydrocarbon Availability to Contaminant-Degrading Bacteria in Soils

• Published in: Environmental science & technology Vol. 37; no. 22; pp. 5168 - 5174
• Main Authors: Bogan, Bill W, Sullivan, Wendy R, Cruz, Kristine H, Paterek, J. Robert, Ravikovitch, Peter I, Neimark, Alexander V
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.11.2003
• Subjects: Alkanes - analysis; Applied sciences; Bacteria; Bacteria - growth & development; Biodegradation; Biodegradation, Environmental; Biological and physicochemical properties of pollutants. Interaction in the soil; Biological Availability; Contamination; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Gram-Negative Aerobic Rods and Cocci - growth & development; Humic Substances - analysis; Hydrocarbon leakage & seepage; Hydrocarbons; Mycobacterium - growth & development; Phenanthrenes - analysis; Pollution; Pollution, environment geology; Polycyclic Aromatic Hydrocarbons - analysis; Pyrenes - analysis; Soil and sediments pollution; Soil Microbiology; Soil Pollutants - analysis; Soils; Species Specificity; Biodegradation; Microbial activity; Organic matter; Phenanthrene; Hydrocarbon; Aliphatic compound; Pollutant behavior; Property of soil; Index; Polycyclic aromatic compound; Soil pollution; Hexadecane; Pyrene; Medium effect; Mineralization; Model compound; Bacteria; Fulvic acid; Humic acid
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es030425w

We report development of a novel parameter for quantifying the amount of humic and fulvic acids per unit surface area in a particular soil. This quantity, the “humic coverage index” (HCI), provides a measurement of the relative spatial extents and/or thicknesses of the humic/fulvic overlayers in different soils, and, therefore, can be used in modeling various soils' behavior in sequestration processes in which humic materials are involved. HCI is herein applied to modeling biodegradation of aromatic and aliphatic hydrocarbons (phenanthrene, pyrene, and hexadecane) by several bacterial strains. Results indicate that, for the cases studies here, contaminant biodegradation is highest at a particular HCI and decreases if the coverage density of humic material is lower or higher than this optimum value. The HCI value at which maximal degradation was observed varied across different strains (indicating strain-specific differences in ability to degrade contaminants sorbed to humic materials) and, to a lesser extent, across different contaminants. The HCI concept is also demonstrated to be useful in explaining soil-, strain-, and contaminant-specific variations in the ability of fulvic acid supplementation to enhance contaminant biodegradation. Finally, we show that, in general, strains which are comparatively better at degrading contaminants in high-HCI soils also show enhanced contaminant mineralization in vitro in the presence of humic acids, such as when hydrocarbons are adsorbed onto these materials.