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Bench‐scale evaluation of in situ bioremediation strategies for soil at a former manufactured gas plant site
Author(s) -
Li Jun,
Pignatello Joseph J.,
Smets Barth F.,
Grasso Domenico,
Monserrate Esteban
Publication year - 2005
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/04-247r.1
Subject(s) - bioremediation , biodegradation , biostimulation , laboratory flask , environmental chemistry , chemistry , biotransformation , nutrient , desorption , polycyclic aromatic hydrocarbon , microorganism , tenax , contamination , adsorption , organic chemistry , bacteria , ecology , biology , genetics , enzyme
We examined the biodegradation and desorption of a set of 15 polycyclic aromatic hydrocarbon (PAH) compounds in coal tar–contaminated soil at a former manufactured gas plant site to evaluate the feasibility of in situ bioremediation. Experiments were conducted in well‐mixed aerobic soil suspensions containing various additives over a 93‐ to 106‐d period. In general, both biotransformation and desorption decreased with PAH ring size, becoming negligible for the six‐ring PAH compounds. Biodegradation by indigenous microorganisms was strongly accelerated by addition of inorganic nutrients (N, P, K, and trace metals). The rates of biotransformation of PAH compounds by indigenous microorganisms in nutrient‐amended flasks outpaced their maximum (i.e., chelate‐enhanced) rates of desorption to an infinite sink (Tenax®) in sterilized systems run in parallel, suggesting that indigenous organisms facilitated desorption. Biodegradation by indigenous organisms in nutrient‐amended flasks appeared to be unaffected by the addition of a site‐derived bacterial enrichment culture, resulting in approximately 100‐fold higher aromatic dioxygenase levels, and by the addition of 0.01 M chelating agent (citrate or pyrophosphate), although such chelating agents greatly enhanced desorption in microbially inactivated flasks. The strong ability of nutrients to enhance degradation of the bioavailable PAHs indicates that their persistence for many decades at this site likely results from nutrient‐limited natural biodegradation, and it also suggests that an effective strategy for their bioremediation could consist simply of adding inorganic nutrients.