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Title: Plant-bacterial combinations to phytoremediate soil contaminated with high concentrations of 2,4,6-trinitrotoluene

Abstract

The explosive 2,4,6-trinitrotoluene (TNT) is a contaminant of concern at abandoned manufacturing and military sites because of its mobility and toxicity. Phytoremediation may play a role in natural attenuation scenarios by reducing TNT levels at point sources. The purpose of this study was to develop a phytoremediation system suitable for use in soils contaminated with high TNT levels. Sixteen grasses were screened for their tolerance to 41 g TNT kg{sup 1} soil. Meadow bromegrass (Bromus erectus Huds.), perennial ryegrass (Lolium perenne L.) and sweet vernalgrass (Anthoxanthum odoratum L.) grew in this soil. Inoculating these grasses with Pseudomonas sp. Strain 14, capable of transforming TNT into mono- and di-amino metabolites, increased the growth of meadow bromegrass but was lethal to perennial ryegrass and sweet vernalgrass. Meadow bromegrass inoculated with strain 14 reduced TNT levels by 30% compared with the control soil and had 50% more plant biomass than noninoculated plants. Meadow bromegrass, combined with strain 14, increased the percentage of the culturable soil heterotrophic population containing the genes involved in 2-nitrotoluene (ntdAa) metabolism 3-fold, as well as the population containing the genes involved in 4-nitrotoluene (ntnM) metabolism 14-fold. strain 14 inoculation of meadow bromegrass altered the portion of the rhizosphere communitymore » involved in nitroaromatic metabolism and led to a reduction in soil TNT levels.« less

Authors:
;
Publication Date:
Research Org.:
Biotechnology Research Inst., Montreal, Quebec (CA)
OSTI Identifier:
20075834
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Environmental Quality; Journal Volume: 29; Journal Issue: 1; Other Information: PBD: Jan-Feb 2000
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE; TNT; SOILS; REMEDIAL ACTION; BIODEGRADATION; PLANTS; PSEUDOMONAS

Citation Formats

Siciliano, S.D., and Greer, C.W. Plant-bacterial combinations to phytoremediate soil contaminated with high concentrations of 2,4,6-trinitrotoluene. United States: N. p., 2000. Web. doi:10.2134/jeq2000.00472425002900010039x.
Siciliano, S.D., & Greer, C.W. Plant-bacterial combinations to phytoremediate soil contaminated with high concentrations of 2,4,6-trinitrotoluene. United States. doi:10.2134/jeq2000.00472425002900010039x.
Siciliano, S.D., and Greer, C.W. Tue . "Plant-bacterial combinations to phytoremediate soil contaminated with high concentrations of 2,4,6-trinitrotoluene". United States. doi:10.2134/jeq2000.00472425002900010039x.
@article{osti_20075834,
title = {Plant-bacterial combinations to phytoremediate soil contaminated with high concentrations of 2,4,6-trinitrotoluene},
author = {Siciliano, S.D. and Greer, C.W.},
abstractNote = {The explosive 2,4,6-trinitrotoluene (TNT) is a contaminant of concern at abandoned manufacturing and military sites because of its mobility and toxicity. Phytoremediation may play a role in natural attenuation scenarios by reducing TNT levels at point sources. The purpose of this study was to develop a phytoremediation system suitable for use in soils contaminated with high TNT levels. Sixteen grasses were screened for their tolerance to 41 g TNT kg{sup 1} soil. Meadow bromegrass (Bromus erectus Huds.), perennial ryegrass (Lolium perenne L.) and sweet vernalgrass (Anthoxanthum odoratum L.) grew in this soil. Inoculating these grasses with Pseudomonas sp. Strain 14, capable of transforming TNT into mono- and di-amino metabolites, increased the growth of meadow bromegrass but was lethal to perennial ryegrass and sweet vernalgrass. Meadow bromegrass inoculated with strain 14 reduced TNT levels by 30% compared with the control soil and had 50% more plant biomass than noninoculated plants. Meadow bromegrass, combined with strain 14, increased the percentage of the culturable soil heterotrophic population containing the genes involved in 2-nitrotoluene (ntdAa) metabolism 3-fold, as well as the population containing the genes involved in 4-nitrotoluene (ntnM) metabolism 14-fold. strain 14 inoculation of meadow bromegrass altered the portion of the rhizosphere community involved in nitroaromatic metabolism and led to a reduction in soil TNT levels.},
doi = {10.2134/jeq2000.00472425002900010039x},
journal = {Journal of Environmental Quality},
number = 1,
volume = 29,
place = {United States},
year = {Tue Feb 01 00:00:00 EST 2000},
month = {Tue Feb 01 00:00:00 EST 2000}
}
  • The addition of food-grade surfactants could improve the use of native soil bacteria to biodegrade explosives-contaminated soil under co-metabolic conditions by enhancing the rates of explosives` desorption from soil, thus increasing the bioavailability of explosives for microbial degradation. The objective of this study is to decrease residence time in the reactor, thereby increasing output and reducing cleanup costs. In this study, Tween 80 (monooleate) served not only as a surfactant but also as the carbon substrate for soil microorganisms. Four 2-L soil slurry reactors were operated in batch mode with soil containing 2,4,6-trinitrotoluene (TNT). Results indicated that TNT was removedmore » in all reactors except the control (no added carbon source). The reactor enriched with surfactant and molasses performed better than reactors with either molasses or surfactant alone. The TNT and its metabolite, 4-amino-2,6-dinitrotoluene, were removed faster in the reactor with surfactant plus molasses than in the reactor with molasses alone as carbon source. A radiolabeling study of the mass balance of TNT in the slurry reactors showed substantial mineralization of TNT to carbon dioxide.« less
  • The successful operation of an aerobic/anoxic laboratory-scale soil slurry reactor showed that soil contaminated with 2,4,6-trinitrotoluene (TNT) and hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX) could be treated in batches or semicontinuously. Batch treatment resulted in the transformation of TNT. Semicontinuous treatment resulted in complete degradation of TNT. In addition to removing TNT, the slurry reactor also removed contaminants such as trinitrobenzene, 2,4-dinitrotoluene, RDX, and octahydro-l,3,5,7-tetranitro-l,3,5,7-tetraazocine (HMX). Radiolabeled TNT incubated with reactor biomass showed that 23% of [{sup 14}C]TNT was mineralized, 27% was converted to biomass, and 8% was adsorbed onto the soil. The rest of the [{sup 14}C]TNT was accounted for as metabolites, includingmore » a ring cleavage product identified as 2,3-butanediol. Increasing the frequency of soil addition from once to two or three times weekly did not affect the TNT removal rates. The soil slurry reactor also maintained the bacterial population fairly well, needing only 0.3% molasses as a cosubstrate.« less
  • The US Army is obligated to restore land previously contaminated with the explosive 2,4,6-trinitrotoluene (TNT). One remediation method that is being tried is composting. In this method, the soil to be treated is mixed with a readily decomposable source of organic carbon, which is usually a mixture of readily available organic material. Samples of composted soil were extracted with solvent, then hydrolyzed with acid or base. The concentrations of extractable, unbound 2,4,6-trinitrotoluene and its mono- and diamino metabolites fell rapidly after the first days of composting. Hydrolysis of the extracted residues released significant quantities of intact metabolites. The objectives ofmore » this work were to differentiate between bound and unbound explosives and their transformation products in composted soil, to investigate the time course of metabolite evolution and binding, and to evaluate various hydrolysis methods.« less
  • Previous studies have failed to provide an acceptable mass balance for 2,4,6-trinitrotoluene (TNT) in soils and plants due to deficiencies in analytical methodology. A high-performance liquid chromatographic (HPLC) method for soil analysis is reported which allowed for a mass balance in excess of 88% during a 2-month study. A method for plant analysis was developed which involved fractionation of organic extracts on Florisil adsorbent, to remove interfering pigments, followed by HPLC analysis of TNT and the primary metabolites, 2-amino-4,6-dinitrotoluene and 4-amino-2,6-dinitrotoluene. Chromatographic recovery of TNT from spiked tissues was 85{plus minus}6%. The methodology was utilized to investigate TNT uptake andmore » metabolism in plants grown in TNT hydroponic solutions.« less
  • The response of potential nitrification activity (PNA), nitrogen-fixation activity (NFA), and dehydrogenase activity (DHA) in soil to 2,4,6-trinitrotoluene (TNT) was assessed. Two garden soils of contrasting texture were spiked with TNT. Soil microbial activities and TNT residues were analyzed 1 week later. The estimated IC50 ranged from 39 to 533 mg/kg of the acetonitrile-extractable (AE) TNT, depending on indicators and soils. The lowest LOEC (lowest-observed-effect concentration) was 1 mg AE TNT/kg. Field soil was collected from three known contaminated sites in an abandoned TNT manufacturing facility. Microbial toxicity significantly correlated to TNT levels in these soils. The LOEC and NOECmore » (no-observed-effect concentration) values were site and indicator specific, with the lowest LOEC being 1 mg AE TNT/kg and the lowest NOEC being 0.4 mg AE TNT/kg. The IC50 of the pooled field samples was 51 mg AE TNT/kg for PNA or 157 mg AE TNT/kg for DHA. These results indicate that microbial responses were consistent and comparable between the laboratory and the field and that TNT could significantly inhibit soil microbial activities at very low levels. Both AE TNT and deionized water-extractable (DW) TNT concentrations correlated well with microbial toxicity, but AE TNT provided a better evaluation of TNT bioavailability than did DW TNT.« less