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Title: Phytoremediation of composition-B derived TNT and RDX in herbaceous plant-vegetated and bare lysimeters
Authors: SpecPro, Inc.
Cold Regions Research and Engineering Laboratory (U.S.)
Strategic Environmental Research and Development Program (U.S.)
Best, E. P. H.
Smith, Jared C.
Ringelberg, David B.
Keywords: Composition-B
Herbaceous plants
Phytoremediation potential
Firing ranges
Training ranges
Soil pollution
Military installations
Environmental management
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: ERDC TR ; 09-10.
Description: Technical Report
Abstract: This report describes a study in which phytoremediation of composition-B (comp-B) derived TNT and RDX was quantified in 0.5-m S. nutans (Indian grass)-vegetated organic matter and nutrient-poor soil over a 92-day period. The vegetation was allowed to establish in 0.5-m-high soil cores prior to amendment with ground comp-B mixed with the same soil, and effects and fate of comp-B derived TNT and RDX were followed in plants, soil, and leachate under greenhouse conditions. Remediation in vegetated soils exceeded that in bare soils for TNT up to a comp-B level of 218 mg kg⁻¹, and for RDX up to a comp-B level of 73 mg kg⁻¹. Thus, phytoremediation can be used as an effective remediation technology in a given range of explosives contamination. The greatest annual remediation potential was 58.5 g TNT m⁻² and 42.4 g RDX m⁻² in vegetated soils, and 54.5 g TNT m⁻² and 51.0 g RDX m⁻² in unvegetated soils. Remediation was attributed to a large degree to processes other than plant uptake, including bioremediation (plant-assisted or not), complexation with plant material and soil components leading to non-extractability, and photolysis (limited to the upper soil layer). Results of a comparison between ¹⁵N-based and chemical-RDX-based mass balances, with ¹⁵N derived from uniformly labeled ¹⁵N-RDX, indicated greater incorporation of ¹⁵N than of RDX in soil and plants of vegetated units than in soil of non-vegetated units. This was attributed to the incorporation of RDX metabolites generated by the increased microbial community biomass and activity, stimulated by exuded plant compounds, and to RDX transformation within the plants themselves. Sorption coefficients for Camp Shelby soil were low, indicating considerable potential for explosives leaching. These coefficients were three times greater for TNT than RDX. Despite the considerable leaching potential derived from the measured sorption coefficients, leaching was very low compared to loss of explosives due to processes other than plant uptake. The microbial communities in the upper soil layer showed decreased biomass with increasing comp-B exposures. Community shifts were subtle if at all. However, a presumed hysteresis effect was observed in the vegetated soil at a comp-B exposure of 146 mg kg⁻¹ soil.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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