Toxicity of explosives contaminated soil to plants

• Published in: Phytopathology 2004-06, Vol.94 (6)
• Main Authors: Simini, M, Checkai, R T, Kuperman, R G, Phillips, C T, Kolakowski, JE, Kurnas, C W
• Format: Article
• Language: English
• ISSN: 0031-949X

Military sites associated with munitions manufacturing, disposal, testing, and training frequently contain elevated levels of explosives and related materials in soil. Their effects on plants have not been sufficiently investigated. To address this problem, the U.S. Environmental Protection Agency, together with stakeholders, is developing Ecological Soil Screening Level (Eco-SSL) values for use in Ecological Risk Assessment of chemicals often found at Superfund sites, including explosives. We performed plant toxicity tests to develop Eco-SSL values for two energetic materials (EMs), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 2,4,6-trinitrotoluene (TNT) using adapted ASTM and U.S. EPA guidelines. Alfalfa, Japanese millet, and perennial ryegrass were subjected to various levels of the two EMs in 5 soil types having different levels of clay (12% to 37%), organic matter (1% to 5%), and pH (4.4 to 7.4). Growth chamber tests were conducted at 22 + 2 degree C and 16 h light/8 h dark cycle with >70% relative humidity. Percent seed germination and shoot wet and dry mass were measured after a two-week growth period. Preliminary results showed TNT toxicity to all species tested. Lowest Observed Adverse Effect Concentration (LOAEC) of TNT ranged from 100 mg/kg to 400 mg/kg. Soil type had no effect on TNT toxicity. RDX was not toxic to any of the species tested in all soils tested up to 10,000 mg/kg. Results of ongoing studies with TNT amended soils will be used to determine the effective concentration producing 20% reduction in biomass (EC sub(20)) for Eco-SSL development.