PT07 Contaminated Harbor and River Sediment
Exhibit Hall
8:00 AM - Tuesday, 11 November 2003
(PT104) Monitoring Toxicological Changes During Biotransformation of Munitions in Sediments: Microbial Community Profiling II.
Johnson, B1, Nipper, M2, Carr, R3, 1 Columbia Environmental Research Center, Columbia, MO, USA2 Texas A&M University, Corpus Christi, TX, USA3 Columbia Environmental Research Center, Columbia, MO, USA
ABSTRACT- The oceans of the world are common repositories for military munitions during both acts of war and times of peace. This investigation examined in microcosm under aerobic conditions the changing toxicity during biotransformation of two explosive chemicals of concern. Trinitrophenol (picric acid) and 2,6-dinitrotoluene (2,6-DNT) were spiked in different marine sediments (sandy vs. loamy, low vs. high TOC) over a 56-day interval (1, 3, 7, 14, 28, and 56) at 10oC and 20oC. Microbial profiles of bacterial diversity of aerobic heterotrophs were obtained using enzyme specific assays: Colilert (Idexx) for total coliforms, SimPlate (Idexx) for total heterotrophs, and EcoPlates (Biolog) for microbial diversity. The biotransformation of both picric acid and 2,6-DNT was faster in the loamy, high TOC sediment at 20oC. HPLC chromatograms suggested that both compounds completely disappeared within 8 to 12 weeks. Most-probable-number assays of total heterotrophic populations clearly reflected significant population changes during biotransformations. An initial increase of total heterotrophs was followed by 2 to 10-fold decrease between Day 1 and Day 3 and then by Day 7 a rapid heterotroph recovery to Day 0. Microbial profiling clearly demonstrated measurable qualitative and quantitative changes in both heterotrophic activity and diversity during 2,6-DNT and picric acid biotransformation in aerobic marine sediments.
Key words: Munitions, Biotransformation, Biodiversity, Profiling