PARENT SESSION
Poster Session # 12: Ecotoxicology, Pathogens, and Disease.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Detection of changes in vegetation properties induced by military range land-contaminants containing TNT.
Entcheva Campbell, Petya*,1, Middleton, Elizabeth*,1, Corp, Lawrence*,1, McMurtrey, James2, Butcher, Ladine*,1, Chappelle, Emmett1, 1 Biospheric Sciences Branch, Greenbelt, MD 20771, USA2 Hydrology & Remote Sensing Laboratory, Beltsville, MD 20705, USA
ABSTRACT- Due to the environmental impacts of toluene, EPA has mandated that land mines on US military ranges must be located and removed. Furthermore, pending international agreements require the removal of land mines placed on foreign lands. Currently, there are no satisfactory methods for locating military range land-contaminants, and for delineation of the ecological impacts of leaked trinitrotoluene (TNT). This research determines the changes in vegetation morphology, bio-physiology, spectral fluorescence (F) and reflectance (R), for vegetation growing on TNT contaminated soils. The study aims at the establishment of indicators (biological, spectral F and R) of the presence of TNT-related compounds sequestered in vegetation. During the summer of 2002, corn (C4), soybean (C3) and pigweed (C4) were grown in a 3x4 factorial study: 3 species, 4 TNT levels (0% = water for control, 25% = 20 ppm TNT, 50% = 40 ppm TNT, 100% = 80 ppm TNT), 12 replicates per treatment. Fully expanded sun leaves from mature plants were used for R and actively induced F measurements. Contemporaneously, foliar photosynthetic function and plant constituent levels (chlorophyll, N and C) were determined. The TNT treatments induced significant changes in vegetation morphology, spectral F and R properties, which were more pronounced for the C4 plants (pigweed and corn). The TNT-treated plants accumulated significantly less biomass, held lower amounts of tissue water, were significantly lighter (DWcorn r2=0.82, p<0.01; DWpigweed r2=0.88, p<0.01), shorter (Hcorn r2=0.72, p<0.05; Hpigweed r2=0.87, p<0.01) and had thinner stems (BDcorn r2=0.75, p<0.01: Hpigweed r2=0.86, p<0.01). Foliar parameters (area, length, dry weight, pigment levels and photosynthetic efficiency) were significantly reduced and the C/N balance altered. This study documents that in the above-ground tissues of vegetation, TNT induces significant morphological and metabolic changes, leading to alterations of vegetation spectral F and R properties that are detectable via remote sensing. Monitoring of vegetation vigor based on fluorescence and reflectance measurements could provide the necessary means for detecting contamination from (TNT), a frequent military range land-contaminant.
Key words: Bio-indicators of vegetation stress, spectral indicators of vegetatrion stress, Remote Sensing: reflectance and fluorescence, delineation of the effects trinitrotoluene