Remote detection of plant physiological responses to TNT soil contamination

Abstract

Our study was aimed at understanding physiological responses to trinitrotoluene (TNT) soil contamination, and using optical methods to detect TNT-induced stress in a woody plant prior to visible changes. Myrica cerifera plants were potted in soil concentrations of TNT ranging from 30-500 mg kg −1 . Physiological measurements were significantly affected by TNT exposure at all treatment levels, and photosynthetic decline likely resulted from metabolic impairment rather than stomatal closure as the experiment progressed. Several reflectance indices were able to detect TNT-induced stress before any changes in chlorophyll concentrations occurred. The most sensitive index was the simple ratio R 761 /R 757 which is linked to fluorescence in-filling of the 0 2 atmospheric absorption. Changes at R 740 /R 850 and R 735 /R 850 may be attributed to both fluorescence and structural characteristics of leaf anatomy in the near infrared region. This could have been influenced by transformation and conjugation of TNT metabolites with other compounds. chlorophyll index (CHL) or in the water band index (WBI 970 ), which are indices typically associated with drought stress, and may provide a means of separating stress due to explosives. Further studies need to be conducted with a combination of stressors (TNT and natural) to determine if responses are in fact generalized or if any of these changes are separable from natural stress. AbbreviationsTNT Trinitrotoluene PPFD photosynthetic photon flux density g wv stomatal conductance A Net net photosynthetic rate F o minimal fluorescence in dark-adapted leaves F m maximal fluorescence in dark-adapted leaves F v /F m maximum quantum use efficiency of PSII in the dark-adapted state F′ o minimal fluorescence in light-adapted leaves F′ m maximal fluorescence in light-adapted leaves F s steady-state fluorescence ΔF/F′ m, fraction of absorbed photons that are used for photochemistry in a light-adapted leaf F′ v /F′ m effective quantum use efficiency of PSII in the light-adapted state PSII photosystem II WBI water band index Plant Soil (

Remote Sensing of Explosives-Induced Stress in Plants: Hyperspectral Imaging Analysis for Remote Detection of Unexploded Threats

“…Research is extremely limited on comparing drought conditions to plant stress caused by explosives [16]. Some studies have explored uptake of explosives by agronomic species [13,17] and how the reflectance of shrubs is affected by explosives [14,16,18], but none have done both. The research presented here was conducted in conjunction with a field-scale drought experiment that utilized the same genotypes assessed with the same aerial-based HSI methods.Hyperspectral imagery has been utilized for decades on vegetation for early stress detection to mitigate potential agricultural crop losses.…”

“…Minimal research has been directed at using plants to detect explosives in soil. Previous energetics detection work involved using handheld spectroradiometers to obtain reflectance of leaves and calculating reflectance indices [14,18]. Reflectance Index values were compared to plant functional traits, and it was found that stomatal conductance and photosynthesis were negatively affected by concentrations as low as 100 mg kg −1 RDX in soil, while pigment concentrations were decreased beginning at 500 mg kg −1 RDX for the coastal pioneer species, Baccharis halimifolia [14].The objective of this contribution was to begin developing effective methods of detecting plant stress from explosives by comparing distinct hyperspectral reflectance signatures of drought and RDX-exposed plants at a species-specific level for canopy-wide application.…”

Right on target: using plants and microbes to remediate explosives

“…By measuring multiple variables representing morphological and physiological responses, such studies identified vegetation responses that could potentially be used to determine levels of TNT and RDX contamination (Ali et al 2014;Via and Zinnert 2016;Via et al 2017Via et al , 2015. Hyperspectral imaging technologies are also being developed to remotely detect vegetation response (Naumann et al 2010) using aerial drones as suitable carriers to record contamination levels on surfaceinaccessible sites.…”

Morphogenesis of sporotrophophyll leaves in Platycerium bifurcatum depends on the red/far-red ratio in the light spectrum

“…Its fluctuations are usually associated with changes in xanthophyll cycle and dissipation of excess energy as heat, allowing to protect photosystem against the effects of intense radiation (Naumann et al 2010;Demmig-Adams and Adams 1996). PRI allows to track changes in the light use efficiency (LUE) in photosynthesis caused by various environmental factors (Gamon et al 1997).…”