Decreased Transpiration in Poplar Trees Exposed to 2,4,6-Trinitrotoluene

Abstract

Abstract-This article discusses the effects of various concentrations of the explosive 2,4,6-trinitrotoluene (TNT) on the transpiration of hybrid poplar trees growing in hydroponic media. Transpiration was measured daily by gravimetric means. The rapid removal of TNT from hydroponic solutions was a result of plant uptake and required a daily dosage of TNT to ensure a relatively constant exposure over time. Transpiration decreased with increasing TNT concentrations Ն5 mg/L. Decreases in transpiration were accompanied by leaf chlorosis and abscission. A comparison between a laboratory study and a pilot-scale experiment showed good scaleup potential.

Identification of Metabolic Routes and Catabolic Enzymes Involved in Phytoremediation of the Nitro- Substituted Explosives TNT, RDX, and HMX

“…Calculation of the concentration of TNT that the positive control represented was around 4 mg/L. This is comparable to previous experiments using poplar tree cuttings where the toxicity level was around 5 mg/L TNT (Thompson et al, 1998a).…”

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“…After that, the growth of the control plant was reduced and then remained stable until the last collection time (28 days), while a gradual reduction in water transpiration was observed in the arsenate treated plants. This may be the result of arsenic toxicity and is in accordance with other investigators (McFarlande and Pfleeger, 1987; Gadallah, 1995; Thompson et al, 1998) who reported that growth and reduction of transpiration could be used to determine toxicity of test chemicals. Trapp et al (2000) investigated the toxicity of cyanide to willow plants and concluded that the water transpiration rate of the cyanide treated plants was reduced due to the toxicity of cyanide to the plant.…”

Tolerance of Tree Reforestation Species (Schizolobium parahyba, Mimosa scabrella and Enterolobium contortisiliquum) to Gasoline and Diesel Phytotoxicity Assays

“…The observed differences between species may be related to weight, size and surface area of leaf, canopy, stage of growth and climatic factors [35]. The reaction time of the contaminant in hydroponic phytotoxicity tests is longer for trees with higher biomass [37], as observed for S. parahyba in the present study. In addition, studies with model simulations predicted that contaminant translocation to leaves takes longer for lipophilic chemicals (e.g., diesel) and for large plants [52,53].…”

“…Typical phytotoxicity studies with trees for phytoremediation application also include elaborated research on uptake potential, metabolic pathways, in vitro systems with cell suspension, hairy root cultures, etc [37][38][39]. Thus far, no standard toxicity method has been developed for analysis on trees.…”