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Plastic wastes burdening Earth’s water and accumulating on land, releasing toxic leachates, are one of the greatest global threats of our time. Bisphenol-A (BPA), a potent endocrine disrupting compound, is a synthetic ingredient of the polycarbonate plastics and epoxy resins used in food containers, cans, and water bottles. Bisphenol-A’s rising concentrations in the environment require a sustainable alternative to current removal practices, which are expensive and/or ecologically unsafe. Switchgrass offers a safe alternative. To investigate its potential for BPA removal, two United States native switchgrass varieties where tested in hydroponic media. Results show minimal hydrolysis and photolysis of BPA over 55 days, confirming its persistence. Both generic and heavy metal switchgrass exhibited statistically significant (p 0.19), and peroxidase between BPA-treated and untreated plants indicates substantial BPA tolerance in both varieties. Kinetic parameters of BPA removal and translocation factors were also determined, which will inform the design of BPA removal phytotechnologies for a variety of soil conditions, including landfills where BPA accumulation is greatest.

Prevention of lead (Pb) poisoning is imperative for public health and environmental justice. This study presents both assessment and affordable mitigation of Pb exposure risks at individual yard scales, which are critically important to homeowners to attain primary prevention, but not yet explored thoroughly.

The effectiveness of vetiver grass in removing 2,4,6-trinitrotoluene (TNT) and the involvement of nitroreductase (NR) enzyme in TNT degradation in vetiver has been documented in our earlier studies. The present study was designed to optimize the parameters influencing NR enzyme-mediated TNT transformation in vetiver. The current study is the first report of detailed kinetic examination of NR enzyme induced by TNT in vetiver. Results show that NR activity in vetiver root increased with exposure time as well as with initial TNT concentration, showing a first-order reaction kinetics at lower and a second-order reaction kinetics at higher TNT concentrations. Nitroreductase activity was higher in shoot compared to root in all TNT treatments. Increasing concentration of TNT resulted in a significant increase in the NR activity in shoot. Very high increase in the shoot NR activity indicates a faster root-to-shoot translocation of TNT. The optimum range of the factors influencing NR-mediated TNT transformation and the kinetic parameters were determined, which will be crucial for the application of vetiver for phytoremediation of TNT-contaminated systems.

In order to select appropriate plant species for phytoremediation of explosive compounds, phytotoxicity, uptake proficiency, capability of the plant to degrade/transform the compounds, and several environmental factors need to be considered. The environmental factors comprise climatic attributes, soil type, the water environment, root penetration depth, contaminant kinetics, and bioavailability. Out of the plant species that have shown efficient TNT uptake, there are only a few that can do so in a variety of environments, which is imperative in case of contaminants that are widespread, such as TNT and RDX. The two most effective species for TNT uptake reported to date are Eurasian water milfoil, Myriophyllum spicatum and vetiver grass, Chrysopogon zizanioides. For RDX phytoremediation, reed canary grass, fox sedge, and rice have shown promise, although degradation of RDX in the plant tissue is limited. Over the past few decades, a considerable amount of information on phytotoxicity and metabolism of TNT and RDX in plants and microorganisms have been collected, which has led to the identification of potential plant species for use in TNT and RDX phytoremediation, as well as candidate genes for developing effective transgenic plants. Recent research has also revealed promising non-transgenic approaches, such as use of chaotropic agents for enhanced solubilization and uptake of TNT, which could prove to be practical and effective for military sites. Field trials of some of these promising new technologies are necessary for the development of effective, low-cost, and environmentally friendly phytoremediation of explosive-contaminated sites.

The arsenic (As) hyperaccumulating fern species Pteris vittata (PV) is capable of accumulating large quantities of As in its aboveground tissues. Transformation to AsIII and vacuolar sequestration is believed to be the As detoxification mechanism in PV. Here we present evidence for a preponderance of exocellular As in fronds of Pteris vittata despite numerous reports of a tolerance mechanism involving intracellular compartmentalization. Results of an extraction experiment show that 43–71% of the As extruded out of the fronds of PV grown in 0.67, 3.3 and 6.7 mM AsV. SEM-EDX analysis showed that As was localized largely on the lower pinna surface, with smaller amounts on the upper surface, as crystalline deposits. X-ray fluorescence imaging of pinna cross-sections revealed preferential localization of As on the pinna surface in the proximity of veins, with the majority localized near the midrib. Majority of the As in the pinnae is contained in the apoplast rather than vacuoles. Our results provide evidence that exocellular sequestration is potentially a mechanism of As detoxification in PV, particularly at higher As concentrations, raising concern about its use for phytoremediation.

The presence of veterinary and human antibiotics in soil and surface water is an emerging environmental concern. The current study was aimed at evaluating the potential of using vetiver grass as a phytoremediation agent in removing Tetracycline (TC) from aqueous media. The study determined uptake, translocation, and transformation of TC in vetiver grass as function of initial antibiotic concentrations and exposure time. Vetiver plants were grown for 60 days in a greenhouse in TC contaminated hydroponic system. Preliminary results show that complete removal of tetracycline occurred within 40 days in all TC treatments. Initial concentrations of TC had significant effect (p < 0.0001) on the kinetics of removaL Tetracycline was detected in the root as well as shoot tissues, confirming uptake and root-to-shoot translocation. Liquid-chromatography-tandem-mass-spectrometry analysis of plant tissue samples suggest presence of metabolites of TC in both root and shoot tissues of vetiver grass. The current data is encouraging and is expected to aid in developing a cost-effective, in-situ phytoremediation technique to remove TC group of antibiotics from wastewater.

Lead (Pb) has limited solubility in the soil environment owing to complexation with various soil components. Although total soil Pb concentrations may be high at a given site, the fraction of soluble Pb that plants can extract is very small, which is the major limiting factor for Pb phytoremediation. The symbiotic effect of arbuscular mycorrhizal (AM) fungus, Glomus mosseae was examined on growth and phytoextraction of lead (Pb) by vetiver grass [Chrysopogon zizanioides (L.)]. A hydroponic study, Phase I (0, 1, 2, and 4 mM Pb) was conducted followed by an incubation pot study, Phase II (0, 400, 800, and 1200 mg kg−1 Pb) where vetiver plants were colonized with G. mosseae. The results obtained indicate that plants colonized by the AM fungi not only exhibit better growth (increase in plant biomass), but also significantly increase Pb uptake in root and higher translocation to the shoot at all given treatments. Moreover, plants colonized with AM fungi had higher chlorophyll content and reduced levels of low molecular weight thiols, indicating the ability to better tolerate metal-induced stress. Results from this study indicate that vetiver plants in association with AM fungi can be used for improved phytoextraction of Pb from contaminated soil.

Environmental contamination by antibiotics not only perturbs the ecological balance but also poses a risk to human health by promoting the development of multiantibiotic-resistant bacteria. This study focuses on identifying the biochemical pathways associated with tetracycline (TC) transformation/degradation in vetiver grass that has the potential to be used as a biological remediation system in TC-contaminated water sources. A hydroponic experimental setup was used with four initial TC concentrations (0, 5, 35, 75 ppm), and TC uptake was monitored over a 30-day period. Results show that TC transformation in the media occurred during the first 5 days, where a decrease in the parent compound and an increase in the concentration of the isomers such as epitetracycline (ETC) and anhyrotetracycline (ATC) occurred, and TC disappeared in 20 days in tanks with vetiver grass. However, the isomers ETC and ATC remained in the control tanks for the duration of the trial. Transformation products of TC in plant tissue were analyzed by using ultra HPLC high-resolution Orbitrap mass spectrometery (HRMS/MS), which indicates amide hydrolysis of TC in vetiver roots. Metabolic profiling revealed that glyoxylate metabolism, TCA cycle, biosynthesis of secondary metabolites, tryptophan metabolism, and inositol phosphate metabolism were impacted in vetiver root by TC treatment.

Previous research in our laboratory investigated the effectiveness of a common agrochemical, urea used as a chaotropic agent to facilitate 2,4,6-trinitrotoluene (TNT) removal by vetiver grass (Vetiveria zizanioides L.). Chaotropic agents disrupt water structure, increasing solubilization of hydrophobic compounds (TNT), and enhancing plant TNT uptake. Our findings showed that urea significantly enhanced TNT uptake kinetics by vetiver. We hypothesized that the beneficial effect of urea on the overall TNT uptake by vetiver grass was not plant-specific. We explored this hypothesis by testing the ability of wheat (Triticum aestivum L.) in removing TNT from aqueous media in the presence of urea. Results showed that untreated (no urea) wheat exhibited a slow, kinetically limited TNT uptake that was nearly half of the urea-treated wheat TNT capacity (250 mg kg-1). Chaotropic effects of urea were illustrated by the significant (P < 0.001) increase in the TNT second-order reaction rate constants over those of the untreated (no urea) controls. Plant TNT speciation showed that TNT and several of its metabolites were detected in both root and shoot compartments of the plant, allowing for 110 and 36% recovery for the untreated and 0.1% urea treated plants. The lower % recovery of the urea-treated plants was attributed to a number of unknown polar TNT metabolites.

One of the major challenges in developing an effective phytoremediation technology for 2,4,6-trinitrotoluene (TNT) contaminated soils is limited plant uptake resulting from low solubility of TNT. The effectiveness of urea as a solubilizing agent in increasing plant uptake of TNT in hydroponic systems has been documented. Our preliminary greenhouse experiments using urea were also very promising, but further characterization of the performance of urea in highly-complex soil-solution was necessary. The present study investigated the natural retention capacity of four chemically variant soils and optimized the factors influencing the effectiveness of urea in enhancing TNT solubility in the soil solutions. Results show that the extent of TNT sorption and desorption varies with the soil properties, and is mainly dependent on soil organic matter (SOM) content. Hysteretic desorption of TNT in all tested soils suggests irreversible sorption of TNT and indicates the need of using an extractant to increase the release of TNT in soil solutions. Urea significantly (p

The high affinity of vetiver grass for 2,4,6 trinitrotoluene (TNT) and the catalytic effectiveness of urea in enhancing plant uptake of TNT in hydroponic media we earlier demonstrated were further illustrated in this soil-pot-experiment. Complete removal of TNT in urea-treated soil was accomplished by vetiver at the low initial soil-TNT concentration (40 mg kg−1), masking the effect of urea. Doubling the initial TNT concentration (80 mg kg−1) significantly (p < 0.002) increased TNT removal by vetiver, in the presence of urea. Without vetiver grass, no significant (p = 0.475) change in the soil-TNT concentrations was observed over a period of 48 days, suggesting that natural attenuation of soil TNT could not explain the documented TNT disappearance from soil.

Most previous investigations comparing the performance of different representations have used recall and precision as performance measures. However, there is evidence to show that these measures are insensitive to an important difference between representations. To explain, two representations may perform similarly on these measures, while retrieving very different sets of documents. Equivalence of representations should be decided on the basis of similarity in performance and similarity in the documents retrieved. This study compared the performance of four representations in the PsycAbs database. In addition, overlap between retrieved sets was also computed where overlap is the proportion of retrieved documents that are the same for pairs of document representations. Results indicate that for any two representations considered, performance values differed slightly while overlap scores were also low, thus supporting the evidence that recall and precision as performance measures mask differences between the sets of retrieved documents. Results are interpreted to propose an optimal ordering of the representations and to examine the contribution of each representation given this combination.