[show abstract][hide abstract] ABSTRACT: Absolute and relative concentrations of heavy metals (HMs) in plant tissue (C)
and substrate leachate (Cp lix) are required for phytoremediation and ecophysiology.
We report the interlaboratory comparison of the absolute and relative C for copper (Cu) and lead (Pb) for different soil/substrate HM concentrations (C) for Tagetes erecta L.–Glomus intraradices and Aldama dentata using atomic absorption spectrometry, neutron activation analysis, and polarized x-ray ﬂuorescence spectrometry, utilizing standard statistical validation. The intertechnique absolute concentration differences at each C were statistically signiﬁcant with the global average relative deviations being 0.5 ± 0.3 to 1.1 ± 0.9. However, the intertechnique Cs correlations across the C, were excellent. Therefore, The relative concentration variation is a robust index, reliably measured by all analytical methods as long as the techniques are applied self-consistently. The absolute concentration exactitudes are discussed with respect to the measurement aspects of each technique, sample presentation, and sample matrix effects. The ﬁndings also suggest the need for standard reference materials for complex/symbiotic systems. spp and Cspp lix
[show abstract][hide abstract] ABSTRACT: Disclaimer: This is a version of an unedited manuscript that has been accepted for publication. As a service to authors and researchers we are providing this version of the accepted manuscript (AM). Copyediting, typesetting, and review of the resulting proof will be undertaken on this manuscript before final publication of the Version of Record (VoR). During production and pre-press, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal relate to this version also. PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the "Content") contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
[show abstract][hide abstract] ABSTRACT: The application of nano-biotechnology to crop-science/agriculture (‘nanoagriculture’) is a recent development. While carbon nanotubes (CNTs) have been shown to dramatically improve germination of some comestible plants, deficiencies in consistency of behavior and reproducibility arise, partially from the variability of the CNTs used. In this work, factory-synthesized multi-walled-CNTs (MWCNTs) of quality-controlled specifications were seen to enhance the germinative growth of maize seedlings at low concentrations but depress it at higher concentrations. Growth enhancement principally arose through improved water delivery by the MWCNT. Polarized EDXRF spectrometry showed that MWCNTs affect mineral nutrient supply to the seedling through the action of the mutually opposing forces of inflow with water and retention in the medium by the ion-CNT transient-dipole interaction. The effect varied with ion type and MWCNT concentration. The differences of the Fe tissue concentrations when relatively high equimolar Fe2+ or Fe3+ was introduced, implied that the ion-CNT interaction might induce redox changes to the ion. The tissue Ca2+ concentration manifested as the antipode of the Fe2+ concentration indicating a possible cationic exchange in the cell wall matrix. SEM images showed that MWCNTs perforated the black-layer seed-coat that could explain the enhanced water delivery. The absence of perforations with the introduction of FeCl2/FeCl3 reinforces the idea of the modification of MWCNT functionality by the ion-CNT interaction. Overall, in normal media, low dose MWCNTs were seen to be beneficial, improving water absorption, plant biomass and the concentrations of the essential Ca, Fe nutrients, opening a potential for possible future commercial agricultural applications.
[show abstract][hide abstract] ABSTRACT: Leaf area LA, is a plant biometric index important to agroforestry and crop
production. Previous works have demonstrated the conservativeness of the
inverse of the product of the fresh leaf density and thickness, the so-called
Hughes constant, K. We use this fact to develop LAMM, an absolute method of LA
measurement, i.e. no regression fits or prior calibrations with planimeters.
Nor does it require drying the leaves. The concept involves the in situ
determination of K using geometrical shapes and their weights obtained from a
subset of fresh leaves of the set whose areas are desired. Subsequently the
LAs, at any desired stratification level, are derived by utilizing K and the
previously measured masses of the fresh leaves. The concept was first tested in
the simulated ideal case of complete planarity and uniform thickness by using
plastic film covered card-paper sheets. Next the species-specific
conservativeness of K over individual leaf zones and different leaf types from
leaves of plants from two species, Mandevilla splendens and Spathiphyllum
wallisii, was quantitatively validated. Using the global average K values, the
LA of these and additional plants, were obtained. LAMM was found to be a rapid,
simple, economic technique with accuracies, as measured for the geometrical
shapes, that were comparable to those obtained by the planimetric method that
utilizes digital image analysis, DIA. For the leaves themselves, there were no
statistically significant differences between the LAs measured by LAMM and by
the DIA and the linear correlation between the two methods was excellent.
[show abstract][hide abstract] ABSTRACT: Phytoremediation is an environmental biotechnology that seeks to remediate pollution caused by bioaccumulative toxins like copper (Cu). Symbiotic mycorrhizal associations can increase the uptake and delivery of low mobility nutrients and micronutrients to the host plant because they solubilize these substances and increase their catchment area. To analyze the effect of mycorrhizae on the phytoaccumulation of Cu, we studied their ability to solubilize Cu(II) and enhance its absorption by the plant Tagetes erecta L. colonized with the arbuscular mycorrhizal fungus Glomus intraradices. Plants were grown for nine weeks in a growth chamber under controlled conditions of temperature, relative humidity and photoperiod. Cu was added in the insoluble form of CuO to simulate the insoluble Cu-O affixed species in soil. The biotic and abiotic parameters of colonization, foliar area, biomass and the pH of leachates were determined as functions of the Cu concentration that was measured in the roots, shoots and leachates by AAS. The results of Cu absorption showed that the colonized plants accumulated more Cu in the roots as well as the whole plant and that both the colonized and non-colonized plants displayed the typical behavior of Cu excluders. Mycorrhizal colonization of the roots resulted in a proliferation of vesicles and this was observed to scale with root tissue Cu concentrations. Also, the G. intraradices-T. erecta system displayed a higher resistance to the toxicity induced by Cu while nonetheless improving the indices of phytoaccumulative yields. These results suggest that G. intraradices possibly accumulates Cu in its vesicles thereby enhancing the Cu tolerance of T. erecta even while increasing root Cu accumulation. The parameters of bioconcentration factor and translocation factor measured in this work suggest that the system T. erecta-G. intraradices can potentially phytostabilize Cu in contaminated soils.
New Biotechnology 06/2011; 29(1):156-64. · 1.71 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aldama dentata Llave & Lex. is a plant native to Latin America that exhibits metallicolous populations. Its ecophysiological (EP) response
to Cu stress, administered as graded soil concentrations (C
s) of the fungicide copper(II) oxychloride, is examined in depth. Using a systems biology- and population dynamics-inspired
approach, an r/K-driven model is proposed that satisfactorily explains the plant Cu concentration (C
p) versus C
s EP response curves for the root, shoot, and whole plant. A. dentata was found to be a Cu excluder (ME). The dual role of Cu as a nutrient and toxin at low and high concentrations, respectively,
manifested as a parabolic variation of the foliar area where the toxicity appeared as a second-order effect. The power-law
variance of biomass (B
p) with C
p expected from the universal allometric scaling law of biology was loosely followed and is discussed in terms of the mode
of Cu uptake by the plant and Cu’s dual physiological role. Biometric growth indices reflected the impact of Cu on the photosynthetic
energy harvest. The general applicability of the r/K-driven model was corroborated by its successful application to the published C
s data of the well-known Cu ME, Silene vulgaris. The r–K factors suggest a new quantitative manner of comparing the phytoavailability of the metal and the plant’s accumulation capability
across soil types. A. dentata with high root C
p but low B
p diminution could potentially find use as a Cu phytostabilizer.
Water Air and Soil Pollution 01/2011; 220(1):37-55. · 1.75 Impact Factor
[show abstract][hide abstract] ABSTRACT: The predictabilities of the three alpha-decay half-life formulae, the Royer GLDM, the Viola-Seaborg and the Sobiczewski-Parkhomenko formulae, have been evaluated by developing a method based on the ansatz of standard experimental benchmarking. The coefficients of each formula were re-derived using the reliable data of the alpha-standards nuclei. The modified formulae that resulted were used to evaluate the accuracies of the formulae towards the prediction of half-lives of a set of nuclides with well-studied alpha- spectroscopic data as well as a set of exotic alpha-emitters. Further, a simple linear optimization of the modified formulae allowed adjustments for the insufficient statistics of the primary data set without changing the modified formulae. While the three modified formulae showed equivalent results for all the medium heavy nuclei except the odd-odd, the modified GLDM showed relatively the best figures of merit for the odd-odd and superheavy nuclides. Comment: 16 pages, 4 tables, 2 figures
European Physical Journal A 10/2009; · 2.04 Impact Factor
[show abstract][hide abstract] ABSTRACT: Alpha decay is one of the two main decay modes of the heaviest nuclei, (SHE), and constitutes one of the dominant decay modes of highly neutron deficient medium mass nuclei (“exotics”). Thus identifying and characterizing the alpha decay chains form a crucial part of the identification of SHE. We report the extension of the previously developed method  for the detailed and systematic investigation of the reliability of the three main extant analytical formulae of alpha decay half-lives: the generalized liquid drop model based formula of Royer &etal;  (FR), the Sobiczewski modified semi-empirical Viola-Seaborg formula  (VSS) and the recent phenomenological formula of Sobiczewski and Parkhomenko  (SP).
[show abstract][hide abstract] ABSTRACT: This work is a study of the inter-relationship between parameters that principally affect metal up-take in the plant. The relationships between the concentration of metal in the growth medium, Cs, the concentration of metal absorbed by the plant, Cp, and the total biomass achieved, M, all of which are factors relevant to the efficiency of phytoremediation of the plant, have been investigated via the macro-physiological response of Brassica juncea seedlings to Ni(II) stress. The factorial growth experiments treated the Ni(II) concentration in the agar gel and the diurnal light quanta (DLQ) as independently variable parameters. Observations included the evidence of light enhancement of Ni toxicity at the root as well as at the whole plant level, the shoot mass index as a possible indicator of shoot metal sequestration in B. juncea, the logarithmic variation of Cp with Cs and the power-law dependence of M on Cp. The sum total of these observations indicate that for the metal accumulator B. juncea with regard to its capacity to accumulate Ni, the overall metabolic nature of the plant is important; neither rapid biomass increase nor a high metal concentration capability favor the removal of high metal mass from the medium, but rather the plant with the moderate photosynthetically driven biomass growth and moderate metal concentrations demonstrated the ability to remove the maximum mass of metal from the medium. The implications of these observations in the context of the perceived need in phytoremediation engineering to maximize Cp and M simultaneously in the same plant, are discussed.
[show abstract][hide abstract] ABSTRACT: The relationships between the concentration of metal in the growth medium, Cs, the concentration of metal absorbed by the plant, Cp, and the total biomass achieved, M, all of which are factors relevant to the efficiency of metal uptake and tolerance by the plant, have been investigated via the physiological response of Brassica juncea seedlings to Ni stress. The factorial growth experiments treated the Ni concentration in agar medium and the diurnal light quanta as independently variable parameters. Observations included the evidence of light enhancement of Ni toxicity in the root, as well as at the whole-plant level. The shoot mass index possibly is an indicator of the amount of shoot metal sequestration in B. juncea, as are the logarithmic variation of Cp with Cs and the power-law dependence of M on Cp. The sum total of these observations indicates that, for the Ni accumulating plant B. juncea, the overall metabolic allocation to either growth or metal tolerance of the plant is important. Neither a rapid biomass increase nor a high metal absorbed concentration favored the removal of high metal mass from the medium. Rather, the plants with a moderate rate of biomass growth and a moderate absorbed metal concentration demonstrated the ability to remove the maximum mass of metal from the medium. The implication of these results as related to the extant model of phyoextraction efficiency is discussed.
International Journal of Phytoremediation 9(3):207-25. · 1.18 Impact Factor