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  • 1
    Electronic Resource
    Electronic Resource
    Cation exchange in isolated xylem cell walls of tomato. I. Cd2+ and Rb+ exchange in adsorption experiments (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 10 (1987), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Purified xylem cell walls were prepared from isolated xylem bundles of tomato (an inbred line of Lycopersicon esculentum Mill, cv. Tiny Tim). Adsorption and exchange experiments were carried out with 115Cd2+, 82Rb+ and 82Br−. The application of γ-ray spectroscopy permitted the simultaneous measurement of several ions applied together. The cell-wall water volume was shown to be independent of the external pH and solution ionic strength, possibly due to the presence of lignin. The Donnan Free Space (DFS) volume could be determined as a constant 0.15 dm3 per kg cell-wall dry weight. Consequently, the total cell-wall cation exchange capacity (CEC) could be estimated based on the DFS volume, and amounted to approximately 1000 mol m−3 negative charges. The results of Cd2+ -Rb+ exchange experiments indicated an apparent CEC value of about 350–450 mol m−3 DFS, at external pH ∼ 4. These data are in agreement with earlier reports on xylem wall CEC, and indicate the weak acid characteristics of the charge groups. The rational selectivity coefficient RCdRb, of the cell wall was shown to depend on external ion fractions and ionic strength, with a maximum RCdRb of 450 at ionic Cd2+ fraction near 0.3, based at the smallest experimental ionic strength of the external solution. The adsorption of Cd2+, applied at relatively high concentrations, was shown to be stimulated by simultaneous application of high Rb+ concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1987.tb02077.x
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  • 2
    Electronic Resource
    Electronic Resource
    Actual escape area and lateral escape from the xylem of the alkali ions Na+, K+, Rb+ and Cs+ in tomato (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 65 (1985), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Approximation of the total escape area of the xylem in an inbred line of tomato (Ly-copersicon escutentum Mill. cv. Tiny Tim) with help of the frequency distribution of xylem vessel radii provides the possibility to calculate realistic escape constant values from uptake experiments of several elements into tomato stem segments. Comparison of the lateral escape rates of 24Na+, 42K+, 86Rb+ and 134Cs+ indicate that Na+ escape is rate-limited by its uptake into a rather constant number of surrounding cells, regardless of changes in the total escape area of the xylem vessels. The escape of K+, Rb+ and Cs+ seems to be proportional to the surface area of the xylem vessels and their escape is apparently controlled by their transport across the cell walls of the transport channels. The calculated small values for the escape rate constants (apparent permeability of the xylem cell walls, ca 2–3 · 10−9 m s−7) are probably due to the presence of lignin in the xylem cell walls, the discrimination between ions as a result of differing affinities and selectivities and the presence of other solutes in the applied solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1985.tb08675.x
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  • 3
    Electronic Resource
    Electronic Resource
    Non-steady state xylem transport of fifteen elements into the tomato leaf as measured by gamma-ray spectroscopy: A model (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 61 (1984), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A model describing the transport of elements through the xylem vessels into the leaf of a red cherry tomato (Lycopersicon esculentum Mill cv. Tiny Tim) in a non-steady state situation is presented. The model describes the upward movement of ions as a mass-flow of the xylem fluid with dissolved elements, with lateral ion escape represented by a first-order process. The model is fitted to data obtained in an experiment in which 15 elements were applied in a solution to a cut stem part with attached leaf and were measured simultaneously by gamma-ray spectroscopy. The model is in good agreement with the transport into the leaf of K+ Na+, Rb+, Cs+, Yb3+, Sm3+ Zn2+, Co2+, Cu2+, Sb(SO4)2 AsO3+4, WO2+4; and Mo7O6+24.Only indirect data could be obtained for Cd2+ and La3+ because of their apparently high affinity for charged sites in the cell walls and high escape constant, respectively. The escape constants were relatively low for all anions, probably due to the presence of a large number of negative charges in the cell walls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1984.tb05176.x
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  • 4
    Electronic Resource
    Electronic Resource
    Cadmium — citric acid — xylem cell wall interactions in tomato plants (1992)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 15 (1992), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Mutual interactions between cadmium ions, citric acid and xylem cell walls were examined. Cadmium and citric acid were measured as 115Cd and [1,5-14C] citric acid, respectively. Xylem cell walls were obtained by bacterial degradation of tomato stem sections (Lycopersicon esculentum Mill, cv. Tiny Tim), and applied as ion-exchange columns. The xylem column material carried 2·4 dm3 H2O kg−1 dry weight, and was temporarily capable of buffering perfusates at pH 5·7. Sorbed cadmium and citric acid were determined from H2O and HCl rinses after perfusion periods. In all experiments, total cadmium and/or citric acid recoveries were better than 98%, indicating both the effectiveness of the rinses applied and the possibility of full regeneration of the xylem column. The results indicate that the presence of 2·45 mol m−3 citric acid causes an approximately 50% reduction of adsorbed cadmium levels, irrespective of the applied total cadmium concentrations (0·04–0·4 mol m−3 Cd(NO3)2.4H2O). This reduction is probably related to a corresponding reduction to approximately 2% of the control applied free Cd2+ concentration, the latter also independent of the total cadmium concentrations. Furthermore, without inducing positively charged citrate complexes in the applied solution, the presence of cadmium resulted in increased levels of citric acid absorbed in the xylem column. The Donnan Free Space accumulation of citric acid in the presence of Cd(NO3)2.4H2O, observed in the experiments described, could be expressed by its distribution coefficient, as approximately 15 times the control accumulation. These data indicate that the xylem column may operate as a ligand exchanger, suggesting the importance of metal ions for the longitudinal and lateral movement of organic complexing compounds in the xylem.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1992.tb01459.x
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  • 5
    Electronic Resource
    Electronic Resource
    Cation exchange in isolated xylem cell walls of tomato. II. Direct determination of chemically bound and electrostatically attracted Cd2+ by γ-γ-directional correlation measurements (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 10 (1987), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Xylem cell walls were isolated from internodes of tomato plants (Lycopersicon esculentum Mill, cv. Tiny Tim). Purification was carried out in Triton X-100. Experiments were conducted in which the adsorption of Cd2+ (applied as 115CdCl2) in the cell walls was measured. The application of γ-γ-directional correlation measurements permitted the direct determination of chemically bound cell wall Cd in experiments where the total adsorption of Cd was also measured. A set of equations is presented by which the adsorption of Cd could be described, thereby considering the presence of co-ions in the polyelectrolyte phase. In experiments with simultaneous ll5CdCl2 and K82Br applications, measurements were carried out of the presence of 82Br− in the Donnan Free Space (DFS), indicating Cl− action in the process of CdCl2 adsorption.The cell wall contents of the relevant ions were determined in such a manner that the measurements gave access to the undisturbed equilibrium concentrations. The very small Br− concentrations in the DFS indicated that, at small applied concentrations, internal free Cd may be considered to exist entirely of Cd2+. The results suggest that simultaneous measurement of internal free counter-ion and co-ion concentrations may be a relatively easy way to check the reliability of values for apparent formation constants in single cation adsorption experiments. From experiments in which the cell walls were incubated in solutions of varying Cd concentrations, the apparent dissociation constant (KCd2+) for the formation of R2Cd complexes could be calculated as 51±6 mol m−3. The exchange coefficient (KCd2+H+) was shown to vary with the internal free proton concentration and the applied Cd2+ concentration, due to the buffering capacity of the carboxylic acid exchanger.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.1987.tb01609.x
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  • 6
    Electronic Resource
    Electronic Resource
    Citric acid in tomato plant roots and its effect on cadmium uptake and distribution (1995)
    Springer
    Plant and soil 171 (1995), S. 333-339 
    Details
    ISSN: 1573-5036
    Keywords: cadmium ; citric acid ; distribution ; roots ; tomato ; uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments were carried out to investigate the effects of root citric acid on uptake and initial distribution of cadmium (Cd) in tomato plants (Lycopersicon esculentum, cv. Tiny Tim). Cd was measured by γ-spectrometry, using 115Cd spikes. Citric acid was measured by UV-detection, and, after spiking with 14C-citric acid, by β-spectrometry. Cd was applied for 48 h periods, in control experiments, in the presence of citric acid, and after 24 h plant pre-incubation with citric acid. Pre-incubation resulted in two-fold increases in fast-exchangeable amounts of root citric acid, as measured by the presence of citric acid in xylem exudates of decapitated and pressurized roots. Simultaneous application of Cd and citric acid did not change Cd accumulation in total plants and in the roots, nor did any significant change occur with respect to Cd root-to-shoot transport, and Cd concentrations in shoot tissues and xylem fluid. After citric acid pre-incubation, total plant uptake of Cd increased twofold, without any significant change in Cd accumulation in the roots. Cd root-to-shoot transport was increased 5–6 fold, and Cd concentrations in shoot tissues and xylem fluid were increased 6–8 fold. Speciation calculations indicated that, under the conditions applied, xylem Cd may be, at least partly, complexed in citric acid. A C Borstlap Section editor
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010289
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  • 7
    Electronic Resource
    Electronic Resource
    Factor analysis of trace-element data from tree-bark samples in The Netherlands (1994)
    Springer
    Environmental monitoring and assessment 32 (1994), S. 207-226 
    Details
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Monte Carlo-assisted factor analysis has been applied to a data set of 20 trace-element concentrations in tree-bark samples obtained from 123 locations in The Netherlands, with the aim to investigate the suitability of bark as a biomonitor for air pollution. A Monte Carlo approach was used to give more insight to the uncertainties and significance levels of the factor analysis results. Notwith-standing a rather strong influence of soil material on the concentration levels, factor analysis enabled the identification of five significant pollution source types, all of which corresponded with source types found in an earlier biomonitoring study in The Netherlands using epiphytic lichens. A more detailed comparison with the lichen results showed a remarkable difference in lead concentrations between bark and lichen. It was concluded that bark can be successfully employed as a biomonitor for air pollution. The power of factor analysis to adequately determine the soil contribution may render extensive sample washing procedures superfluous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00546277
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  • 8
    Electronic Resource
    Electronic Resource
    Moss interspecies comparisons in trace element concentrations (1995)
    Springer
    Environmental monitoring and assessment 35 (1995), S. 263-286 
    Details
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Within the framework of a European-scaled moss survey, various moss species were sampled throughout The Netherlands [NL], Germany [D], and Switserland [CH], and used in moss interspecies comparisons of elemental concentrations. Moss species considered were Pleurozium schreberi [NL,D,CH], Brachythecium rutabulum [NL], Hypnum cupressiforme [D,CH], Hylocomium splendens [D,CH], and Scleropodium purum [D]. Element analysis was carried out directly (The Netherlands, Instrumental Neutron Activation Analysis: As, Br, Ce, Cr, Cs, Fe, La, Mn, Na, Rb, Sc, Se, Sm, Th, Ti, V and Zn), or after sample digestion (The Netherlands, ICP-MS: Pb, Germany, AAS/ICP-AES: Cd, Cr, Cu, Fe, Ni, Pb, Ti, V, and Zn; Switzerland, ICP-AES/ICP-MS: Co, V, and Zn). Local variations (=within sampling sites) in element concentrations were estimated, based upon in-site multiple sampling and analysis of Pleurozium schreberi species in The Netherlands. Element concentrations in moss species were compared in linear correlations, both in unweighted and weighted fits, with weighing factors based on the local variation data. Weighted fits were shown to generally improve the calibration characteristics, as tracked by X 2 calculations. The calibration data suggest the presence of previously unnoticed outliers in element concentrations. The absence of further information, however, may prescribe the use of all data in comparison procedures. These results indicate that interlaboratory analysis of replicate samples and the use of dedicated certified reference materials may help solving problems in the analysis of the sample series. For several of the considered interspecies comparisons, weighted calibrations could be based on significant correlations (P=0.05). Actual use, however, will remain arbitrarily decided upon, and may be based on decisions as to what to accept with respect to the levels of uncertainty in the calibration parameters. Furthermore, the use of calibrations in extrapolation modes is greatly restricted by the necessary reservations in geographically larger-scaled applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00547636
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  • 9
    Electronic Resource
    Electronic Resource
    The influence of pre-treatment, temperature and calcium ions on trace element uptake by an alga (Scenedesmus pannonicus subsp. Berlin) and fungus (Aureobasidium pullulans) (1989)
    Springer
    Environmental monitoring and assessment 13 (1989), S. 21-33 
    Details
    ISSN: 1573-2959
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Experiments were carried out in order to obtain information on the uptake characteristics of metals in the algal and fungal components of lichens. The uptake of 115Cd, 65Zn, 64Cu, 140La, 187W and 76As in the alga Scenedesmus pannonicus, subsp. Berlin and the fungus Aureobasidium pullulans was determined at pH 7 and 5 respectively, in 4 h experiments varying with respect to temperature and Ca2+ solution concentrations. Furthermore, the effects of pre-rinsing the cell suspensions on metal uptake were investigated. Pre-rinsing resulted in decreased uptake of W and As by algae and in increased uptake of all elements measured by fungi, which may be attributed to combined effects of starvation and changing densities. For algae, the uptake rates of As, W, Zn and Cd were markedly increased at the highest temperature employed. For Cu and La hardly any effects of temperature were observed, indicating the absence of metabolically controlled uptake. For fungi, but for As no relation of uptake with temperature could be determined. The presence of Ca2+ ions in the solution applied hardly affected the uptake of As but resulted in increased uptake of W by both the algae and the fungi. The effects of Ca2+ on the uptake of Cu and La were relatively small, probably due to specific binding sites in the cell walls for Cu and to the ‘supercalcium’ status of the La-ion. The presence of Ca2+ caused decreased uptake of Cd2+ and Zn2+ by algae, but hardly affected the uptake of Zn2+ by fungi. The results indicate component-specific uptake and accumulation behaviour in intact lichens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00398733
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  • 10
    Electronic Resource
    Electronic Resource
    Factor analysis of atmospheric trace-element deposition data in the netherlands obtained by moss monitoring (1995)
    Springer
    Water, air & soil pollution 84 (1995), S. 323-346 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Monte Carlo-Assisted Factor Analysis has been applied to a data set of trace element concentrations in samples of the moss species Pleurozium schreberi, collected in 1992 from 66 locations in the Netherlands. A Monte Carlo approach was used to give more insight in the uncertainties and significance levels of the factor analysis results. Using a selection of 23 elements, factor analysis enabled the identification of 8 significant pollution source types. Two source types were assumed to be related to the influence of foliar leaching from higher plants. The remaining source types were found to correspond with the major source types obtained in earlier biomonitoring surveys in the Netherlands using lichen and bark, i.e. crustal material, sea aerosol and various types of industrial pollution sources, associated with metallurgical industries, refuse incineration and oil combustion or processing of oil products. The contribution of the industrial pollution sources appeared to have decreased between 1987 and 1992.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00475347
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