Phytoremediation is an emerging technology that employs the use of higher plants for the clean-up of contaminated environments. Progress in the field is however handicapped by limited knowledge of ...the biological processes involved in plant metal uptake, translocation, tolerance and plant–microbe–soil interactions; therefore a better understanding of the basic biological mechanisms involved in plant/microbe/soil/contaminant interactions would allow further optimization of phytoremediation technologies. In view of the needs of global environmental protection, it is important that in phytoremediation and plant biology studies the analytical procedures for elemental determination in plant tissues and soil should be fast and cheap, with simple sample preparation, and of adequate accuracy and reproducibility. The aim of this study was therefore to present the main characteristics, sample preparation protocols and applications of X-ray fluorescence-based analytical techniques (energy dispersive X-ray fluorescence spectrometry—EDXRF, total reflection X-ray fluorescence spectrometry—TXRF and micro-proton induced X-ray emission—micro-PIXE). Element concentrations in plant leaves from metal polluted and non-polluted sites, as well as standard reference materials, were analyzed by the mentioned techniques, and additionally by instrumental neutron activation analysis (INAA) and atomic absorption spectrometry (AAS). The results were compared and critically evaluated in order to assess the performance and capability of X-ray fluorescence-based techniques in phytoremediation and plant biology studies. It is the EDXRF, which is recommended as suitable to be used in the analyses of a large number of samples, because it is multi-elemental, requires only simple preparation of sample material, and it is analytically comparable to the most frequently used instrumental chemical techniques. The TXRF is compatible to FAAS in sample preparation, but relative to AAS it is fast, sensitive and multi-elemental. The micro-PIXE technique requires rather expensive instrumentation, but offers multi-elemental analysis on the tissue and cellular level.
A detailed localization of elements in leaf tissues of the field-collected Cd/Zn hyperaccumulator Thlaspi praecox (Brassicaceae) growing at a highly metal-polluted site was determined by ...micro-proton-induced X-ray emission (micro-PIXE) in order to reveal and compare nutrient and non-essential element accumulation patterns in the case of multiple metal accumulation within particular leaf tissues, including the detailed distribution between apoplast and symplast regions. On the larger scans, the highest concentrations of metals were observed in the epidermis, S and Ca in the palisade mesophyll, Cl in the spongy mesophyll and vascular bundles, and P and K in the vascular bundles. On the more detailed scans, the highest Cd, Pb, Cl and K concentrations were observed in vascular bundle collenchyma. The relative element distribution (%) was calculated based on concentrations of elements in particular leaf tissues and their relative weight portions, indicating that most of the accumulated Zn was located in epidermises, while the majority of Cd and Pb was distributed within the mesophyll. Detailed scans of epidermal/mesophyll tissues revealed that Zn was mainly accumulated and detoxified in the symplast of large vacuolated epidermal cells, Cd in the mesophyll symplast, and Pb in the mesophyll symplast and apoplast.
Localization of cadmium (Cd) and other elements was studied in the leaves of the field-collected cadmium/zinc (Cd/Zn) hyperaccumulator Thlaspi praecox from an area polluted with heavy metals near a ...lead mine and smelter in Slovenia, using micro-PIXE (proton-induced X-ray emission). The samples were prepared using cryofixation. Quantitative elemental maps and average concentrations in whole-leaf cross-sections and selected tissues were obtained. Cd was preferentially localized in the lower epidermis (820 μg g⁻¹ DW), vascular bundles and upper epidermis, whereas about twice the lower concentrations were found in the mesophyll. Taking into account the large volume of the mesophyll compared with the epidermis, the mesophyll is indicated as a relatively large pool of Cd, possibly involved in Cd detoxification/dilution at the tissue and cellular level.
Iron gall ink, also referred to as iron gallotannate ink, is one of the most important inks in the history of western civilisation, and was in widespread use from the middle ages until the 20th ...century. Unfortunately, iron ions and acids present in these inks induce enhanced degradation of paper, thus severely damaging numerous historical artefacts. Yet, when examining documents, it is frequently observed that not all materials containing iron gall ink are suffering from ink corrosion. While some are completely destroyed, others may be in excellent condition even centuries after their creation. In order to establish the main properties of materials, common to severely degraded documents, the effects of the type and quantity of metal ions in the ink, as determined by in-air PIXE method, pH of the ink on paper, grammage of paper, its absorptivity and the width of ink lines were evaluated against the extent of corrosion. Using multiple linear regression analysis, a correlation has been obtained between the width of the applied ink lines, pH, grammage of paper and the extent of ink corrosion. Based on these factors, which can be acquired non-destructively from most historical documents, it is therefore possible to predict the stability of historical iron gall ink containing paper.
Cd, Zn and Pb accumulation, spatial distribution within seeds and germinating seedlings, and seeds fitness of metal hyperaccumulating
Thlaspi praecox were investigated in order to gain more knowledge ...on plant reproductive success at metal polluted sites. The seeds contained up to 1351
μg
g
−1 (dry weight) of Cd, 121
μg
g
−1 of Zn and 17
μg
g
−1 of Pb. Seed fitness was negatively influenced by seed Cd hyperaccumulation. Nevertheless, the viability of seeds was decreased by maximally 20%, indicating very efficient tolerance of the plant embryos to Cd. Localisation by micro-PIXE revealed preferential storage of most elements in the embryonic axis. Cd and Zn were preferentially localised in the epidermis of cotyledons. The restriction of seed Pb and Zn uptake and hyperaccumulation of Cd, accompanied by partitioning of Cd in the epidermal tissues of cotyledons, may enable the survival of
T. praecox embryos and seedlings in Cd polluted environments.
Hyperaccumulation of Cd with partitioning in the epidermis of cotyledons was observed in T. praecox embryos.
The chemical element profiles of iron-gall ink writing before and after water treatment and deacidification were determined. A 17th century manuscript of rag paper was used in the study. The chemical ...elemental analysis was performed non-destructively by the Proton Induced X-ray Emission (PIXE) method. The concentration profiles of 15 elements ranging from Na to Pb were measured with the precision of 0.3 mm. Quantitative composition of ink and paper was determined and the elemental concentration changes due to the aqueous treatments were traced by PIXE. It is considered that the method can be developed and could help conservators in a decision making process.
L'objet de l'analyse consistait à déterminer le profil des éléments chimiques de l'encre gallique sur un document écrit avant et après un traitement aqueux et une désacidification. A cet effet une étude a été réalisée sur un manuscrit en papier chiffon datant du 17ème siècle. La méthode utilisée pour cette analyse, consistant dans l'émission de rayons X induite par des protons (Proton Induced X-ray Emission) est une méthode qui ne détruit pas les éléments chimiques. Les profils de concentration de 15 éléments allant de Na à Pb ont été mesurés avec une précision de 0,3 mm. De cette façon il a été possible de déterminer la composition quantitative d'encre et de papier ainsi que de suivre les changements de concentration subis par les éléments au cours des traitements aqueux enregistrés par la méthode PIXE. Il semble que cette méthode mériterait d'être développée et qu'elle pourrait devenir un instrument de travail efficace pour les conservateurs.
Es wurde ein Profil der Elemente in einem im 17. Jh. mit Eisengallustinte beschriebenen Blatt Hadernpapier erstellt. Hierzu wurde eine nicht-materialzerstörende Methode eingesetzt, nämlich die Proton-induzierte Röntgenstrahlenemmission PIXE (Proton Induced X-ray Emission). Die Verteilungsprofile der Konzentration von 15 Elementen zwischen Na und Pb wurde mit einer Genauigkeit von 0,3 mm gemessen. Auf diese Weise wurde die quantitative Zusammensetzung von Tinte und Papier erfaßt sowie die Veränderungen, welche die gemessenen Elemente infolge einer wässrigen Behandlung erfuhren. Die Methode kann zu Werkstattroutine entwickelt und so zu einer Entscheidungshilfe für den Konservator werden.
Analysis of iron gall inks by PIXE Budnar, Miloš; Uršič, Mitja; Simčič, Jure ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
02/2006, Volume:
243, Issue:
2
Journal Article
Peer reviewed
Micro- or non-destructive analytical approach is an imperative when analysing historical artefacts. Due to its practically non-destructive character, proton induced X-ray spectrometry (PIXE) has ...become a method of choice for the study of historical documents. In the present paper, use of in-air PIXE method for analysis of iron gall inks applied at handwriting of documents is evaluated. The errors arising from the non-uniform ink deposit, proton penetration depth and size of the proton beam versus width of ink lines, effects of surface roughness, as well as the importance of the PIXE set-up geometry on the accuracy of the results are discussed. It follows that the main problems can be attributed to the fact that PIXE is a surface technique and that the analysis is limited to a small amount of material, while ink deposit on the paper is usually non-uniform in depth as well as on the paper surface. Despite possible systematic uncertainties when applying the PIXE method, good correlation between determinations obtained by PIXE and atomic absorption spectroscopy (AAS) on model samples clearly demonstrate that the errors are well within a reasonable limit of a few percents.
The iron gall inks were one of the writing materials mostly applied in historical documents of the western civilization. Due to the ink corrosive character, the documents are faced with a danger of ...being seriously, and in some cases also irreversibly changed. The elemental composition of the inks is an important information for taking the adequate conservation action Project InkCor,
http://www.infosrvr.nuk.uni-lj.si/jana/Inkcor/index.htm, and references within. Here, the in-air PIXE analysis offers an indispensable tool due to its sensitivity and almost non-destructive character. An experimental approach developed for precise and automatic analysis of documents at Jožef Stefan Institute Tandetron accelerator is presented. The selected documents were mounted, one at the time, on the positioning board and the chosen ink spots on the sample were irradiated by 1.7 MeV protons. The data acquisition on the selected ink spots is done automatically throughout the measuring pattern determined prior to the measurement. The chemical elements identified in the documents ranged from Si to Pb, and between them the significant iron gall ink components like Fe, S, K, Cu, Zn, Co, Mn, Ni were deduced with precision of ±10%. The measurements were done non-destructively and no visible damage was observed on the irradiated documents.
Application of the PIXE method to organic objects Vodopivec, Jedert; Budnar, Miloš; Pelicon, Primož
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
09/2005, Volume:
239, Issue:
1
Journal Article
Peer reviewed
The contribution presents the application of proton induced X-ray emission (PIXE), as a non-destructive analytical method, to the identification and study of historic paper, parchment and textile ...objects. The results show the possibilities for identification of inks, pigments, dyes, surface layers and inorganic impurities in historic objects made of organic materials.
The measurement of elemental concentrations in these materials provides a sound basis for investigation of their composition and of degradation processes. PIXE has been found useful in evaluating the viability of a range of potential conservation treatments by measuring the elemental changes before and after the process has been carried out.
Like any other form of analysis, the PIXE method has its limitations, but its great strength is in its non-destructiveness, high sensitivity and accuracy in determining composition and concentration distribution over a wide range of chemical elements. For objects made of complex organic materials the information obtained should be interpreted in combination with other analytical methods.
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