Department of Agro-Environmental Chemistry and Plant Nutrition Czech University of Life Sciences Prague Kamýcká 129 165 21 Prague - Suchdol Czech Republic
Abstract: This handbook is intended to doctoral students, young teachers and young scientists. It comprehends an overview about presentation media used in scientific and pedagogic fields. The aspects of printed matterâs design are described and spelt out by a practical manner. The practical examples and advices are supplemented by problem-tasks and project-tasks at the end of each chapter. At the end of the handbook is terminological glossary focused on typographical and design sphere. The book helps to its readers to pass by formidable begins of presentation of own results and ideas.
Abstract: Electrospray ionization was used as a technique for the characterization of the interactions between cadmium(II) ions and malic acid (1) in aqueous solution. Particular attention was paid to the nature of the species formed, which generally correspond to complexes of CdX+ cations with neutral malic acid, where X either is the counterion of the metal salt used as a precursor (i.e. X = Cl, I) or corresponds to singly deprotonated malic acid. In pure water solutions, also highly coordinated complexes [Cd(1-H)(1)2]+ and [CdCl(1)2]+ were detected, whereas the most abundant complexes detected in a sample of soil solution were: [Cd(1-H)(1)]+ and [CdCl(1)]+. With respect to possible application in environmental analysis, the effects of (i) metal salts present in solution, (ii) modest mineralization, and (iii) the matrices of real soil solutions were probed. While the presence of other metals leads to additional complexes, the characteristic species containing both cadmium(II) and malic acid can still be detected with good sensitivity.
Abstract: The knowledge of thermodynamic balances among metals species in environmental matrixes can help in the understanding of processes related to the environmental stress of plants and in the design of suitable phytoremediation strategy. In these processes, low-molecular-weight organic acids (LMWOAs) play a very important role, and therefore the determination of metals species with LMWOAs is of current research interest. Electrochemical techniques available for the trace analysis of metal ions are suitable for speciation studies including the computation of stability constants and the determination of the stoichiometries from the properties of voltammograms/polarograms (pseudopolarograms). Additionally, labile and inert (stable) complexes can be distinguished by several electrochemical methods. A new approach is the hyphenation of electrochemistry (EC) with electrospray ionization mass spectrometry (ESI-MS), which provides assistance to the description of the electrochemical behavior of the complexes as far as both thermodynamic aspects and kinetic properties of metals complexes with LMWOAs are concerned.
Abstract: Electrospray ionization mass spectrometry (ESI-MS) is used to probe the complex formation between tebuconazole (1) and copper(II) salts, which both are commonly used fungicides in agriculture. Experiments with model solutions containing 1 and CuCl(2) reveal the initial formation of the copper(II) species [(1)CuCl](+) and [(1)(2)CuCl](+) which undergo reduction to the corresponding copper(I) ions [(1)Cu](+) and [(1)(2)Cu](+) under more drastic ionization conditions in the ESI source. In additional experiments, copper/tebuconazole complexes were also detected in samples made from soil solutions of various origin and different amount of mineralization. The direct sampling of such solutions via ESI-MS is thus potentially useful for understanding of the interactions between copper(II) salts and tebuconazole in environmental samples.
Abstract: This study presents a new analytical approach for the determination of heavy metals complexed to low-molecular-weight-organic acids in soil solutions, which combines the sensitivity of differential pulse anodic stripping voltammetry (DPASV) with the molecular insight gained by electrospray ionization mass spectrometry (ESI-MS). The combination of these analytical methods allows the investigation of such complexes in complex matrixes. On the voltammograms of the soil solutions, in addition to the expected complexes of oxalic acid with cadmium and lead, respectively, also peaks belonging to mixed complexes of cadmium, lead, and oxalic acid (OAH(2)) were observed. In order to verify the possible formation of complexes with OAH(2), aqueous solutions of OAH(2) with traces of Cd(II) were investigated as model systems. Signals corresponding to several distinct molecular complexes between cadmium and oxalic acid were detected in the model solutions using negative-ion ESI-MS, which follow the general formula [Cd(n)(X,Y)((2n+1))](-), where n is the number of cadmium atoms, X=Cl(-), and Y=OAH(-). Some of these complexes were also identified in the ESI mass spectra taken from the soil solutions.
Abstract: Air, waters and soils has being in increased levels contaminated with various metals, inorganic or organic compounds (partly products of human activity). To secure the normal processes in the living (plant or animal) cells, it is necessary to realize transport of various inorganic and organic compounds (nutrients, etc.), across the cell membrane into or out of the cells or various sub-cellular structures. Not only the useful and usual metabolic compounds are transported into the cells, across the membranes; however, the above mentioned undesired ions, compounds and particles, which are connected with pollution of human environment, are participated in the transporting processes. They are based on many principles, which we intend to study using electrochemical methods (electrochemical impedance spectroscopy, voltammetry, conductometry, patch-clamp techniques etc.). In this contribution, there are described the results of experiments realized on model of supported membranes and some ways of preparation of protoplasts, which would be suitable for patch clamp studies of the charged particles transport. The anodic stripping voltammetry, cyclic voltammetry and related methods were successfully applied for determination and characterization of heavy metal complexes with low-molecular-weight organic acids (LMWOAs) in soil solutions sampled from rhizosphere and bulk soil. All these experiments help us to explain the transporting processes of heavy metals across the real membranes of protoplasts.
Notes: Cited By (since 1996): 1 xD;Export Date: 2 July 2011 xD;Source: Scopus xD;Language of Original Document: English xD;Correspondence Address: Navrátil, T.; Department of Biophysical Chemistry, J. Heyrovský Institute of Physical Chemistry of AS CR, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic; email: tomas.navratil@jh-inst.cas.cz
Abstract: The Cd and Pb complexes with oxalic (OA) and citric acid (CA) were detected in model and soil solutions using cyclic and stripping voltammetry. A mixed complex consisting of Cd, Pb, and OA was found; its peak potential varied from -582.0 to -542.5 mV (vs. Ag/AgCl/KCl(3 mol L-1)). For mixed complex formation, the presence of PbOH+ species and Cd2+ in oxalic acid solution was necessary. Only the simple complexes of CA with Pb and Cd were found in the model solution. The existence of all investigated metal complexes is confined to neutral pH range. The mixed complex was also found in real soil solutions.
Abstract: Current university education is characterized by mass education and student anonymity even though individual education is much more effective. The student usually depends on self-education though it is limited. This report deals with the ways and means that can be used by a university teacher for student motivation to self-education, such as e-learning programs and blended learning.
Abstract: In experiments with willow planted in cadmium- or lead-contaminated Knopp nutrient solutions, the ability of willow and chelex gel in the diffusive gradient in a thin film (DGT) unit to absorb these elements was observed and compared. A method to compare the accumulated amount of metals by the willow and the sorbed amount of metal onto the DGT unit was designed. The accumulated/sorbed amount of metals was recalculated to the same units (mg cm-2 day-1). The study of Cd(Pb) dynamic uptake by willow showed an exponential decrease of metal content in the exposure solution. The willow planted in the Knopp nutrient solution accumulated Cd(Pb) less than did the DGT unit in the same matrix. The willow planted in the soil/water system accumulated more lead than did the willow in a lead-contaminated aquatic system nor did the DGT unit in the nitrate matrix. The willow further accumulated lead from the soilywater system due to the active co-uptake of nutrients and lead. The DGT technique was considered as very good comparative method to measure heavy metals plant uptake. This technique is suitable for use in water as well as in soil systems.
Abstract: Low-molecular-weight organic acids (citric, acetic and oxalic), which are common in soil solutions, decrease accumulation and diffusion flow of cadmium. The flows
depend on the amount and type of organic acid in solution. The order of focused acids according to the degree of diffusion retardation is: acetic < oxalic < citric acid. The relative diffusion flow (Fr) was obtained as the gradient of the time dependences of real amounts of accumulated Cd. From Fr and real flow of free Cd, the kinetic flow was calculated, which characterizes the retardation impact of
the acids on cadmium diffusion.
Abstract: The activity-aided teaching using e-learning program was assessed in studentsâ training in Agrochemistry subject in the first year of bachelor degree study at the Faculty of Agrobiology, Food and Natural Resources of Czech University of Life Sciences Prague. The e-learning program integrated with active methods had greater efficiency in the studentsâ education than in classical, formal teaching. The study was achieved on two groups of students; control group (with classical teaching) and tested group (with activated teaching). Students were distributed into groups randomly and the input knowledge in chemistry followed the Gaussian distribution. Basic studentsâ knowledge on general chemistry was very low on the average and did not correspond with the curricular programs for secondary schools established in the Czech Republic. Activated methods of Agrochemistry teaching consisted mainly from motivation, regularly repetition connected with homework and from usage of e-learning program for self-study. The teaching effectiveness was proved by studentsâ score from three particular tests and by effective progression and by relative progression. The score from particular tests was related to the score from the entrance test. There were two coefficients of the studentsâ progression defined properly, and are applicable for a numerical or percentage value. Students from the tested group achieved statistically significantly (α = 0.05) higher scores (186 points) than students in the control group (136 points) in all three particular tests. Evaluation according to effective progression and relative progression proved the higher progress in the tested group compare to the control group. The evaluation of teaching efficiency can be proved by effective as well relative progression. The effective progression was 55 % in tested group and 26 % in control group. Higher significance of tested studentsâ progression was shown on relative progression; 64 % in tested students and 19 % in control students. The e-learning teaching integrated with active methods can be recommended for higher education.
Abstract: In the soil solutions obtained in situ with suction cups from soils (Cambisol and Fluvisol) of pot experiment with Salix smithiana
Smith, Lolium perenne L. and Thlaspi caerulescens J. & C. Presl heavy metals species (Cd, Pb and Cu) were assayed by differential
pulse anodic stripping voltammetry and diffusive gradient in thin films. Prediction of accumulation performed best at free metal ion
concentrations in unchanged pH (in 10-3 mol L-1 NaClO4 base electrolyte). The speciation provided by differential pulse anodic stripping
voltammetry according to pH can provide a detailed description of the soil solution matrix. The concentration of free metals in
unchanged pH represents a small part of the total content and varied from 0.04 to 0.75% with two exceptions found for accumulating
plants (the content of Cd2+ in the soil solution from T. caerulescens was about 6% and the content of Cu2+ in the soil solution from S.
smithiana was about 30%). The available concentration as determined by diffusive gradient in thin films was not in correlation with the
heavy metals concentration in plant biomass.
Abstract: The Diffusive Gradient in Thin-films (DGT) technique have been applied for assessment of general mobility (detectable by GF-AAS and ICP-OES) and speed mobility (detectable by ASV) of cadmium, copper, lead, and zinc in three soils (Fluvisol, Luvisol, Chernozem) differing in their physicochemical properties and total element levels. The element concentrations measured by ASV and GF-AAS (ICP- OES) substantially differed because of the soils have very different sorption capacity and content of organic matter. What is more, the proportion representations of labile metal-complexes with organic matter differed significantly according to each investigated element because of different rate of metals competition in reaction with the soil organic matter.
