Implementation of the EU Water Framework Directive in monitoring of small water bodies in Hungary, I. Establishment of surveillance monitoring system for physical and chemical characteristics for small mountain watercourses

The EU Water Framework Directives (WFD) prescribes to achieve a good status of surface waters by 2015. To keep this deadline of a new three level (surveillance, operational and investigative) monitoring system is required, including hydro-morphological, biological and chemical elements. The status of a water body should be related to the reference conditions, depending on surface water types. In Hungary, the standard monitoring network for surface water quality has been operated for rivers and large lakes; however no satisfactory information is available for small water bodies. Therefore, there is an urgent need to design a methodology to develop a monitoring network for small watercourses. For this purpose a slightly impacted mountain stream (Nagy Stream in Mátra Mountains), was selected and intensively monitored during three years (May 2002 → May 2005). Hydrological, biological and chemical parameters required by WFD were monitored in this program. Variability of parameters vs. time and space was also investigated. The minimum frequency of sampling was determined for chosen physico-chemical components to meet the WFD standards for confidence. It was found that the minimum frequency of sampling suggested by WFD in space and time may not be adequate for precise and accurate characterization of water quality.     

Multi-way modeling of hydro-chemical data of an alluvial river system--a case study

A large data set pertaining to water quality of an alluvial river was analyzed using multi-way data analysis methods with a view to extract the hidden information, spatial and temporal variation trends in the river water quality. Four-way data (8 monitoring sites × 22 water quality variables × 10 monitoring years × 12 sampling months) analysis was performed using PARAFAC and Tucker3 models. A two component PARAFAC model, although explained 35.1% of the data variance, could not fit to the data set. Tucker3 model of optimum complexity (2,3,1,3) explaining 39.7% of the data variance, allowed interpretation of the data information in four modes. The model explained spatial and temporal variation trends in terms of water quality variables during the study period and revealed that sampling sites in mid-stretch of the river were dominated mainly by the variables of anthropogenic origin. The results delineated the mid stretch of the river as critical from pollution point of view and also identified summer months as having high influence on river water quality in this stretch. The information regarding spatial and temporal variations in water quality generated by the four-way modeling of data would be useful in developing long-term water resources management strategies in the river basin.     

Water quality study of the Struma river basin,Bulgaria (1989–1998)

The present paper deals with an estimation of the water quality of the Struma river. Long-term trends, seasonal patterns and data set structures are studied by the use of statistical analysis. Nineteen sampling sites along the main river stream and different tributaries were included in the study. The sites are part of the monitoring net of the region of interest. Seventeen chemical indicators of the surface water have been measured in the period 1989–1998 in monthly intervals. It is shown that the water quality is relatively stable throughout the monitoring period, which is indicated by a lack of statistically significant trends for many of the sites and by chemical variables. Several seasonal patterns are observed at the sampling sites and four latent factors are identified as responsible for the data set structure.     

Kirkwood factor for dipolar hard sphere fluids. hindered rotation model

Possibilities of using various physicochemical models of polar liquids for describing the dielectric properties of model systems (one-, two-, or threedimensional dipolar hard spheres) are analyzed. Simple analytical formulas for the Kirkwood factor of the model systems are derived using the generalized hindered rotation model in a nearest neighbor interaction approximation. In the onedimensional case, an exact formula is obtained. For two- and three-dimensional spheres, the formulas adequately reproduce the available data of computer simulations over a wide range of thermodynamic parameters. In the lowtemperature limit (highly polar fluid), the expressions for the Kirkwood factor coincide with those in Pople’s bent hydrogen bond model. The associated equilibrium model also adequately describes the available experimental data in this limit, but leads to nonphysical results at high temperatures. The worst results are obtained in Wertheim’s mediumsphere approximation. Translated fromZhumal Struktumoi Khimii, Vol. 39, No. 5, pp. 843–850, September–October, 1998.     

Water Quality in Watercourses of the Transboundary Narva River Basin

A procedure has been developed for the assessment of transboundary river water quality. The procedure is based on the calculation of the chemical index and classification of water quality. The quality of river waters is assessed by measuring a set of chemical parameters in water samples, followed by data representation in the form of the chemical index CJ which characterizes generalized water quality. A classification system has been proposed for the estimation of contamination of transboundary water bodies on the basis of a “broken bar” model. Using the developed procedure, year-to-year, within-year, and seasonal dynamics of water quality in watercourses of the transboundary Narva River basin have been determined.     

The structure and chemical and acid-base state of the surface of solid solutions and binary components in the InSb-CdS system

The surface physicochemical properties, including microstructure, chemical composition, and acid-base surface properties, of solid solutions and binary components in the InSb-CdS system obtained for the first time were studied. Films of all the components had a polycrystalline structure with a nonuniform character of the distribution of crystallites, which associated into agglomerates. The chemistry of the surface was mainly determined by adsorbed H₂O and CO₂ molecules, OH⁻ groups, and, to a lesser extent, oxygen and hydrogen carbon compounds. The strength, concentration, and nature of acid centers were determined. Coordination-unsaturated In and Cd atoms, adsorbed water molecules, and OH-groups were responsible for acid-basic centers. Changes in the acid-base properties of the surface of InSb-CdS system components caused by composition variations were studied. They correlated with the “specific conductivity-composition” dependence, reflected the special features of donor-acceptor interactions in solid solutions, and could be used to predict adsorption-catalytic properties.     

Thermal properties of polyurethanes synthesized using waste polyurethane foam glycolysates

In this work thermal transitions and thermal stability of polyurethane intermediates and polyurethanes were investigated. The intermediates were obtained by glycolysis of waste polyurethane (PUR) in the reaction with hexamethylene glycol (HDO). The excess of HDO was not separated from the product after the glycolysis process was finished. The effects of different mass ratio of HDO to PUR foam on selected physicochemical properties (hydroxyl number, Brookfield viscosity and density) were also determined. The polyurethanes were synthesized from the obtained intermediates by the prepolymer method using diisocyanate (MDI) and glycolysis product of molecular mass in range 700/1000 g mol^–1. Hexamethylene glycol, 1,4-butanediol and ethylene glycol were used as chain extender agents. Influence of NCO groups concentration in prepolymer on glass transition temperature (T _g) and storage and loss modulus (E’, E’’) of polyurethanes were investigated by the DMTA method. Thermal decomposition of obtained glycolysates and polyurethanes was followed by thermogravimetry coupled with Fourier transform infrared spectroscopy. Main products of thermal decomposition were identified.     

Support vector machines in water quality management

Support vector classification (SVC) and regression (SVR) models were constructed and applied to the surface water quality data to optimize the monitoring program. The data set comprised of 1500 water samples representing 10 different sites monitored for 15 years. The objectives of the study were to classify the sampling sites (spatial) and months (temporal) to group the similar ones in terms of water quality with a view to reduce their number; and to develop a suitable SVR model for predicting the biochemical oxygen demand (BOD) of water using a set of variables. The spatial and temporal SVC models rendered grouping of 10 monitoring sites and 12 sampling months into the clusters of 3 each with misclassification rates of 12.39% and 17.61% in training, 17.70% and 26.38% in validation, and 14.86% and 31.41% in test sets, respectively. The SVR model predicted water BOD values in training, validation, and test sets with reasonably high correlation (0.952, 0.909, and 0.907) with the measured values, and low root mean squared errors of 1.53, 1.44, and 1.32, respectively. The values of the performance criteria parameters suggested for the adequacy of the constructed models and their good predictive capabilities. The SVC model achieved a data reduction of 92.5% for redesigning the future monitoring program and the SVR model provided a tool for the prediction of the water BOD using set of a few measurable variables. The performance of the nonlinear models (SVM, KDA, KPLS) was comparable and these performed relatively better than the corresponding linear methods (DA, PLS) of classification and regression modeling.     

Spectral and photochemical characteristics of CdSe nanoparticles stabilized in polymer-containing media

The optical characteristics of CdSe nanoparticles, produced in aqueous solutions and polymer films in the reaction of cadmium chloride and sodium selenosulfate, were studied. The main parameters that make it possible to vary the forbidden band width were identified. The absorption, photoluminescence, Raman, and nonstationary decolorization spectra of CdSe nanoparticles of various sizes were analyzed. It was demonstrated that under the conditions of pulsed irradiation the CdSe nanoparticles are capable of accumulating excess electrons and inducing redox transformations in components of the solution (oxygen, methylviologen, and sulfite ions). __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 3, pp. 150–155, May–June, 2006.     

Relationship between the gas chromatographic behaviour and the molecular structure of hydrocarbon samples and various stationary phases Part I. Correlation of retention data and thermodynamic functions with chemical structure

Summary Retention parameters of different hydrocarbon classes were determined at 90–120°C on non-polar and medium-polar stationary phases. The specific retention volumes, and the thermodynamic functions of solution were calculated and the relationship between these data, the physicochemical properties and the chemical structure of the solutes (samples) and solvents (liquid phases) investigated.     

Energetics of the interaction of water and other liquids with the surface of hydrophilic and hydrophobic sorbents according to data on the heats of wetting

Papers on the energetics of the interaction of various substances with the surface of hydrophilic and hydrophobic sorbents using the data from heats of wetting are reviewed. The thermodynamics of wetting is examined, and the important role of the heats of wetting for the production of quantitative data on the surface energy of solids is demonstrated. The uniqueness of the information on the physicochemical characteristics of the sorbents and catalysts obtained from the immersion wetting isotherms is emphasized, and up-to-date information on the extent, structure, and characteristics of the boundary layers of water is analyzed. It is shown that the calorimetric data serve as an experimental base for obtaining data on the structural ordering-disordering of the boundary layers of water. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 1, pp. 1–23, January–February, 2008.     

Technological quality determination of pharmaceutical disintegrant by DSC cooling and DSC photovisual

A number of disintegrants are available on the market. They improve tablets’ disintegration. The objective of this work is the comparison of the technological quality parameters of disintegrants using different analytical techniques. Three batches of disintegrants and their binary mixtures (water:disintegrants) were investigated. Cooling experiments were used from –30 up to 200°C. The data obtained showed calorimetric differences between the samples. In the binary mixtures water showed different crystallization behaviour from the one found in the literature. According to the results DSC technique helped the quality control of different disintegrants.     

Isothermal kinetics of dehydration of equilibrium swollen poly(acrylic acid) hydrogel

An isothermal dehydration of equilibrium swollen poly(acrylic acid) hydrogel in the temperature range from 306 to 361 K was investigated. The specific parameters connected with shape of the conversion curves were defined. The activation parameters (E, lnA) of the isothermal dehydration of equilibrium swollen poly(acrylic acid) hydrogel were calculated, using Johnson-Mehl-Avrami (JMA), ‘initial rate’ and ’stationary point’ methods. The reaction models for the investigated dehydration are determined using the ‘model-fitting’ method. It was established that both, the reaction model and activation parameters of the hydrogel dehydration were completely different for the isothermal process than for the non-isothermal one. It was found that the increase in dehydration temperature lead to the changes in isothermal kinetic model for the investigated hydrogel dehydration. It was established that the apparent activation energy (E) of hydrogel dehydration is similar to the value of the molar enthalpy of water evaporation.     

Harrington’s desirability function for natural water quality assessment

The theoretical analysis of the possible application of Harrington’s desirability function for the state of natural ecosystems assessment was made. It was shown that the desirability function with double limiting should be used for water quality objects assessment. The function makes it possible to eliminate arbitrary rule while the number of quality classes at different ways of optimization (typification, classification etc.) of information was determined. This resulted in mathematically valid limitation to the maximum 5 types of the first level. It was underlined that if even one particular response or a particular desirability function does not satisfy the requirements, the general estimation should be considered unsatisfactory, in spite of the fact that the other parameters (properties) of the studied system were satisfied. The tables were made which gave the possibility to assess the up-to-date state of the Rybinsk Reservoir ecosystem according to the content of nutrients and organic matters on the basis of future mesurments. The seasonal pattern of hydrophysical, hydrochemical and hydrobiological processes should be taken into account in order to make more accurate the water quality assessment at the concrete time in the definite site in the Rybinsk Reservoir area.     

Chemometric assessment of thermal oxidation of some edible oils

The effect of microwave heating was studied in six varieties of edible oil. Variations in physicochemical properties were observed and compared with the data obtained by hot plate heating. Fourier-transform infrared spectra of the oils showed substantial variations after both types of heating in the region of hydrogen’s stretching (C–H) vibration, region of double bond’s stretching (C=O), and fingerprint region. The visible spectra of mustard and olive oil showed the reduction in carotenoid, flavonoid, and chlorophyll pigments after heating. The oil samples were discriminated as saturated, monounsaturated, and polyunsaturated fats using chemometric techniques on physical and spectroscopic measurements.     

Composite solid electrolytes

Studies of composite ionic conductors are overviewed. Mechanisms of defect formation at ionic crystal surfaces and at interphase boundaries in the composites are discussed; the Stern model that allows calculating surface potential has been involved. Methods for the calculating of the composite’s electrical conductance and other physicochemical characteristics are suggested. Thermodynamic stability of nanocomposites and the genesis of their morphology during sintering are analyzed. General regularities of changes in ionic-salt properties over wide range of the “ionic salt-oxide” systems, as well as size effects are discussed.     

Laccase

The present review was dedicated to laccase—the enzyme, belonging to the group of multinuclear copper, containing so called “blue” oxidases. The molecular structure, metals content, substrate specificity, and other physicochemical properties were described in this article. The authors considered the mechanism of enzymatic action and electrocatalytic oxygen reduction catalyzed by laccase in details. The data of laccase application in organic synthesis, biosensors, and immunoenzyme assay were presented.     

Water quality assessment of Toledo River and determination of metal concentrations by using SR-TXRF technique

The region of Toledo River, Paraná, Brazil is characterized by intense anthropogenic activities. Hence, metal concentrations and physical–chemical parameters of Toledo River water were determined in order to complete an environmental evaluation catalog. Samples were collected monthly during one year period at seven different sites from the source down the river mouth, physical–chemical variables were analyzed, and major metallic ions were measured. Metal analysis was performed by using the synchrotron radiation total reflection X-ray fluorescence technique. A statistical analysis was applied to evaluate the reliability of experimental data. The analysis of obtained results have shown that a strong correlation between physical–chemical parameters existed among sites 1 and 7, suggesting that organic pollutants were mainly responsible for decreasing the Toledo River water quality.     

Multivariate Association of Graph-Theoretic Variables and Physicochemical Properties

Abstract

We used canonical correlation analysis to examine the multivariate association between two distinct data sets commonly measured or calculated for approximately 600 chemicals: (1) measured or calculated values of select physieochemical properties (i.e., K _ow, boiling point, heat of vaporization, molecular weight, water solubility, molecular volume, hydrogen bonding potential, and vapor pressure) and (2) calculated algorithmically-derived variables (i.e., topological and neighborhood indices derived from graph theory). Canonical correlation analysis identified eight highly significant associations between linear combinations of graph-theoretic variables and linear combinations of physicochemical properties. The set of graph theoretic variables was significantly related to all physieochemical properties, explaining 55% to 99% of the variation in these properties.