Determination of Quality Indicators of Prut River Water

This study presents an assessment of water quality of Prut River using the Water Quality Index (WQI), calculated according to the weighted arithmetic water quality index method. The obtained results show that the water of Prut River may be classified according to WQI as good water quality of grade B for sampling points Sculeni and Cislita-Prut villages, and very poor water quality of grade D collected in the sampling point Criva village

Undergrountd water potabilization using physical, physico - chemical and chemical proceses

Introduction. In the last 70 years, as a result of the intensive development of industry, agriculture and the living standards of the population on Earth, the water quality has deteriorated catastrophically. This endangers the health of the population, causing the spread of infections and the appearance of chronic diseases. The study carried out by researchers from the Water Chemistry Laboratory of the Institute of Chemistry over the last 25 years, aimed at the establishing of the chemical indices of natural water quality showed that in most cases, water from underground wells does not comply with the required sanitary norms of the “Drinkable Water” STAS. Scientific research has been carried out using physical, chemical and physico-chemical processes such as aeration, oxidation, ion exchange, adsorption on activated carbon, and reverse osmosis. Material and methods. The water samples of the underground wells from different geographical areas of the Republic of Moldova were taken in plastic bottles, of which three 1-litre bottles were completely filled and transported to the laboratory in refrigerated boxes for a maximum of 5 hours for being analyzed. The concentration of hydrogen sulfide and soluble sulfides, ammonia and ammonium ions, nitrite ions, nitrates, chlorine, fluorine, sulphates, iron, manganese, calcium, magnesium, and permanganate oxidability was determined using the analytical methods and standardized spectrometry. The removal of chemical components that exceeded the maximum allowable concentration (MAC) in drinkable water was performed using the unique pilot plant developed and built at the Laboratory of Ecological Chemistry of the Institute of Chemistry. The research leading to these results has received funding from Innovation Staff Exchange Programme and institutional project DISTOX, no. 20.80009.7007.21 Results. The analysis of chemical water quality indices retrieved from 115 artesian wells from different geographical areas of the Republic of Moldova revealed that the most frequent MAC values exceeding these indices are the values of ammonia concentrations and ammonium ions, hydrogen sulfide and soluble sulfur, sodium ions, iron, manganese nitrites, nitrates, as well as the oxidability of the permanganate. It has been established that out of the 115 artisanal wells under study, 96% do not fully comply with the quality indices required for drinkable water. Water taken from underground wells, showing chemical quality standards exceeding MAC has been treated under dynamic conditions using the following consecutive processes: mechanical filtration, aeration, oxidation, ion exchange, adsorption on activated carbons. Conclusions. The underground waters from the Republic of Moldova are of poor quality. Using consecutive processes of filtration, aeration, oxidation, ion exchange, adsorption on activated carbons, reverse osmosis, water with drinkable qualities can be obtained

A global look at time: a 24-country study of the equivalence of the Zimbardo Time Perspective Inventory

In this article, we assess the structural equivalence of the Zimbardo Time Perspective Inventory (ZTPI) across 26 samples from 24 countries (N = 12,200). The ZTPI is proven to be a valid and reliable index of individual differences in time perspective across five temporal categories: Past Negative, Past Positive, Present Fatalistic, Present Hedonistic, and Future. We obtained evidence for invariance of 36 items (out of 56) and also the five-factor structure of ZTPI across 23 countries. The short ZTPI scales are reliable for country-level analysis, whereas we recommend the use of the full scales for individual-level analysis. The short version of ZTPI will further promote integration of research in the time perspective domain in relation to many different psycho-social processes

DETERMINATION OF COPPER AND ZINC IN MINERAL WATERS BY ATOMIC ABSORPTION SPECTROPHOTOMETRY

The content of copper and zinc in mineral waters were determined by atomic spectroscopy with preliminary extraction of metals. Validation of the technique was carried out by the method of standard additions and proved the reliability of analytical data

ASSESSMENT OF HEAVY METALS CONTENT IN BOTTOM SEDIMENTS AND THEIR INTERSTITIAL WATER OF THE RIVER PRUT (MOLDOVA)

Assessment of heavy metals content in bottom sediments and their interstitial water of the River Prut (Moldova) Composition and quality of natural waters, determined by several factors depending on environmental conditions, is influenced also by the equilibrium of mobilization-immobilization processes of pollutants at the interface of the various phases, in particular, water-particulate materials-bottom sediments system. The peculiarities of spatial, seasonal and multi-annual dynamics of heavy metals content (Cu, Ni, Cr, Zn, Pb, Cd) in aquatic sediments and their interstitial water along the Prut River were established. In order to determinate total content of heavy metals in bottom sediments the procedure recommended by the Geological Agency of USA was used. Obtained results revealed the accumulation of most metals in bottom sediments on the lower course of the Prut River. Maximal content of Zn was recorded on the middle course of the river

Topology of 2‑Periodic Coordination Networks: Toward Expert Systems in Crystal Design

We have performed comprehensive topological analysis of 2-periodic coordination networks in 10 371 metal–organic compounds. Both local and overall topologies of complex groups were determined, classified, and stored in the electronic databases. Two plane nets, square lattice (<b>sql</b>) and honeycomb (<b>hcb</b>), were found to compose two-thirds of all the coordination networks. Strong correlations were found between local topological characteristics (coordination numbers of atoms or complex groups, coordination figures, formalized coordination modes of ligands and coordination formula) and the overall topology that in many cases allowed us to predict possible topological motifs from the data on chemical composition with high probability. The possibility to develop an expert system that could envisage local and overall topology of periodic coordination networks is discussed, and an example is given of how such a system can work

Topology of 2‑Periodic Coordination Networks: Toward Expert Systems in Crystal Design

We have performed comprehensive topological analysis of 2-periodic coordination networks in 10 371 metal–organic compounds. Both local and overall topologies of complex groups were determined, classified, and stored in the electronic databases. Two plane nets, square lattice (<b>sql</b>) and honeycomb (<b>hcb</b>), were found to compose two-thirds of all the coordination networks. Strong correlations were found between local topological characteristics (coordination numbers of atoms or complex groups, coordination figures, formalized coordination modes of ligands and coordination formula) and the overall topology that in many cases allowed us to predict possible topological motifs from the data on chemical composition with high probability. The possibility to develop an expert system that could envisage local and overall topology of periodic coordination networks is discussed, and an example is given of how such a system can work

ADSORPTION OF STRONTIUM IONS FROM WATER ON MODIFIED ACTIVATED CARBONS

Adsorption of strontium ions from aqueous solutions on active carbons CAN-7 and oxidized CAN-8 has been studied. It has been found that allure of the adsorption isotherms for both studied active carbons are practically identical. Studies have shown that the adsorption isotherms for strontium ions from aqueous solutions are well described by the Langmuir and Dubinin-Radushkevich equations, respectively. The surface heterogeneity of activated carbons CAN-7 and oxidized CAN-8 has been assessed by using Freundlich equation