The investigation of the natural waters in the Southern Aral Sea coastal region is an important problem because the ecological situation in the region is directly tied to the change in the chemical composition and other physicochemical properties of natural waters [1,2]. The methods for monitoring the quality of drinking water are unproductive. Then do not allow for multielement analysis. Instrumentational neutron-activation analyis was used to obtain quantitative data on the elemental composition of natural objects and their interrelationship with one another, for example, soils, plants, and natural waters.The objects of investigation were the waters of Amu Darya and the drainage-sewer waters in northern Kara-Kalpak.To determine the optimal conditions for performing neutron-activation analysis, aside from optimizing the time regime, the conditions of analysis with respect to the volume or mass of dry residue were varied because of the high mineralization of the waters (up to 600-800 mg/liter). To improve the efficiency of determining individual elements, the method of screening thermal neutrons with a cadmium screen was used. In this case the samples are activated by resonance neutrons. The cadmium ratio of 24 Na, 42 K, and 82 Br, which predominate in the γ-ray spectrum of the sample, was measured. The following values were obtained for the cadmium ratios: 48.2 for 24 Na, 37.8 for 42 K, and 2.2 for 82 Br. When the samples are irradiated in cadmium vessels (1 mm), favorable conditions are created for selective activation of the elements which have resonance activation levels.Water samples with a volume of 1 ml were dried in polyethylene boats at temperatures not exceeding 60°C. The water samples were irradiated for 15 sec in a cadmium vessel by a flux with density 5·10 13 sec -1 ·cm -2 . After "cooling" for 20 min, photopeaks of the following radionuclides were found in the γ spectrum of this sample: 128 I (442.9 keV), In this regime, the γ spectra of the radionuclides which are present are covered less by the Compton background of 24 Na. The following photopeaks clearly stand out in the γ spectrum of the same sample after cooling for 5 h: 438.3 keV -69 Zn, 482.5 keV -90m Y, 511 keV -64 Cu + These are sufficient for quantitative determination of these elements. In this regime it is convenient to determine magnesium without inteference by 27 Mg, yttrium according to the 483 keV line, and 98m Y and nickel according to 65 Ni.To determine other chemical elements, 50 ml of water was used, the activation time was increased to 15 h, and the cooling time was 12 days. The following photopeaks are identified in the spectrum: 103.3 keV ( 153 Sm + The selectivity of the determination of Sm, Au, La, Sr, and Br according to the area of the photopeaks is >3, and for the photopeaks 208.3 keV -177 Lu (K = 2.1) and 497.8 keV -131 Ba (K = 2.1) the selectivity is adequate for quantitative determination of these elements in highly mineralized waters from the waters of the Aral Sea coastal zone.The following elements were determined f...
The samples of soils, drinking water and hair of habitants of 15 districts in Tashkent region studied using the method of neutron activation analysis. The results obtained from soil and drinking water analyses indicated that contents of Zn, Co, Cu and other elements in a number of districts are higher in comparison with average values throughout the region. This is related to developed industry in these regions. The analysis of the habitants' hair also indicated increased values, which are caused by environmental contamination and working conditions. For generalized assessment of environmental condition it was suggested to use the logarithm of multiplication of the lithophylic elements (Ba, Ca, K, La, Na, Rb, Sc, Sr) content, characterizing the geochemical condition. And similarly, the logarithm of multiplication of potential pollutants, typical for this area, such as Br, Co, Cr, Sb, U, Zn content in soil, water and hair was used as conditional index of overall pollution. It was demonstrated, that fluctuations of lithophylic elements content logarithm value throughout the districts of the region are insignificant and fall within range of 3941, while logarithm values for the potential pollutants vary from 3.1 to 9.3. The distribution of a hypothetical integral pollutant is presented in the cartogram. The correlation analysis conducted has established a relationship between the content of elements in environmental objects and some diseases, indicating that increased or decreased content of elements in the hair is highly likely one of the signs of a particular disease, especially in environmentally disadvantaged districts of the region.
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