The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
DEVELOPMENT AND APPLICATION OF RADIOACTIVATION METHODS
IN STUDYING OF PHYSICAL AND CHEMICAL FORMS OF HEAVY
METALS IN ATMOSPHERIC AIR.
R.A.KULMATOV. A. AZIZOV. National university o f Uzbekistan.
Toxic properties o f heavy metals for human organism are connected with their form o f migration in the atmospheric air. In particular, submicron aerosols with a size less than <0.4 microns are the more toxic for human organism. A submicron particles are not hold in respiratory system of people and easily gets into blood through alveolus’s of lungs.
Not enough sensitivity and accuracy of exist physical-chemical methods of analyzes stipulate necessity of developing and applying complex high-sensitively and many component methods of determination of contents and migration forms of HM in atmospheric air.
For the determining of concentration of large number HM and dispersed element contents of aerosols, and phase distribution of HM in atmospheric air suggested method of neutron-activatation analyze, based on using of multistage impactor and method of condensation.
Aerosol phase caught on the filter of type AFA, and vapour-gas phase by method o f condensation on traps. Mass median diameters (MMD) of aerosol particles on steps of the modified impactor Mea were as follow: on 1st step - 11.5; on 2nd - 3.6; on 3rd - 1.8; on 4th - 1.03; on
Section III. Radiation Ecology
The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
5th - > 0.4 mkm. The efficiency of division of aerosol particles on the impactor by electronic microscope was estimated.
Elements containing in composition o f particle with size < 0.4 mkm, caught on impactor behind consecutively connected cascade of cryogenic traps. Cryogenic traps were quartz vessel, containing three consecutively connected parts, which are cooling in mixture of hard carbonic acid with spirit or acetone, which gives temperature - 80°C.
Volume velocity pumping of air through the system is V=17.5 1/min. After selection of aerosol and of vapour-gas condensate form of HM, separately packed and analyzed by method of neutron-activation analyzes. Samples are irradiated in nuclear reactor WWR-CM in flow o f thermal neutrons /= 5 * 1013 n*cm-2*cm-1. Radioactivities of samples are measured by semi-conductor Ge (Li) detector and many-channel analyzer.
By using this method we have study laws of space-temporarily changes of concentrations and migration forms about 15 HM in atmospheric air o f cities of Uzbekistan.
Average contents of HM in city aerosols fluctuated from 10 till 100 mkg/m3 for Fe, Al, Na and Cl, and from 0.001 till 0.1 mkg/m3 for Au, U, As, Co, Se, Cd and Hg.
Studying of migration forms of HM in atmospheric air o f industrial cities expose follow laws: In atmospheric air cities most of HM such as Hg, Se, Zn, Cr, Au and Br in prevalent quantity migrates in content of particle with size < 0.4 mkm or vapour-gas phase.
Depending on year seasons and type sources of basic industry pollutant emissions in cities importantly differences in the migration forms of HM. In particular for city Almalyk, where located mountain-metallurgical enterprises is ftmctioning, characteristically prevent migration o f Cu, Zn, Cd, As and Pb in atmospheric air cities in content of bringing particles with size < 0.4 mkm.
For cities Fergana, Samarkand and Navai were established that, the elements Fe, Th, Sc and La are migrates in content of particle with size 3.6 < t < 0.4 mkm.
The distribution and migration of HM in atmospheric air of reserves (Sarychelek, Zamin) appreciably differ from the cities. In particularly, there was established that, in atmospheric air o f reserve Sarychelek the many of elements such as Hg, Se, As, Br, Au, Sb, Cu and Zn enriched in comparison with lithosphere and considerable part of (>50%) migrates in content of submicron particles or vapour-gas phase with size < 0.4 mkm, that allows to bring them to the number o f global polluting matters, which have comparatively more time of life in the atmosphere air.
Particle with size < 0.4 mkm are containing HM, easily migrates in air, insufficiently for catching by dust-gas-cleaning structures and represent more danger for human health. Aerosol particles with size < 0.4, mkm containing HM, badly caught in human nasopharynx.
The received data are used for an estimation of distribution, toxicity o f heavy metals on the environment and human organisms.
