Search Results

You are looking at 91 - 100 of 331 items for :

  • "population" x
  • Chemistry and Chemical Engineering x
  • All content x
Clear All

Abstract  

New experimental data has been obtained on heavy metal and rare-earth element concentrations in environmental objects, namely pine needles and soils, caused by atmospheric pollution in different regions of the Kola Peninsula. The investigation was performed with the use of epithermal neutron activation analysis at the IBR-2 fast pulsed reactor. Analysis of nearly 40 element distribution in pine-needles and solids from the studied geographical points testifies of a strong contamination source —the nickel smelting complex in Monchegorsk. The contamination levels for Ni, Co, Cr, Se, and others are also high and may be hazardous to the population of this region because some of these elements are carcinogenic.

Restricted access

Abstract  

The objective of the present work is the estimation of the210Po content in some beverages and in tobacco, in order to assess the corresponding collective doses to the population in Argentina. Yerba mate, tea leaves, their infusions and ground coffee were analyzed, as well as tobacco. Collective doses due to the annual consumption of the beverages described were found to be from 6 man.Sv to 1200 man.Sv. Results for210Po in tobacco ranged from 10 Bq·kg–1 to 80 Bq·kg–1. Lung doses due to the use of tobacco vary from 75 Sv·y–1 to 600 Sv·y–1.

Restricted access

Abstract  

Ten macro and trace elements were determined in the hair of GuiZhou and XinHuang mercury mine workers and children living near the mine by INAA and AFS. Comparative studies demonstrated that concentrations of certain elements were greater than those corresponding to the nonexposed population. The hair mercury contents of normal adults and children were 1.1 and 1.37 g g–1, respectively. Workers and children living in the polluted area show a mercury level range of 3.52–317 and 1.50–34.7 g g–1, respectively.

Restricted access

Abstract  

As an example of the mapping of human hair composition, the territory of Uzbekistan was chosen. The data and the maps obtained were compared with the environmental situation and medical statistics. World maps were drawn on the basis of various authors' data. The possibility of using human hair for radioactivity studies is discussed on the basis of data obtained in the Chemobyl area. The proposed scheme of human hair analysis may be used for world mapping for chemical elements, radionuclides, pesticides, dioxines, PCBs, etc., either to picture the global situation or as a health status on the level of populations.

Restricted access

Abstract  

In an attempt to characterize radon distribution in residential settings, the USEPA initiated two distinct survey programs, the National Residential Radon Survey (NRRS) and the State/EPA Residential Radon Survey (SRRS). Each survey is different in their level of analysis, with the NRRS concentrating on a national sample, and the SRRS concentrating on individual statewide samples. Both surveys are random and statistically-valid, enabling the survey samples to be extrapolated to represent a much larger population. This paper details each survey's design and provides an examination of the unique approach each program uses to generate sound characterizations of radon distribution in the United States.

Restricted access

Abstract  

Tritium (3H) concentrations in diet samples from Akita City, northern Japan, and in human tissue samples from the general population of Akita Prefecture were analyzed to study fallout3H transfer.3H concentrations in human soft-tissue samples have been previously found to be similar to those in diet samples. In this study, higher organically-bound3H (OBT) concentrations were found in human costal cartilage and sternum samples than in the soft-tissues. Mean residence times of OBT in the cartilage and sternum were estimated to be 57 years and <6 years, respectively, with a single compartment model which took into account compartment growth.

Restricted access

Abstract  

The distribution of natural radionuclides,40K,226Ra, and232Th, in freshwater sediments and in coal-fired power-plant ash repositories has been tested for lognormality. Thereafter, lognormality for natural radionuclide concentration frequency distribution was accepted with a high probability. The lognormal natural radionuclide distribution in sediments and coal-ash indicated single population groups. The anthropogenic modifications of the natural radionuclide concentrations in the environment are indicated. The adsorbed dose rates, in mGy y–1, in air from gamma field of the natural radionuclides were calculated.

Restricted access

Abstract  

The sandwiched pellet technique using Makrofol-E plastic track detectors has been employed to determine trace quantities of uranium in nine brands of flavored chewing tobaccos consumed by the Indian population. In this technique the nuclear reaction,235U(n,f), is used for the quantitative estimation of uranium. The maximum value of uranium (1.88 ppm) has been found in raw tobacco leaves (Surti), while the minimum (0.13 ppm) in Tulsi (Double Zero brand). Other seven brands showed intermediate values of U-contents which are also reported in this paper. These values are compared with the U-contents reported in the literature for other forms of tobaccos.

Restricted access

Abstract  

The 11 th CITES Conference in 2000 decided to maintain a total worldwide ban on trade of elephant ivory. The 12 th Conference in 2002 decided to allow a conditional trade in stockpiled ivory in 2004. Reopening of the ivory trade would require methods to identify the origin of the ivory so that legal ivory can be distinguished from the black-market ones. In this study, we describe the X-ray fluorescence multi-element analysis of ivory samples from various regions of Africa and Southeast-Asia to characterize ivory of the various elephant populations.

Restricted access

Summary  

Iron(III) spin-crossover complexes [Fe(pap)2]ClO4 . H2O (1), [Fe(pap)2]BF4 . H2O (2), [Fe(pap)2]PF6 . CH3OH (3), [Fe(CH3-pap)2]ClO4 . H2O (4), [Fe0.5Al0.5(pap)2]ClO4 . CH3OH (5) and [Fe0.25Al0.75(pap)2] ClO4 . CH3OH (6)were prepared andthe spin transition behaviors of the complexes have been studied from magnetic susceptibility and Mössbauer spectroscopy measurements. The magnetic properties of light-induced metastable state are measured using Hg-Xe light source. T 1/2is temperature at which the populations of the high-spin and low-spin species are fifty-fifty. Metastable HS is produced by light irradiation at 5 K. T(LIESST) is the temperature at which the populations of the metastable high-spin species decrease to one half and cooperativity factor Cis defined as the parameter which presents the strength of cooperativity. The value of T(LIESST) decreases as T 1/2increases and the plots of T(LIESST) vs. Cshow linear correlation. The effect of cooperativity of the complexes on the relaxations in solid was confirmed for the iron(III) complexes.

Restricted access