Radium Detection

In contrast to thermal ionization methods, where the tracer added must be of the same element as the analyte, tracers of different elemental composition but similar ionization efficiency can be utilized for inductively coupled plasma mass spectrometry (ICPMS) analysis. Hence, for ICPMS work, uranium can be added to thorium or radium samples as a way of correcting for instrumental mass bias (e g., Luo et al. 1997 Stirling et al. 2001 Pietruszka et al. 2002). The only drawback of this approach is that small inter-element (e g., U vs. Th) biases may be present during ionization or detection that need to be considered and evaluated (e.g., Pietruszka et al. 2002). 

Figure 2. Alpha spectrum for a radium adsorbing manganese-oxide thin film exposed to a groundwater sample, after Surbeck (2000) and Eikenberg et al. (2001b). A 2x2 cm sheet is exposed to O.l-l.O L of sample for 2 days, capturing nearly all of the radium in the sample. These sample discs can be used directly for low-level alpha spectrometry without the need for further separation and preparation methods to produce planar sample sources. Energy resolution is nearly as good as for electroplated sources, and detection limits are typically 0.2 mBqA (6 fg Ra/L) for Ra and " Ra for a one-week counting period. These sensitivities are comparable to traditional methods of alpha spectrometry. [Used by permission of Elsevier Science, from Eikenberg et al. (2001), J Environ Radioact, Vol. 54, Fig. 4, p. 117]...

In 1900 Ernest Rutherford (1871-1937) detected the radon-220 isotope as a decay product of thorium. In the same year, Dorn showed the radon-222 isotope to be a decay product of radium. 

Other uses are to produce phosphorescence and fluorescence in organic compounds and for scintillation screens on instruments used to detect radiation. Radium salts were used in the past to paint the dials of luminous clock faces that glow in the dark. 

Since the discovery of radium compounds, many radio-active substances have been isolated. Only exceedingly minute quantities of any of them have been obtained. The quantities of substances used in experiments on radio-activity are so small that they escape the ordinary methods of measurement, and are scarcely amenable to the ordinary processes of the chemical laboratory. Fortunately, radio-activity can be detected and... 

According to the technology developer, geochemical fixation can treat dissolved hexavalent chromium and other metals in groundwater at concentrations ranging from the detection limit to several hundred parts per milhon. The developer asserts that geochemical attenuation can treat most of the common heavy metals, trace elements, and namral radionuclides that occur in groundwater, such as metal-cyanide complexes, arsenic, cadmium, chromium, copper, lead, selenium, uranium, and radium. 

The radium-228 content of fly ash has varied from 1.8 to 3.1 pCi/g (0.07 to 0.12 Bq/g) (Eisenbud and Petrow 1964). If it is assumed that the total radium content of fly ash is 5 pCi/g (0.19 Bq/g), and that 1% of the ash generated at all coal-fired power plants in the United States escapes into the atmosphere, then an order-of-magnitude estimate of the amount of radium released each year would be 2.2 Ci (81,000,000 kBq) (Roy et al. 1981). Eisenbud and Petrow (1964) estimated that a single 1000-megawatt coal-fired power plant will discharge about 28 mCi (1,037,000 kBq) of total radium per year. Radium-226 has been detected in soils in industrial regions at levels up to 8.1 pCi/g (0.30 Bq/g) (Jaworowski and Gryzbowska 1977). 

Land releases of radium are related to atmospheric fallout of coal fly ash (see Section 5.2.1). For example, elevated radium-226 concentrations in snow have been detected near a coal-fired power plant in Poland (Jaworowski et al. 1971). Other land releases may include the disposal of coal fly ash, lime slurry derived from water softening processes, and uranium mine tailings and associated wind-blown dusts. However, no information was located on the total amount of land-released radium... 

The purpose of this chapter is to describe the analytical methods that are available for detecting and/or measuring and monitoring radium in environmental media and in biological samples. The intent is not to provide an exhaustive list of analytical methods that could be used to detect and quantify radium. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used to detect radium in environmental samples are the methods approved by federal agencies such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by a trade association such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that refine previously used methods to obtain lower detection limits and/or to improve accuracy and precision. 

Because small amounts of radium radionuclides in environmental samples may be regarded as hazardous, it is usually necessary to detect very small quantities of radium which may require processing large quantities of sample (Quinby-Hunt et al. 1986). This introduces possibilities for contamination and sample loss. Specifically, in the case of water samples, sorption of the radionuclide to container walls and to suspended matter may be important sources of error. 

Effects specifically associated with radium exposure have not been identified. The development of methods for detecting biomarkers of radium s effects would be useful. 

Schlundt H, Nerancy JT, Morris JP. 1933. The detection and estimation of radium in living persons IV. The retention of soluble radium salts administered intravenously. Am J Roentg Rad Therapy 30 515-522. 

Kastler, A. (1950). Quelques suggestion concentrant la production optique et la detection optique d une inegalite de population des niveaux, J. Phys. Radium, 11, 225-265. 

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