Radium-226, activity

Sanchez F, Rodriguez-Alavarez MJ (1999) Effect of pH, conductivity and sediment size on thorium and radium activities along Jucar River (Spain). J Radioanal Nucl Chem 242 671-681 Sarin MM, Krishnaswami S, Somayajulu BLK, Moore WS (1990) Chemistry of U, Th, and Ra isotopes in the Ganga-Brahmaputra river system Weathering processes and fluxes to the bay of Bengal. Geochim Cosmochim Acta 54 1387-1396... 

Figure 8. Specific activity of Radium in ordinary plants and algae (solid line) compared to Characeae algae (dotted line), showing roughly a linear relationship with the Radium activity concentration in the water.

FIGURE 4. Radium activity concentration in the well water, Bq/L. 

Gr. aktis, aktinos, beam or ray). Discovered by Andre Debierne in 1899 and independently by F. Giesel in 1902. Occurs naturally in association with uranium minerals. Actinium-227, a decay product of uranium-235, is a beta emitter with a 21.6-year half-life. Its principal decay products are thorium-227 (18.5-day half-life), radium-223 (11.4-day half-life), and a number of short-lived products including radon, bismuth, polonium, and lead isotopes. In equilibrium with its decay products, it is a powerful source of alpha rays. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300-degrees G. The chemical behavior of actinium is similar to that of the rare earths, particularly lanthanum. Purified actinium comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.6-year half-life. It is about 150 times as active as radium, making it of value in the production of neutrons. 

Joly observed elevated "Ra activities in deep-sea sediments that he attributed to water column scavenging and removal processes. This hypothesis was later challenged with the hrst seawater °Th measurements (parent of "Ra), and these new results conhrmed that radium was instead actively migrating across the marine sediment-water interface. This seabed source stimulated much activity to use radium as a tracer for ocean circulation. Unfortunately, the utility of Ra as a deep ocean circulation tracer never came to full fruition as biological cycling has been repeatedly shown to have a strong and unpredictable effect on the vertical distribution of this isotope. 

The final member of the group, actinium, was identified in uranium minerals by A. Debieme in 1899, the year after P. and M. Curie had discovered polonium and radium in the same minerals. However, the naturally occurring isotope, Ac, is a emitter with a half-life of 21.77 y and the intense y activity of its decay products makes it difficult to study. 

The curie was supposed to be the activity of a one-gram sample of radium, the element discovered by the Curies it isn t quite.)... 

Curie (Ci)—A unit of radioactivity. One curie equals that quantity of radioactive material in which there are 3.7xl010 nuclear transformations per second. The activity of 1 gram of radium is approximately 1 Ci. 

The activity is a measure of the quantity of radioactive material. For these radioactive materials it is customary to describe the activity as the number of disintegrations (transformations) per unit time. The unit of activity is the curie (Ci), which was originally related to the activity of one gram of radium, but is now defined as that quantity of radioactive material in which there are ... 

Soil is a mixture of solid materials, air and, usually, water and organic matter. The radium content of soil often reflects that of the rocks from which the solid materials are derived by physical and chemical activity. The observed ranges are from 0 to 20 Bq kg for ultrabasic rocks (dunite) to 1 to 1835 Bq kg for igneous metamorphic rocks (gneiss) (Wollenberg, 1984). While these ranges are broader than those for measured for soils, the mean values for rocks, excluding alkali rocks, is consistent with the means observed for soils. 

Briggs, G.H., Distribution of the Active Deposits of Radium, Thorium and Actinium in Electric Fields, Phil. Mag. 41, 357, 1921. 

Wellisch, E.M. The Distribution of Active Deposit of Radium in an Electric Field, Philosophical Magazine 26 623-635 (1913). 

The subsoil is the principal source of radon in this house. Both the activity concentration of radium-226 in subsoil and of radon in soil gas are above levels for building ground that might result in significant indoor radon concentrations. The radon decay-product concentration in the dwelling before remedial measures were taken was substantially higher than the reference value of 120 mWL. 

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