[en] A simple method is described for the isolation and determination of plutonium isotopes in sediments. The method involves leaching of sample with nitric acid and subsequent separation of plutonium on an anion-exchange column. Major matrix elements and several potential radiochemical interferences are removed during 8M HNO₃ sample loading on the column. Thorium is removed by thorough washing with 10M HCl. Plutonium(IV) is eluted with 4M HCl. Source for alpha-particle spectrometry is prepared by LaF₃ coprecipitation technique at which stage a complete separation from uranium(VI) is also achieved. The entire analytical procedure is completed in about two days. (author)

[en] A method is described for the non-destructive determination of ²¹⁰Pb and ²²⁶Ra in sediments. The procedure is based on the direct counting of the 46.5 keV γ-ray of ²¹⁰Pb and the 351.9 keV γ-emission of ²¹⁴Pb. The self-absorption of the 46.5 keV γ-ray is corrected using a technique involving direct gamma transmission measurements on sample and efficiency calibration standard. Several reference materials when assayed by the described method yielded results in general agreement with the certified values. The application of the method is illustrated through the analysis of the excess ²¹⁰Pb profile of a Lake Ontario sediment core. (author) 29 refs.; 3 figs.; 3 tabs

[en] The levels of Chernobyl-derived radionuclides were measured in several rain, snow and water filtration plant floc samples collected from various locations in Canada. The data indicate that the Chernobyl release had negligible effect on the radiological quality of Lake Ontario waters. The detection of some activation products in pre-Chernobyl samples, presumably arising from the accidental release of radioactivity during weapon testing at the Nevada site, is also reported. Some data from the ongoing measurements on rain samples are presented to discuss the possible use of Chernobyl radionuclides for delineating tropospheric transport processes. Fractionation factors for the major radionuclides are also reported. (Auth.)

[en] The chemistry of uranium and its eight associated daughters were considered in Lake Ontario water along with that of selected transuranic elements. These transuranics arise mainly from fallout, and to a lesser extent from nuclear fuel reprocessing. Most exist as free ions or oxides of various kinds, uranium probably exists as a strong uranyl carbonate complex. (author)

[en] Water samples were analyzed for total U, Ra-226, Cs-137, Sb-125 and tritium. Levels are generally low, and no time trends were discernible during the monitoring period. Temporal variations among the quarterly analyses are mostly insignificant. Except for total U at certain locations, all other radionuclide levels were much below the 'target concentration' guidelines for Canadian drinking water. The main contribution to the radiological dose commitment was from total U and Ra-226. Contributions from individual radionuclides to cumulative dose were in the order: total U > Ra-226 > tritium > Cs-137 > Sb-125. The limited sediment data suggest that the nuclear facilities along the Ottawa River have increased the levels of Cs-137 and Co-60 but have not affected those of Pb-210 and Ra-226. Total U and Ra-226 activities data suggest disequilibrium; the levels of total U in water were much higher than those of Ra-226. Concentrations of the two radionuclides, however, were positively correlated for most surface waters

[en] A method is described for the determination of ²²⁸Th, ²³⁰Th, and ²³²Th in sediments. The analytical protocol employs direct determination of ²²⁸Th by high-resolution γ-ray spectrometry. Isotopic ratios are determined by α-particle spectrometric assay of the thorium fraction purified by a simple anion-exchange technique. Three sediment and soil reference materials when analyzed by the described method gave results in general agreement with the certified values. 21 references, 3 figures, 1 table

[en] Environmental radioactivity is explained for the Canadian non-specialist under the following headings: sources of radiation and their relative significance, disposal of radioactive wastes, environmental distribution, biogeochemical cycling of radionuclides, environmental radionuclides as tracers, radiation and ecosystem health, radiation and human health. The authors conclude that although radiation performs many useful tasks, and remains an integral part of our lives, yet nevertheless some anxiety will remain

[en] Airborne radioactive materials readily contaminate plant surfaces and thus are incorporated into the food chains. Most of the nuclear fission products and naturally occurring radionuclides in the air are carried on solid particles ranging in size from a few submicrons to several millimetres in diameter. Of many available mechanisms, rainfall plays a dominant role in the deposition and removal of radioactive particles from plants. Mechanisms for the deposition of submicron particles, which carry significant amounts of radioactivity, are still not very well understood. Available information on the physicochemical aspects of the retention of radionuclides by plants is inadequate in explaining radionuclide uptake and desorbability. Much of the work reported so far has been carried out on selected fission products only. There is a dearth of data pertaining to naturally occurring radionuclides, especially ²²²Rn and its daughters, significant amounts of which are released to the environment during uranium mining and milling operations. Radiation damage in plants is difficult to detect except at levels of contamination thousands of times higher than those attained in most real life situations. Existing reports give conflicting accounts of the damage induced by low-level radiation in plants. The literature data discussed in this review are presented as basic information needed for the conduct and interpretation of useful research. (orig.)

[en] The coal available in India for use in coal-burning thermal power plants is of a very inferior quality. It has a low calorific value and a high ash content (40 to 50%). Consequently Indian thermal power plants produce large quantities of fly ash which is disposed as waste. The thermal power plants of the Maharashtra State Electricity Board (MSEB) dispose fly ash by wet disposal method. This method requires large areas of land which are lost to agriculture or forestation. Construction of earthen bunds to make disposal areas requires clay soil which is generally top fertile soil. This also affects agriculture adversely. Moreover the effluent water from ash disposal areas is found to be polluted with suspended solids beyond acceptable limits. MSEB is trying to minimise these adverse environmental impacts by: (1)using fly ash as hearting material to construct bunds, (2) raising tree plantations on ash-filled areas, (3) using effluent water to irrigate forestry or tree plantations, (4) recirculation of ash water, and (5) establishing coal washeries at the site of collieries. This last measure will reduce consumption of fuel required for coal transport and also reduce transportation cost. (M.G.B.). 5 refs

[en] Four possible sources of analytical error in the measurement of unsupported ²¹⁰Pb and/or nuclear fallout radionuclide (such as ¹³⁷Cs) profiles in sediment core are (1) Freezing the entire sediment core prior to precise sectioning; (2) Sectioning the sediment core at room temperature or lower; (3) Determining ²¹⁰Pb via its 5.01-day half-life beta emitting daughter ²¹⁰Bi; (4) Determining ²¹⁰Pb via the 138-day alpha-emitting granddaughter ²¹⁰Pb. Simple procedural modifications can substantially improve the quality of analytical data that are subsequently used to develop intricate mathematical models to aid the interpretation of observed radionuclide profiles. These modifications include (1) Always store subsamples for sufficiently long periods of time to ensure equilibrium between ²¹⁰Po and unsupported ²¹⁰Pb; (2) Always use ²⁰⁸Po as yield monitor and assay autoplated sources on an alpha-particle counter since the alpha particle energies of ²⁰⁸Po and ²¹⁰Po are separable only on a spectrometer using a detector; (3) Never use any glassware for radiochemical work involved polonium since several polonium compounds are known to absorb onto glass surfaces. Quartz is perhaps the best choice though Teflon or similar materials are also suitable for most situations. Avoid heating above 120 C during HCl leaching and above 90 C during plating since PoCl₄ is highly volatile