Artisans in Masisi and other parts of the North Kivu province in the eastern Democratic Republic of Congo (DRC) mine columbite-tantalite mineral ores (also called 'coltan') for the tantalum content. The potential occupational radiation exposures in the course of this operation, due to the presence of naturally occurring radioactive material (NORM), have been investigated in this screening survey. Activity concentrations of the naturally occurring radionuclides in samples of coltan were measured using gamma-ray spectrometry. The average values in Bq g(-1) are 10.75 +/- 5.11 for (238)U, 7.06 +/- 3.39 for (226)Ra, 1.75 +/- 0.85 for (232)Th, and 1.63 +/- 0.52 for (40)K. Based on these values and the working scenarios involved in artisanal coltan mining, the occupational doses that may accrue from a variety of exposure pathways were determined by model calculations. The results, assuming conservative dust load and dilution factors, indicate that grinding and sieving coltan can give rise to high occupational doses, up to 18 mSv per annum on average.

No abstract

Soil quality assessment (SQA) is important for modulating agricultural productivity and thus requires simple and rapid analysis of soil (macro & micro) nutrients (here called soil quality indicators – SQIs). We report proof of concept of a chemometrics‐assisted energy dispersive X‐ray fluorescence and scattering (EDXRFS) spectroscopy technique for direct rapid analysis of SQIs. The EDXRFS method exploits, in addition to fluorescence, the X‐ray scatter peaks obtained non‐invasively from soils to develop a calibration strategy for quantitative analysis of SQIs in model clay soils doped with micronutrients (Fe, Cu, and Zn) and macronutrients (NO3−, SO42−, and H2PO4−). The soil samples and certified reference materials IAEA Soil‐7 and IAEA Soil‐1 (used to build spectral library for soil classification) were irradiated at various live times (to simulate different signal‐to‐noise ratios of analyte signals and analysis speed) in a teflon holder and were analyzed using a 109Cd‐excited XRF spectrometer. Principal components analysis was used for spectral data compression and pattern recognition (including for those SQI spectral signatures without any visibly discernible characteristic X‐ray lines), whereas partial least squares regression and artificial neural networks were used to build a calibration and quantitative analysis strategy. The method furnishes soil micronutrient and macronutrient information simultaneously and rapidly (t = 200 s). To the best of the authors' knowledge, this is the first time that an XRF method has demonstrated spectroanalytical potential for quantitative macronutrients analysis in soils applicable to routine SQA. Coupling EDXRFS with multivariate chemometrics enables rapid and reliable assessment of chemical SQIs. Copyright © 2011 John Wiley & Sons, Ltd.

No abstract

In Kenya, beetroot bulbs are occasionally used as a blend in fruit juices and salads, as a livestock feed and for treatment of diseases. Analysis of essential elements in beetroot bulbs was performed using Energy Dispersive X-ray fluorescence (EDXRF) in order to determine the nutritional content of the bulbs. The beetroot bulbs were sampled from five different geographical regions in Kenya; Karatina, Gilgil, Naivasha, Joska and Kisumu. The results of the concentrations of the essential elements had a range of: 10000 mg kg-1 to 61000 mg kg-1 for potassium, 500 mg kg-1 to 4500 mg kg-1 for calcium, 15.0 mg kg-1 to 230 mg kg-1 for manganese, 24.0 mg kg-1 to 770 mg kg-1 for iron and 16.0 mg kg-1 to 680 mg kg-1 for zinc. In general, the trend in the concentrations of the essential elements was K > Ca > Fe > Mn > Zn. Karatina samples registered the highest concentrations for all the elements of interest in this study. The results of analysis of variance (ANOVA) for all the five sampled regions show that there is a significant difference in the Ca, Fe and Mn concentration levels. Beetroots were found to contain sufficient amounts of the essential elements, therefore, are a suitable vegetable source of essential elements of K, Ca, Mn, Fe and Zn and can be used as an immune system booster. This study is supportive to the Government's efforts of improving health care and in the fight against "hidden hunger-malnutrition" in the country.