Radiometric, SEM and XRD investigation of the Chituc black sands, southern Danube Delta, Romania

• Published in: Journal of environmental radioactivity Vol. 138; pp. 72 - 79
• Main Authors: Margineanu, R.M., Blebea-Apostu, Ana-Maria, Celarel, Aurelia, Gomoiu, Claudia-Mariana, Costea, C., Dumitras, Delia, Ion, Adriana, Duliu, O.G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2014; Elsevier
• Subjects: Applied sciences; Background Radiation; Black sand; Brackish; Chituc sand bank; Dominance; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Feldspars; Geologic Sediments - chemistry; High background; Marine; Microscopy, Electron, Scanning; Natural radioactivity; Pollution; Pollution sources. Measurement results; Pollution, environment geology; Radiation Monitoring; Radioactivity; Radioisotopes; Radioisotopes - analysis; Romania; Sands; Soil and sediments pollution; Soil Pollutants, Radioactive - analysis; Spectrometry, Gamma; Spectrometry, X-Ray Emission; Underground; Western Black Sea shore; X-Ray Diffraction; Romania; Eastern Europe; East Mediterranean; Mediterranean Sea; Black Sea; Europe; MED, Black Sea; MED, Romania; MED, Black Sea, Danube Delta; Western Black Sea shore; High background; Natural radioactivity; Black sand; Chituc sand bank; scanning electron microscopy; Natural origin pollution; gamma-ray spectroscopy; Littoral zone; Cesium 137; Radioactive pollution; Black sands; X-ray diffraction; radiometry; Geogenic factor; radioactive isotopes; radioactivity surveys; Anthropogenic factor
• ISSN: 0265-931X; 1879-1700
• DOI: 10.1016/j.jenvrad.2014.08.006

The black sand of the Chituc marine sand bank, northern of the city of Navodari (Romania), presents anomalous high radioactivity. Field measurements recorded in some places dose rate up to 200 nSv/h, significantly overpassing the average value of 44 ± 20 nSv/h along the entire Southern sector of Romanian Black Sea shore. Gamma ray spectrometry performed on both Slanic-Prahova Underground Low Background Laboratory and Geological Institute of Romania Radiometric Facilities showed with clarity the dominance of 228Ac radioisotope in the 50 microns fraction together with the 226Ra and traces of 40K. No significant amount of anthropogenic 137Cs was identified. Based on radiometric as well as on SEM–EDAX and XRD determinations we come to the conclusion that the evidenced radioactivity could be attributed to both uranium and thorium series in the zircon and monazite fractions and to a lesser extent to potassium in the feldspars. •High background radioactivity (up to 200 nSv/h) evidenced.•Radiometric measurements showed a maximum radioactivity of U and Th confined to 50–100 μm fraction.•XRD and SEM–EDAX data revealed the presence of k-feldspars, ilmenite, zircone, monazite and garnets.