Heavy metals concentrations and speciation of Pb and Ni in airborne particulate matter over two residential sites in Greater Cairo - reflection from synchrotron radiation.

Synchrotron radiation-based techniques [X-ray absorption near-edge structure (XANES) and X-ray fluorescence (XRF)] combined with inductively coupled plasma-mass spectrometry (ICP-MS) were used for the assessment of heavy metals concentrations as well as lead (Pb) and nickel (Ni) speciation in airborne particulate matter (PM10) over two residential sites in Greater Cairo. Nineteen 24 h high-volume samples collected at Giza (G) Square and Helwan (H) University (Egypt) were selected for this study. Mean concentrations of heavy metals in PM10 at both sites were found to have the same descending order of Pb > Cu > Ni > Cd > Co > As, of which concentrations of Pb, Cu, Ni and Cd in H samples were higher than those in G samples. For Pb, synchrotron-based XRF results were in good agreement with concentrations obtained by ICP-MS. The XANES spectra of PM10 at the Pb L2-edge and Ni K-edge were compared with those of Pb and Ni in model standard compounds to provide information on the potential oxidation states as well as the chemical forms of those elements. The data show that Pb has similar chemical environments in both series G and H with the predominance of Pb2+ oxidation state. Nickel was found as Ni(OH)2, NiO and Ni metal in the analyzed samples. However, the content of Ni in the background filter shows a very strong interference with that of the collected PM10. Carcinogenic and non-carcinogenic risks resulting from the inhalation of the studied heavy metals were assessed for children and adult residents and were found below the safe limits, at both sites.

Soil-to-plant uptake of 137Cs and 85Sr in some Egyptian plants grown in Inshas region, Egypt.

The transfer of 137Cs and 85Sr from soil to different plants has been studied in two successive pot field-grown experiments. Five plant species (Oryza Sativa, Tritichum Vulgares, Vicia Faba, Sesamum Orientale and Trifolium Alexandrinum) were grown in pots with sandy clay loam soil contaminated with varying amounts of 137Cs or 85Sr. The absorption of the radioisotopes was measured in different parts of the plants and their activity concentration was significantly increased with increasing radioactivity of both radioisotopes in the soil. The distribution pattern of the total absorbed 137Cs or 85Sr in different plants after soil contamination shows that the shoots of these plants contained the highest percentage of both radionuclides (65.8-73.8% for 137Cs and 77.3-80.7% for 85Sr) followed by roots (16.4-22.4% for 137Cs and 19.5-21.4% for 85Sr) and finally by grains/seeds (4.9-12.9% for 137Cs and 0.3-1.3% for 85Sr). The transfer factors of 85Sr were higher than those of 137Cs for shoots of the tested plants, and were in the ranges of 2.3×10-2 - 4.8×10-2 and 8.8×10-2 - 2.0×10-1 for 137Cs and 85Sr, respectively. The transfer factors of grains or seeds were significantly lower than those of roots or shoots. Also, the transfer factors of leguminous plants were higher than those of cereal plants. Regarding Trifolium plant, the highest activity concentration of both isotopes was found in the second harvest samples.

Distribution of 137Cs and 85Sr in selected Egyptian plants after foliar contamination.

The transfer of 137Cs and 85Sr from fallout to plants was studied in two successive pot experiments. Five plant species (Oryza Sativa, Tritichum Vulgares, Vicia Faba, Sesamum Orientale and Trifolium Alexandrinum) were grown in pots containing sandy clay loam soil. For simulating foliar contamination, radioactive 137Cs and 85Sr solutions were sprayed once with different activity concentrations gently on the shooting system. After 8 weeks of radioactivity application to the above first four plants and 4 weeks to the last one, the total absorption of 137Cs and 85Sr and their distribution in different parts of the tested plants were determined. Most of the absorbed 137Cs and 85Sr accumulated in shoots with proportions ranged from 70.8 to 81.9% and from 88.9 to 95.0%, respectively for different plants. The absorbed 137Cs and 85Sr by grains/seeds followed that of shoots with values ranged from 11.9 to 19.2% and from 5 to 10.9%, respectively. The percentage of 137Cs absorbed by roots ranged from 6.2 to 10.0% among different plants, while 85Sr in roots of plants was below the minimum detectable activity of the detector. For Trifolium, most of the absorbed 137Cs and 85Sr accumulated in the first harvest (81.9 and 98.6%). The aggregated transfer factors (Tag) of both radionuclides under foliar conditions were to a great extent similar. The average values of Tag factors (m2kg-1) of 137Cs and 85Sr, respectively, in rice grains were 3.4 × 10-4 and 1.6 × 10-4; in wheat grains were 4.2 × 10-4 and 2.1 × 10-4; in bean seeds were 4.9 × 10-4 and 2.6 × 10-4; and in sesame seeds were 2.8 × 10-4 and 1.2 × 10-4. Those Tag factors of grains/seeds were substantially lower than those obtained with straw of the corresponding plant species.

EFFECT OF WORKING CONDITIONS AND NATURAL RADIOACTIVITY LEVELS ON OCCUPATIONAL DOSES TO WORKERS OF AN OLD MANGANESE MINE.

The aim of this work was to use RESRAD-Build model to predict the resulting external and internal radiological doses received by the workers of manganese mine located in Southern Sinai. In order to achieve that goal, measurement of the activity concentrations of natural radionuclides in rock samples collected from the inside gallery of such mine, using hyper pure germanium (HPGe) detector. Radon gas concentrations were also measured. The average activity concentrations of 238U, 226Ra, 232Th, 40K and 210Pb in rock samples were 207.3, 155.5, 59.7, 304.5 and 119.3 Bq kg-1, respectively. The average radon activity concentration was 1254.6 Bqm-3, which is equivalent to 0.135 WL. The radon concentration increases further as going deep inside the mine up to 6238 Bqm-3. RESRAD-Build model occupational effective dose equivalent (EDE) received by the workers, from natural radionuclides, dominated by 222Rn emanated from the parent nuclide 226Ra.There was good agreement between the occupational annual EDE calculated from the measured rock samples and that predicted by modeling, with estimated values of 83.8 and 82.1 mSvy-1, respectively. This radiological dose assessment indicated the predominance of internal pathways owing to radon decay products, in both cases (measured and modeled). The occupational radiological dose from the inhalation of radon and radon decay products resulted in a high lung cancer risk based on the current measurements and ventilation conditions within the mine.

Environmental assessment of radionuclides levels and some heavy metals pollution along Gulf of Suez, Egypt.

This work aims to evaluate radioactivity levels of 238U (226Ra), 232Th(228Ra), and 40K and the associated radiological hazard indices, as well as to assess the current status and concentrations of heavy metals along the coastline of the Gulf of Suez, in order to identify potential sources of contamination and to construct radioactivity baseline for this area. Measurements of the activity concentrations of 238U(226Ra), 232Th(228Ra), and 40K in Bq kg-1 of the collected samples were carried out using high-purity germanium (HPGe) detector. Heavy metals in seawater, shore sediment, and algae samples were determined using ICP-OES. The average activity concentrations of 238U(226Ra), 232Th(228Ra), and 40K were found to be 13.79 ± 0.75, 14.57 ± 1.15, and 128.9 ± 4.15 Bq kg-1, respectively. The radiological hazard indices of absorbed dose rate in nGy h-1 (D), annual effective dose rate in mSv y-1, AED, radium equivalent activity in Bq (Raeq), external and internal hazard indices (Hex, Hin), and cancer risk factor were calculated and compared with the worldwide averages. The distribution patterns of annual effective dose (AED) at the Suez Gulf showed that the south east of the Gulf is characterized by higher AED. Water quality parameters (water temperature, salinity, pH, DO, and Eh) reveal that Suez Gulf was undoubtedly affected by the rate of the human activities. Heavy metal concentrations in shore sediments showed some variation within the study area and followed the following order: Fe > Mn > Zn > Al > B > Co > Ni > Pb > V > Cr > Mo > Cu > Cd. Furthermore, heavy metal concentrations indicated that northern part of the Gulf contains the highest levels of these metals compared to the southern one.