In this work the radiological dose and risks resulting from recycling of radioactive contaminated NORM scrap metal that produced from one of oil and gas production companies in Egypt, were determined by using RESRAD-R...In this work the radiological dose and risks resulting from recycling of radioactive contaminated NORM scrap metal that produced from one of oil and gas production companies in Egypt, were determined by using RESRAD-RECYCLE computer code. Two scenarios were used: the first was the workers’ scenario, while the second was end-use product scenario. Workers’ scenario was used in this study for evaluating the dose and risk to workers who process recycled materials. This scenario focused on the transport of radioactive NORM scrap metal from the place of origin to the smelter (scrap delivery step). Scenarios for six different workers were included under the scrap delivery step: two workers scrap cutter, two workers scrap loader, and two workers scrap truck driver. The values for each scenario were specified on the basis of processing 200 tons of NORM scrap metal. Because these operations occur before melting of the metal, mass and radionuclide partitioning factors were not applied in the scrap metal delivery step. The radionuclide concentration of the NORM scrap metal was used directly in the dose calculation. The maximum doses received from direct external exposure to all radio nuclides during cutter/sorter, scrap truck driver and unloading of scrap metals were 2.14E-04, 1.4E-06 and 1.86E-05 (mSv) respectively. The excess cancer risks for all radio nuclides during cutter/sorter of scrap metals reached 1.25E-07. Radiation exposures incurred by the scrap unloaders and scrap cutters/sorters were greater than those incurred by the other workers for their closer exposure distances and longer time.展开更多
Radium isotopes can be analyzed by different analytical methods based on gamma spectrometric measurements or alpha spectrometry. An improved method was developed to determine radium isotopes from water using gamma spe...Radium isotopes can be analyzed by different analytical methods based on gamma spectrometric measurements or alpha spectrometry. An improved method was developed to determine radium isotopes from water using gamma spectrometry after radiochemical separation. The Radium was selectively extracted from acidified samples using co-precipitation procedure with iron hydroxide and followed by precipitation of radium as radium sulphate Ba(Ra)SO4. The precipitate Ba(Ra)SO4 was filtered through the Millipore filter paper, dried and weighed to calculate chemical yield. 226Ra and 228Ra activities were measured using low-background gamma spectrometry in water samples. Radium was pre-concentrated from environmental samples by co-precipitation with BaSO4. The amounts of 226Ra and 228Ra on the sample were obtained by gamma-ray spectrometry for the 351 keVγ-ray from 214Pb and for the 911 keV γ-ray from 228Ac, both in radioactive equilibrium with precursors, respectively. The accuracy, selectivity, traceability, applicability and Minimum Detectable Activity (MDA) of the technique were discussed. Also, the effect of physical and chemical characteristics of the water samples such as TDS, pH, soluble species, sulphate and bicarbonate that effect on the radium determination were taking into consideration. The method has been validated with a certified reference material supplied by the International Atomic Energy Agency and reliable results were obtained. The radiochemical yields for radium were 70% - 90% and recovery was 97% and 80% for 226Ra and 228Ra, respectively.展开更多
In this work, the Styrene-butadiene rubber (SBR)/lead oxide and the Styrene-butadiene rubber (SBR)/lead nitrate composites were prepared as gamma-radiation shielding materials. The investigated materials were prepared...In this work, the Styrene-butadiene rubber (SBR)/lead oxide and the Styrene-butadiene rubber (SBR)/lead nitrate composites were prepared as gamma-radiation shielding materials. The investigated materials were prepared with three different weight percentage of lead oxide and lead nitrate (30, 50 and 70 wt%). The mass attenuation coefficients (μ<sub>m</sub>) for all composite samples were measured experimentally at 511 and 661.6 keV photon energies. The measurements were made by performing transmission experiments with a 3'' × 3'' NaI (Tl) scintillation detector, which had an energy resolution of 7% at 0.662 MeV for the gamma-rays from the decay of <sup>137</sup>Cs. The effective atomic numbers (Z<sub>eff</sub>) and the effective electron densities (N<sub>eff</sub>) were determined experimentally. Also they were determined theoretically using the obtained μ<sub>m</sub> values for the studied composites samples by WinXCom program. The obtained results show that the experimental values of the composites are found to be in a good agreement with the theoretical values. It is recognized that the mass attenuation coefficient (μ<sub>m</sub>), effective atomic numbers (Z<sub>eff</sub>) and the effective electron densities (N<sub>eff</sub>) are increased in the composite samples which contain lead oxides than which contain lead nitrates. Finally, the Styrene-butadiene rubber (SBR)/lead oxide is better than Styrene-butadiene rubber (SBR)/lead nitrate polymer as gamma radiation shielding.展开更多
The aim of this study was the determination of various levels in date palm kernel(DPK)flour for enhancing production performance of animals natural feed in Sudan,in addition to protecting the environment from waste.Th...The aim of this study was the determination of various levels in date palm kernel(DPK)flour for enhancing production performance of animals natural feed in Sudan,in addition to protecting the environment from waste.The material used is flour of date seeds from the following date varieties:Berkawi,Gandilla,Tamouda,Klmah,Mashreq Wad Khatib,Mashreq Wad Lagi.This research was conducted at the following institutions:Geological Research Authority of Sudan,preparation of the DPK;Institute Penyelidikan Produk Halal of University Putra Malaysia,determination of amino acids using high performance liquid chromatography mass spectroscopy mass spectroscopy(HPLC MSMS)fluorescence;University of Medical Sciences and Technology-Sudan,determination of fatty acids using gas chromatography-mass spectrometry(GC-MS).Seeds were collected from various areas of Sudan and from factories.All seeds were mixed together and they weigh 8 kg.Sample preparation includes five steps,namely(1)washing,(2)soaking,(3)flushing,(4)drying,(5)grinding.The flour was then used to determine its contents of amino acids by high performance liquid chromatography-fluorescence detector(HPLC-FLD)and fatty acids by GC-MS.Concentrations of the following amino acids were determined in the sample(percentages in w/w are indicated between parenthesis):hydroxyprofine(0.224),aspartic acid(7.029),serine(6.350),glutamic acid(1.745),glycine(3.183),histicline(0.705),arginine(7.262),threonine(ND),alanine(15.558),proline(4.302),cysteine(34.326),tyrosine(2.070),voline(0.402),methionine(2.989),lysine(4.723),isoleucine(2.203),leucine(4.485),phenylalanine(2.442)while the determined fatty acids are:lauric acid(11.765),tetradecanoic acid(14.214),methyl palmitoleate(16.235),palmitic acid(16.431),cis-10-Heptadecenoic acid,methyl ester(17.253),margaric acid(17.464),linoleic acid(18.183),oleic acid(18.236),stearic acid(18.449),methyl ester(20.106)and arachidic acid(20.308).The seeds of the dates are found to be rich in amino acids as well as fatty acids,which means they can be used as natural feed for animals.These seeds are now dealt with as waste so using them as source of nutrition means protecting the environment and also reducing the cost of animal feed.展开更多
The present work is carried out to obtain quantitative information of some natural radioactive materials and heavy metals in water and sediment samples along the Alexandria Coastline, as a step to construct the baseli...The present work is carried out to obtain quantitative information of some natural radioactive materials and heavy metals in water and sediment samples along the Alexandria Coastline, as a step to construct the baseline map of the background radioactivity level in the Egyptian environment and also as a base data to assess the future physicochemical changes of surface coastal water and sediment in the studied area. The distribution of natural gamma emitting radionuclides such as 238U, 232Th and 40K has been established by gamma spectrometry. The results show that the area of Alexandria coast is affected by the existence of high back-ground radiation from the Rashid coast at the eastern side which has high levels of radioisotope concentrations due to black sand deposits which are dominant in this area. The absorbed dose rate (D, nGy·h-1), annual effective dose equivalent, external hazard index (Hex) and representative level index (Ir) of the investigated radioactive materials were calculated. The concentration of Pb2+, Cd2+, Ni2+, Mn2+, Cu2+, Co2+, Zn2+ and Cr3+ ions has been determined using Atomic Absorption Spectroscopy. The total dissolved solids (TDS) in water samples ranged from 33,000 mg/l to 42,000 mg/l, the salinity ranged from 37.9% to 40.5% and pH ranged from 7.6 to 7.9. Some of the sediment quality guidelines are calculated and they are the metal pollution index (MPI), the contamination factor (CF), degree of contamination (Cdeg), and Pollution load index (PLI).展开更多
In this work, the specific activities of natural radionuclides, namely <sup>238</sup>U series, <sup>232</sup>Th series and <sup>40</sup>K, have been measured in collected sedimentar...In this work, the specific activities of natural radionuclides, namely <sup>238</sup>U series, <sup>232</sup>Th series and <sup>40</sup>K, have been measured in collected sedimentary phosphate deposits samples from El-Hamraween, El-Quser and Safaga phosphate mines in Egypt. HPGe γ-spectrometry was used. This study was undertaken to estimate the radiation hazard indices in phosphate mining at the studied mines on their occupational workers, to establish correlation relationships between the some measured heavy metals such as As, Cd and Pb in blood workers and their concentration in phosphate rock ores and to determinate the biomarkers in the blood workers such as malondialdehyde (MDA) and superoxide dismutase (SOD). The phosphate mine sample of El-Hamrawein has the lowest activity concentration of <sup>226</sup>Ra, <sup>232</sup>Th and <sup>40</sup>K in comparison to the phosphate mine samples of El-Quseir and Safaga (El-Hamrawein kg<sup>-</sup>1</sup><sup></sup>, 122.4 to 188.3 Bq·kg<sup>-</sup>1</sup></sup> and 115.4 to 165.8 Bq·kg<sup>-</sup>1</sup></sup> for Safaga, El-Quseir and El-Hamrawein, respectively. For <sup>232</sup>Th activity concentrations varied from 135.6 to 212.3 Bq·kg<sup>-</sup>1</sup></sup>, 112.8 to 167.4 Bq·kg<sup>-</sup>1</sup></sup> and 132.8 to 188.6 Bq·kg<sup>-</sup>1</sup></sup> for Safaga, El-Quseir and El-Hamrawein, respectively. For <sup>40</sup>K activity concentrations varied from 225.2 to 312.8 Bq·kg<sup>-</sup>1</sup>, 168.7 to 268.9 Bq·kg<sup>-</sup>1</sup></sup> and 95.2 to 155.8 Bq·kg<sup>-</sup>1</sup></sup> for Safaga, El-Quseir and El-Hamrawein, respectively. The workers of old ages have higher concentration of the investigated heavy metals than those of young ages. There is a good relation between the concentration of the investigated metals in phosphate mine samples and their concentration in blood of the occupational workers in these mines.展开更多
MCNPX(Monte Carlo N-Particle Transport Code)computer code is used to design a model to CANDU(Canada Deuterium Uranium)reactor core and its shielding system.It is assumed that reactor core is fueled with natural uraniu...MCNPX(Monte Carlo N-Particle Transport Code)computer code is used to design a model to CANDU(Canada Deuterium Uranium)reactor core and its shielding system.It is assumed that reactor core is fueled with natural uranium.The core radiation sources are calculated which consider prompt neutrons,neutron induced gamma and prompt gamma radiations.The total neutron flux and dose rate are calculated along the shield and at outer shield points.The results indicated that the major dose rate component at outer shield points is due to neutron induced gamma dose rate(μSv/h).展开更多
This paper presents a comprehensive hydrogeologic view of the Quaternary aquifer in north eastern Cairo area, Egypt. The hydrogeologic, hydrochemical and isotopic features of the aquifer are determined to assess the g...This paper presents a comprehensive hydrogeologic view of the Quaternary aquifer in north eastern Cairo area, Egypt. The hydrogeologic, hydrochemical and isotopic features of the aquifer are determined to assess the groundwater geochemistry and quality for different uses. The groundwater in the aquifer is shallow and flows towards the heavily pumping areas (cultivated and industrial areas). The concentrations of total dissolved solids (TDS) vary considerably in the aquifer, ranging from 225.6 mg/L to 1219 mg/L. Wide variations in the concentrations of major ions, trace elements, nitrate, δ18O and δ2H are detected, indicating the variation in the geologic and recharge conditions. This further indicates the effect of natural processes (weathering, dissolution and ion exchange) as well as anthropogenic activities on the quality of groundwater. Moderate levels of contamination with nitrate, aluminum and manganese are recorded in the groundwater below the cultivated area. The contamination is linked to the extensive use of fertilizers for agriculture and the leakage of wastewater from improper sewage system. The computed nitrate pollution index reveals that about 69.69% of groundwater is safe for drinking, while the rest of groundwater is unsuitable. The calculated water quality index indicates that about 78.79% of groundwater is safe for human consumption and the rest of groundwater is poor for consumption because of the contamination with the high levels of manganese, total hardness, pH, sulphate, aluminum, and nitrate. The contaminated groundwater needs to be treated before consumption. Hence, periodic groundwater quality checks are recommended.展开更多
Groundwater samples with high total dissolved solids (TDS) were collected from private wells in Al Sharqiya and Tabouk regions in Saudi Arabia to determine the 222Rn activities and to investigate the factors that may ...Groundwater samples with high total dissolved solids (TDS) were collected from private wells in Al Sharqiya and Tabouk regions in Saudi Arabia to determine the 222Rn activities and to investigate the factors that may control the presence of radon in these wells. The radon activity levels in Al Sharqiya groundwater wells showed an average value below the maximum contaminant level proposed by EPA for drinking water. In contrast, all the sampled wells in Tabouk region exhibited 222Rn concentrations exceeding 300 pCi/L, the maximum contaminant level (MCL) recommended by the USEPA, which may be explained by the nature of aquifers in both regions. Within the limited number of groundwater samples, it was observed that the radon content of Al Sharqiya sampled wells has good correlations with some chemical parameters (TDS and Eh) in these wells. The observed correlations between the water chemistry and the radon activities in groundwater do not necessarily imply a relationship between the two events. Furthermore, these chemical parameters may reflect the presence of nearby radium in rocks surface. Radon wasn’t influenced by the chemical environment in the investigated Tabouk wells but, may be is more controlled by other factors: the direct parent 226Ra content and the nature of the aquifer matrix (grain size and permeability in the Saq aquifer rocks).展开更多
Hydrologic conditions of the ground water of the Quaternary aquifer in west Ismailia area, Egypt, were characterized based on new hydrologic data collected in 2017. The Quaternary aquifer consists of alluvial deposits...Hydrologic conditions of the ground water of the Quaternary aquifer in west Ismailia area, Egypt, were characterized based on new hydrologic data collected in 2017. The Quaternary aquifer consists of alluvial deposits. The grain size distribution results indicate that the major part of the aquifer deposits is formed of medium to coarse grained sand with medium uniformity coefficients ranging between 2.5 and 10. They also reflect the heterogeneity, anisotropy and high productivity of the aquifer. The estimated aquifer parameters range from 29% to 41% for total porosity, from 18.71 m/day to 63.95 m/day for horizontal hydraulic conductivity, from 8.94 m/day to 61.6 m/day for vertical hydraulic conductivity, from 1.01 to 4.27 for anisotropy and from 1870 m2/day to 6549 m2/day for transmissivity. The ground water flows mainly from the north and northeast recharge sources (Ismailia and El Manaief canals) and from the south recharge area (Miocene aquifer), with an average hydraulic gradient of 0.00438. The recharge rate to the aquifer (from the southern area) and the Darcy’s velocity of ground water are estimated to be 447 × 106 m3/year and 0.203 m/day (on average), respectively. A great change in the hydrologic setting of the aquifer is occurred during the period of 1992-2017, where the groundwater flow has changed during that period. The aquifer contains fresh to saline water. An oxidizing (alkaline) environment is reported for the aquifer, as revealed from the relationship between the redox potential (185 - 836 mV) and pH (5.2 - 7.5 standard units). This indicated the capability of ground water to dissolve heavy metals associated to rock-forming minerals. A wide variation in the concentrations of total dissolved solids (320 - 7385 mg/l) and dissolved oxygen (2.13 - 8.4 mg/l) in the Quaternary aquifer is observed, reflecting the local variation of the environmental and geologic conditions and indicating the influence of different recharge sources.展开更多
文摘In this work the radiological dose and risks resulting from recycling of radioactive contaminated NORM scrap metal that produced from one of oil and gas production companies in Egypt, were determined by using RESRAD-RECYCLE computer code. Two scenarios were used: the first was the workers’ scenario, while the second was end-use product scenario. Workers’ scenario was used in this study for evaluating the dose and risk to workers who process recycled materials. This scenario focused on the transport of radioactive NORM scrap metal from the place of origin to the smelter (scrap delivery step). Scenarios for six different workers were included under the scrap delivery step: two workers scrap cutter, two workers scrap loader, and two workers scrap truck driver. The values for each scenario were specified on the basis of processing 200 tons of NORM scrap metal. Because these operations occur before melting of the metal, mass and radionuclide partitioning factors were not applied in the scrap metal delivery step. The radionuclide concentration of the NORM scrap metal was used directly in the dose calculation. The maximum doses received from direct external exposure to all radio nuclides during cutter/sorter, scrap truck driver and unloading of scrap metals were 2.14E-04, 1.4E-06 and 1.86E-05 (mSv) respectively. The excess cancer risks for all radio nuclides during cutter/sorter of scrap metals reached 1.25E-07. Radiation exposures incurred by the scrap unloaders and scrap cutters/sorters were greater than those incurred by the other workers for their closer exposure distances and longer time.
文摘Radium isotopes can be analyzed by different analytical methods based on gamma spectrometric measurements or alpha spectrometry. An improved method was developed to determine radium isotopes from water using gamma spectrometry after radiochemical separation. The Radium was selectively extracted from acidified samples using co-precipitation procedure with iron hydroxide and followed by precipitation of radium as radium sulphate Ba(Ra)SO4. The precipitate Ba(Ra)SO4 was filtered through the Millipore filter paper, dried and weighed to calculate chemical yield. 226Ra and 228Ra activities were measured using low-background gamma spectrometry in water samples. Radium was pre-concentrated from environmental samples by co-precipitation with BaSO4. The amounts of 226Ra and 228Ra on the sample were obtained by gamma-ray spectrometry for the 351 keVγ-ray from 214Pb and for the 911 keV γ-ray from 228Ac, both in radioactive equilibrium with precursors, respectively. The accuracy, selectivity, traceability, applicability and Minimum Detectable Activity (MDA) of the technique were discussed. Also, the effect of physical and chemical characteristics of the water samples such as TDS, pH, soluble species, sulphate and bicarbonate that effect on the radium determination were taking into consideration. The method has been validated with a certified reference material supplied by the International Atomic Energy Agency and reliable results were obtained. The radiochemical yields for radium were 70% - 90% and recovery was 97% and 80% for 226Ra and 228Ra, respectively.
文摘In this work, the Styrene-butadiene rubber (SBR)/lead oxide and the Styrene-butadiene rubber (SBR)/lead nitrate composites were prepared as gamma-radiation shielding materials. The investigated materials were prepared with three different weight percentage of lead oxide and lead nitrate (30, 50 and 70 wt%). The mass attenuation coefficients (μ<sub>m</sub>) for all composite samples were measured experimentally at 511 and 661.6 keV photon energies. The measurements were made by performing transmission experiments with a 3'' × 3'' NaI (Tl) scintillation detector, which had an energy resolution of 7% at 0.662 MeV for the gamma-rays from the decay of <sup>137</sup>Cs. The effective atomic numbers (Z<sub>eff</sub>) and the effective electron densities (N<sub>eff</sub>) were determined experimentally. Also they were determined theoretically using the obtained μ<sub>m</sub> values for the studied composites samples by WinXCom program. The obtained results show that the experimental values of the composites are found to be in a good agreement with the theoretical values. It is recognized that the mass attenuation coefficient (μ<sub>m</sub>), effective atomic numbers (Z<sub>eff</sub>) and the effective electron densities (N<sub>eff</sub>) are increased in the composite samples which contain lead oxides than which contain lead nitrates. Finally, the Styrene-butadiene rubber (SBR)/lead oxide is better than Styrene-butadiene rubber (SBR)/lead nitrate polymer as gamma radiation shielding.
文摘The aim of this study was the determination of various levels in date palm kernel(DPK)flour for enhancing production performance of animals natural feed in Sudan,in addition to protecting the environment from waste.The material used is flour of date seeds from the following date varieties:Berkawi,Gandilla,Tamouda,Klmah,Mashreq Wad Khatib,Mashreq Wad Lagi.This research was conducted at the following institutions:Geological Research Authority of Sudan,preparation of the DPK;Institute Penyelidikan Produk Halal of University Putra Malaysia,determination of amino acids using high performance liquid chromatography mass spectroscopy mass spectroscopy(HPLC MSMS)fluorescence;University of Medical Sciences and Technology-Sudan,determination of fatty acids using gas chromatography-mass spectrometry(GC-MS).Seeds were collected from various areas of Sudan and from factories.All seeds were mixed together and they weigh 8 kg.Sample preparation includes five steps,namely(1)washing,(2)soaking,(3)flushing,(4)drying,(5)grinding.The flour was then used to determine its contents of amino acids by high performance liquid chromatography-fluorescence detector(HPLC-FLD)and fatty acids by GC-MS.Concentrations of the following amino acids were determined in the sample(percentages in w/w are indicated between parenthesis):hydroxyprofine(0.224),aspartic acid(7.029),serine(6.350),glutamic acid(1.745),glycine(3.183),histicline(0.705),arginine(7.262),threonine(ND),alanine(15.558),proline(4.302),cysteine(34.326),tyrosine(2.070),voline(0.402),methionine(2.989),lysine(4.723),isoleucine(2.203),leucine(4.485),phenylalanine(2.442)while the determined fatty acids are:lauric acid(11.765),tetradecanoic acid(14.214),methyl palmitoleate(16.235),palmitic acid(16.431),cis-10-Heptadecenoic acid,methyl ester(17.253),margaric acid(17.464),linoleic acid(18.183),oleic acid(18.236),stearic acid(18.449),methyl ester(20.106)and arachidic acid(20.308).The seeds of the dates are found to be rich in amino acids as well as fatty acids,which means they can be used as natural feed for animals.These seeds are now dealt with as waste so using them as source of nutrition means protecting the environment and also reducing the cost of animal feed.
文摘The present work is carried out to obtain quantitative information of some natural radioactive materials and heavy metals in water and sediment samples along the Alexandria Coastline, as a step to construct the baseline map of the background radioactivity level in the Egyptian environment and also as a base data to assess the future physicochemical changes of surface coastal water and sediment in the studied area. The distribution of natural gamma emitting radionuclides such as 238U, 232Th and 40K has been established by gamma spectrometry. The results show that the area of Alexandria coast is affected by the existence of high back-ground radiation from the Rashid coast at the eastern side which has high levels of radioisotope concentrations due to black sand deposits which are dominant in this area. The absorbed dose rate (D, nGy·h-1), annual effective dose equivalent, external hazard index (Hex) and representative level index (Ir) of the investigated radioactive materials were calculated. The concentration of Pb2+, Cd2+, Ni2+, Mn2+, Cu2+, Co2+, Zn2+ and Cr3+ ions has been determined using Atomic Absorption Spectroscopy. The total dissolved solids (TDS) in water samples ranged from 33,000 mg/l to 42,000 mg/l, the salinity ranged from 37.9% to 40.5% and pH ranged from 7.6 to 7.9. Some of the sediment quality guidelines are calculated and they are the metal pollution index (MPI), the contamination factor (CF), degree of contamination (Cdeg), and Pollution load index (PLI).
文摘In this work, the specific activities of natural radionuclides, namely <sup>238</sup>U series, <sup>232</sup>Th series and <sup>40</sup>K, have been measured in collected sedimentary phosphate deposits samples from El-Hamraween, El-Quser and Safaga phosphate mines in Egypt. HPGe γ-spectrometry was used. This study was undertaken to estimate the radiation hazard indices in phosphate mining at the studied mines on their occupational workers, to establish correlation relationships between the some measured heavy metals such as As, Cd and Pb in blood workers and their concentration in phosphate rock ores and to determinate the biomarkers in the blood workers such as malondialdehyde (MDA) and superoxide dismutase (SOD). The phosphate mine sample of El-Hamrawein has the lowest activity concentration of <sup>226</sup>Ra, <sup>232</sup>Th and <sup>40</sup>K in comparison to the phosphate mine samples of El-Quseir and Safaga (El-Hamrawein kg<sup>-</sup>1</sup><sup></sup>, 122.4 to 188.3 Bq·kg<sup>-</sup>1</sup></sup> and 115.4 to 165.8 Bq·kg<sup>-</sup>1</sup></sup> for Safaga, El-Quseir and El-Hamrawein, respectively. For <sup>232</sup>Th activity concentrations varied from 135.6 to 212.3 Bq·kg<sup>-</sup>1</sup></sup>, 112.8 to 167.4 Bq·kg<sup>-</sup>1</sup></sup> and 132.8 to 188.6 Bq·kg<sup>-</sup>1</sup></sup> for Safaga, El-Quseir and El-Hamrawein, respectively. For <sup>40</sup>K activity concentrations varied from 225.2 to 312.8 Bq·kg<sup>-</sup>1</sup>, 168.7 to 268.9 Bq·kg<sup>-</sup>1</sup></sup> and 95.2 to 155.8 Bq·kg<sup>-</sup>1</sup></sup> for Safaga, El-Quseir and El-Hamrawein, respectively. The workers of old ages have higher concentration of the investigated heavy metals than those of young ages. There is a good relation between the concentration of the investigated metals in phosphate mine samples and their concentration in blood of the occupational workers in these mines.
文摘MCNPX(Monte Carlo N-Particle Transport Code)computer code is used to design a model to CANDU(Canada Deuterium Uranium)reactor core and its shielding system.It is assumed that reactor core is fueled with natural uranium.The core radiation sources are calculated which consider prompt neutrons,neutron induced gamma and prompt gamma radiations.The total neutron flux and dose rate are calculated along the shield and at outer shield points.The results indicated that the major dose rate component at outer shield points is due to neutron induced gamma dose rate(μSv/h).
文摘This paper presents a comprehensive hydrogeologic view of the Quaternary aquifer in north eastern Cairo area, Egypt. The hydrogeologic, hydrochemical and isotopic features of the aquifer are determined to assess the groundwater geochemistry and quality for different uses. The groundwater in the aquifer is shallow and flows towards the heavily pumping areas (cultivated and industrial areas). The concentrations of total dissolved solids (TDS) vary considerably in the aquifer, ranging from 225.6 mg/L to 1219 mg/L. Wide variations in the concentrations of major ions, trace elements, nitrate, δ18O and δ2H are detected, indicating the variation in the geologic and recharge conditions. This further indicates the effect of natural processes (weathering, dissolution and ion exchange) as well as anthropogenic activities on the quality of groundwater. Moderate levels of contamination with nitrate, aluminum and manganese are recorded in the groundwater below the cultivated area. The contamination is linked to the extensive use of fertilizers for agriculture and the leakage of wastewater from improper sewage system. The computed nitrate pollution index reveals that about 69.69% of groundwater is safe for drinking, while the rest of groundwater is unsuitable. The calculated water quality index indicates that about 78.79% of groundwater is safe for human consumption and the rest of groundwater is poor for consumption because of the contamination with the high levels of manganese, total hardness, pH, sulphate, aluminum, and nitrate. The contaminated groundwater needs to be treated before consumption. Hence, periodic groundwater quality checks are recommended.
文摘Groundwater samples with high total dissolved solids (TDS) were collected from private wells in Al Sharqiya and Tabouk regions in Saudi Arabia to determine the 222Rn activities and to investigate the factors that may control the presence of radon in these wells. The radon activity levels in Al Sharqiya groundwater wells showed an average value below the maximum contaminant level proposed by EPA for drinking water. In contrast, all the sampled wells in Tabouk region exhibited 222Rn concentrations exceeding 300 pCi/L, the maximum contaminant level (MCL) recommended by the USEPA, which may be explained by the nature of aquifers in both regions. Within the limited number of groundwater samples, it was observed that the radon content of Al Sharqiya sampled wells has good correlations with some chemical parameters (TDS and Eh) in these wells. The observed correlations between the water chemistry and the radon activities in groundwater do not necessarily imply a relationship between the two events. Furthermore, these chemical parameters may reflect the presence of nearby radium in rocks surface. Radon wasn’t influenced by the chemical environment in the investigated Tabouk wells but, may be is more controlled by other factors: the direct parent 226Ra content and the nature of the aquifer matrix (grain size and permeability in the Saq aquifer rocks).
文摘Hydrologic conditions of the ground water of the Quaternary aquifer in west Ismailia area, Egypt, were characterized based on new hydrologic data collected in 2017. The Quaternary aquifer consists of alluvial deposits. The grain size distribution results indicate that the major part of the aquifer deposits is formed of medium to coarse grained sand with medium uniformity coefficients ranging between 2.5 and 10. They also reflect the heterogeneity, anisotropy and high productivity of the aquifer. The estimated aquifer parameters range from 29% to 41% for total porosity, from 18.71 m/day to 63.95 m/day for horizontal hydraulic conductivity, from 8.94 m/day to 61.6 m/day for vertical hydraulic conductivity, from 1.01 to 4.27 for anisotropy and from 1870 m2/day to 6549 m2/day for transmissivity. The ground water flows mainly from the north and northeast recharge sources (Ismailia and El Manaief canals) and from the south recharge area (Miocene aquifer), with an average hydraulic gradient of 0.00438. The recharge rate to the aquifer (from the southern area) and the Darcy’s velocity of ground water are estimated to be 447 × 106 m3/year and 0.203 m/day (on average), respectively. A great change in the hydrologic setting of the aquifer is occurred during the period of 1992-2017, where the groundwater flow has changed during that period. The aquifer contains fresh to saline water. An oxidizing (alkaline) environment is reported for the aquifer, as revealed from the relationship between the redox potential (185 - 836 mV) and pH (5.2 - 7.5 standard units). This indicated the capability of ground water to dissolve heavy metals associated to rock-forming minerals. A wide variation in the concentrations of total dissolved solids (320 - 7385 mg/l) and dissolved oxygen (2.13 - 8.4 mg/l) in the Quaternary aquifer is observed, reflecting the local variation of the environmental and geologic conditions and indicating the influence of different recharge sources.