Assessment of Heavy and Trace Metals in Surface Soil Nearby an Oil Refinery, Saudi Arabia, Using Geoaccumulation and Pollution Indices.

The present study deals with the measurement of heavy and trace metals in the soils of Ras Tanura city nearby one of the oldest and largest oil refineries located on Arabian Gulf, eastern Saudi Arabia. Metals were analyzed in 34 surface soil samples using plasma atomic emission spectrometer (ICPE-9820). The result showed that the mean values of the metals concentrations were in the order: Cd > Mo > Tb > Ce > Hf > Eu > Yb > U > Sm > Rb > Cr > Ni > Pb > Sc > Cs > Zn > Lu > Co. The mean values of Cd (39.9 mg/kg), Mo (13.2 mg/kg), Eu (4.01 mg/kg), Hf (6.09 mg/kg), Tb (8.23 mg/kg), and Yb (3.88) in soil samples were higher than the background values in soil and the world average. The obtained results indicated to elevated levels of Cd and Mo in most samples, with mean concentrations exceeded the background levels by 113 times for Cd and 5 times for Mo. Pollution index (PI) and Geoaccumulation (Igeo) for each metal were calculated to assess the metal contamination level of surface soil in the study area. The assessment results of PI and Igeo revealed a significant pollution by Cd, Mo, Eu, Hf, Tb, and Yb in most of sampling sites nearby Ras Tanura refinery.

Noise and transmission performance improvement of broadband distributed Raman amplifier using bidirectional Raman pumping with dual order co-pumps.

We demonstrate a low noise bidirectional broadband distributed Raman pumping scheme combining dual order co-propagated pumps without increasing the signal RIN level. The noise performance improvement is compared experimentally and numerically with conventional counter-pumping only and bidirectional pumping with only a 2nd order co-pump for a 70nm bandwidth and 61.5km distributed Raman amplifier. The proposed broadband pumping scheme shows 1.2dB maximum noise figure improvement and extends the long-haul transmission reach up to 6150km with a Q-factor improvement of ~0.7dB compared with counter-pumping only scheme.

Ultra-flat wideband single-pump Raman-enhanced parametric amplification.

We experimentally optimize a single pump fiber optical parametric amplifier in terms of gain spectral bandwidth and gain variation (GV). We find that optimal performance is achieved with the pump tuned to the zero-dispersion wavelength of dispersion stable highly nonlinear fiber (HNLF). We demonstrate further improvement of parametric gain bandwidth and GV by decreasing the HNLF length. We discover that Raman and parametric gain spectra produced by the same pump may be merged together to enhance overall gain bandwidth, while keeping GV low. Consequently, we report an ultra-flat gain of 9.6 ± 0.5 dB over a range of 111 nm (12.8 THz) on one side of the pump. Additionally, we demonstrate amplification of a 60 Gbit/s QPSK signal tuned over a portion of the available bandwidth with OSNR penalty less than 1 dB for Q2 below 14 dB.

Elemental characterization of Hazm El-Jalamid phosphorite by instrumental neutron activation analysis.

Instrumental neutron activation analyses (INAA) have been used to achieve accurate knowledge about the elemental analysis of phosphate ore deposits collected from Hazm El-Jalamid Northeast of Saudi Arabia. The samples were prepared for irradiation by thermal neutrons using a thermal neutron flux of 7×10(12)ncm(-2)s(-1) at ACT Lab Canada. The concentrations of 19 elements were determined. These included 12 major, minor and trace elements (Au, As, Ba, Br, Cr, Mo, Sb, Sc, Sr, Th, U and Zn) and 7 rare earth elements (REEs) (La, Ce, Nd, Sm, Eu, Yb and Lu). Major elements (Si, Al, Fe, Ca, Mg, Na, K, Cr, Ti, Mn, P, Sr and Ba) were determined using an inductively coupled plasma-mass spectrometer (ICP-MS). The comparison of the concentration of U and the REEs in the Hazm El-Jalamid phosphate samples with those of the Umm Wu'al phosphate from Saudi Arabia and El-Sibayia and El Hamrawein phosphate from Egypt shows that the contents of U and REEs are clearly higher in the Umm Wu'al, El-Sibayia and El Hamrawein phosphates than in the Hazm El-Jalamid phosphate samples. The results of major, trace elements, uranium and rare earth elements (REE) from El Jalamid phosphate have been compared with the global values of these elements. The concentrations for most of the elements studied are lower than the concentrations reported in the literature. The acquired data will serve as a reference for the follow-up studies to assess the agronomic effectiveness of the Hazm El-Jalamid phosphate rocks.

Ecological impacts of Al-Jalamid phosphate mining, Saudi Arabia: Soil elemental characterization and spatial distribution with INAA.

Phosphate (P) industries will be one of the main industrial sectors in Saudi Arabia within the next few years. Al-Jalamid phosphate mine, which started operation a few years ago, is one of the biggest mining locations in the Middle East region. It is planned to mine 12 million tons run of mine ore per year (Mty) and produce about 4.5 Mty of phosphate concentrate for the next 20 years. Long term ecological impacts of phosphate mining activities on soil and groundwater should be investigated. The contaminated soil acts as a long term source of environmental contamination. The main aim of this work was to shed more light on the elemental characterization and spatial distributions in soil areas located in the vicinity of the phosphate mining activities. A total of sixty eight surface and subsurface soil samples from 34 locations around Al-Jalamid phosphate mine have been collected. The elemental characterization of soil samples was achieved using instrumental neutron activation analysis (INAA). Pollution indices, geoaccumulation (I(geo)) and pollution load (PLI) indices were calculated from some elements to evaluate the soil pollution. Until now, there is no existing pre-operational elemental characterization in soil to evaluate the foreseen ecological impacts of phosphate mining. Our results are the first to evaluate the present situation that will be the base for the future evaluations. The main aim of this work was to shed more light on the elemental characterization and spatial distributions in soil and their relation to phosphate mining activities, and to better understand the behavior of different elements in soil in an arid environment.

Assessment of natural radioactivity level and radiation hazards in soil samples of Wadi Al-Rummah Qassim province, Saudi Arabia.

The present work deals with estimation and distribution of natural radionuclides in 40 soil samples collected from Wadi Al-Rummah (Qassim part) Central Saudi Arabia. Estimations were carried out using NaI (Tl) gamma-ray spectrometer. Activity concentrations ranged from 5.3 to 45.0 Bq kg-1, from 4.3 to 33.8 Bq kg-1 and from 38 Bq kg-1 to 273.1 Bq kg-1 for 226Ra, 232Th and 40K, respectively. The average activity concentrations of 226Ra, 232Th and 40K in soil samples was 15.5 Bq kg-1, 14.1 Bq kg-1 and 143.1 Bq kg-1. The results of this study were compared with other studies around the world. Radiation hazard parameters such as radium equivalent activity, annual dose, external hazard were calculated and compared with the recommended levels quoted from International Commission on Radiological Protection (ICRP-60) and United Nations Scientific Committee on the Effects of Atomic Radiation UNSCEAR reports.

Radon activity measurements in irrigation water from Qassim Province by RAD7.

The present study deals with investigating radon level in groundwater, which is being used for irrigation in the environs of Qassim province, Saudi Arabia. Ninety nine samples of groundwater were collected from eight cities in Qassim province. Radon concentrations in the collected water samples were measured with RAD7 electronic radon detector connected to RAD- H2O accessory (Durridge Co., USA). The concentration of (222)Rn in 99 irrigation groundwater samples ranged from 1.20 to 15.43 Bq l-1Radon level in? 5 samples 2 from Al-Asyah, 2 from Al shamasia and one sample from Al Moznib exceeded the permissible level of radon 11 Bq l-1 in groundwater. The total annual effective dose varied with increase in radon concentration. The calculated effective dose per liter (EDL) and annual effective dose (AED) ranged from 6.1 to 77.15 nSvL-1 and 4.45 to 56.16 µSv y-1, respectively. It was evident that the total annual effective doses resulting from radon in 95% from groundwater in Qassim area were significantly lower than the permissible limit of 1 mSv y-1 for the public.

Skin dose measurements using radiochromic films, TLDS and ionisation chamber and comparison with Monte Carlo simulation.

Estimation of the surface dose is very important for patients undergoing radiation therapy. The purpose of this study is to investigate the dose at the surface of a water phantom at a depth of 0.007 cm as recommended by the International Commission on Radiological Protection and International Commission on Radiation Units and Measurement with radiochromic films (RFs), thermoluminescent dosemeters and an ionisation chamber in a 6-MV photon beam. The results were compared with the theoretical calculation using Monte Carlo (MC) simulation software (MCNP5, BEAMnrc and DOSXYZnrc). The RF was calibrated by placing the films at a depth of maximum dose (d(max)) in a solid water phantom and exposing it to doses from 0 to 500 cGy. The films were scanned using a transmission high-resolution HP scanner. The optical density of the film was obtained from the red component of the RGB images using ImageJ software. The per cent surface dose (PSD) and percentage depth dose (PDD) curve were obtained by placing film pieces at the surface and at different depths in the solid water phantom. TLDs were placed at a depth of 10 cm in a solid water phantom for calibration. Then the TLDs were placed at different depths in the water phantom and were exposed to obtain the PDD. The obtained PSD and PDD values were compared with those obtained using a cylindrical ionisation chamber. The PSD was also determined using Monte Carlo simulation of a LINAC 6-MV photon beam. The extrapolation method was used to determine the PSD for all measurements. The PSD was 15.0±3.6% for RF. The TLD measurement of the PSD was 16.0±5.0%. The (0.6 cm(3)) cylindrical ionisation chamber measurement of the PSD was 50.0±3.0%. The theoretical calculation using MCNP5 and DOSXYZnrc yielded a PSD of 15.0±2.0% and 15.7±2.2%. In this study, good agreement between PSD measurements was observed using RF and TLDs with the Monte Carlo calculation. However, the cylindrical chamber measurement yielded an overestimate of the PSD. This is probably due to the ionisation chamber calibration factor that is only valid in charged particle equilibrium condition, which is not achieved at the surface in the build-up region.

Analytical approach for radioactivity correlation of disc sources with HPGe detector efficiency.

The HPGe detector efficiency is measured as a function of source to detector separation using disc sources of (131)I with diameter ranging from 10 to 400mm. Detector efficiencies are characterized using single photon point-like standard sources at different distances; the calculated efficiencies for disc sources were analyzed by utilizing the double point detector model (DPDM) and the efficiency transfer method. The developed approach provided satisfactory results. The axial variation and radial dependence for disc sources efficiency determination in gamma-ray spectrometry were described with both gamma ray standard sources and measured samples as their extended sources.

Elemental analysis of natural quartz from Um Higlig, Red Sea Aea, Egypt by instrumental neutron activation analysis.

A scheme for INAA of 25 elements: As, Ba, Ca, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sc, Sm, Th, U, Yb, Zn and Zr in quartz collected from the eastern desert along the Egyptian Red Sea coast is proposed. The samples were prepared together with standard reference material and irradiated in a neutron flux of 7×10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The gamma spectra were collected by a HPGe detector and the analysis was done by a computerized multichannel analyzer.The accuracy of the procedure is evaluated by the analysis of two geo-standard reference materials (Dolerite WSE and Microgabro PMS). The choice of the nuclear reaction, irradiation and decay times and of the proper gamma radiation in counting are presented and discussed. The data presented here are our contribution to understanding the elemental composition of the quartz rock. Because there are no existing databases for the elemental analysis of quartz, our results are a start to establishing a database for the Egyptian quartz. It is hoped that the data presented here will be useful to those dealing with geochemistry, quartz chemistry and related fields.

Elemental analysis of marble used in Saudi Arabia by different nuclear analytical techniques.

Instrumental neutron activation analysis (INAA) and HPGe detector γ-spectroscopy were used to determine a total of 22 elements qualitatively and quantitatively for the first time from marble rock samples collected from local markets in Saudi Arabia. The elements determined are Mg, Ca, V, Na, Mn, As, La, Sm, U, Sc, Cr, Fe, Co, Zn, Sn, Ba, Ce, Eu, Yb, Lu, Hf, and Th. The samples were properly prepared together with their standard reference material and simultaneously irradiated by thermal neutrons at the TRIGA Mainz research reactor at a neutron flux of 7 × 10(11) n/cm(2) s. XRF was also used. The concentrations of natural radionuclides (226)Ra, (232)Th and (40)K were also determined by gamma ray spectroscopy to estimate the radiological parameters such as radium equivalent activity, and the external hazard index was calculated to estimate the exposure risk from usage of marble as raw materials in construction. For the sake of comparison the results of concentration levels and radium equivalent activities are compared with similar studies carried out in other countries.

Elemental analysis of granite by instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF).

The instrumental neutron activation analysis technique (INAA) was used for qualitative and quantitative analysis of granite samples collected from four locations in the Aswan area in South Egypt. The samples were prepared together with their standards and simultaneously irradiated in a neutron flux of 7×10(11)n/cm(2)s in the TRIGA Mainz research reactor. Gamma-ray spectra from an hyper-pure germanium detector were analyzed. The present study provides the basic data of elemental concentrations of granite rocks. The following elements have been determined Na, Mg, K, Fe, Mn, Sc, Cr, Ti, Co, Zn, Ga, Rb, Zr, Nb, Sn, Ba, Cs, La, Ce, Nd, Sm, Eu, Yb, Lu, Hf, Ta, Th and U. The X-ray fluorescence (XRF) was used for comparison and to detect elements, which can be detected only by XRF such as F, S, Cl, Co, Cu, Mo, Ni, Pb, Se and V. The data presented here are our contribution to understanding the elemental composition of the granite rocks. Because there are no existing databases for the elemental analysis of granite, our results are a start to establishing a database for the Egyptian granite. It is hoped that the data presented here will be useful to those dealing with geochemistry, granite chemistry and related fields.

Natural radioactivity levels and heavy metals in chemical and organic fertilizers used in Kingdom of Saudi Arabia.

The present work deals with identifying and determining the activity levels of natural occuring radionuclides, (226)Ra and (232)Th series, their decay products and (40)K, in chemical and organic fertilizers used in Kingdom of Saudi Arabia. A total of 30 samples: 20 phosphatic fertilizers (single super-phosphate SSP and triple super-phosphate,TSP) and 10 organic fertilizers (cow, sheep and chicken) collected from markets and farms. The gamma-ray spectrometer consists of NaI(Tl) detector and its electronic circuit was used for measuring γ-ray spectra. The ranges of radioactivity levels of (226)Ra, (232)Th and (40)K in chemical fertilizers are 51.5±5.2-106.3±7.5, 5.1±1.6-9.9±3.2. and 462.6±21-607.3±14Bqkg(-1), respectively. The activities of (226)Ra, (232)Th and (40)K in natural fertilizers (cow, sheep and chicken) are lower than the activities in chemical fertilizers. The obtained data are compared with available reported data from other countries in literature. The Ra(eq) in chemical fertilizer ranges from 100.37 to 161.43Bqkg(-1) and in organic fertilizer ranges from 34.07 to 102.19Bqkg(-1), which are lower than the limit of 370Bqkg(-1) adopted from NEA-OECD (1979). The average heavy metal (Pb, Cd, Ni, Co and Cr) contents of the fertilizers marketed in the Kingdom of Saudi Arabia are also determined and within the limits of those used worldwide.

Effect of Rayleigh-scattering distributed feedback on multiwavelength Raman fiber laser generation.

We experimentally demonstrate a Raman fiber laser based on multiple point-action fiber Bragg grating reflectors and distributed feedback via Rayleigh scattering in an ~22-km-long optical fiber. Twenty-two lasing lines with spacing of ~100 GHz (close to International Telecommunication Union grid) in the C band are generated at the watt level. In contrast to the normal cavity with competition between laser lines, the random distributed feedback cavity exhibits highly stable multiwavelength generation with a power-equalized uniform distribution, which is almost independent on power.

Distribution and environmental impacts of metals and natural radionuclides in marine sediments in-front of different wadies mouth along the Egyptian Red Sea Coast.

Forty-four marine sediment samples were collected in-front of wadis mouth along the Egyptian Red Sea coast: Wadi El-Hamra, Wadi El-Esh, Wadi Abu-Shaar, Wadi El-Gemal and Wadi Khashir (Hamata). Several investigations of natural activity and trace metals of surface sediments were carried out. Distributions of naturally occurring radioactive materials (NORM) of (226)Ra, (232)Th and (40)K in the marine sediments were determined using NaI (Tl) γ-ray spectrometry. The average activities (range) of natural radionuclides in all wadis in the studied areas are 27.38 (18-48) Bq kg(-1) for (226)Ra, 38.45 (34-110) Bq kg(-1) for (232)Th and 419.4 (214-641) Bq kg(-1) for (40)K. These results are in agreement with earlier reported data. A comparison of radionuclide activities in the sediment of the studied areas and in other coastal and aquatic environments is given. The radiation hazard parameters (absorbed dose rate, radium equivalent activity and external hazard index) are calculated and compared with the reported data. The results of measurements will serve as base line data and background reference level for Egyptian coastlines.

Terrestrial gamma radioactivity levels and their corresponding extent exposure of environmental samples from Wadi El Assuity protective area, Assuit, Upper Egypt.

Representative environmental samples (sandy soil, limestone, marble and gravels) collected from Wadi El Assuity, protective area, Assuit governorate in Upper Egypt have been investigated radiometrically using NaI (Tl) gamma-ray spectrometer. The specific activity of the radionuclides in Bq kg⁻¹ for soil ranged between 10.5 and 18.7 for ²²6Ra, 1.5 to 4.6 for ²³²Th and from 94 to 107 for 4°K, for limestone ranged between 19 and 27.1 for ²²6Ra, 32.9 to 50 for ²³²Th and from 49 to 7 3 for 4°K, where, for marble ranged between 12.2 and 30.7 for ²²6Ra, 32.6 to 59.5 for ²³²Th and 55 to 70 for 4°K and for gravels ranged between 7.8 and 21.8 for ²²6Ra, 19.8 to 30.0 for ²³²Th and from 151 to 260 for 4°K. The mean activity concentrations of measured radionuclides were compared with other literature values. The absorbed dose rate, radium equivalent activity and external hazard index were calculated and compared with internationally recommended values. The gamma absorbed dose rates in the samples ranged between 8.44 and 50.89 nGy h⁻¹. These dose rates are consistent with the accepted worldwide average 55 nGy h⁻¹ for the public. All values obtained for radium equivalent activity are < 370 Bq kg⁻¹, which are acceptable for safe use. The calculated values of external hazard index obtained varied from 0.12 to 0.24. Since these values are lower than unity, one can say that the radiation hazard is insignificant for the population living in the investigated area. This permits the use of these materials sediments as building materials in any probable development projects at this area.

Determination of chromium and trace elements in El-Rubshi chromite from Eastern Desert, Egypt by neutron activation analysis.

Neutron activation analysis (NAA) is one of the most powerful analytical techniques for multielement determination of rocks. In the present work NAA and HPGe detector gamma-spectroscopy was used to determine chromium and 15 minor and trace elements qualitatively and quantitatively from chromite rock samples collected from El-Robshi area in the Eastern Desert, Egypt. The samples were properly prepared together with their standards and simultaneously irradiated by thermal neutrons at the TRIGA Mainz research reactor. Short time irradiation (1-5min) was used to determine Mg, Ti and Mn. Long time irradiation (6h) was used to determine Na, Ga, As, La, Sc, Cr, Fe, Co, Zn, Zr, Ce, Ce, Yb, Lu, Hf and Ta. In El-Robshi chromite comprises 18 sites, more than 100 lenses of massive chromite, more than 2700 tons averaging 44% Cr(2)O(3) and the average of (51)Cr 40.2%.

Dual-wavelength, ultralong Raman laser with Rayleigh-scattering feedback.

We present experimental demonstration of a 200-km-long, dual-wavelength Raman laser utilizing two slightly different-wavelength fiber Bragg gratings, one on each side of the fiber span. The obtained results clearly prove the generation of two independent Raman lasers with a distributed "random" Rayleigh scattering mirror forming a cavity together with each of the individual fiber Bragg grating reflectors.

Rare earth elements content in geological samples from eastern desert, Egypt, determined by instrumental neutron activation analysis.

Twenty representative geological samples (tonalite, granodiorite, adamellite, syenogranite, rapakivi syenogranite, alkali feldspar granite and monzogranite) were collected from G. Kattar area in Eastern Desert, Egypt, for analysis by instrumental neutron activation as a sensitive nondestructive analytical tool for the determination of 14 rare earth elements (REEs) and to find out the following: (1) what information could be obtained about the REEs and distribution patterns of REEs in geological samples under investigation, (2) to estimate the accuracy, reproducibility and detection limit of the INAA method in case of the given samples. The samples were properly prepared together with standard reference material and simultaneously irradiated in a neutron flux of 7x10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The gamma spectra were collected by an HPGe detector and the analysis was done by means of a computerized multichannel analyzer. The choice of the nuclear reaction, irradiation and decay times, and of the proper gamma radiation in counting are presented and discussed. The results are found to be in good agreement with certified values.

INAA and DNAA for uranium determination in geological samples from Egypt.

Uranium isotopes found in soil, rock, water, plants, air, etc., contribute to the natural radiation exposure of the population. U concentrations in some Egyptian environmental samples like Toshki soil, Aswan iron-ore, and phosphate samples from El-Sibayia in the Nile Valley and El-Quseir in the Red Sea coast were determined using instrumental neutron activation analysis (INAA) and delayed neutron activation analysis (DNAA) in the Mainz TRIGA research reactor. The results showed that the phosphate rocks are rich natural sources of uranium among the other minerals forming the earth crust.