Time filter

Source Type

El-Taher A.,Al Azher University | Madkour H.A.,National Institute of Oceanography and Fisheries of Egypt
Applied Radiation and Isotopes | Year: 2011

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 226Ra, 232Th and 40K 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)Bqkg-1 for 226Ra, 38.45 (34-110)Bqkg-1 for 232Th and 419.4 (214-641)Bqkg-1 for 40K. 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. © 2010 Elsevier Ltd. Source

Abdallah M.A.M.,National Institute of Oceanography and Fisheries of Egypt
Environmental Technology | Year: 2011

Sediment quality of Lake Maryout (one of the four Nile Delta shallow brackish water lakes on the south-eastern coast of the Mediterranean Sea) is of concern as this lake is used for land reclamation and aquaculture and is an important fishing source. The magnitude and ecological relevance of metal pollution in Lake Maryout Main Basin was investigated by applying different sediment quality assessment approaches. The aim of this study was to estimate ecological risk of trace elements (Cd, Ni, Pb, Cr, Cu and Zn) in the surficial sediments (63 m fraction) of Lake Maryout. Heavily contaminated sediments were evaluated by the Sediment Quality Guideline (SQG) of the US Environmental Protection Agency. The degree of contamination (Cd) was estimated as very high for each site. Two sets of SQGs effect range-low/effect range-median values and threshold effect concentration (TEC) and probable effect concentration (PEC) values were used in this study. Sediments from each site were judged toxic when more of the PEC values exceeded EPA guidelines. Based on the geoaccumulation index (Igeo) of target trace elements, the Main Basin of Lake Maryout has to be considered as extremely polluted with Cd (I geo≤5), strongly polluted with Zn (2≤Igeo≤3), moderately polluted with Cu (1≤Igeo≤2), unpolluted to moderately polluted with Cr and Pb (0≤Igeo≤1 for each) and unpolluted with Ni (Igeo≤0). Lake Maryout sediments had heavy accumulations of Cd, which apparently come from drains that include industrial and raw domestic wastes. Therefore, a sequential extraction technique was applied to assess the five fractions (exchangeable, metals bound to carbonate, acid-reducible, oxidizable-organic and residual) of Cd in surface sediments. The Cd concentration in most sampling stations was dominated by the non-resistant fraction (anthropogenic). The result showed that those stations located in the vicinity of municipal and mixed waste drains posed a high potential risk to fauna and flora of Maryout Lake. © 2011 Taylor & Francis. Source

Abdallah M.A.M.,National Institute of Oceanography and Fisheries of Egypt
Environmental Monitoring and Assessment | Year: 2013

The use of natural resources for the removal of phenol and phenolic compounds is being looked upon by researchers in preference to other prevailing methods. In the present study, different biosorbents, brown algae (Padina pavonia), fresh water macrophyta (Ceratophyllum demersum), and black tea residue, were tested as adsorbent for the removal of phenol from aqueous solutions. The optimum conditions for maximum adsorption in terms of concentration of the adsorbate and pH were identified. The results show that the initial concentration increases as the removal of phenol increases in C. demersum; in the case of the other two adsorbents, the initial concentration increases as the removal of phenol decreases, especially for an initial concentration lower than 100 and 1,000 μg/L for P. pavonia and black tea residue, respectively. Maximum percentage removal of phenol by each adsorbent is 77, 50.8, and 29 % for C. demersum, P. pavonia, and black tea residue, respectively. Also, the biosorption capacity was strongly influenced by the pH of the aqueous solution with an observed maximum phenol removal at pH of around 6-10. The first biosorbent (black tea residue) displays the maximum adsorption capacity at a pH of 10 with a percentage sorption capacity of 84 %; P. pavonia revealed a greater adsorption percentage at pH 10, reaching 30 %, while for C. demersum, the removal of phenol increases with the increase in initial pH up to 6.0 and decreases drastically with further increase in initial pH. The Freundlich, Langmuir, and Brauner-Emmet-Teller adsorption models were applied to describe the equilibrium isotherms. The results reveal that the equilibrium data for all phenol adsorbents fitted the Freundlich model which seemed to be the best-fitting model for the experimental results with similar values of coefficient of determination. © 2012 Springer Science+Business Media Dordrecht. Source

Abdallah M.A.M.,National Institute of Oceanography and Fisheries of Egypt
Bulletin of Environmental Contamination and Toxicology | Year: 2013

Along the Alexandria coast of the Egyptian Mediterranean Sea, five edible species of bivalve molluscs and one gastropoda species (Mactra coralline, Ruditapes decussates, Paphia undulate, Venerupis rhomboids, Crista pectinata and Coralliophila meyendorffi) were analyzed for content of metals (Cadmium, Chromium, Lead, Cobalt and Nickel) in the muscle and in the sediments where they live. The potential health risks of metals to humans via consumption of seafood were assessed by estimated daily intake and target hazard quotient. Significant positive correlations (p < 0.05) were obtained between tissue concentrations for all pairs of metals, with the exception of Cadmium. Significant positive correlations were also obtained for the concentrations of Cd and Ni in tissues of all studied species relative to their concentrations in surface sediments. However, correlations between tissue and sediment concentrations for Chromium, Lead and Cobalt were negative. Ruditapes decussates and C. meyendorffi had the highest values for the summed target hazard quotient and may pose a potential risk to local inhabitants through their consumption in the diet. The potential risk would arise from exposure to high tissue concentrations of Cd and Pb, which exceeded published guidelines for safety of seafood products in some cases. Chromium contributed a considerable fraction of the total target hazard quotient for all metals combined, but did not exceed the published guidelines. Cobalt and Ni did not contribute greatly overall to the target hazard quotient, except in the case of Ni in V. rhomboids. © 2013 Springer Science+Business Media New York. Source

Abd-El-Khalek D.E.,National Institute of Oceanography and Fisheries of Egypt | Abd-El-Nabey B.A.,Alexandria University
Desalination | Year: 2013

The antiscale properties of sodium hexametaphosphate (SHMP) were studied using electrochemical impedance spectroscopy (EIS), and chronoamperometry techniques in conjunction with a microscopic examination. The corrosion inhibitive characteristics were investigated using EIS and potentiodynamic polarization measurements. Mineral scales were deposited from the brine solution by cathodic polarization of the steel surface at ?. 0.9. V (vs. SCE). Comparative study was carried out between antiscalant efficiencies of SHMP and polyacrylic acid (PAA). Potentiodynamic polarization curves indicated that SHMP inhibits the corrosion of steel by controlling the cathodic oxygen reduction process. The results showed that SHMP can inhibit corrosion of steel and scale build-up under the conditions tested. © 2012 Elsevier B.V. Source

Discover hidden collaborations