Levels of Selected Metals in Canned Fish Consumed in Kingdom of Saudi Arabia

In the present paper, seven heavy metals (Pb, Cd, Ni, Cu, Zn, Cr and Fe) in canned salmon, sardine and tuna fish were determined by using atomic absorption spectroscopy. Cadmium and lead levels were determined by graphite tube AAS whereas Ni, Cu, Cr and Fe were determined by flame AAS. Analytical results were validated by spiking the samples with various concentrations of these metals for recovery. The metal contents, expressed in μg/g, wet weight, varied depending upon the specie studied. The levels of Pb ranged from 0.03–1.20 μg-g⁻¹ with an average of 0.313 μg-g⁻¹ for salmon; 0.03–0.51 μg-g⁻¹ with an average of 0.233 μg-g⁻¹ for tuna and 0.13–1.97 μg-g⁻¹ with an average of 0.835 μg-g⁻¹ for sardines. The levels of Cd ranged from 0.02–0.38 μg-g⁻¹ with an average of 0.161 μg-g⁻¹ for salmon; 0.07–0.64 μg-g⁻¹ with an average of 0.227 μg-g⁻¹ for tuna and 0.010–0.690 μg-g⁻¹ with an average of 0.183 μg-g⁻¹ for sardines. Comparative evaluation of these metals in three varieties of fish showed that average concentration of lead in sardines is about 4 times and Ni about 3 times higher as compared to tuna. Generally, the levels of these metals follow the order sardine > salmon > tuna. The data generated in the present study compared well with the similar studies carried out in different parts of the world. The results indicate that canned fish, in general and tuna in particular, have concentrations within permissible limits of WHO/FAO levels for these heavy metals. Therefore, their contribution to the total body burden of these metals can be considered as negligibly small.     

Assessment of metal status in drainage canal water and their bioaccumulation in Oreochromis niloticus fish in relation to human health

The purpose of this study was to assess metal concentrations (Al, Cd, Pb, Hg and Ni) in Sabal drainage canal (Al-Menoufiya Province, River Nile Delta, Egypt) water as well as their accumulation in some selected organs (skin, muscles and kidneys) of Oreochromis niloticus fish to evaluate their hazard levels in relation to the maximum residual limits for human consumption. Drainage canal water was found to be heavily polluted with metals which far exceeded the permissible limits. It was found that metals accumulated in organs of O. niloticus in concentrations higher than those of canal water. Kidneys of O. niloticus contained the highest concentrations of the detected metals, while skin appeared to be the least preferred site for the bioaccumulation of metals as the lowest metals concentrations were detected in this tissue. The present study shows that fish organs contained high levels of metals exceeding the permissible limits values. Metals in muscle of fish were higher than the maximum permissible concentrations for human consumption. Thus, consuming fish caught from drainage canals is harmful to the consumers.     

Speciation of Trace Metals in Coastal Sediments of El-Mex Bay South Mediterranean Sea–West of Alexandria (Egypt)

Sediments of El-Mex Bay estuary on the southern Mediterranean Sea have been analyzed for trace metals after sediment fractionation by sequential leaching. A sequential extraction procedure was applied to identify forms of Mn, Cu, Cd, Cr, Zn and Fe. The five steps of the sequential extraction procedure partitioned metals into: CH₃COONH₄ extractable (F1); NaOAC carbonate extractable (F2); NH₂OH.HCl/CH₃COOH reducible extractable (F3); H₂O₂–HNO₃ organic extractable (F4) and NHO₃/HClO₄/HF acid soluble residue (F5). Extracted concentrations of trace metals analyzed after all five steps, were found to be (μg/g) for Mn: 1930.2, Cu: 165.3, Cd: 60.9, Cr: 386.3, Zn: 2351.3 and Fe: 10895. Most of elements were found in reducible fraction except Fe found in acid soluble residue, characterizing stable compounds in sediments. Labile (non-residual) fractions of trace elements (sum of the first four fractions) were analyzed because they are more bioavailable than the residual amount. Correlation analysis was used to understand and visualize the associations between the labile fractions of trace metals and certain forms, since Fe-and Mn-oxides play an important role in trace metals sorption within aquatic systems, especially within El-Mex Bay sediments that characterized by varying metal bioavailability.     

Investigating the performance of aerobic,semi-aerobic,and anaerobic bioreactor landfills for MSW management in developing countries

Three different laboratory bioreactors, each duplicated, with dimensions 0.5 × 0.5 × 1 m were set up and monitored for 160 days. Municipal Solid Wastes with an organic content of ~80 % and a density of 550 kg/m³ were placed in bioreactors. Fresh leachate collected from waste collection vehicles was used with a recirculation rate of 28 L/day. Aerobic bioreactors were aerated at a rate of 0.15–0.24 L/min/kg of waste. Almost the same level of treatment was observed in terms of chemical oxygen demand reduction of leachate, which was in the range of 91–93 %. However, for anaerobic bioreactor, it took almost twice the time, 160 vs. 76 days, to reach the same level of treatment and stabilization. The behavior of semi-aerobic bioreactor was somewhere between the aerobic and anaerobic ones. Total biogas production for anaerobic bioreactors was 90 L/kg of waste, which contained 57–63 % methane. Methane concentration measured in semi-aerobic bioreactor was below 5 %. The main advantage of aerobic bioreactor was the fast rate of the process, while for semi-aerobic bioreactor, it was the elimination of the need for energy to maintain aerobic conditions, and for anaerobic bioreactor it was the production of biogas and potential energy recovery.     

Prenatal sonographic diagnosis of a third ventricle choroid plexus papilloma

We report a case of fetal hydrocephalus secondary to a third ventricle choroid plexus papilloma detected by ultrasound at 33 weeks' gestation. The prenatal sonographic and colour flow Doppler findings of this rare fetal intracranial tumour are discussed.     

Orientation and navigation during adult transport between nests in the ant Cataglypis iberica

  Cataglyphis iberica is a polydomous ant species in which adult transports between nests are frequently observed. When pairs of workers were captured and released at the same location, the transporters (Ts) fled directly towards their destination nest and reached it in most of the cases. The transportees (Te), on the other hand, fled in the opposite direction and only a third of them eventually reached their nest of departure. Additional experiments suggest that this result may be explained by the fact that the Ts ants have a memory of the compass direction of the nest they are heading to and that they adjust their course by using a sequence of memorised landmarks. As regards to the Te, the reversal of their direction of transport seems to be based essentially on celestial cues. Received: 20 October 1999 / Accepted in revised form: 10 May 2000     

Assessment of the role of thymol in combating chromium (VI)-induced oxidative stress in isolated rat erythrocytes in vitro

Thymol, the main phenolic compound in Thymus vulgaris, has been shown to have various biological effects. The main objective of this study was to investigate the efficacy of thymol on counteracting hexavalent chromium-induced oxidative damage in rat erythrocytes in vitro. The radical scavenging activity of thymol was examined using the 1, 1-diphenyl-2-picrylhydrazyl assay. Erythrocytes resistance to oxidative damage, lipid peroxidation, osmotic pressure, hemolysis as well as morphological alterations were evaluated in the presence of 2.5 µg thymol mL^?1 with or without 5 µmol hexavalent chromium mL^?1 of the incubation media. Results from the 1,1-diphenyl-2-picrylhydrazyl assay denoted good radical scavenging activity of thymol. Thymol caused a significant increase in superoxide dismutase and catalase activities and reduced glutathione content in erythrocytes intoxicated with hexavalent chromium. In contrast, the presence of thymol resulted in markedly less-elevated malondialdehyde levels, hemolysis, and destabilization of erythrocytes exposed to hexavalent chromium. Microscopically, thymol markedly reduced hexavalent chromium-induced morphological alterations in rat red blood cells. Conclusively, thymol counteracted hexavalent chromium-induced oxidative damage in rat erythrocytes.     

Alteration of photosystem II activity by atrazine on Chlamydomonas reinhardtii synchronized and asynchronized cell cycle cultures

Inhibition of photosystem II (PSII) activity by atrazine was investigated in the green alga Chlamydomonas reinhardtii during different states of the cell cycle. The algal cultures were maintained under continuous light or under light/dark cycle (16/8?h) to obtain homogenized cell cycle distribution. The cycle state of algal population was determined by the DNA content using flow cytometry and defined as newly divided cells before the initiation of DNA replication (G₀/G₁) and cells at the end of the replication cycle with fully duplicated DNA content (G₂/M). Under different synchronized states of the cell population, the photosynthetic activity was investigated after treatment at 10, 100, and 1000?µmol?L^?1 atrazine exposed for 24?h by using fluorescence parameters related to PSII activity measured with a plant efficiency analyzer and pulse-amplitude modulated methods. In this study, we found that the atrazine effect was different depending on cell cycle phases and the period of illumination. Algal cells under light–dark cycle showed inhibition of the PSII electron transport leading to an increase of heat energy dissipation by the PSII reaction center. Algal cells grown under continuous light was shown to be more resistant to atrazine than the cells grown under light–dark cycle.     

Use of activated Chromolaena odorata biomass for the removal of crystal violet from aqueous solution: kinetic,equilibrium, and thermodynamic study

Environmental Science and Pollution Research - In the present study, biomass from the Chromolaena odorata plant’s stem was activated using sulfuric acid to adsorb crystal violet (CV) dye. The...     

Does foreign direct investment asymmetrically influence carbon emissions in sub-Saharan Africa? Evidence from nonlinear panel ARDL approach

Environmental Science and Pollution Research - In recent decades, the relationship between foreign direct investment (FDI) and carbon emissions has garnered the extensive attention by researchers...