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.     

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.     

Sulfonated cross-linked polyethylenimine for selective removal of mercury from aqueous solutions

Polymeric materials are among the most promising, effective, and increasingly important adsorbents for the removal of toxic metals from wastewater. This study was dedicated to the development of an insoluble, modified chelating polymer for use as an adsorbent for abstraction of Hg from aqueous solutions. Cross-linked polyethylenimine (CPEI) was sulfonated by 3-chloropropanesulfonyl chloride for selective removal of Hg. The binding affinity of the sulfonated CPEI (SCPEI) to Hg was assessed as well as its ability to be regenerated for reuse. It exhibited high removal percentage for Hg up to 87% in synthetic solutions, with high selectivity even in the presence of competing ions: “Mn, Ni, Fe, Pb, Zn, and Cr.” The removal mechanism followed was observed to be adsorption and precipitation at pH 3 and 8, respectively. High adsorption capacities were also observed for wastewater to which the polymer was applied. The Freundlich isotherm was found to be the best fit describing the adsorption process of Hg onto the SCPEI. The pseudo second-order equation was found to better explain the adsorption kinetics, implying chemisorption. The thermodynamic study of the adsorption revealed high activation energies which confirmed the chemisorption as the mechanism of adsorption. The polymer exhibited up to 72% removal efficiency after regeneration, thus showing potential for re-use.     

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...     

Environmental risk appraisement of disinfection by-products (DBPs) in plant model system: Allium cepa

The organic toxicants formed in chlorinated water cause potential harm to human beings, and it is extensively concentrated all over the world. Various disinfection by-products (DBPs) occur in chlorinated water are genotoxic and carcinogenic. The toxicity is major concern for chlorinated DBPs which has been present more in potable water. The purpose of the work was to evaluate genotoxic properties of DBPs in Allium cepa as a plant model system. The chromosomal aberration and DNA laddering assays were performed to examine the genotoxic effect of trichloroacetic acid (TCAA), trichloromethane (TCM), and tribromomethane (TBM) in a plant system with distinct concentrations, using ethyl methanesulfonate (EMS) as positive control and tap water as negative control. In Allium cepa root growth inhibition test, the inhibition was concentration dependent, and EC₅₀ values for trichloroacetic acid (TCAA), trichloromethane (TCM), and tribromomethane (TBM) were 100 mg/L, 160 mg/L, and 120 mg/L respectively. In the chromosome aberration assay, root tip cells were investigated after 120 h exposure. The bridge formation, sticky chromosomes, vagrant chromosomes, fragmented chromosome, c-anaphase, and multipolarity chromosomal aberrations were seen in anaphase–telophase cells. It was noticed that with enhanced concentrations of DBPs, the total chromosomal aberrations were more frequent. The DNA damage was analyzed in roots of Allium cepa exposed with DBPs (TCAA, TCM, TBM) by DNA laddering. The biochemical assays such as lipid peroxidation, H₂O₂ content, ascorbate peroxidase, guaiacol peroxidase, and catalase were concentration dependent. The DNA interaction studies were performed to examine binding mode of TCAA, TCM, and TBM with DNAs. The DNA interaction was evaluated by spectrophotometric and spectrofluorometric studies which revealed that TCAA, TCM, and TBM might interact with Calf thymus DNA (CT- DNA) by non-traditional intercalation manner.

     

Hepatoprotective effect of nicorandil against acetaminophen-induced oxidative stress and hepatotoxicity in mice via modulating NO synthesis

Environmental Science and Pollution Research - Acetaminophen (APAP) overdose can produce hepatotoxicity and consequently liver damage. This study investigated the hepatoprotective impacts of...     

The change in O3, SO2 and NO2 concentrations in Lithuania

Due to the dynamic nature of the atmosphere, substantial amounts of gaseous and particulate pollutants are transported to the areas distant from their sources. In order to determine the regional concentration levels of atmospheric pollutants in Lithuania, concentrations of gaseous O₃, SO₂, NO₂ and other pollutants have been measured at the Preila background station (55°20′ N and 21°00′ E, 5 m a.s.l.) since 1981. The long-term concentration data set enabled us to get temporal trends, both on a seasonal and longer time scale, to identify source areas of pollutants and to relate them to the emission data. Based on the data obtained, the different tendencies in the pollutant concentration changes were revealed. Positive trends for ozone (of 2.9% per year during 1983–2000) and a distinct negative trend for both sulphur dioxide (of 3.8% per year during 1981–2000) and nitrogen dioxide (of 3.8% per year during 1983–2000) were found. The air mass back-trajectory analysis was used to assess the source region of air pollutants transported to Lithuania. The pollutant concentration levels were compared with their emission changes in Europe and Lithuania. The general trends in SO₂ as well as in NO₂ concentrations observed are consistent with changes in SO₂ and NO₂ emissions in Europe and Lithuania.     

Job insecurity and crossover of burnout in married couples

We investigated crossover of burnout between spouses in 98 married couples in an organization undergoing downsizing. Burnout was found to be associated with feelings of job insecurity, self‐control and social undermining. Using SEM, findings supported the crossover of burnout from husbands to wives and the impact of burnout on undermining behavior. They also supported the research hypothesis of a direct relationship between job insecurity and burnout among husbands but not among wives. Sense of control was found to have a negative impact on burnout and on the spouse's undermining behavior and a positive impact on the spouse's sense of control. Copyright © 2001 John Wiley & Sons, Ltd.     

The front basitarsal brush in Pachycondyla apicalis and its role in hydrocarbon circulation

Summary. Worker postpharyngeal gland (PPG) chemistry of Pachycondyla apicalis constitutes a blend of hydrocarbons including alkanes, alkenes, and alkadienes, with 5,9-pentacosadiene, 5,9-heptacosadiene and 5,9-nonacosadiene as the major products as well as fatty acids. There is a large congruency between the PPG and cuticular hydrocarbons, however the latter had higher proportion of tricosane and pentacosane, but only traces of fatty acids. These ants have a well-developed cuticular hair brush on the front legs that they frequently pass through the mouth while grooming. Since these brushes have higher amounts of hydrocarbons than either the middle or hind legs, we hypothesized that they are involved in hydrocarbon circulation. We assessed the role of the front basitarsal brush in hydrocarbon circulation by isolating them from the buccal cavity, either by restraining the front legs or by blocking the mouth with glue. In both experiments, preventing contacts between the basitarsal brushes and the mouth for 24 hrs resulted in a considerable increase in hydrocarbon amounts in the brushes with a parallel decrease in the PPG. When the ants were kept alive for an additional 24 hrs after their legs were freed, hydrocarbon amounts in both the PPG and the front legs returned to normal. Analyses of crop content revealed the same hydrocarbons profile as in the PPG, but their amounts were very variable and there were no differences in amounts between the treatment and the control. We assume that part of the PPG hydrocarbons are cleared via the alimentary canal. Grooming behavior of ants restrained for 24 hrs and then freed was followed for four hours thereafter. There was a significant increase in total grooming during the first third and fourth hour, but not during the second. Grooming involving the front legs-mouth, and front legs-antennae, and the front and hind legs was especially intensive during the first hour. Grooming involving the hind legs - body was more intensive in the treated ants during the third hour following their release. We conclude that the front basitarsal brush is a site of hydrocarbon accumulation and that the PPG receives frequent charging during self-grooming.