Journal of School of Public Health and

Background and Aim:We studied the biosorption of lead(II) and cadmium(II) from aqueous solutions by the brown algae Sargassum sp. biomass in a batch system.

The heavy metal uptake was quite rapid, reaching 88-96% of the equilibrium capacity of biosorption in 15 minutes.

Material and Methods: Kinetic data were analyzed using the pseudo first-order, pseudo second-order, and saturation and second-order rate equations.

Results: The pseudo second-order and saturation rate equations gave the best fit with the experimental data(R² > 0.99). The data obtained from experiments of single-component biosorption isotherm were analyzed using the Freundlich, Langmuir, Freundlich-Langmuir and Redlich-Peterson isotherm models. The Redlich-Peterson equation was found to provide the best fit with the experimental data (R² > 0.99). Also the other models described the isotherm of lead(II) and cadmium(II) biosorption with relatively high correlation coefficients (R² > 0.93).

Conclusion: Using the Langmuir model, the maximum uptake capacities (q_m) of Sargassum sp. for Pb²⁺ and Cd²⁺ were 1.70 and 1.02mmolg^-1, respectively.

Background and Aim: Agricultural and industrial activities, as well as population growth, have resulted in increases in the amounts of pollutants in the environment, the human body, and other organisms. Cadmium is one of the common heavy metals entering the biological cycles through different paths causing disease in humans, animals and plants. This study aimed at determining cadmium levels and physicochemical and biological factors in water and sediment samples, as well as determining relationships between culturable bacterial counts and cadmium toxicity and assessing bacterial resistance/tolerance spectrum through MIC and MBC.

Materials and Methods: Surface water and sediment samples were taken from five stations in areas believed to be polluted along the Kor River. The stations included 1. Dorudzan Dam outflow, 2. Petrochemistry Bridge, 3. Khan Bridge, 4. Doshakh Bridge, and 5. the mouth of the Kor River to the Bakhtegan Lake. Two sets of samples were taken. Set 1was used for measuring cadmium level, physicochemical and biological factors, while Set 2 was used for the isolation and identification of cadmium resistant/tolerant bacteria and determination of their resistance spectrum. Pure cultures of each bacterial species were prepared and the more resistant bacteria were identified by exposure to media with different cadmium concentrations.

Results: Stations 2 and 3 were found to be significantly more polluted with cadmium than the other 3 stations (p<0.001). The cadmium level in sediments of all the stations was higher than in water (p<0.001) and quite high as compared with the existing standards. The data also showed a lower BOD/COD ratio in the last 2 stations and higher phosphate levels in the last 4 stations. As compared to control, the bacterial count decreased in the presence of 1 mM cadmium chloride solution (p<0.001). Cadmium-resistant bacterial counts were higher in stations 3 and 5 than in the others (p<0.001). The most cadmium-resistant/tolerant bacteria were P. aeruginosa ETs and Bacillus ABs with MIC 6 and 4 and MBC 7 and 5 mM, respectively. The most resistant bacteria were gram-negative, isolated from the sediments.

Conclusion: Cadmium pollution, especially in stations 2 and 3, are due to man's activities. Although many bacterial types were found to be sensitive to cadmium in this study, some of them showed resistance/tolerance to it to different extents. Our findings also show that unlike water, which is an unstable environment, sediments are stable and provide a suitable environment for bacteria to form biofilms as a way to reduce cadmium accumulation. The most resistant bacteria were found in the stations with the highest cadmium concentrations. This may be a result of cadmium-resistant gene expression in the presence of this heavy metal. The use of these resistant strains in biofilters and wastewater bioremediation can potentially help to reduce cadmium pollution, a problem in some rivers.

Background and Aim: The objective of this study was to determine the contents of heavy metals Hg, Cd and Pb in the muscle, liver and gill tissues of Liza abu fish in the Dez and Bahmanshir Rivers in Khoozestan Province, Iran in winter 2010. 

Materials and Methods: The study included 108 samples of Liza abu tissues. The metals were extracted from the tissues using the wet-digestion method and their concentrations were determined by atomic absorption spectrophotometer Perkin Elmer 4100. Analysis of the data was done using the SPSS17 software, the statistical test being the t-test ((p≤0.05).). 

Results: The highest concentrations (mg/Kg) of Hg (0.029±0.005), Cd (0.506±0.047) and Pb (1.07±0.096) were found in the gill and their lowest concentrations, 0.023±0.001, 0.346±0.040 and 0.903±0.030, respectively, in the muscle. The concentrations of Cd in the gull, muscle and liver were significantly different (p≤0.05) between the Dez and Bahmanshir River fish samples, but the differences with regard to Hg and Pb concentrations were not different between the 2 rivers (p≥0.05). 

Conclusion: The mercury content of Liza abu tissues was lower, while the lead and cadmium contents were higher, than the respective WHO standards (permitted levels).

  Background and Aim: Exposure to heavy metals always causes serious health problems in people working in the industry. Heavy metals may interfere with enzyme functioning or accumulate in specific body organs, leading to various health problems. Cadmium is a toxic heavy metal widely used in various industries and, therefore, workers in metal industries are at risk of exposure to it.

  Materials and Methods: A solid-phase sorbent was synthesized and factors influencing its sorption and elution steps were optimized (R>95%). The validated sorbent (chemically, physically and as regards reproducibility) was used to determine the cadmium content of the worker`s urines.

  Results: Optimized conditions for sorption and elution step were found to be as follows: pH= 7 sorption and elution time (both)= 5 min elution volume= 6 mL, and elution concentration= 2 mol L^-1. The great selectivity and the nano-particle size of the sorbent resulted in its highly precise performance (0.6ppb) and high validity and accuracy (CV<3%).

  Conclusion: Using the nano-magnetic sorbent technique and some such laboratory methods as flame atomic absorption spectroscopy, one can easily measure trace amounts of heavy metals in urine. This technique is relatively less expensive and rapid since, when using it, one can omit the filtration and centrifugation steps.