جستجوی مقالات مرتبط با کلیدواژه « lead » در نشریات گروه « زیست شناسی »

Qualitative assessment by macro-invertebrates is known as a suitable method to determine the health of the river. In this study, the diversity and abundance of Baliqlu River macro-invertebrates were evaluated from June 2019 to May 2021. SamplingsSamples were taken by Surber sampler during four seasons and physico-chemical parameters such as TEM, DO, pH, BOD, and some heavy metals (Cd and Pb) were measured. Diversity indices (Shannon-Wiener), and biotic indices (EPT, HFBI, and BMWP) were calculated in four stations. A total of 8328 macro-invertebrates from the Diptera, Ephemeroptera, and Isopoda were identified. The highest frequency percentage of the dominant groups was related to the Caenidaed, Chironomidae, and Simuliidae. The results of heavy metal accumulation in two classes showed more cadmium and lead accumulation in the Clitellata class (suborder Hirudinea) than the Insecta class (Caenidae family). The results of conventional comparative analysis (CCA) demonstrate that the distribution of most macro-invertebrate families is influenced by the DO parameter. According to the HFBI, the water quality decreased from upstream to downstream in all seasons, and the level of pollution was higher in station 5 compared to other stations, due to human activities, cattle crossing, and sewage output of fish farms.

Environmental pollution with heavy metals is one of the most serious environmental problems. There are several methods for removing heavy metals that require a lot of energy and are expensive. Therefore, the use of adsorbents such as algae has been considered. In this study, the efficiency of three species of microalgae Scenedesmus acutus, Scenedesmus incrassatulus, and Scenedesmus obliquus in adsorption of lead-heavy metal was investigated. For this purpose, pH (3 to 7), algal density (0.25 to 2 g), contaminant concentration (20 to 200 mg / l), time (30 to 150 minutes), and temperature (15 to 35 ° C) were investigated. it placed. The results showed that the rate of absorption of heavy metals by these three species was not significantly different. However, pH, algal density, pollutant concentration, time, and the temperature had a significant effect on the efficiency of algae in removing contaminants from the environment. The highest amount of lead uptake by microalgae occurred at pH 6, 25 ° C, adsorbent level of 0.5 g, contact time of 120 minutes, and density of 150 mg / l lead. Lead uptake had no effect on lipid and biodiesel production by microalgae.

Amending biochar alone or with microbial inoculation, as a soil amendment, helps to reduce the toxicity of heavy metals in contaminated agricultural soils. On the other hand, the interaction of inoculation with microorganisms and the application of biochar on the absorption of lead and zinc and the growth and yield of plants are somewhat unclear. The objective of this greenhouse experiment was to explore the influences of the application of biochars (obtained from peanut shells and carrot pulps) and conidial suspension of Trichoderma fungi (Trichoderma harzianum Rifai-T22) on seedling growth and some physiological characteristics of sainfoin grown in the soil polluted with heavy metals Pb and Zn. The application of biochars and inoculation with Trichoderma fungus improved the growth parameters of sainfoin seedlings such as root length, plant height, fresh and dry leaf weight. Also, the synergy of these treatments caused an increase in the total protein content, the soluble sugars, the total flavonoids in roots and leaves, catalase and peroxidase activity and also the rate of seedling germination compared to the control treatment (no use of biochar and conidial suspension). Overall, the application of biochar and Trichoderma in soils contaminated with heavy metals caused enhanced growth of sainfoin seedlings by improving some physiological parameters in the leaves, increasing root growth, alleviating the oxidative stress-induced damage and thus possible improvement in water and nutrient uptake.

In order to study the effect of salinity stress and different concentrations of lead under the influence of stress ameliorator, a factorial experiment was carried out in a completely randomized design with three replications. The experiment consisted of salinity stress at three levels (0, 25 and 75 mM of sodium chloride), lead in three concentrations (0, 10-5, 10-3 M of Lead nitrate) and stress ameliorators included 0 and 5 mg/L sodium selenate and 200 μm sodium hydrogen sulfide. The results showed that salinity and lead caused a significant reduction in root and shoot dry weight, absorption of potassium and zinc in root and shoot. Different concentrations of Lead had different effects on the studied traits. At 10-5 M of lead nitrate was observed, the reduction in absorption of lead and as a result improvement in root and shoot dry weight than without salinity. Whereas, application of selenium and hydrogen sulfide significantly improved the growth traits of garlic under salinity stress and Lead. Application of 5 mg/L sodium selenate and 200 μm sodium hydrogen sulfide cause reduce in the accumulation Pb in garlic seedlings and this is followed by an improvement in the content of the elements and as a result, growth increased under salinity stress and lead concentration especially at 10-5 Pb However, in the concentration of lead 10-3M, this effect was not observed. It is worth noting that in the present experiment, the positive effect of selenium on sodium hydrogen sulfide was more pronounced.

Today, the removal of heavy metals from industrial effluents is significantly increasing, which can play an important role in protecting the environment and human health. In recent years, researchers have resorted to biological methods, especially biological and microbial methods to remove toxic heavy metals. Biosorption of heavy metals is a relatively new technology for the treatment of industrial effluents, and its purpose is to remove toxic metals and clean the environment, as well as recycle precious metals. This process is a rapid reaction between the metal and the cell surface (extracellular bonding) in which the metal adheres to the surface of molecules like a surface protein. Conventional biological processes in the biological purification of metals are biosorption, bioaccumulation and bio-sedimentation. In the present study, sprulina platensis ability to absorb heavy metal lead from aqueous solutions was investigated by optimizing the absorption conditions for live spirulina microalgae. The aim of the present study is to provide a solution for biological removal of lead heavy metal using biosorption method using spirulina microalgae.

Three parameters of algae concentration (0.5, 1, 1.5 and 2 g/l), lead concentration (20, 40 and 60 mg/l) and contact time (30, 60, 90, 180 and 360 minutes) was considered.as experimental parameters. In order to perform the tests, 12 culture samples were placed. By examining the growth rate and after the cultures reached the desired concentration, three concentrations of lead were added to the samples and after certain periods of time, the culture was sampled and the adsorption rate was measured. The adsorption isotherm was then plotted to determine the theoretical capacity of the contaminant absorption.

The results showed that the optimum growth occurred in light conditions of 3000 lux and pH 10 and the maximum optical density was 1.421. The results showed that higher concentrations of algae had a higher rate of biosorption and the maximum absorption efficiency was obtained at a concentration of 2 g/l spirulina. Examination of contact time effect shows that by increasing contact time up to 180 minutes, the amount of biosorption increases and then decreases, which is probably due to the toxicity of the remaining heavy metal on spirulina microalgae cells. The maximum removal of heavy metal was 81.33% and occurred at a concentration of 2 g/l spirulina and a dose of 20 mg/l lead in a contact time of 180 minutes. The results showed that the Langmuir isotherm could fit the experimental data better than other models.

The process of biological adsorption by spirulina consists of two stages of rapid absorption (first 20 minutes) and slow absorption thereafter. The absorption efficiency is upward for about 60 minutes and then gradually decreases. Also, the high absorption rate in the first 30 minutes (more than 50% of the total biological absorption in all samples) indicates the existence of a rapid absorption phase in the first minutes. The reason for the rapid absorption in the first 30 minutes is due to the rapid physical adsorption at the active sites of the algal cell, known as the negative sites, and the adsorption occurs by electrostatic force.

Lead as one of the most expanded metals in environment, effects on human health. Besides, the biological absorption by algae leads to the reduction of heavy metal pollutions in aqueoussolutions. In this study, accumulation and bioabsorption of Pb+ on biochemical characteristics of green alga Entromorpha was investigated. For this purpose, effects of  different concentrations of Pb2+ (0, 50, 100 and 150 µM Pb(SO4)2) in presence of two concentrations of Ca2+ (0 and 0.5 mM CaCl2) was studied in Entromorpha collected on Caspian Sea in two times of 3 and 8 days in random complete design with 4 replications for photosynthetic pigments content, membrane lipid peroxidation and antioxidant enzymes activity. The results indicated a decreasing rate of chlorophylla and b, total chlorophyll and carotenoid and also activity of polyphenoloxidase enzymewith increase of Pb2+ concentration and stress during. In membrane lipid peroxidation assay, malondialdehyde increased significantly by increase of Pb2+concentration. For these traits including chlorophyll, and carotenoid content and also membrane lipid peroxidation assay, effects of Pb2+ stress decreased by using CaCl2 treatment. The results of antioxidant assay showed that catalase, ascorbate peroxidase and peroxidase activities in both 3 and 8 days stress was high without CaCl2 treatment than using it. In general, the results of this study showed that Pb2+causes oxidative stress and biochemical changes in Enteromorpha green algae. Also, the presence of CaCl2 treatment reduces the effects of stress.

In recent years, earthworms have been used to clean soil contaminated with heavy metals. The aim of this study was to investigate the Bioaccumulation factor of earthworms in soils contaminated with heavy metals. The sewage sludge added to soil at levels of 0, 10, 20, 30, 40 and 50 tons per hectare. Earthworm (Eisenia foetida) was added to the polluted soil in order to study the effect of organic amendments. The total concentration and fractionation of heavy metals, the weight and mortality of earthworm were evaluated after 42 days. Sampling of earthworms was performed at eight weeks. The maximum accumulation of heavy metals by earthworms was found in 20 tons per hectare treatment. Bioaccumulation factor was more than 1 for the zinc and cadmium which shows the ability of earthworm (Eisenia foetida) for accumulation of these metals in the contaminated soil with heavy metals. The loss of weight was found for all treatment during the experimental period. Despite earthworm weight loss in all treatments, the highest number of deaths was observed in the control group which were free of sewage sludge. In general, the results showed that the use of earthworms could play an important role in clearing heavy metals in the soil.

Soil contamination with heavy metals is one of the most important environmental problems in many parts of the world. Nickel (Ni) and lead (Pb) are heavy metals that are major contributors to environmental pollution. Since dill (Anethum graveolens L.) is cultivated as a leafy vegetable in various places, even in heavy metal-contaminated areas, this study was conducted to investigate the effects of lead and nickel on the activity of dill antioxidant enzymes and antioxidant compounds. In this study, dill seeds were planted into pots containing coco peat and perlite and treated with lead nitrate (0, 500 and 1000 μM) and nickel nitrate concentrations (0, 100 and 200 μM) in three replications. After the treatments, the length, fresh weight and dry weight of root and shoot, photosynthetic pigments content, the amount of phenolic compounds, flavonoids, anthocyanins, catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX), superoxide dismutase (SOD) activity and the concentration of Pb and Ni in the shoot and root were evaluated. Use together of lead with nickel on the plant showed that plant length, Chlorophyll a, chlorophyll b, and total chlorophyll decreased respectively to 1.32, 1.02, and 2.03 compared to the control with values of 6.26, 4.54, and 10.32 mg / g under lead and nickel treatments. The anthocyanins, total phenols and flavonoid contents were respectively 4.7, 0.69 and 0.51 mg/g which increased by 23.5, 8.6 and 6.37 compared to the control. CAT, APX and SOD activities increased. Whereas, carotenoid content, fresh and dry weight of roots and shoots, guaiacol peroxidase activity were not affected. Simultaneous use of lead and nickel led to an increase in the amount of lead and nickel in shoot and root. The presence of lead reduces the uptake of nickel by the plant. Accordingly, it seems the plant uses antioxidant compounds such as phenols and some antioxidant enzymes to counter lead and nickel oxidative stress from. On the one hand, the treatment had no effect on fresh and dry weight and also roots and stem length decreased slightly. A number of antioxidant enzymes were activated and the antioxidant compounds increased and the more accumulation of elements in the root, it is possible that even if the plant is not resistant to these stresses, it can grow in the Pb and Ni contaminated soil without serious damage.

In order to quantify the response of canola (Brassica napus L.) plant to lead different levels, an experiment was conducted in completely randomized design with three replications. Treatments were twelve lead concentrations from lead nitrate source (0, 10, 50, 100, 500, 1000, 1500, 2000, 2500, 3000, 3500, 4000 mg/kg soil). Results showed that decrease in vegetative traits fitted with segmented model when lead concentration increased. Also, chlorophyll a, b, a+b contents and SPAD index value declined about 23, 47, 30 and 22%, respectively. Chlorophyll a/b ratio (a/b) and carotenoid, however, showed increasing trend by 46 and 39% in 4000 mg/kg of soil as compared to the control. In addition, the activity of catalase, peroxidase and ascorbate enzymes increased until about 10, 447 and 18 mg/kg of soil, respectively and then decreased when lead concentration was increased. Superoxide dismutase activity in 4000 mg/kg of soil was about 2.3 times greater than the control. Also, malon-di-aldehyde (MDA) and H2O2 concentrations in 4000 mg/kg of soil were about two times and proline concentration was about 12% greater than the control. In conclusion, up to 100 mg/kg of soil vegetative traits and photosynthetic pigments particularly showed the highest sensitivity. Among photosynthetic pigments, the sensitivity of chlorophyll b was higher than chlorophyll a. Also, the higher activity of superoxide dismutase enzyme than the other enzymes and proline can be a possible reason for ameliorating the damage of high levels of lead in canola.

This study was aimed to investigate the effects of different concentrations of Lactobacillus casei on some serum biochemicals and antioxidant factors in rainbow trout exposed to foodborne lead toxicity. For this purpose, 375 juvenile fish (15±4.6g) were randomly divided into five groups in three replications. Group 1, 2 and 3 were respectively fed with a diet containing 5×106, 5×107 and 5×108 CFU/g Lactobacillus casei throughout the experiment. Group 4 (negative control) was fed with a basal diet (no probiotic and lead) during all experiment period. Group 5 (positive control) was fed with the basal diet for 45 days and was subsequently fed with diets containing 500 µg/kg lead nitrate similar to the probiotic groups for 21 days. Blood sampling was performed to measure the parameters on days of 0, 45, 52, 59, and 66. The results showed that LDH, cholesterol and triglyceride levels were significantly reduced in most probiotic treatments after probiotic consumption for 45 days compared to a negative control group (P<0.05). After exposure to lead, serum ALP and LDH values in group 2 were significantly lower than group 5 (P<0.05). In group 2, GSH enzyme levels significantly increased compared to group 5 on day 52 (P<0.05). The findings of this study showed that supplementing the diet with Lactobacillus casei in rainbow trout can be effective in preventing the chronic effects of lead poisoning by improving the biochemical and antioxidant indices. It seems that level of 5×107 CFU/g of probiotic bacteria had an ameliorative effect on improving of the biomarkers.

Soil contamination to heavy metals such as lead and zinc in and around mines causes a change in structure, complexity, diversity and activity of soil microbial communities like bacteria. In the present research, PCR-DGGE approach was used to investigate the effects of Pb and Zn-contamination in Bama mine near Isfahan city on bacterial diversity, structure and complexity. Basal Respiration (BR) and Substrate Induced Respiration (SIR) was also used to assess microbial activities. Nine samples from three locations (3 for each) with different levels of heavy metal contamination were taken (from low to high), then their DNA were directly extracted. Also a 468 base pair of their 16S rRNA genes were amplified using specific primers, and their fingerprints were obtained by denaturing gradient gel electrophoresis (DGGE). BR and SIR were measured, and metabolic quotient was calculated. Finally, soil microbial activity in polluted conditions was achieved. Our findings illustrate that heavy metal contamination has negative effects on bacterial diversity. By increasing the bioavailability of Pb and Zn, the complexity and diversity of bacterial communities decreased and the frequency of resistant bacteria increased. By increasing Pb and Cd contamination, SIR reduced and this shows the reduction in microbial biomass. In these conditions, SIR and metabolic quotient was more sensitive than BR, so they are better ecological indicators in polluted soils.
Discussion and Although bacterial diversity showed reduction in polluted soils, diversity is still relatively high. Bacterial ability to adapt in heavy metal contamination, bacterial resistance and their important functional roles in such conditions are valuable in soil ecosystem suggesting further researches on them.

The beneficial root endophytes play a crucial impact in improving plant performance, and participate in enhancing phytoremediation efficiency of host in metal-polluted sites. This experiment investigated the influence of root endophyte fungus Serendipita indica on lead (Pb) accumulation and translocation, some physiological attributes, and antioxidant system of leaf in Carthamus tinctorius L. (safflower) cv. Sina in soil contaminated with different levels Pb (0, 400, 800 and 1200 mg Pb/kg soil). By increasing Pb levels in soil, Pb uptake by root, and Pb accumulation in root and shoot were significantly elevated. A significant increase on Pb accumulation in root and a significant reduction on shoot Pb amount were observed under fungal symbiosis. Also, S. indica-inoculated plants had lower translocation factor (TF) and bioaccumulation factor of Pb in shoot (BFS), whereas higher bioaccumulation factor of Pb in root (BFR), in compare to non-inoculated ones. Presence of S. indica yielded in greater growth parameters, photosynthetic pigments, chlorophyll fluorescence parameters, and antioxidant enzymes activities of CAT, APX and SOD, under all levels Pb in soil. We suggest the consideration of this endophyte for fungus-assisted phyto-stabilization/immobilization of Pb in host roots. Also, we concluded that S. indica mediated different tolerance strategies to mitigate Pb toxicity and higher performance of safflower.

Selenium as a metalloid and useful element has different effects on plants. It enhances plant growth at low concentrations while high concentrations of this element can cause stress in plants. The aim of this study was to investigate the effect of different concentrations of selenium (0, 20, 40, 120 and 240 µM) equivalent to (0, 2, 4, 11 and 22 mg/L), at the 4-leaf stage, on shoot and tuber growth and some physiological parameters of the Allium iranicum Wendelbo and Allium ampeloprasum L..The results showed that with increasing concentrations of selenium, the growth rate (height, weight gland and the aerial parts as well as chlorophyll content) of two species significantly decreased which the most reduction was occurred in plants grown at 22 mg/L treatment. Malondialdehyde content was increased in treatments of more than 2 mg/L compared to the control group. With increasing levels of selenium in the medium, catalase activity decreased, while antioxidant compounds content such as carotenoids, carbohydrates and protein increased. The results showed that low selenium concentrations (0-2 mg/L) promote the growth by increasing the amount of chlorophyll as well as the synthesis of carbohydrates, but higher concentrations of selenium (4-22 mg/L) reduced the growth due to the production of reactive oxygen species and reduces the biomass. The overall results of this study showed that different levels of selenium concentration, affect morphological and physiological characteristics of tuber and shoot of two species. The important morphological symptoms of selenium toxicity were tuber and aerial growth reduction and chlorosis of young leaves.

Date have a significant contribution in the food basket of humans in many countries of the world, including Iran and it’s one of the most valuable foods that make up most of it sugar. Water, cellulose, pectin, ash and minerals are other ingredients of the date composition. So dates are one of the most important sources of mineral salts in a balanced diet. For this reason, the presence of toxic pollutants in dates causes many diseases in humans. Therefore, monitoring the quality and health of this natural product is essential. For this purpose, in 2016, a study was conducted to investigate the amount of heavy metals (lead, cadmium, copper and zinc) in consumer dates in Ahwaz. This experiment was carried out 3 replications and in the form of the completely randomized design (CRD). Statistical analyses were performed using the MSTST-C statistical package and means were compared with Duncan test at 5 percent level. Experiments related to the estimation of the amount of the metals were carried out using atomic absorption of furnace to detect heavy metals (Cadmium, lead) and atomic absorption of flame for the detection of heavy metals (Zinc and Copper). The results of this study showed that the average of total concentration of Cd, Pb, Cu, and Zn in date samples were equal to 0.713±1.96 ,3.53± 2.74, 0.136± 0.072 and 4.433±0.324. The results of analysis of variance indicated that there was a significant difference between the samples in terms of heavy metals (lead, Cadmium, Zinc and Copper) at 1% level. The results showed that the Dairy date had the highest amount of lead (8 µg. g-1) and Cadmium (33.6 µg. g-1), Zahedi date had the highest copper (0.31 µg. g-1) and Gentar date had the highest Zinc content (29.1 µg. g-1), indicating a low level of these heavy metals in comparison with the date standard, which indicated a high degree of confidence in the determination of their health and safety for consumption.