کادمیوم

Soil pollution by heavy metals, especially in industrial regions is one of the main environmental problems. Cadmium (Cd) is a heavy metal that causes oxidative stress in plants and has many destructive effects on product quality. Nowadays, various methods are used to reduce the negative effects of high concentrations of heavy metals in the soil. In this regard, using biochar is a cost-effective and environmentally-friendly method and its influence on the reduction of heavy metals bioavailability of soil is an important advantage. Biochar is a carbon-rich material obtained by pyrolysis of biomass, such as agricultural residues and manures in conditions without oxygen or with limited oxygen content.

In this study, a factorial experiment was conducted in a completely randomized blocks design with three replications on Marigold (Calendula officinalis L.) medicinal plant with six levels of Cd (0, 1, 3, 5, 7, and 10 mg/l) and three levels of biochar (0, 1.5, and 3 w/w). The effect of experimental treatments was investigated separately and combined on the morphological (wet and dry weights of aerial parts and roots), physiological (the amount of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid), and biochemical (soluble sugar, catalase, peroxidase, and proline) characteristics of this medicinal plant. Means comparisons were done by Duncan's multiple range test at a probability level of 5%.

The results showed that different concentrations of Cd decreased the wet and dry weights of roots and aerial parts of the plant. The most reduction effect was related to the concentration of 10 mg/l of Cd. The interaction effect of biochar and Cd was significant only on the dry weight of aerial parts. The effect of stress caused by increasing the concentration of Cd on the plant's physiological processes was different. Considering that the first effect of Cd on the plant is the reduction of photosynthesis and chlorosis of the leaves, at the highest level of Cd, the amount of total chlorophyll decreased by 40% compared to the control sample, but the amount of carotenoid increased by 50% (p<0.05). The reduction of chlorophyll content under Cd stress can be due to oxidative damage and inhibition of different stages of chlorophyll synthesis. However, the increase in carotenoids in response to heavy metal stress occurs because these molecules, as part of the non-enzymatic antioxidant defense system, play a protective role against oxidative stress. In contrast, the use of biochar treatment caused a significant increase in the wet weight of aerial parts, the amount of chlorophyll a and carotenoid. Also, the interaction effect of the treatments indicated that at different levels of Cd, the characteristics of the dry weight of aerial parts, the amount of chlorophyll b, and the total chlorophyll increased with the increase in the biochar level. Among the investigated biochemical traits, the interaction effect of the treatments was significant only on the amount of soluble sugar (p<0.05) and catalase (p<0.01). This means that the absorption of Cd by biochar and the reduction of its toxicity effect on seedlings provided the conditions for more production of soluble sugar and catalase. In fact, biochar had high adsorption of Cd due to its high cation exchange capacity, high specific surface, and presence of functional groups.

In total, the results showed the biochar capacity to stabilize and inactivity Cd absorption. Therefore, the incorporation of biochar to soil can improve Cd bioavailability by plants in the phytoremediation, although the effect of type and plant variety on the amount of decreasing Cd stress should not be ignored.

Phytoremediation is a low-cost and environmentally-friendly technology. The aim of this study was to determine the efficiency of tomato and cotton plants in stabilizing urban sewage sludge with an emphasis on organic carbon, lead and cadmium removal.

In this experimental study on pilot scale, in order to achieve the research objectives, we planted Tomato and Cotton plants in a condensed sludge bed. Also, a non-plant bed was considered as control bed. The performance of the phytoremediation was measured by the changes of organic carbon, pH, electrical conductivity and heavy metals of lead and cadmium during 120 days.

Results of statistical analysis showed that after 120 days, the removal efficiency of organic carbon, lead and cadmium in Tomato were 35 ± 0.4%, 74.29 ± 0.3% and 91.42% respectively and in Cotton were 38 ± 3.7%, 54.93 ± 3.2% and 93.2± 0.3% respectively. The difference in mean efficiency in Tomato and Cotton was not significant until 30 days (p>0.05). Moreover, the results of this study showed that the concentration of organic carbon, cadmium and lead in sludge treated with Tomato and Cotton plants was significantly lower than that of control treatment sludge.

The results showed that the noted plants have a high ability to stabilize urban sewage sludge and eliminate organic carbon, lead and cadmium. Therefore, this method can be used as an option to stabilize sewage sludge and reduce its organic and inorganic pollutants on a large scale.

Emissions of particulate matter from car exhaust, tire wear, engine lubricants and street fence wear contain heavy metals, which are dangerous for the urban ecosystem. However, most of the particles are deposited on the canopy and soil of plants, which are absorbed by them. Pollution-resistant species with a high capacity to absorb suspended particles can be used to remove suspended particles from the urban environment. For this reason, in this study, concentrations of heavy metals in the leaves and soil of tree species in Bandar Abbas were measured and evaluated. Also, species with the highest potential for adsorption of heavy metals were identified. 

First, three tree species including Azadirachta indica, Conocarpus and Prosopis juliflora were selected as the dominant plants in Bandar Abbas and in 30 points of the fields with 5 points of the non-polluted environment outside the city (control), and sampled from the surface soil and leaves of these species. After preparing and digesting the samples, the concentration of heavy metals (cadmium, manganese, zinc and lead) emitted from urban traffic was measured using atomic absorption spectrometry in soil and tree leaf samples. Next, the difference in heavy metal concentrations between tree species was analyzed by ANOVA and between soil and leaves and between urban and control environments was analyzed by t-student test. Then, to determine the tree species with high accumulation of heavy metals, two indices of heavy metal accumulation (BCF) and bioaccumulation index (MAI) were used.

The results showed that the pattern of heavy metals in soil and leaves of tree species was Mn> Zn> Pb> Cd. The maximum concentrations of heavy metals in the soil and leaves were detected in Conocarpus, Azadirachta indica and Prosopis juliflora, respectively. Spatially, the highest concentration of heavy metals in the sampling points was related to Imam Hossein Street. However, the minimum concentration of heavy metals was observed in the Persian Gulf Street. The concentrations of Mn and Pb in the soil of plant species were different and their differences were significant at 95% level, but the concentration of Cd and Zn was not different in the soil of tree species. Pb, Mn and Zn concentrations were not different in the shoots of the studied tree species and their differences were not significant at the 95% level. However, the concentration of Cd in the shoots of the species was different and the difference between the species was significant at the 95% level. There was a significant difference in the concentration of heavy metals between soil and leaves at 95 and 99%. Also, the concentration of heavy metals in soil and leaves between urban and control fields was significantly different at 95%. The pattern of the BCF index in all species was Zn> Pb> Mn> Cd and heavy metals had moderate accumulation for tree species. Bioaccumulation index (MAI) showed that Conocarpus had the highest adsorption potential of heavy metals and the lowest adsorption potential was observed in Prosopis juliflora.

Conocarpus, by absorbing pollutants from urban traffic, purifies the polluted air of Bandar Abbas; However, Prosopis juliflora, which is one of the migratory trees in the city of Bandar Abbas, with strong and deep roots, dries up the surface and groundwater of the region. On the other hand, its potential to absorb urban air pollutants is weak. Therefore, despite their resistance to drought and heat, Conocarpus trees have a high potential to purify urban pollution and can replace Prosopis juliflora.

The behavior of heavy metals in the soil as one of the environmental challenges has attracted the attention of many researchers. The present study was conducted to evaluate the phosphorus solubilizing bacteria on remobilization of cadmium (Cd) and lead (Pb) in two calcareous soils.

Phosphorus, cadmium and lead in the forms of KH2PO4, Cd(NO3)2 and Pb(NO3)2 simultaneously were introduced to the soils to promote the formation of phosphate minerals of added metals in two selected soils. Ater two months the soils were inoculated with two Pseudomonas species and incubated for 3 months. Sequential extraction scheme were applied to determine the chemical forms of Cd and Pb 5, 25, 60 and 90 days after incubation.

The results showed that application of phosphorus solubilizing bacteria changed chemical forms of Cd and Pb. Inoculation with Pseudomonas decreased the soluble and exchangeable cadmium while increased organic matter-bound Cd concentration. Inoculation by Pseudomonas increased carbonate-bound Pb and decreased Fe-Mn oxide and organic matter bound Pb. In the other hand, phosphate solubilizing bacteria (Pseudomonas) decreased mobility and bio-availability of cadmium and immobilization of lead.

In fact, the behavior of heavy metals in the presence of phosphorus solubilizing bacteria was different and depends on the type of metal and soil properties. In present study, bacteria cause immobilization of cadmium and remobilization of lead.

Protected areas are vital tools in the management and conservation of both terrestrial and marine environments. However, the conflict between conservation priorities and resource extraction from protected areas is increasing worldwide. Due to its high biodiversity, Mouteh National Park and Wildlife Refuge hold significant conservation value; nevertheless, in recent years, it has been heavily exploited due to rich mineral attractions. Consequently, the current study investigates the Cd concentration in the soil and plants in the Mouteh Basin, its transfer factor, and the influencing factors.

45 soil samples were collected from a depth of 0-30 cm, and leaf samples of the Artemisia sieberi plant were obtained at 15 locations within the plain region of the Mouteh National Park and Wildlife Refuge, which spans an area of 423 km2. The concentrations of Cd in these samples were determined using an atomic absorption spectrometer. The uptake of Cd by the plants was calculated and interpreted using the transfer factor. The Inverse Distance Weighting method in ArcGIS software was used to identify areas contaminated with Cd, with concentrations exceeding 5 mg/kg in soil and 2.0 mg/kg in plant leaves, based on the standard limits set by the WHO and U.S. EPA. Finally, linear, logarithmic, power, exponential and polynomial regression models were employed to examine the impact of road transportation on Cd pollution.

The mean Cd concentrations in plants and soil (mg/kg) were found to be 0.39 ± 0.11 and 2.97 ± 0.15, respectively. The highest soil concentration of this element was recorded in the central areas of the region, reaching 15.00 ± 0.69 mg/kg. This concentration gradually decreased towards the southern parts of the region. The highest concentration of Cd in the leaves of Artemisia sieberi was observed in the northern sections of the region, at 0.62 ± 0.05 mg/kg, while the lowest value was recorded in the central part (0.32 ± 0.05 mg/kg). The transfer factor of Cd ranged from 0.005 to 0.544, with a mean of 0.934. According to the standard limit of 5 mg/kg for Cd in soil, an area equivalent to 20.80% of the region was identified as Cd-contaminated. However, considering the permissible limit of 0.2 mg/kg in plants, a significant portion of the vegetation cover in the area (more than 95%) was found to be contaminated with Cd. The best regression model was achieved in the exponential form with a coefficient of determination of 0.301, indicating that road transportation is one of the most significant human factors contributing to the increase in Cd pollution in the Mouteh soil and plant species Artemisia sieberi.

The exploration of gold and the establishment of multiple mines in the Mouteh region, as well as the construction of highways in the northern province of Isfahan, have led to significant threats to the ecosystem and species of this area. Based on the results, the soils of the Mouteh plain region have been contaminated with Cd. The high concentration of this element in soils near the roads and its decrease with increasing distance from the road are indicators of the impact of road transportation on soil pollution. Therefore, preventing the construction of transportation routes in areas with rich biodiversity, improving the quality of fuels and vehicles, and reducing traffic congestion are among the most important measures for protecting the environment and reducing pollution from potentially toxic elements in natural areas.

During the past two decades, computer aid models for simulation of heavy metals have been remarkably developed. Prediction of soil pollution plays an important role in pollution control and land management. But in large areas, collecting data in a direct way is challenging in terms of cost and time. In recent years, the use of indirect methods such as artificial neural network (ANN) and other similar models to estimate heavy metals has been considered. There are 27 salt mines in Garmsar city. Of these, 16 mines are active. Salt extracted from these mines are used as one of the food spices. On the other hand, due to mining activities, the soils of this region may be contaminated with heavy metals. Therefore,in this study, the effectiveness of terrain and spectral indices for predicting total soil Cadmium (Cd) around the soils of Garmsar salt mines was evaluated by ANN – multilayer perceptron (MLP) model.

For this research, 49 soil samples were collected from the 0-20 cm Physicochemical properties of soil samples such as percentage of clay, sand, silt, soil acidity (pH), electrical conductivity (EC) and lime percentage were determined. Total Cd concentration was measured by atomic absorption spectroscopy (AAS) (Varian, Spectra 220). All terrain attributes used in this study were derived from a digital elevation map (DEM) and to calculate the spectral indices, Landsat-8 OLI/TIRS bands image with a resolution of 30 meters were used. Twenty-five auxiliary data variables derived from a DEM and Landsat-8 were used to predict total soil Cd in the study area. Based on the auxiliary data obtained and the correlation coefficients between these data and the predicted total Cd value, 2 models were evaluated. The collected data were randomly divided into categories training and validation and were used to evaluate the MLP model.

The results of this study show that the auxiliary data extracted from landsat-8 bands (with the highest accuracy and lowest error rate) were the effective parameters in predicting soil contamination with Cd. Based on the results obtained from the evaluation of ANN performance in estimating total Cd, the value of root mean square error (RMSE) and coefficient of explanation (R2) were 0.05 and 0.95 for the first model and 0.10 and 0.80 for the second model. In model 1, saturation index (Sat I), grain size index (GSI), carbonate index (CrI), soil color index (color I) and gypsum index (GI) were important and main parameters in total Cd modeling. The results of the present study showed the high efficiency of the ANN model in predicting total soil Cd.

Due to the development of machine learning models in the field of environmental engineering especially in simulation of heavy metals, having a turning point for their advancement is very important. The results of this research show that the MLP model is suitable for total soil Cd prediction and this method can save the cost of soil sampling and analysis. Therefore, it is recommended to validate the method applied in this study to prepare total soil Cd map in similar areas.

An alternative and environmentally friendly method for purifying the environment from pollution is the use of biosurfactant derived from microorganisms. The advantage of biosurfactant is biodegradability, low toxicity, and effectiveness in increasing biological decomposition. Unlike chemical surfactants, surface active substances produced by microbes are easily decomposed, and for this reason, they are very suitable for environmental applications, especially bioremediation. The aim of this study was bioremediation and investigation of the absorption kinetics of heavy metals and Rhodamine B from water by biosurfactant produced from Pseudomonas aeruginosa bacteria.

In this study, a biosurfactant-producing bacterium that was isolated and identified as Pseudomonas aeruginosa HAK02 from the Kahrizak waste site in the south of Tehran was used to produce a surface bioactive agent to remove pollutants. Zeta potential test was performed to detect the load of biosurfactant produced and used in bioremediation. The amount of color removal was done by UV device and the removal of heavy metals was done by ICP_AES analysis.

Due to the negative charge of the substance, it was used to remove heavy metals and Rhodamine B cationic dye. Biosurfactant produced with Pseudomonas aeruginosa was able to remove 95% rhodamine B, 43% Cd2+, and 35% Co2+. Examining the kinetic model of absorption showed that better correlation with pseudo-second order kinetic model.

Bioremediation using surfactants to remove heavy metals and dyeing is a fast and environmentally friendly method. This sample is very suitable for the removal of Rhodamine B and has the moderate ability for heavy metals Cd2+ and Co2+.

Some heavy metals such as cadmium and lead have no role in the natural metabolism of aquatic animals and these metals are toxic to living organisms even at low concentrations. This study was conducted to study the effect of body size (total length and total weight) on the accumulation of lead and cadmium in common redfish (Lutjanus lohni) in three regions of Bandar Abbas, Bandar Lengeh and Jask in Hormozgan province. The number of samples in each station was sampled separately. In the laboratory, after bioassay, muscle tissue was separated and lead and cadmium were extracted by chemical digestion and their concentrations were read by atomic absorption spectrometry. The results of the study showed that the concentration of lead and cadmium in the muscle tissue of redfish in three areas of Bandar Jask, Bandar Abbas and Bandar Lengeh with body size (body length and weight) had a negative Pearson correlation coefficient (r) and was significant (p>0.05). The results of tissue analysis of common red fish muscle in the study areas have the highest and lowest concentrations of lead metal equal to 0.2686+0.1 and 0.550+0.1 μg/g and for cadmium metal, respectively. It was shown with 0.021+0.01 and 0.057+0.01 μg/g. The results also show that the Jask port area is significantly different from Bandar Abbas and Bandar Lengeh areas in terms of the amount of lead and cadmium elements in muscle tissue (p>0.05).It can be concluded from the data of this study that in the study areas in the Persian Gulf (Bandar Abbas, Bandar Lengeh and Jask) a very weak relationship between the body size of the studied species has been shown. The trend of accumulation of the studied elements in ordinary redfish has not affected the sex (male or female) and also the contamination of these elements in the present study has been less than the international standards reported.

In recent years, salinity and pollution due to municipal solid waste compost, has caused many problems. The main purpose of this research is to investigate the effect of mixing rose greenhouse waste with urban waste on the quality of produced compost and the chemical and physical properties of the soil after using this fertilizer.

 An experiment in CRD design as factorial was conducted to investigate the effect of Rose greenhouse wastes on quality of compost with two factors consisted of 1) waste type with 2 rates: a) separated and b) unseparated waste) and 2) amendment ratio with 3 rates: a) 100% waste-0% amendment, b) 80% waste-20% amendment and c) 60% waste-40% amendment, with three replications. Then a field experiment based on CRD, with 7 treatment (consisted of soil mixed with six types of produced compost in previous stage and control) and 3 replications was conducted to investigate the effects of produced compost on some characteristics of soil.

Results showed that the separation of wastes at the source, increased compost nitrogen by 2.75 times, cation exchange capacity by 4.14 times, phosphorus by 2.14 times, water holding capacity by 2 times and organic carbon by 69% compared to the non-separation. But reduced available potassium, pH and sodium of the compost. In soil, it also reduced bulk density, salinity, and cadmium and lead concentrations, and increased soil MWD. Adding Rose greenhouse waste in rate of 40%, reduced compost EC by 58% campared to control. It also reduced available sodium and potassium and increased pH of the compost. In soil, reduced bulk density, salinity and concentration of lead and cadmium. Treatment of soil and separated compost with 40% of amendment, increased soil Si by 0.078 unit and soil organic carbon by 32% compared to the control.

Results showed that separation of wastes at the source and adding Rose greenhouse waste can improve physical and chemical properties of compost and soil.

These days, contamination of sediment and water resources to heavy metals, especially cadmium, cause severe human health and other organism’s disorders due to its high toxicity. Remediation of cadmium-contaminated sediments is of particular importance and several studies have been carried out on various remedial techniques. Considering that the remedial actions of sediment are diverse and each of them has its own pros and cons, Choosing the suitable and proper method based on geographical, economical, and social conditions is not only challenging but also plays a key role in implementing a successful remediation action. In this study, multi-criteria decision making model and fuzzy hierarchical analysis were used to find the best approach for restoring polluted sediment. In this regard, important methods and indicators have been determined consisting literature review and experts’ opinions. Based on the Weights determination by FAHP, the cost with 46% of weight, the availability of technology (39%), the potential of Pollutant recovery (9%), and time (6%) were determined as the main indicators of decision-making process. Moreover, by using VIKOR as a multi-criteria decision making model, the best options for cadmium-contaminated sediment were identified. Ranking the options shows that the absorption method by using biological adsorbents (Q=0.002, S=0.274, R=0.205) and electrokinetic (Q=0.005, S=0.271, R=0.214) has been selected as the best possible approaches.

Soil pollution and accumulation of heavy metals such as lead, cadmium, silver and mercury in agricultural products of industrial areas is one of the most important environmental issues that threaten the lives of plants, animals and humans. Harmful effects of these pollutants on living organisms, including disruption of biological activities, adverse effects on plants and humans due to their entry into the food chain have been proven. As well as, oil pollution is one of the most common of pollution in terrestrial and aquatic ecosystems. The development of the petrochemical industry and the non-observance of environmental requirements, have led to the introduction of large amounts of hydrocarbon pollutants into the environment in recent decades.Biomarkers include biological processes, species, or communities of living organisms that are used to assess the quality of the environment and how the environment changes over time. In recent years, the use of biomarkers to identify environmental pollutants, especially heavy metals and petroleum hydrocarbons, has increased. Collembolan arthropods are one of the most important soil decomposers with high species diversity and density, especially in forest ecosystems. These organisms are widely used organisms as biomarkers due to their short life cycle, high density and high susceptibility to various contaminants in terrestrial ecosystems. This research was aimed to identify the collembola fauna in soils contaminated with heavy metals and petroleum hydrocarbons in two industrial areas of Isfahan and to investigate the impact of these contaminants on the diversity and population abundance of these organisms as a biological indicator of soil contamination.

Soil samples were taken from the lands around Isfahan Oil Refinery and the area around Mobarakeh Steel factory, as contaminated areas to petroleum hydrocarbons and heavy metals respectively. Also, a sample of pristine soil (non-contaminated soil) was taken from the test areas as a control. Heavy metals concentration was measured by atomic absorption method and the amount of petroleum hydrocarbons in the samples was measured by Soxhlet method. The terrestrial arthropods were collected using Berlese funnel. To identify the Collembola species, microscopic slides were prepared and identified according to the taxonomic keys.

Diversity of Collembola in contaminated soilsThe results of chemical analysis of soils showed that there were different degrees of contamination with petroleum hydrocarbons and heavy metals including lead, cadmium and nickel in the sampled areas, and the soil of the control area was free of any contamination. The highest concentration of heavy metal in the studied soils was related to cadmium with 21.92 mg/kg and the lowest concentration of nickel was related to 42.85 mg/kg. Sampling was performed to collect collembolan arthropods throughout the year and a total of 11 species of collembola from 6 families and 2 suborders were collected (table 1).As shown in Figure 1a, Istomiella minor, Ceratophysella stercoraria, Hypogastrura sp.1, Entomobrya sp.1 and Onychiurus sp.2 species are more abundant in heavy metal contaminated area than uncontaminated soil (control). Also, Folsomia candida was not found in the soil samples around the steel factory. On the other, the diversity and abundance of Collembola species collected in soils contaminated with petroleum compounds around the oil refinery were similar to soils contaminated with heavy metals (Figure 1-b). In these soils, the highest abundance of collembolan communication is related to Hypogastura sp.1, I. minor and C. stercoraria, respectively. Also, the frequency percentage of F. candida, Pseudosinella sp.2 and Onychurus sp.1 was zero and no samples of these species were collected, which indicates the high sensitivity of these species to petroleum products and hydrocarbon compounds.Sampling was performed to isolate terrestrial Collembola in different seasons of the year. The results showed that these arthropods were active only in spring and summer. In both autumn and winter, no samples of Collembola were collected in either of the two areas contaminated with heavy metals and petroleum compounds. The interesting point in this study was that no significant difference was observed between the collembola population of contaminated soils and non-contaminated soils in spring. However, in summer, the population of non-contaminated soils was much higher than soils contaminated with heavy metals and petroleum compounds and a significant difference (p ≥ 0.05) was observed between them.As shown in Figure 2, the frequency of Hypogastrura sp.1 and Pseudosinella octoppuncta species in oil-contaminated soils is higher than their frequency in heavy metal-contaminated soils. The frequency of Hypogastrura sp.1 in oil-contaminated soils (40%) was significantly higher (p ≥ 0.05) than the frequency of this species in heavy metal-contaminated soils (12.5%) (Fig. 2). Therefore, Hypogastrura sp.1 is the most resistant species to petroleum products among the species studied in this research. Also, the I. minor showed the highest frequency (28.13%) in soils contaminated with heavy metals. Therefore, this species is the most resistant to heavy metals among the studied species.

The main purpose of this study was to compare the Collembola fauna in soils contaminated with heavy metals and petroleum compounds as a biological indicator in the some industrial regions of Isfahan. In this study, a total of 11 species belonging to 6 families from 2 suborders of Collembola were collected. F. candida was not isolated from contaminated soils with heavy metals, while this species has acceptable population abundance in pristine and non-polluted soils. These results indicate the high sensitivity of this species to heavy metals. Lead and cadmium have very destructive effects on the reproduction of F. candida and cause a significant reduction in reproduction of this species. According to Sandifer and Hopkin (1996), when the cadmium concentration in the soil reaches to 1.2 μg / kg, the reproduction of Folsomia species decreases dramatically. The soils studied in this study were also highly contaminated with cadmium and the concentration of this element in some samples was 21.92 mg / kg, which is several hundred times than the global pollution standard, this is why F. candida was not collected from these soils. Also the species F. candida, Pseudosinella sp.2 and Onchiusus sp.1 were not collected from soils contaminated with petroleum hydrocarbons. Studies by Fountain and Hopkin (2005) show the very high susceptibility of these species, especially F. candida, to chemical contaminants and introduce this species as a reliable biomarker against soil pollutants. In contrast, populations of some species such as I. minor, C. stercoraria and Hypogastrura sp.1 was higher in soils contaminated with heavy metals and petroleum compounds than in non-contaminated soils. These results may be due to the fact that some species of Collembola have the ability to detoxify and remove of poisonous chemicals from their bodies with repeated molting. In Conclusion, the genus Folsomia is one of the most well-known soil collembolan which whose species, due to non-migratory living and its low dependence on sub-habitats, make them important organisms for determining air and soil quality and tracking pollution. Among the identified species of this genus, F. candida has been considered as an ecological criterion and biological indicator of soil. In this study, this species was not isolated in soils contaminated with heavy metals and petroleum compounds and was introduced as the most sensitive species to chemicals. On the other hand, I. minor with a population frequency of about 25% in the studied soils was introduced as the most resistant species to chemical compounds.

The aim of this experimental study was to investigate the effect of cadmium (Cd) on the expression of matrix metalloproteinase 9 (MMP9) and tissue inhibitor of metalloproteinase 2 (TIMP2) genes and to investigate the protective role of N-acetylcysteine ​​(NAC) on cadmium toxicity in the liver tissue of rats. In this study, male Wistar rats were randomly divided into 5 groups: control (G1), single dose of cadmium (80 mg/kg) (G2), continuous dose of cadmium (2.5 mg/kg) (G3), Single dose of cadmium (80 mg/kg) and continuous dose of NAC (50 mg/kg) (G4) and continuous dose of cadmium (2.5 mg/kg) and continuous dose of NAC (50 mg/kg) (G5). Hematoxylin and eosin (H&E) staining was used to study histopathological changes. Cadmium concentration was measured by graphite furnace spectroscopy in the liver samples. The expression of MMP9 and TIMP2 genes was evaluated using RT-PCR. Cadmium exposure, especially at continuous dose, was associated with severe tissue damage and increased inflammatory cells in the liver. The mean tissue of cadmium concentration was significantly increased by 27% (P<0.05) in the G2 group and 60% (P<0.01) in G3 group. NAC treatment in G4 group (P<0.01) and G5 group (P<0.01) significantly reduced the tissue concentration of cadmium. Cadmium also increased the expression of MMP9 gene (P<0.001) and TIMP2 gene (P<0.01) in G2 and G3 groups. NAC treatment significantly reversed these effects. Our results suggested that NAC protects liver cells by decreasing the accumulation of cadmium and reducing the expression of TIMP2 and MMP9 genes.

Declining water resources caused usage of recycled water that sometimes not purified well.  The growing population and consequently increasing water demand, along with a shortage of available freshwater resources have inevitably led to the use of unconventional water resources. Irrigation lands with urban wastewater requires quality and quantity control for achieving food security. Therefore, the present study was conducted to investigate the effects of irrigation with urban wastewater on the concentration of Nickel and Cadmium in soils and their effects on plant, root, shoot, and functional characteristics of wheat.

  Field sampling was carried out at random from a depth of 0 to 20 cm. Wheat samples were taken at harvest from a 1-meter by 1-meter area. A total of 20 samples for Cadmium metal and 20 samples of Nickel metal were taken.

The results showed that the average concentration of Cadmium and Nickel was 10.6 and 49.43 kg, respectively, which resulted in an accumulation in various parts of the wheat plant. Increasing the concentration of Cadmium and Nickel in the soil increases the accumulation in the root, upper parts, and wheat seeds. Also, increasing the concentration of Cadmium and Nickel in the soil decreases the dry weight of the root, the shoot, and the weight of the thousand seed. However, there was no significant effect on two traits, number of grains per spike and number of spikes per square meter. The effect of Cadmium concentration was higher than that of Nickel.

Increasing 1 mg of soil Cadmium caused increasing, 0.81, 0.56, 0.6 mg Cadmium in root, upper parts and seed. For Nickel increasing the soil concentrations caused 0.29, 0.29, 0.11 mg in root, upper parts and seed.

Nowadays, the entry of effluents containing heavy metals, which are mostly the result of industrial activities, into the ecosystem of aquatic organisms and, consequently, the accumulation of these metals in the body of aquatic animals is a major concern which is aquatic life and biodiversity of aquatic ecosystems affects. The Caspian Sea is one of the most important aquatic ecosystems that the entry of various pollutants has caused serious damage to these ecosystems. The Caspian seal, the only mammal in the Caspian Sea, is endangered. The aim of this study was to measure cadmium in some Caspian seal tissues on the southeastern shores of the Caspian Sea.

In the present study, ten corpses of Caspian seals were collected and inseminated from the coast of the Caspian Sea. Liver, kidney and fat samples were digested to measure cadmium content. The concentration of cadmium was measured by a mass spectrometer machine.

The highest concentration of cadmium in kidney tissues was 13.59±0.73 μg / kg which higher than the liver with mean of 1.6±0.16 μg / kg and greater than mean of 0.07±0.02 fat. The concentration of cadmium in male and female tissues was investigated and there was no significant relationship between cadmium metal concentration and sex of seals. The presence of significant amounts of cadmium in 90% of the samples shows the high pollution of the Caspian Sea with heavy metals, including cadmium metal, which is even toxic at very low levels.

Considering the significant decrease in the population of the Caspian seals in recent years and the persistence of heavy metals, the use of these toxic metals in the industry has to be reduced, as well as the sources of the input of these pollutants to the Caspian Sea to prevent the entry of these toxic metals into the Caspian Sea or before filtration proceed. This will reduce the pollution of the Caspian Sea and helps the health of the aquatic environment.

Pollution caused by petroleum compounds (PAHs) and heavy metals due to their properties Cumulative and High toxicity Causing major environmental problems. These compounds, although detected in air and water, are the final and main receptive soil. Soil washing process using surfactants is a high-performance physicochemical technology for the removal of phenanthrene and cadmium from the soil environment and transferring them to the aqueous phase.

In this study, the efficiency of the process with the BBD method, with RSM, was designed to optimizing parameters such as surfactant concentration in the range 1000,1500 and 2000 mg/L, washing Time 2,12, 24 hours with L/S 10, 20 and 30 ml/g. To contaminated soil samples were added high concentrations Phenanthrene (500 mg/kg) and Cadmium (80 mg/kg), surfactant Tween 80 and EDTA.

The final concentration of Phenanthrene and Cadmium was measured by HPLC and atomic absorption spectrometry (ASS). The results showed that the efficiency of the process under optimal conditions for the separation of 76% Phenanthrene and 81% Cadmium in separate concentrations of Tween 80 and EDTA was reached in 2000 mg/L, L/S 30 ml/g (v/w), washing time 2 hours. Surfactant concentration was the most influential variable in this regard (p< 0.0001).

The separation of phenanthrene and Cadmium from the soil through the help of surfactants is an effective technique for remediation of contaminated soil.

In Asyabk Zarandieh town, located in Central Province, sewage discharge is released within 20 meter from arable land of wheat. This research is to determine the concentration of lead and cadmium in contaminated soils, sewage, irrigation water and wheat grown in the area around the town Asyabk and the correlation between them and assessing the potential risks arising from the consumption of wheat grown in the region.

The sampling of drainage and irrigation water, surface soil, wheat was done by random. Lead and cadmium concentrations in all samples were measured. The results were statistically analyzed. Also the zonation map was prepared by GIS software.

Concentration of lead and cadmium in soil samples obtained less than limit permissible but concentration of Cd and pb in wheat obtained exceeded the national standard of Iran. Based on the correlation results between the amount of   lead and cadmium in the wheat samples, soil and irrigation water, there was a strong positive correlation. While there was no relationship between the concentrations of these elements in the wheat samples and the amount of metals in the wastewater samples.

The lack of correlation between the concentration of lead and cadmium in wheat and wastewater showed sewage spread in the region unaffected in the process of increasing the concentration of lead and cadmium in wheat. The main reason of increase Pb and Cd in wheat samples is related to irrigation water (well water). The risk index (HQ) of wheat consumption in the region obtained smaller than 1 for lead and cadmium.

In the present study, the electrochemical coagulation process (electrocoagulation) in the mining industry was investigated in order to remove one of the heavy metals, cadmium, from the leaching solution of the copper processing plant. The response surface methodology (RSM) was used to optimize the factors affecting the removal of this metal in the electrocoagulation process. For this purpose, Behnken Box Designv(BBD)  was used to optimize the experiments. The effects of three independent parameters such as pH (X1), electrolysis time (X2), current density (X3) were investigated in order to investigate the removal of cadmium from the leaching solution. The quadratic model was used to respond to the cadmium removal efficiency. The most important independent variables and the interaction between them were evaluated using ANOVA test. This study showed that the optimal operating conditions for cadmium removal are 96.96% at initial pH: 6.83, electrolysis time: 116 min and current density: 69.262 A/m2. The results showed that the ability of electrocoagulation process can be considered as a reliable method to remove cadmium from industrial effluents, especially in mineral processing plants.

Although heavy metals naturally occur in the aquatic environment, but their level elevating by human activities. These contaminants concentrate in the aquatic organisms and their concentrations increase throughout the food chain. The presence of heavy metals in fish is important to humans because of food consumption. Therefore, in this study, 30 Atherina boyeri were collected from Anzali International Wetland in the summer of 2013 and the concentrations of zinc (Zn) and cadmium (Cd) in their muscle tissues were determined using atomic absorption spectrometry. The results showed there was a significant difference between the mean concentrations (µg/g) of Cd (0.08± 0.035) and Zn (9.27±1.24) in the muscle tissue of A. boyeri (p < 0.05). Target hazard quotient levels for each metal as well as TTHQ were lower than one, indicating that consumers would not experience health risks. In general, comparing the concentrations of Zn and Cd with international standards indicated that the levels of these metals were lower than the standards. Daily and weekly intake of Zn and Cd by the consumption of A. boyeri were lower than the acceptable intake recommended by the JECFA. In stand of Zn and Cd, adults can consume 2.27 and 0.8 kg/day and children 0.47 and 0.16 kg/day, respectively, without causing any non-carcinogenic health effects. In general, there appears to be little risk of exposure to metals associated with the consumption of A. boyeri for consumers.

The contamination of ecosystems with heavy metals is an important issue in current world. Removal of heavy metals from contaminated sites using microorganisms is a cheaper alternative to chemical technologies. The aim of present study was isolation and characterization of Cadmium resistant bacteria, determination of Minimum Inhibitory Concentration (MIC) and bio removal potential of the isolates.

Isolation of Cadmium resistant bacteria was carried out by enrichment method by medium supplemented with Cadmium chloride. The minimum inhibitory concentration of Cd2+ was determined by the agar plate dilution method and the Cadmium removal evaluated by atomic absorption spectroscopy. Identification was carried out in accordance with Bergey's Manual of Systematic Bacteriology and phylogenetic analysis was performed based on 16S rRNA gene sequences.

A total of 40 Cadmium resistant strains were isolated from Salour River in Islamshahr. The results showed that bacterial strain ST1 isolated from sediments was highly resistant to Cadmium. The MIC of Cd2+ for selected isolate was 6 mM. The isolate was able to remove 65.2% of Cadmium at Cadmium concentration of 1 mM. Phylogenetic analysis showed that ST1 belongs to the genus Proteus with 99% similarity to Proteus mirabilis then designated as Proteus sp. HM_AF12. The strain had a wide pH tolerance of 5.5–9.0, and salt tolerance was up to 7.5% NaCl.

The results implied that Proteus sp. HM_AF12 can be a low cost and environmental friendly bio sorbent that may have important application in Cd2+removal from polluted environment.