samaneh habibi; Mahmoud Behrouzi; ahmad Nohegar
Abstract
Introduction: Emissions of particulate matter from car exhaust, tire wear, engine lubricants and street fence wear contain heavy metals which is dangerous for urban ecosystem; However, most of the particles are deposited on the canopy and soil of plant which absorbed by the plant. Pollution-resistant ...
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Introduction: Emissions of particulate matter from car exhaust, tire wear, engine lubricants and street fence wear contain heavy metals which is dangerous for urban ecosystem; However, most of the particles are deposited on the canopy and soil of plant which absorbed by the plant. Pollution-resistant species with 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 leaves and soil of tree species in Bandar Abbas were measured and evaluated. Also the species with the highest potential for adsorption of heavy metals were identified.Materials and methods: In order to achieve the research approach, at 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 non-polluted environment outside the city (control), and sampled from the surface soil and leaves of these species, and after preparing and digesting the samples, the concentration of heavy metals (cadmium, manganese, zinc and lead) emitted from urban traffic, were 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.Results and discussion: 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 Conocarpus, Azadirachta indica and Prosopis juliflora, respectively. Spatially, the highest concentration of heavy metals in the sampling points was related to Imam Hossein street, which has an east-west extension and passes through the north of Bandar Abbas and the north-south streets of the city are connected to it; However, the minimum concentration of heavy metals was observed in the Persian Gulf streets. The concentrations of Mn and Pb in the soil of plant species were different and their differences were significant at 95% level, but concentration of Cd and Zn wasn't different in the soil of tree species. in Pb, Mn and Zn concentrations weren't differences in the shoots of the studied tree species and their differences were not significant at 95% level; However, the concentration of Cd in the shoots of the species was different and the difference between the species was significant at 95% level. There was a significantly 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 field was significantly different at 95%. The pattern of 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 has the highest adsorption potential of heavy metals and the lowest adsorption potential was observed in Prosopis juliflora. In the spatial distribution of this index, Imam Hossein street and the streets that originate from it, have the highest index of bioaccumulation of heavy metals.Conclusion: Conocarpus, by absorbing pollutants from urban traffic, purifies the polluted air of Bandar Abbas; but 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 very weak. Therefore, Conocarpus despite their resistance to drought and heat, have a high potential in purifying urban pollution, can replace Prosopis juliflora.
somayeh moharami; mahdi Sadeghi Pour Marvi; Rahman Sharifi
Abstract
Introduction: 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 ...
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Introduction: 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.Material and Methods: 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. Results and discussion: 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.Conclusion: 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.
Sara Abdollahi; Seyed Mohammad Hossein Hosseini; Reyhane Dehghan
Abstract
Introduction: Monitoring the quality of groundwater around the landfill is very important for environmental health. Due to the increase in the population and their living standards and technological advances, the amount of solid wastes from human and industrial activities are increasing. The aim of this ...
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Introduction: Monitoring the quality of groundwater around the landfill is very important for environmental health. Due to the increase in the population and their living standards and technological advances, the amount of solid wastes from human and industrial activities are increasing. The aim of this study was to investigate the amount of heavy metals e.g. lead, cadmium, copper, and zinc in water wells near Azadshahr (in Golestan province) Landfill. Material and methods: In this research, to investigate the concentration of heavy metals in groundwater resources around the landfill site of Azadshahr city, sampling of water was carried out from seven deep wells around the landfill site in spring and summer of 2016. Sampling was carried out in accordance with standard methods. Samples were immediately transferred to the water and wastewater laboratory of the School of Public Health in Gorgan University of Medical Sciences, in glass bottles surrounded by ice. After preparation of the standard solution of each heavy element, the concentration of lead, cadmium, copper and zinc elements was read in micrograms per liter using the metrological polarogram. After determining the concentration of the above parameters, statistical analysis and drawing of the corresponding graphs were performed by Excel and SPSS software to analyze the results and compare the concentrations in downstream and upstream. Results and discussion: The results showed that the amount of lead in the wells around the landfill was 3.1± 2.1 μg/l and cadmium content was 1.1± 0.37 μg/l, which was not statistically different between spring and summer. According to the standard of 1053 countries, the maximum lead and cadmium levels for drinking water are 10 and 3 μg.l, respectively, which demonstrates that our calculations are within the allowable range. The copper content of wells around landfill was 5.22 ± 5.21 μg/l and there was no statistical difference between spring and summer. Also, according to the standard of 1053 countries and WHO, the maximum allowable amount of copper for drinking water is 2 and 1 mg.l, respectively. So, the copper content of the studied water was within the allowable range. Although there was no statistically significant difference between upstream and downstream copper, its content in downstream wells was about 1.27 times more than that of upstream wells. This may be due to the organic matter penetration into the groundwater. The amount of zink in the wells around the landfill was 23.1 ± 5.31 μg/l, which was not statistically different between spring and summer. According to the standard of 1053 countries, the maximum allowable amount of zink for drinking water is 3 mg/l. Although there was no statistically significant difference between the upstream and downstream waters, its value in the downstream wells was about 1.16 times higher than that of the upstream wells, which can still be due to infiltration organic substances leach into the groundwater. Conclusion: The results of this study showed that the concentration of chemical parameters of water wells around the landfill was below the drinking water standard of the country. Also, the concentration of all elements in downstream wells was calculated more than the upstream wells. Since the Azadshahr is an agricultural area, the groundwater pollution that is used in agriculture can transfer heavy metals to humans through agricultural products and, therefore, strict measures should be taken to prevent groundwater contamination in the area.
Masoud Motamedi; Azita Behbahaninia; Forugh Farsad
Abstract
Introduction: One of the major contaminants of surface water resources are heavy metals. Heavy metals are natural components of the earth's crust, but human activities, and geochemistry and biochemical cycles may disturb their balance and release them into the environment. Release of pollutants into ...
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Introduction: One of the major contaminants of surface water resources are heavy metals. Heavy metals are natural components of the earth's crust, but human activities, and geochemistry and biochemical cycles may disturb their balance and release them into the environment. Release of pollutants into the aquatic environment will affect both water body and sediments, mostly sediments because they are less dynamic. Therefore, the concentration of heavy metals in river bed sediments reveals the pollution more intensity or its history far better than the water body. This research was carried out to determine the concentration of heavy metals in water and sediments of Shahrud River with the aim of determining the condition of heavy metal contamination and their sources in the study area. Material and methods: The Shahrud River is one of the main branches of the Sefid-Rud River which originates from the central Alborz Mountains, and is the only river in the southern part of the Alborz, which flows into the Caspian Sea. In this study, the concentration of heavy metals namely lead, cadmium, and arsenic in the Shahrud River and sediments in Lowshan city has been studied. Accordingly, the physiochemical properties of water and sediments were investigated in the first stage of sampling. Moreover, five sampling stations were determined and four sampling stages (autumn and winter 1395- spring and summer 1396) were carried out. Totally, 40 samples of water and sediments were taken along the river and the concentration of the considered parameters was measured. Results and discussion: The results demonstrated that COD was lower that the EPA standard in all sampling stations except station 5. Furthermore, regarding the IRWQI (SC) water quality index, all stations were ranked from average to bad classes of quality. The BOD in all sampling stations was higher than the EPA standard and according to the IRWQI (SC) index, all stations were ranked "semi-bad" to "bad" class of quality. The concentrations of lead, cadmium, and arsenic in water samples were compared with the guidelines of the Iranian National Standards Organization, Department of Environment, WHO and EPA. Moreover, it was ranked based on IRWQI (ST). Our results proved that the mean concentration of lead at all stations was lower than the standard except stations 3 and 4. The concentration of these heavy metals was relatively ranked into moderate to good classes. The average concentration of cadmium was lower than the standard at all stations except stations 1 and 3, and in regard to the descriptive index, it is categorized into good to fairly bad, respectively. In addition, the average concentration of arsenic was lower than the standard values at all stations. Also, it was classified as good, regarding the descriptive index. The concentration of heavy metals in sediment samples at sampling stations showed that the concentration of lead at all stations was lower than TEL values in NOAA and SQGs standards, and the concentration of cadmium at all stations was higher than the PEL values. The concentration of arsenic at all sampling stations was lower than the PEL values and at stations 2 and 5 was higher than TEL values. To quantitatively assess the sediments, contamination factors (Cf), degree of contamination (mCd), molar accumulation index (Igeo) and ecological risk assessment (Ri) were considered. Results showed high manmade contamination of cadmium and significant ecological risk in sediments of the study area. The use of phosphorus fertilizers in fields and gardens as well as the location of the cement factory, which is near the river, are the main causes of cadmium pollution in the study area. Additionally, the high levels of BOD and COD in water indicated high levels of organic contaminants, due to industrial and traditional olive processing centers, olive oil mills and poultry slaughterhouses in the study area. Conclusion: The study area was contaminated with heavy metals, which is mainly caused by the high concentration of cadmium in sediments of Shahrud River. It is essential to mention that its negative impact on humans, organisms and urban environment in Lowshan city and downstream of the Shahrud river is undeniable.
Somayeh Bakhtiari; Sina Choghadi
Volume 15, Issue 4 , January 2018, , Pages 45-64
Abstract
Introduction:
In recent years, zero-valent iron has drawn a great attention in wastewater treatment and ground water remediation. It can effectively remove priority water contaminants, but there are some disadvantages in the use of nZVI particles, such as high tendency to agglomerate, lack of stability, ...
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Introduction:
In recent years, zero-valent iron has drawn a great attention in wastewater treatment and ground water remediation. It can effectively remove priority water contaminants, but there are some disadvantages in the use of nZVI particles, such as high tendency to agglomerate, lack of stability, secondary iron pollution, separation and recovery of the fine nZVI particles after utilization. Using supporting material for nZVI is a promising way to solve these problems. Clay minerals as abundant natural resources are appropriate candidates to act as supporting materials. In this study, the use of fibrous clays-supported nZVI composite for the remediation of contaminated aqueous solutions will be discussed.
Materials and methods:
Sepiolite and Palygorskite- nano zero valent iron composites were made using green tea extract. In order to determine sorption capacity of nZVI - sepiolite and palygorskite composites for phosphorous, cadmium and nickle based on isotherm models, different concentrations of these ions were equilibrated with the composites in 1% suspensions for 24 h. After adsorption, the supernatant liquids were filtered and the residual pollutants concentrations were determined.
Results and discussion:
Results showed that Langmuir and Freundlich models were the best models describing p sorption on both composites. The estimated maximum adsorption capacity of the Sep-nZVI and Pal-nZVI using the Langmuir model (qmax) was 11.38 mg P/g and 8.57 mg P/g . The cadmium adsorption data of both sorbents best fitted to the Langmuir, Fruendlich and dubinin–radushkevich models. Results clearly demonstrateD the much higher Cd sorption potential of sepiolite compared to palygorskite. Sorption capacities (qmax) of Sepiolite- nZVI and palygorskite nZVI composite for Ni were 11.14 and 32.3 mgr/gr, respectively. The Ni sorption affinity (KL) of palygorskite nZVI was also greater than that of Sepiolite- nZVI. The favorability of a sorption system can be predicted by the constant separation factor RL. In the current study, RL values for palygorskite nZVI and Sepiolite- nZVI were greater than zero and less than unity indicating favorable sorption of P, Cd and Ni onto the two composites.
Conclusion:
Fibrous clays – nano zero valent iron can be used as efficient sorbents for phosphorus removal from urban wastewater and removal of cadmium and nickle from industrial wastewater due to their friendly environmental nature and high performance toward pollutants removal.
Zahra Soleimannejad; Ahmad Abdolzadeh; Hamidreza Sadeghipour
Volume 15, Issue 3 , October 2017, , Pages 173-186
Abstract
Introduction:
Heavy metals are one of the most important environmental pollutants that have been highly regarded in recent decades. The accumulation of elements in the soil, especially in agricultural land, has been gradual and the concentration of heavy elements can reach to the level that threaten ...
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Introduction:
Heavy metals are one of the most important environmental pollutants that have been highly regarded in recent decades. The accumulation of elements in the soil, especially in agricultural land, has been gradual and the concentration of heavy elements can reach to the level that threaten human food security. Among heavy metals, cadmium is considered as one of the most dangerous elements due to its high mobility in biological systems, high toxicity, high solubility in water and rapid absorption by the root system of many plant species. Therefore, in this research, the growth, accumulation and phytoremediation potential of cadmium in two species Ethiopian mustard (Brassica carinata) and Hindi mustard (Brassica juncea) is studied.
Materials and methods:
Plants in contaminated soils with concentrations of 0, 75 and 150 mg kg-1 of cadmium were grown in greenhouse and harvested after 7 weeks to measure some growth characteristics.Results and discussion: The results showed that cadmium treatments had no significant effect on growth traits and chlorophyll content of two plant in compared with control. Both plant showed high stress tolerance index and low stress tolerance to cadmium. With increasing cadmium concentration in soil, cadmium concentrations in root and shoot of both plants B. carinata and B. juncea significantly increased. The translocation factor of B. juncea was about 70% higher than B. carinata.The highest translocation factor was observed in the treatment of 75 mg kg-1 of cadmium in B. juncea.
Conclusion:
The comparison of two plants of B. carinata and B. juncea showed that both species are able to tolerate and accumulate cadmium, but translocation factor, uptake and accumulation of cadmium in plant B. juncea was more than B. carinata. So it seems B. juncea had better performance for use in phytoremediation process.
Donya Mottaghi; Mehdi Homaee; Rasoul Rahnemaie
Volume 13, Issue 2 , July 2015, , Pages 75-88
Abstract
Soil contamination is one of the most recent and important environmental challenges worldwide. The so-called phytoremediation is one of the reclamation technologies used to decontaminate polluted soils. Application of some chelate agents can increase the efficiency of phytoremediation. However, this ...
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Soil contamination is one of the most recent and important environmental challenges worldwide. The so-called phytoremediation is one of the reclamation technologies used to decontaminate polluted soils. Application of some chelate agents can increase the efficiency of phytoremediation. However, this technology has not been evaluated for decontamination of heavy metals under multicropping system. The objective of this study was to evaluate the phytoremediation capability of cress and radish, as a mixed-culture by using some natural and synthetic chelates in Cd-contaminated soils. Consequently, a factorial experiment in a completely randomized design with 20 treatments and three replications was conducted. The experimental factors were consisted of five levels of cadmium (0, 3, 10, 25, 50 mg Cd kg-1 soil, added as Cd(NO3)2, EDTA and NTA chelates, and chelate concentrations of 1 and 2.5 mmol kg-1 soil. Results indicated that the Cd phytoextraction potential in multicropping culture is higher than the single-cropping system. Phytoextraction of cadmium from contaminated soils for both cress and radish plants, in EDTA2.5 and Cd50 treatments was 7.7 and 5.7 kg Cd ha-1 in multicropping system and was 4 and 5.4 kg Cd ha-1 in the single-cropping system. Furthermore, radish could phytoextract more cadmium than cress from the contaminated soils. The results further indicated that EDTA could enhance more Cd phytoextraction than NTA and can better assist to transfer cadmium from roots to shoots.
Marziyeh Sarmadi; Mahbubeh Irani; Francoise Bernard
Volume 8, Issue 3 , April 2011
Abstract
Phytoremediation is a technology for extracting or inactivating pollutants. In this study, the ability of Glycyrrhiza glabra (var. glabra and var. glandulifera) for phytoremediation, tolerance to cadmium and accumulation of it within plant was investigated. The seeds of G. glabra var. glabra and var. ...
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Phytoremediation is a technology for extracting or inactivating pollutants. In this study, the ability of Glycyrrhiza glabra (var. glabra and var. glandulifera) for phytoremediation, tolerance to cadmium and accumulation of it within plant was investigated. The seeds of G. glabra var. glabra and var. glandulifera were cultured in pots and were watered with distilled water (control) and 100 & 200 μM cadmium chloride solution (treatment). Then the plants were analyzed after 20 days. Cadmium causes a decrease in seed germination. The dry weight of root in both variety and the length of root in var. glandulifera decreases significantly in proportion to the control group. Whereas, the dry and fresh weight of shoot, the length of shoot and the fresh weight of root in both variety and the length of root in var. glabra didn’t change significantly. No metal-toxicity symptoms such as burning and redness of the tissue were observed in Cd treatment. Plants containing more than 100 mg.kg-1 of Cd in dry shoot tissues should be considered as hyperaccumulators of this metal. Cd concentrations in the aerial organs of var. glabraand var. glandulifera were 116.9-147.9 and 116/0-119.5 mg.kg-1 (on a dry weight basis), respectively. We conclude that plantlet of G. glabra is a hyperaccumulator of Cd. G. glabra and so shows promise in the phytoremediation of Cd from polluted sites.
