Soil science
M. Rafati; M. Malekzadeh; M. Firoozi
Abstract
Intruduction
Increasing industrial activities with the production of pollutants, including heavy metals, is one of the serious problems of modern communities, which has led to their accumulation in the environment. Heavy metals are also one of the important pollutants in landfill leachate. Plants and ...
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Intruduction
Increasing industrial activities with the production of pollutants, including heavy metals, is one of the serious problems of modern communities, which has led to their accumulation in the environment. Heavy metals are also one of the important pollutants in landfill leachate. Plants and soil near the landfill may be contaminated by the leachate. Landfilling is the oldest method of solid waste disposal which can be a threat to the environment and health. Due to its easy operation and cost-effective, landfill is the most widely used method of municipal solid waste disposal in the world. Pollution cleaning technologies to reduce the harmful effects in the locations contaminated with heavy metals can be done by physical, chemical and biological methods. Phytoremediation, as a biological method, uses the green plants to extract, sequester, and detoxify pollutants. This method is a low-cost technique, environmentally friendly, and due to the non-production of by-products, is non-destructive for natural ecosystems. Considering the high moisture of wastes in Iran and their potential to produce leachate, as well as the possibility of contamination of water and soil in the landfill, especially with heavy metals, this study was conducted with the aim of evaluating the accumulation of lead (Pb) and cadmium (Cd) heavy metals in the soil, shoots and roots of artiplex (Atriplex sp.) and oleander (Nerium olander) plants in Aradkooh landfill of Tehran.
Materials and Methods
This study was conducted in Aradkooh landfill which is located in the south of Tehran in the Kahrizak region. About 5200 tons of municipal solid waste were sent to this landfill every day. A part of the solid waste in Aradkoh was placed in various processes to energy and compost, and about 2500 tons of the solid waste was landfilled. According to previous reports, it is estimated that 250 cubic meters of leachate are produced daily in the Aradkoh landfill. In the studied landfill, there is an atriplex plant in four areas and a hand-planted oleander in one area. Ten samples of soil, root, and shoot, totaling 120 total were randomly selected from each growing area of the atriplex plant. Oleander shoots and soil were also tested from 10 different plants for a total of 40 samples. Then the levels of Cd and Pb in the soil, roots, and shoots were assessed. In this study, the outcomes were analyzed employing four key indices: the bioconcentration factor (BCF), the translocation factor (TF), the pollution index (PI), and PINemerow. The BCF and TF indices were employed to assess the phytoextraction and phytostabilization capabilities of plants, while the PI and PINemerow methods were used to pinpoint the most environmentally hazardous heavy metal in the soil.Results and Discussion
According to the results, the concentration of Pb and Cd in shoots of atriplex area 2 (with an average of 19.7 and 5.75 mg/kg, respectively) were significantly higher than in other areas, while the concentration of these metals in root of oleander (with an average of 8.17 and 1.06 for Pb and Cd, respectively) were higher than the shoot. The amount of Pb element in soil of the oleander plant (with an average of 35.13 mg/kg) and Cd in soil of the atriplex area 2 (with an average of 3.78 mg/kg) were significantly higher than other areas. Additionally, the levels of heavy metals in the soil of two plants were higher than the Nemerow index, which indicated high levels of pollution in the sampling areas, but still below the safe levels that was set by national standards (3.9 and 300 mg/kg for Cd and Pb respectively) and the World Health Organization (5 and 40 mg/kg for Cd and Pb, respectively). In addition, bioaccumulation factor of shoot in all growth atriplex areas for Pb and Cd (with an average of 1.44 and 1.3, respectively) were higher than 1.0 while, the root bioaccumulation factors of this plant in any of the growth areas, were not higher than 1.0. In the case of oleander, the shoot and root bioconcentration factors for Pb and Cd were not reported more than one.
Conclusion
In general, it appears that atriplex, a native plant in the Aradkooh landfill, exhibits superior capabilities for absorbing heavy elements compared to oleander. Therefore, atriplex seems well-suited for the extraction of Pb and Cd from the soil, as it can accumulate these metals in its shoots. In contrast, oleander is not well-suited for phytostabilization or phytoextraction of these elements, as it exhibits limited ability to accumulate these heavy metals in its roots and shoots. Consequently, atriplex can be a valuable choice as a resilient species for phytoremediation projects in landfills and areas near mines. It is worth noting that the Pb content in the soil is higher than that of Cd. Although both metals fall within the permissible limits of national and WHO standards, the soil in the Aradkooh landfill is considered to be significantly polluted based on the Nemerow index.
Soil science
Naghshineh Yari Nilavareh; Ali Beheshti Ale Agha; Mahin Karami; Marzieh Sadeghi
Abstract
IntroductionCrude oil is a complex combination of many hydrocarbon and non-hydrocarbon compounds, including heavy metals, which affect the physical and chemical properties of the soil, cause the soil particles to stick and connect and then cause the soil to become stiff and impenetrable. Contamination ...
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IntroductionCrude oil is a complex combination of many hydrocarbon and non-hydrocarbon compounds, including heavy metals, which affect the physical and chemical properties of the soil, cause the soil particles to stick and connect and then cause the soil to become stiff and impenetrable. Contamination of soil with petroleum hydrocarbons is a significant environmental problem, which has received remarkable attention in recent decades. Petroleum hydrocarbons are resistant and hazardous pollutants. Some petroleum hydrocarbons such as benzene are mutagenic and carcinogenic materials for humans. There are many physical and chemical methods to remediate oil-contaminated soils. Phytoremediation is a relatively new technology for refining contaminated soils in which resistant plants are used to remove or reduce the concentration of inorganic, radioactive, and organic pollutants, especially petroleum compounds, from the environment.Materials and MethodsSufficient amounts of about 50 kg of soil contaminated with petroleum hydrocarbons were collected from regions (0-30 cm soil depth) adjacent to the oil wells west of Kermanshah province. Uncontaminated soil samples were also taken from sites at the lowest distance to the contaminated sites. The aim of this study was to compare the efficiency of different plants to remove total petroleum hydrocarbons from oilfield soils. In this study, after determining the total amount of petroleum hydrocarbons, the contaminated and uncontaminated soils were mixed in 4 treatments with different weight ratios (0, 10, 25, and 35%). This experiment was established as completely randomized design with 3 replications for 6 different plants (Barley, Grass, Alfalfa, Hemp, Camelina, and Vicia ervilia). One treatment without plant was considered to remove soil matrix effects on petroleum hydrocarbon concentrations. Plants were harvested at the end of their growing season (90-120 days). Soils and plant samples from the experimental pots were analyzed for their important properties (including some physiological characteristics of the plants, as well as the percentage of reduced petroleum hydrocarbons in the soils). The gravimetric method was used to determine the concentration of petroleum hydrocarbons in the soil. After measuring the properties of the soil and plant, the normality of the data was checked by the Anderson–Darling test, and the homogeneity of the variance of the treatments was checked by using Levene's test. Analysis of data variance was done using ANOVA and average data comparison was done using LSD test at 5 and 1 percent probability levels (SAS 9.4 and SPSS 26).Results and DiscussionIn general, the growth of most plants showed a decreasing trend in proportion to the increase in soil pollution levels. However, the growth decline rates of different plants were not similar. Camelina was very sensitive to oil pollution and the plant could not tolerate pollution even at 10% level. After camelina, alfalfa was highly sensitive to oil pollution. The highest dry weight of the aerial parts of the hemp plant in the soil without oil contamination was observed at the rate of 111.22 grams in the pot. The leaf area of all studied plants in contaminated soils decreased compared to the control treatment (without contamination) so with the increase in the percentage of contamination, the leaf area of the plants was significantly reduced. The highest amount of leaf surface was observed in unpolluted soil and in the hemp plant. Except for the Camelina plant, which was completely destroyed at different levels of pollution, the rest of the plants showed a noticeable decrease in growth. The total petroleum hydrocarbons in soil were measured again 120 days after the start of cultivation, and its difference with the total amount of petroleum hydrocarbons at the beginning of cultivation was determined as the reduction of petroleum hydrocarbons and reported as a percentage. According to the mean comparison results, the percentage of reduced petroleum hydrocarbons was not significantly different among cultivated and non-cultivated treatments, although, it was significantly affected by soil pollution levels. Since all the studied soils contained natural bacteria and were not sterilized, the eliminated part of petroleum hydrocarbons is probably decomposed and removed by native bacteria in the soils. Therefore, the strengthening of native bacteria in these soils may increase the decomposition and degradation of petroleum hydrocarbons.ConclusionThe results of this research show that the presence of petroleum hydrocarbons in the soil caused a decrease in growth and other physiological characteristics in all studied plants. Although the Camelina was able to germinate in soils contaminated with petroleum hydrocarbons, the presence of these pollutants in the soil prevented the optimum growth of the plant, so its use in subsequent studies of phytoremediation of oil-contaminated soils, was not recommended. The results showed that there is no statistically significant difference between cultivated and non-cultivated treatments at different pollution levels, and the reduction of the total petroleum hydrocarbons in the soil was probably done by native microorganisms in the soil. It is recommended to take into consideration the efficiency of the plant species used, the type of polluting hydrocarbons, and the duration of contamination in future research to obtain better results.
N. Mehrab; M. Chorom; M. Norouzi Masir
Abstract
Introduction: Decontamination of heavy metals (HMs), especially cadmium (Cd) which has high mobility in the soil, is very important due to the effects of HMs pollution on the soil, environment, and human. Numerous efforts have been made to develop technologies for the remediation of contaminated soils, ...
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Introduction: Decontamination of heavy metals (HMs), especially cadmium (Cd) which has high mobility in the soil, is very important due to the effects of HMs pollution on the soil, environment, and human. Numerous efforts have been made to develop technologies for the remediation of contaminated soils, including ex-situ washing with physical-chemical methods, and the in-situ immobilization of metal pollutants. These methods of clean up are generally very costly, and often harmful to properties of the soil (i.e., texture, organic matter, microorganisms). Recently, the phytoremediation of HMs from contaminated soils has attracted attention for its low cost of implementation and many environmental benefits. Several chelating agents, such as DTPA, EDTA, and NTA, have been studied for their ability to dissolve metals, leach heavy metals, and enhance the uptake of metals by plants. Although many researchers have reported that EDTA is excellent solubilizing agents for HMs from contaminated soils, it is quite persistent in the environment due to the low biodegradability. Hence recently the easily biodegradable chelating agent NTA has been proposed to enhance the uptake of HMs in phytoremediation as well as the leaching of HMs from the soil. Therefore, in the present study attempts are made to investigate the effect of applicability NTA in Cd leaching and the refining of Cd from contaminated-soil by maize.
Materials and Methods: In this research, the effect of NTA on Cd leaching and its absorption by maize in contaminated-soil in a greenhouse experiment were investigated. The experiment was a factorial experiment based on a completely randomized design. The treatments consisted of three levels of Cd contamination (0, 25 and 50 mg kg-1soil) and three levels of NTA (0, 15 and 30 mmol per pot) in loamy soil and in the cultured and non-cultured conditions under three irrigation conditions. The soil was contaminated with cadmium chloride (CdCl2.2.5H2O). Nitrogen, phosphorus, and potassium (in the form of urea, triple superphosphate and potassium phosphate, respectively) were added to the pots. NTA was added in three steps to the pots. The first step of adding NTA was beginning 4 weeks after cultivation, occurring approximately once in 14 days. Also, 7 days after adding NTA, the pots were irrigated with an amount corresponding to 20% more water than the moisture of soil saturation condition. The drainage water collected from each irrigation event was kept in a refrigerator at 5°C prior to Cd analysis. The plants were cut about 5 mm above the soil surface after 10 weeks of maize growth and were dried for analyzing Cd in the plant. Analysis of variance was used to study the effects of different treatments of Cd and NTA on Cd contents in drainage water, plant, and soil. Statistical analysis were performed using SPSS. Means of treatments were compared using Duncan’s Multiple Range Test (DMRT) and the graphs were plotted in Excel.
Results and Discussion: The contrasting impact between irrigation rounds and Cd treatments, as well as NTA treatments on Cdtotal leached was significant (P<0.05). The highest Cd leached was in 50 mgCd kg-1soil (Cd50) and 30 mmol NTA (NTA30) in the first irrigation round. In the next two rounds, the Cd leached from the soil was inconsiderable. Different levels of Cd and NTA showed a significant difference in Cd concentration in the first round of leaching. In non-cultivated pots, the amount of Cd leaching in Cd50NTA15 and Cd50NTA30 treatments increased by 8 and 15 times, respectively than that in Cd50NTA0 treatment. In the case of similar treatments in the presence of maize, the Cd leaching rate increased by 5.8 and 6 times, respectively, than that in (NTA0). Cd absorbed by maize in (Cd50, NTA30) was maximum and that measured 58% more than that in (Cd50, NTA0), while dry weight decreased significantly (30% in the shoot and 40% in the root). After the cultivation and leaching process, the maximum amount of DTPA-extractable Cd was observed in (Cd50, NTA0). While using (NTA15, NTA30) at the same level of Cd-contamination (Cd50), there was a significant decrease in DTPA-extractable Cd (due to the increase in Cd dissolved, Cd leached and Cd absorbed by plants). Due to pH between 2-3 and EC about 2.5-3.5 in NTA solutions, the application of NTA in soil decreased pH and increase EC in the soil. On the other hand, the decrease in pH of soil increased solubility of calcium carbonate equivalent (CCE), thereby reduced CCE in the soil. The results of this study showed that the soil pH was effective on HMs absorption by plants, therefore the availability of Cd after the use of NTA may be due to the decrease of alkalinity in the soil. The presence of organic-metal bonds in chelate-metal compounds causes metals to be less exposed to colloids, hydroxides, and oxides thus will prevent their stabilization in the soil. So it can be said that one of the effective methods for increasing the absorption of HMs from the soil by the plant is to reduce the pH of the soil. Some of the soil properties, such as pH and total heavy metal concentration, improves the efficiency of the chelator agent.
Conclusion: The results showed that an increase in the amount of Cd contamination and NTA applied increased Cd content in drainage water and Cd which was uptake by maize. Also, results showed well, the combined of maize planting and the use of NTA is successful in refining Cd from contaminated-soil. It seems that Adding NTA as a natural chelator in Iranian calcareous soils can increase the dissolution of Cd and extract it from the soil during a leaching period without contamination of the environment, as well as increase the efficiency of removing Cd by maize.
Saeed Bagherifam; A. Lakzian; A. Fotovat; R. Khorasani
Abstract
Introduction: Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised ...
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Introduction: Arsenic is a highly toxic metalloid in group 15 of periodic table. The information on environmental behaviour of arsenic, however, is still scarce. Contamination of soils and water with arsenic and antimony due to their widespread industrial application and mining activities has raised serious environmental concerns. Nearly all Arsenic-contaminated soils results from human activities and it has different environmental and sociological impacts. Various strategies and methods have been proposed for environmental management and remediation of contaminated soils. Among all methods, the phytoremediation is receiving more attention due to its cost effective and environmental friendly characteristics. In the case of arsenic contaminated soils, there are effective factors such as soil fertility, nutrients content and microorganisms function, which can improve the uptake of As by plants. Up to now, several studies have been evaluated the effects of symbiotic fungal association in plants on increasing nutrients and toxic elements uptake. Many of authors reported that the mycorrhizal symbiosis increases the uptake of toxic elements in root and shoot of plants and consequently improve the efficacy of phytostabilization and phytoextraction processes. There are conflicting results about the effect of arbuscular- mycorrhizal fungi (AMF) on As uptake by various plants. Chen et al. (4) found that Glomus mosseae symbiosis with plant reduces As concentration and enhance phosphorus content in shoot and root of plant. Whilst Cozzolino et al. (7) reported that the AMF increases as concentration in shoot and root of cabbage. Phosphorus has important role on mycorrhizal symbiosis and also As uptake by plants. Therefore, current study was conducted to evaluated effect of Glomus intraradices and Glomus mosseae symbiosis with sunflower and also soil phosphorus concentration on uptake of arsenic from arsenite and arsenate contaminated soils.
Materials and Methods:The soil sample (Typic Haplorthids) was collected, air dried and passed through 2 mm sieve and then were heated in 80 centigrade degree temperature for two times. A pot experiment was conducted in a completely randomized design with factorial arrangement and three replications in greenhouse condition. The experimental factors included two species spices of inorganic As (50 mg kg-1 of Arsenite and Arsenate), two levels of phosphorus (0 and 60 mg Kg-1) and three spices of arbuscular mycorrhizae (control, Glomus intraradices and Glomus mosseae). Soil samples spiked with Na2HAsO4.7H2O, NaAsO2 (Arsenite and Arsenate) and Ca (H2PO4)2 (phosphorus) and incubated in greenhouse condition for 4 week. Sunflower seeds were planted and seedlings harvested after 60 day of sowing and then dry weight of sunflower, concentration of As and phosphorus in shoot and root of plant and root colonization percentage determined using standard methods.
Results and Discussion:The results revealed that Glomus intraradices (GI) and Glomus mosseae (GM) symbiosis significantly (P
T. Mansouri; A. Golchin; J. Fereidooni
Abstract
Introduction: Soil contamination by heavy metals is one of the most important environmental concerns in many parts of the world. The remediation of soil contaminated with heavy metals is necessary to prevent the entry of these metals into the human food chain. Phyto-extraction is an effective, cheap ...
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Introduction: Soil contamination by heavy metals is one of the most important environmental concerns in many parts of the world. The remediation of soil contaminated with heavy metals is necessary to prevent the entry of these metals into the human food chain. Phyto-extraction is an effective, cheap and environmental friendly method which uses plants for cleaning contaminated soils. The plants are used for phytoremediation should have high potential for heavy metals uptake and produce enormous amount of biomass. A major problem facing phyto-extraction method is the immobility of heavy metals in soils. Chemical phyto-extraction is a method in which different acids and chelating substances are used to enhance the mobility of heavy metals in soil and their uptake by plants. The aims of this study were: (a) to determine the potential of radish to extract Pb from contaminated soils and (b) to assess the effects of different soil amendment (EDTA and H2SO4) to enhance plant uptake of the heavy metal and (c) to study the effects of different levels of soil Pb on radish growth and Pb concentrations of above and below ground parts of this plant.
Materials and Methods: Soil samples were air dried and passed through a 2 mm sieve and analysed for some physico-chemical properties and then artificially contaminated with seven levels of lead (0, 200, 400, 600, 800 and 1000 mg/kg) using Pb(NO3)2 salt and then planted radish. During the growth period of radish and after the initiation of root growth, the plants were treated with three levels of sulfuric acid (0, 750 and 1500 mg/kg) or three levels of EDTA (0, 10 and 20 mg/kg) through irrigation water. At the end of growth period, the above and below ground parts of the plants were harvested, washed, dried and digested using a mixture of HNO3, HCl, and H2O2. The concentrations of Pb, N, P and K in plant extracts were measured. Statistical analysis of data was performed using MSTATC software and comparison of means was carried out using duncan's multiple range test.
Results and Discussion: The results showed that the effects of the type and rate of soil amendment and Pb levels of polluted soils were significant on dry weight and Pb concentrations of above and below ground parts of radish (p< 0.01). The dry weights of above and below ground parts of radish decreased as the Pb levels of polluted soils increased. By increasing the soil pollution level (1200 mg Pb/kg soil), the total dry weight of plant decreased by %47.3 which was probably due to phytotoxicity of lead and deficiency of several essential nutrients such as phosphorus. When the Pb levels of the polluted soils increased up to 400 mg/kg soil, the concentrations of Pb in above and below ground parts of the plant increased. But when the Pb levels of the polluted soils were higher than 400 mg/kg soil, the Pb concentration in above ground part of the plant decreased but in below ground part of the plant significantly increased. The decrease in Pb concentration in above ground part of radish was probably due to formation of insoluble lead complexes in soil. the use of soil amendments increased the concentrations of Pb in above and below ground parts of radish. The Application of EDTA increased the concentration of Pb in aerial part of radish more than the application of H2SO4. Also, the application of EDTA and H2SO4at low concentrations increased dry weight of plant since, the availability of micro- and macro elements enhanced and plant uptake of nutrients increased. But at the high concentrations of these amendments the increased availability of lead caused the reduced plant growth due to phytotoxicity. But the ability of the low level of sulfuric acid to absorb lead was more than EDTA. An antagonistic effect between phosphorus and lead uptake was also observed.
Conclusion: The results of the experiment showed that the Radish plant had the ability to absorb and accumulate the high concentration of lead in its tissues and so can be used for the phytoremediation of lead-contaminated soils. The EDTA application had higher potential for enhancing lead mobility and phytoavailability than H2SO4, But the ability of the low level of sulfuric acid to absorb lead was more than EDTA. The rate of amendment also had a significant effect on phyto-extraction process and the process was adversely affected by high concentrations of the amendments.
Z. Ahmadpoor; M. Khoramivafa; S. Jalali Honarmand; K. Cheghamirza; M. Khan Ahmadi
Abstract
Introduction: There is necessary to clean up the nitrate and phosphate from surface waters before effluence of them to environment and eutrophication formation because of water health importance and considering to nitrate and phosphate consequences. Nitrate and ammonium as the - forms of inorganic and ...
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Introduction: There is necessary to clean up the nitrate and phosphate from surface waters before effluence of them to environment and eutrophication formation because of water health importance and considering to nitrate and phosphate consequences. Nitrate and ammonium as the - forms of inorganic and nitrogen have been subjected to the center of issues related to environment pollutants and water resources in a long time. The nitrate is more important than other inorganic nitrogen forms such as ammonium because of various reasons such as high dynamics and causing diseases such as some of digestion system and lymph nodes cancers in adults and methemoglobinemia in infants. Therefore the maximum concentration of this ion in drinking water has been determined as 45 mg.Lit-1 by WHO. Regarding the importance of the water health and the complications due to existence of some compounds such as nitrate and phosphate, in this experiment, the possibility of elimination or decreasing excess nitrate and phosphate from water in hydroponic conditions using of two watercress and pennyroyal plants was evaluated. Watercress(Nasturtiumofficinale) and pennyroyal (Menthapulegium)were selected because of some properties such as adaptability with the most climates of Iranamd less requirements care.
Materials and Methods: Two RCD factorial experiments were carried out to evaluate the ability of watercress and pennyroyal to biosorption of nitrate and phosphate from polluted water in hydroponic conditions. First factor was plant species including watercress and pennyroyal. Second factor included nitrate (50, 100, 150 Mg/L) and phosphate (5, 10, 15 Mg/L) in first and second experiment respectively.The final concentrations of nitrate and phosphate in water was measured using spectrophotometer in wavelength of 410 nm and 690 nm by sulphatebrucine and chloride methods , respectively, which are mentioned in Standard Methods for the Examination of Water and Wastewater. At the end of the each experiment, watercress and pennyroyal plants were brought out from the pots carefully and their roots and shoots were separated. Roots and shoots were placed in aluminum foil separately and were dried by oven method (50°C and 48 h). The weights of dried samples were measured by a digital balance scale (0.001 gr accuracy). Three accumulation indices including Bio-concentration Factor, Translocation Factor and Tolerance Index were calculated by measuring of nitrate and phosphate accumulation in roots and shoots
Results and Discussion: According to the results, root phosphate accumulation in two plants was different significantly (p ≤ 0.05). Also, the level values of nitrate and phosphate were resulted to their root accumulation significantly. In this regard, the phosphate accumulation in watercress root changed to 10 mg. Lit-1 significantly and reached to 4.3 mg.Kg-1 dry weight in this concentration. While for pennyroyal, there was no significant increasing in roots phosphate accumulation when its concentration was increased in medium (p ≤ 0.05). Although phosphate accumulation was difference between the two plants in root and shoots, there was similar the alteration of phosphor bioconcentration trend. Because increasing of phosphate concentration resulted in significant decreasing of this index. Whilst both of watercress and pennyroyal accumulated high amount of nitrate and phosphate, quantity of accumulation in shoots was higher than of roots. Consequently, nitrate translocation factor was 1.3 in watercress and 1.07 in pennyroyal, and phosphor translocation factor was 1.07 and 0.94 in watercress and pennyroyal respectively.
Conclusions: Results indicated that two plants were pollutants purified of nitrate and phosphate (The nitrate translocation factors were 1.3 and 1.07 in watercress and pennyroyal and the phosphate translocation factors were 1.07 and 094 in watercress and pennyroyal, respectively). Generally, it was found that watercress and pennyroyal have extractive behavior completely about nitrate and phosphate. Because of the high ability of these plants in biosorption of phosphate and nitrate, with recovery of nitrogen and phosphorus cycle, they can be used as organic resources of nitrogen and phosphor supply in agricultural soil and prevent from entrancing them to seas. It is more important about phosphate, which has slowly cycle. Therefore two main roles for watercress and pennyroyal in aquatic ecosystems are expected. First, perform as bio-filter and returning the nitrogen and phosphor from surface water or wastewater for preventing the environmental pollution and second as secondary saleable or utilizable crop such as green manure and so on.
A. Taheripur; Sh. kiani; A. Hosseinpur
Abstract
Introduction: Mining and smelting activities have contributed to increasing levels of copper (Cu) and zinc (Zn) in soils around of Sarcheshmeh copper mine (Kerman, Iran). Soil chemical analysis showed that the available of Cu and Zn (extracted with DTPA-TEA) were 260.1 and 9.2 mg kg-1 soil, respectively. ...
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Introduction: Mining and smelting activities have contributed to increasing levels of copper (Cu) and zinc (Zn) in soils around of Sarcheshmeh copper mine (Kerman, Iran). Soil chemical analysis showed that the available of Cu and Zn (extracted with DTPA-TEA) were 260.1 and 9.2 mg kg-1 soil, respectively. Phytoextraction is one of the most popular and useful phytoremediation techniques for removal of heavy metals from polluted soils. For chemically-assisted phytoextraction, different chelating agents such as EDTA and citric acid are applied to soil to increase the availability of heavy metals in soil for uptake by plants. A pot experiment was conducted to elucidate the performance of chelating agents addition in improving phytoextraction of Cu and zinc Zn from a naturally contaminated soil by maize (Zea mays L.) cultivars.
Materials and Methods: A factorial experiment in a completely randomized design was carried out bythree factors of chelate type, chelate concentrations and maize cultivars with three replications in 2012 at ShahreKord University. Chelating agents were Ethylene Diamine Tetra Acetic Acid (EDTA) and citric acid (CA). They were applied in concentration levels of 0, 0.75 and 1.5 mmole kg-1 soil with irrigation water. The three maize cultivars used were single cross 704 (SC-704), three v cross 647 (TVC-647), and single cross 677 (SC-677). The pots were 23 cm in diameter and 23 cm deep, and were filled with 4 kg of a silty loam, calcareous soil taken from the surface layer of Sarcheshmeh copper mine area. Maize plant s was grown under greenhouse conditions over 90 days. After the harvest, soil available Cu and Zn contents (extracted with DTPA-TEA) were determined by atomic absorption spectrophotometry (AAS). Plant samples (shoot and root) were dried for 48 h at 70ºC to determine their dry matter content (yield). Total Cu and Zn concentrations in root and shoot of maize were measured after digestion plant samples by AAS method. The shoot and root uptakes were calculated by multiplying Cu and Zn concentrations by dry mass. The effects of chelating agents and maize cultivars over the measured properties were evaluated using the two-ways ANOVA. The least significant difference (LSD) was used to compare means of treatments using SAS 8.02.
Results and Discussion: The results revealed that applying both chelates caused an increase of soil available Cu and Zn contents. The maximum of soil Cu (401.9 mg kg-1 soil) and Zn (17.1 mg kg-1 soil) were obtained by using EDTA with 1.5 mmole kg-1 soil in TVC-647 and SC-704 cultivars, respectively. This was due to formation of water-soluble complexes between EDTA with Cu and Zn in soil and help in their desorption from soil particles. EDTA was more effective than CA at increasing Cu and Zn available in the soil. The results indicated that EDTA-addition in 1.5 mmole kg-1 soil significantly reduced root and shoot fresh weight in all maize cultivars compared with the control (except root fresh weight in SC-677). This reduction was due to increasing soil available Cu and Zn contents and their toxic effects on plant growth as well as toxic impacts of EDTA on soil microorganisms and growth of plant.on the other hand0.75 mmole kg-1 soil CA addition induced significant increases in root fresh weight as compared to the control (except root fresh weight in TVC-647). Application of CA in concentration level of 0.75 mmole kg-1 soil led to the greatest quantity of shoot (12.85 g pot-1) and root (21.38 g pot-1) fresh weight in TVC-647 and SC-704 cultivars, respectively. Citric acid has a natural origin and is easily biodegraded in soil. It is not toxic to plants; therefore plant growth is not limited. The highest Cu concentration in root and shoot of maize (2506.1 and 335.6 mg kg-1 dry weight, respectively) were obtained in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA – 62.2% and 422.9% greater than those obtained with control. The highest shoot Cu (871.1 μg pot-1) and Zn (76.7 μg pot-1) accumulations were recorded in TVC-647 cultivar using 1.5 mmole kg-1 soil of EDTA and CA, respectively.
Conclusion: Due to importance of Cu contamination in studying soil, it is suggested that EDTA-addition at 1.5 mmole kg-1 soil can be an appropriate chelator candidate for TVC-647 maize cultivar for environmentally safe phytoextraction of Cu in soil. It is noticed that application of EDTA in soil for long time has not recommended for phytoextraction of heavy metals. Because EDTA is non biodegradable substance and can leach into ground-water and causes other environmental hazardous risks.
M. Bahraminia; M. zarei; abdolmajid ronaghi; R. Ghasemi
Abstract
A greenhouse experiment was conducted to evaluate the effectiveness of arbuscular mycorrhizal (AM) fungi in phytoremediation of zinc contaminated calcareous soil by vetiver grass. Experiment was a factorial arranged in a completely randomized design (CRD) with three replications. Two factors consisted ...
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A greenhouse experiment was conducted to evaluate the effectiveness of arbuscular mycorrhizal (AM) fungi in phytoremediation of zinc contaminated calcareous soil by vetiver grass. Experiment was a factorial arranged in a completely randomized design (CRD) with three replications. Two factors consisted of Zn levels (10, 150, 300 and 600 mg kg-1 as ZnSO4.7H2O) and AM fungi (control, Glomus intraradices, Glomus versiforme). Shoot and root dry weights decreased as Zn levels increased. Mycorrhizal inoculation increased those plant measured parameters compared to those of control. With increasing Zn levels, and mycorrhizal inoculation, Zn uptake of shoot and root increased. Root colonization with mycorrhizal inoculation increased, but decreased as Zn levels increased. Mycorrhizal inoculation increased zinc extraction, uptake and translocation efficiencies. Zinc translocation factor decreased as Zn levels increased, however inoculation with AM fungi increased it. Zinc extraction and uptake efficiencies of G. intraradices were more than G. versiforme,while zinc translocation efficiency and factor were vice versa.
Mohammad Reza Naderi; A. Danesh-Shahraki; F. Raiesi
Abstract
The right selection of an appropriate cultivar, which can be adapted with a particular pollutant and environmental conditions, is a crucial factor for a successful phytoremediation technology. Sunflower might be a suitable plant to remove the toxic metals from soil of polluted sites due to its rapid ...
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The right selection of an appropriate cultivar, which can be adapted with a particular pollutant and environmental conditions, is a crucial factor for a successful phytoremediation technology. Sunflower might be a suitable plant to remove the toxic metals from soil of polluted sites due to its rapid growth and high biomass production. In order to evaluate the efficiency of six sunflower cultivars in lead (Pb) phytoextraction from a contaminated soil, an experiment was carried out using a completely randomized design with three replications in Research Station of Shahrekord University. Sunflower cultivars used in this experiment were Alestar, Serena, Sanburu, Hysun 33, Record and Euroflor. Results showed that there was a significant difference in shoot lead concentration, translocation factor and total lead harvested by shoot among sunflower cultivars at 1% probability level. Generally, due to translocation factor of all cultivars was less than 1, this can be stated that none of cultivars had the proper efficiency for extraction of lead from contaminated soil. However, high root lead concentration and low translocation factor of these cultivars show that efficiency of them for use in phytostabilization technique is more than phytoextraction technique.
Y. Azimzadeh; H. Shariatmadari
Abstract
Phytoremediation is one of the lowest-cost methods for remediation of soils contaminated with heavy metals. This study was conducted to investigate the phytoremediation potential of corn and canola, grown under single and mixed culture systems. Thus, a pot experiment was carried out on a calcareous ...
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Phytoremediation is one of the lowest-cost methods for remediation of soils contaminated with heavy metals. This study was conducted to investigate the phytoremediation potential of corn and canola, grown under single and mixed culture systems. Thus, a pot experiment was carried out on a calcareous soil contaminated by Pb and Zn. Treatments included single culture of corn, single culture of canola and mixed culture of corn and canola. Results showed that bioavailability of metals, lead, zinc, nickel and copper increased with decreasing soil pH and increasing DOC as influenced by root activity. Root uptake of metals; lead, zinc, copper and nickel in mixed culture, was more than that of in canola and lower than that of in corn. Zinc and nickel uptake by shoots of canola and mixed culture, were more than corn. Also, the results concerning the uptake of metals in the total biomass (sum of roots and shoots) showed uptake of copper and nickel in corn was more than mixed culture and it was more than canola while, uptake of lead and zinc in corn and mixed culture was more than canola. Also, the total yield of corn and canola in mixed culture increased. Therefore, it seems use of mixed culture system may extract metals, zinc and nickel more than corn, and copper more than canola, in single culture systems.
S. Rajaei; F. Raiesi; S.M. Seyedi
Abstract
The contamination of ecosystem components with petroleum and its derivatives is considered as one of the most crucial environmental threat in Iran, particularly in southern areas. Bioremediation has frequently been regarded as an appropriate and more practical alternative to clean-up petroleum hydrocarbons ...
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The contamination of ecosystem components with petroleum and its derivatives is considered as one of the most crucial environmental threat in Iran, particularly in southern areas. Bioremediation has frequently been regarded as an appropriate and more practical alternative to clean-up petroleum hydrocarbons in the contaminated environments. Bioremediation optimizes conditions for microbial hydrocarbon degradation and uses the microorganisms and plants potential to metabolize contaminants resulting in their removal or attenuation in situ. This study aims at remedying an aged petroleum-contaminated soil using bioaugmentation and phytoremediation techniques. A consortium has been prepared using oil-degrading bacteria; 10% oil-contaminated soil was then inoculated with the consortium. Additionally, oat and/or barley were planted in certain treatments to separately evaluate the effects of plant-bacteria interaction on Total Petroleum Hydrocarbon (TPH) degradation and inoculum's efficiency. TPH degradation value under unplanted and uninoculated conditions was only 2.4% in the studied petroleum -contaminated soil after 4 months. However, the presence of the two plants elevated TPH degradation up to 30%, and bacterial inoculation resulted in only 20% TPH degradation. The significance of the plants in enhancing TPH degradation could be probably explained by promoting microbial populations, growth and activities. The highest amount of TPH degradation recorded was 44% and was observed with inoculated plants. The presence of plants in petroleum-contaminated soils promoted microbial populations and activities with increased microbial respiration and biomass well developed petroleum-degrading microbial population and decreased microbial metabolic quotient (qCO2), hence, increased biodegrading of hydrocarbons.
