Parvin Kabiri; hamid reza motaghian; Alireza Hosseinpur
Abstract
Introduction: Anthropogenic activities have transformed the global geochemical cycling of heavy metals. Mine tailings are of great concern due to the detrimental effects of toxic inorganic elements causing environmental risks. Zinc (Zn) as an essential element is required in small amounts for various ...
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Introduction: Anthropogenic activities have transformed the global geochemical cycling of heavy metals. Mine tailings are of great concern due to the detrimental effects of toxic inorganic elements causing environmental risks. Zinc (Zn) as an essential element is required in small amounts for various biochemical reactions and physiological functions. However, high concentrations of Zn can induce oxidative stress. Applying an organic amendment is a promising, in situ phytostabilization approach to alleviate the phytotoxic effects of heavy metal in contaminated soils. The application of biochar as an amendment may be a solution to reduce the risk of pollutant diffusion. Biochars is a fine-grained biological residue combusted under low oxygen conditions, resulting in a porous, stable carbon-based material. The potential biochar applications include carbon sequestration, soil fertility improvement, and pollution remediation; therefore, it can reduce pollutants mobility and bioavailability.
Materials and Methods: Results of this research indicated that biochars decreased Zn concentration in maize shoots and roots. They reduced Zn concentration in the shoot/root of maize. Zinc concentration in shoots and roots of maize (Zea mays L.) harvested at 60 days after sowing, decreased with increasing thermochemical temperature and application rate of biochar. In treated soil with 2% (w/w) biochar prepared at 600 °C, Zn concentration in shoots and roots decreased by 21.6 and 33.0 % respectively (p
Mahshid Shafigh; reza ghasemi; abdolmajid ronaghi
Abstract
Introduction: Plants can uptake, bioaccumulate and immobilize different metals in their tissues. Phytoremediation technique has been used to remove hazardous substances including heavy metals from the environment. Assisted phytoremediation is usually the process of applying a chemical additive to heavy ...
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Introduction: Plants can uptake, bioaccumulate and immobilize different metals in their tissues. Phytoremediation technique has been used to remove hazardous substances including heavy metals from the environment. Assisted phytoremediation is usually the process of applying a chemical additive to heavy metal contaminated soils to enhance the metal uptake by plants. The main objective of present study was to investigate the effectiveness of plant growth regulators (PGRs) and a humic substance (HS) on Ni phytoremediation by maize in a Ni-pollutrd calcareous soil.
Materials and Methods: The experiment designed as a 5×3 factorial trial arranged in a completely randomized design with three replicates. Three kilograms of soil was placed in plastic pots and pots were watered with distilled water to field capacity and maintained at this moisture level throughout the experiment by watering the pots to a constant weight. The soils were polluted with 250 mg Ni Kg-1 as Ni-nitrate Ni (NO3)2. Six maize (Zea mays L.) seeds were planted 2 cm deep in soil and thinned to three uniform stands 1 week after emergence. Treatments consisted of three levels of soil application of commercially humic substance, HS, (0, 3, and 6 mg kg as Humax 95-WSG containing about 80% humic acid, and about 15% fulvic acid) and five levels of PGRs (0 or 10 µM GA3, IAA, BAP and SA). The HS was applied as split doses in three times at 15 day intervals along with irrigation water. The seedlings were exposed to aqueous solutions of HS 16 days after sowing for the first time. Prepared solutions of PGRs were sprayed three times at 15 day intervals from emergence. Seven weeks after planting, shoots were harvested and roots were separated from soil carefully, both parts were rinsed with distilled water and dried at 65°C for 72 h, weighed, ground, and dry meshed at 550°C. Root and shoot dry matter and Ni concentration and uptake and phytoremediation criteria were considered as plant responses. Data were statistically analyzed using SAS and SPSS software packages. Application of different PGRs had no considerable effect on phytoextraction or translocation efficiencies. Among the four PGRs studied application of SA and BA significantly increased mean uptake efficiency.
Results and Discussion: Among four PGRs evaluated, application of GA3 increased mean shoot dry matter yield and application of SA increased mean root dry matter yield. Application of the highest HS level (6 mg kg-1) decreased both mean root and shoot dry weight. Application of SA increased Ni concentration in both maize root and shoot. Application of BA only increased Ni concentration in maize root. Although application of the highest HS level (6 mg kg-1) caused an increase in Ni concentration in maize shoot, this effect was attributed to the influence of HS on the decrease in decreasing dry weight of maize shoot. Application of all PGRs except GA3 increased leaf greenness criterion. Addition of HS had no significant effect on leaf greenness. Application of PGRs enhanced root concentration factor (RCF) and decreased translocation factor (TF). Among PGRs evaluated, BA was the most effective on TF, and SA or BA was the most effective on RCF. However HS were not significantly influenced these phytoremediation criteria, as compared with control. The efficiency of PGRs in root Ni uptake was in the order of SA > BA > GA3 > IAA. Application of BA had a significant effect on Ni distribution among root and shoot, in comparison with other PGRs, and caused an increase and a decrease in root and shoot uptake of Ni, respectively. However HS had a negative effect on tolerance index and its application decreased root and shoot dry weights. Results showed that the values of Ni in maize root was considerably higher than that of maize shoot demonstrated that phytostabilization was the main mechanism involved in the phytoremediation of Ni by maize and application of PGRs was effective on this mechanism.
Conclusion: Results reported here indicated that although the addition of HS did not cause a significant effect on Ni phytoremediation, application of most studied PGRs had a positive effect on Ni phytoremediation by maize. Application of SA and BA increased uptake efficiency and RCF and application of GA3 increased shoot dry matter and tolerance index. The fact that Ni uptake by roots was significantly higher than that of shoots demonstrated that phytostabilization was the main mechanism involved in the phytoremediation of Ni by maize. According to results reported herein the addition of PGRs especially SA is likely to be promising in phytostabilization of Ni in calcareous soils polluted with this metal.
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
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.
