Enhancing PHYTOEXTRACTION with aminopolycarboxylic acids (APCAs) associated with fast growing and metal tolerant plants species has been proposed for the clean-up of heavy metal contaminated soils. The objectives of this study were to assess the efficiency of EDTA and NTA for desorbing Pb from soil and to compare their effects for enhancing of Pb extraction with Land Cress (Barbara verna). The experimental factors were including 0, 100 and 800 mg Pb kg-1 soil, EDTA and NTA (0, 5 and 10 mmol kg-1 soil). The results indicated that EDTA was much more efficient for enhancing root to shoot Pb translocation. In 800 mg Pb kg-1 soil, as a result of 10 mmol EDTA kg-1 soil, a value of 1075 mg Pb kg-1 DW shoot was obtained. The soils treated with EDTA showed higher values of soluble Pb concentration than NTA and no chelate. Also, MLPI was higher (0.87) in presence of 5 mm EDTA kg-1 concentration. In high concentrations of Pb and APCAs, both EDTA and NTA caused acute symptoms on leaves which showed wilting, necrotic areas and curling of borders. Finally, Land Cress due to high lead resistance can be introduced as a Pb hyperaccumulator to chelate-induced PHYTOEXTRACTION technology.

Heavy metals such as cadmium mainly enter in the environment and ecosystem as a result of human activities. This study was conducted in order to evaluate the ability of bacterial inoculants to enhance efficiency of PHYTOEXTRACTION in a calcareous soil. Three plants (Amaranthus retroflexus, Helianthus annus and Medicago sativa), along with three levels of inoculants and four levels of Cd were evaluated. The experiment design was factorial with three replications. The ANOVA results showed that application of inoculants led to significant increase (P<0.01) of cadmium concentration in plant’s root and shoot. Furthermore, as cadmium concentration increased in different treatments, fresh weight of plant’s root and shoots decreased in all treatments but, weight reduction of plant’s organs was less in treatments with inoculants application. The amaranthus highest amount of absorption, translocation of Cd to shoot, Translocation factor (TF) and Cd PHYTOEXTRACTION. Thus, amaranthus among studied plants is more appropriate for PHYTOEXTRACTION of cadmium.

The present study was undertaken to evaluate the growth response of Vetiveria zizanioides amended with organic amendments to arsenic (As) in contaminated soils and its ability to sequester As. The test results indicate that the plants exhibited high tolerance to As in the soils and their normal growth continued even though As concentrate on reached 500 mg/kg. However, when As concentrations in soils were in the range of 1000~2000 mg/kg the plants could not survive no matter whether the soils were amended. The accumulation of As in roots (185.4 mg/kg) was higher than that in shoots (100.6 mg/kg). The As level in the contaminated soil was reduced from 500 mg/kg to 214 mg/kg after six months of As PHYTOEXTRACTION. Microbial population was not affected in the As contaminated soil amended with dairy sludge, mycorrhizae and Azotobacter.

Soil contamination with heavy metals is one of the most important challenges in soil and water conservation area. Remediation of Cd as one of the most important environmental contaminants from contaminated soils due to its high mobility in soil-plant-human chain and adverse effects on human and animals, is very important. PHYTOEXTRACTION is one of the biological remediation methods in which hyperaccumulator plants are used to take up pollutants from contaminated soils. The objective of this study was to investigate the capability of Land Cress (Lepidium sativum) for phytoremediation of cadmium from Cd-contaminated soils. For this purpose, a randomized block experimental design with six treatments of 0, 3, 5, 10, 25 and 50 mg Cd/ kg soil and four replicates was established in the greenhouse. When plants were fully developed, plants were harvested and cadmium concentrations in the soil, roots and shoots were measured. The results indicated that by increasing Cd concentration in soil, its accumulation in plant tissues was also increased. By increasing cadmium concentration in soil, its concentration within the roots and shoots was increased to 19.3 and 34 times, respectively. This indicates the high capability of both roots and shoots for cadmium uptake from contaminated soils. Total average cadmium concentration in roots and shoots was 65.18 and 60.86 mg/kg, respectively. With increasing cadmium concentration, the time needed for PHYTOEXTRACTION was also increased. The minimum time needed for PHYTOEXTRACTION was belonged to the 3 mg/kg Cd treatment. Since Land Cress has short growing period and high biomass, it can be used as hyperaccumulator plant to remediate cadmium from Cd-contaminated soils.

Festuca ovina L. is a hyperaccumulating plant which has aroused considerable interest with respect to its possible use for phytoremediation of contaminated soils. This study has been conducted to evaluate the potentials ofF. ovina L. to serve as a phytoremediation plant in the cleaning up of Cu in the polluted soils and to identify extraction efficiency of Ethylene Diamine Tetraacetic Acid (EDTA) for desorbing copper in relation to chelator dosage. Seeds have been sown in control and Cu contaminated pots (artificially contaminated with 150 mg kg-1 Cu). Results revealed that Cu negatively affected growth and tolerance indices ofF. ovina and the root length was the most sensitive parameter among all measured parameters. The treatments used for assessing EDTA efficiency were 1.5, 3, 6, 15+1.5, 3+3 mmolkg-1, control (C: uncontaminated soil without EDTA) and W (contaminated soil without EDTA). Results showed that the application of 1.5 mmolkg-1 of EDTA did not significantly improve the PHYTOEXTRACTION of Cu and statistically, there was no significant difference in Cu uptake between single and split applications of 1.5 mmolkg-1 of EDTA. A sharp increase in root Cu concentration was observed when 3 mmolkg-1 of EDTA was applied. The highest amount of Cu extracted for the plant tissues was achieved at the doses of 6 mmolkg-1 and 3+3 mmolkg-1 EDTA, respectively. Higher Remediation Factors (RF) were obtained for the plants grown in contaminated soil and the highest RFs (0.08% and 0.07%) were recorded after the addition of 6 and 3+3 mmolkg-1, respectively. Application of EDTA showed a relatively decrease in TI (Tolerance Index) value and the lowest value of TI was recorded in 6 mmolkg-1 EDTA treatment. According to the experiment, EDTA has appeared to be an efficient amendment when Cu phyto-extraction withF.ovina was addressed. But further studies would be needed on investigating the reduction of percolation risk by the amount and process of chelate application.

A pot experiment was conducted to investigate the influence of elemental sulfur, gypsum and chelating agent (Ethylenediaminetetraacetic acid) on copper, zinc, nickel, cadmium, chromium and lead uptake by Brassica juncea from sewage sludge. Addition of sulphur acidified the sludge, which caused the pH decrease to 5.4 with an initial pH 6.7. The shoot and root biomass were increased with sulfur addition, while decreased with Ethylenediaminetetraacetic acid addition. Applications of Ethylenediaminetetraacetic acid and sulfur resulted in a considerable increase in copper and lead concentrations in the plant. The highest root concentration of copper obtained to be 110 mg/kg dw at Ethylenediaminetetraacetic acid treatment. For sulfur treatment, lead concentrations in shoots indicated almost high concentrations 77 mg/kg, about twofold increases relative to roots (34 mg/kg). The Transportation Index of all studied metals were quite low (TI < 0.5), whereas the Bioaccumulation Factor values were much higher, varied from 0.01 to 9.67. Furthermore, the plant showed better Bioaccumulation Factor for copper and lead metals in both shoot and root. The efficiency to remove copper and lead from sludge is high in this plant. As a result, elemental sulfur will be effective amendment for PHYTOEXTRACTION of heavy metals from sewage sludge.