الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
SUMMARY AND CONCLUSION
Soil contaminated by various activities including industrial, medical, researches, agricultural, nuclear and non-nuclear activities. Phosphate fertilizers are an essential component of the agricultural activities that help increasing the crop production and improving the properties of the nutrient-deficient lands. However, a possible negative consequence of phosphate fertilizers is the contamination of cultivated lands by heavy metals, uranium and some naturally occurring radioactive materials.
Phytoremediation has been developed as an economically and environmentally attractive approach to clean up heavy metal-polluted soils and restore the soil quality. One of the phytoremediation techniques, the so-called phytoextraction, relies on using of some plants to extract metals from the soil and translocate them to the shoots. The aim of phytoextraction is to reduce the concentration of metals in the contaminated soils to regulatory levels within a reasonable time frame. Two approaches have currently been proposed to reach such goal: using of plants of exceptionally high natural metal-accumulating capacity named hyperaccumulators and utilization of high-biomass crop plants in association with a chemically enhanced method of phytoextraction.
The plan of this study was proposed to decontaminate the polluted soil with uranium and some heavy metals employing the phytoremediation technique. Thus, two known hyperaccumulators plants (indian mustard and ryegrass) were utilized and enhanced their uptake efficiency using some low molecular weight organic acids (LMWOA) and chelate agent (citric acid, oxalic acid and EDTA).
Accordingly, two pot experiments were set up during 2014/2015 and 2015/2016 seasons in the greenhouse of Nuclear Materials Authority (NMA) to investigate the ability of citric acid C6H8O7 (CA), oxalic acid H2C2O4.2H2O (OA) and Ethylenediaminetetraacetic acid ( EDTA) on enhancing phytoextraction of uranium and heavy metals by indian mustard and ryegrass. Different concentrations of amendments were used (2.5, 5 and 7.5 mmol/ Kg soil).
Effect of metal uptake process in conjunction with organic amendments on some plant parameters (growth performance, evaluation of pigments and proline) were examined. In addition, three amendments (citric acid, oxalic acid and EDTA) were applied to the used phytoremediators to investigate their role on enhancing the metals uptake by these plants.
Finally, uranium and the other heavy metals were desorbed from the loaded plants then recovered by ion exchange for uranium and direct precipitation for heavy metals.
The present data showed that:
1-The plant height (shoot and root length), fresh weight and dry weight of both plants were negatively affected by the applied amendments at the different concentrations particularly with EDTA and followed by citric acid then oxalic acid .
2-Weight of 100 seeds and number of seeds /plant were determined only in indian mustard to evaluate the effect of different applications on yield. All treatments decreased numbers of seeds /plant, especially with EDTA application. Weight of 100 seeds didn’t affect with citric acid and oxalic acid but significantly decreased comparing to the control with EDTA application.
3-Pigments were significantly decreased with all applications due to toxic effects of heavy metals. EDTA was the most effective on pigments decreasing and followed by citric acid > oxalic acid.
4-Chlorophyll a was clearly decreased in ryegrass compared to indian mustard under the different treatments but decreasing magnitude in the chlorophyll b reach the same level of significance in both plants while carotenoids revealed more decreasing content in indian mustard than ryegrass .
5-Chelating agent and LMWOA increased proline concentration in the plants with increasing the plants uptake of uranium and heavy metals.
6-EDTA was the most effective in increasing proline concentration followed by citric acid then oxalic acid where concentration of proline increased from 5 µmol/ g fresh weight of control to 12.5 µmol/ g fresh weight with EDTA application in indian mustard, while in ryegrass, proline concentration increased from 2.6 µmol/ g fresh weight in control to 8.2 µmol/ g fresh weight with EDTA application.
7-Uranium uptake increased with all tratments in indian mustard shoots compared with the control. Citric acid and EDTA imposed the highest effect at concentration of 5 and 7.5 mmol /Kg soil.
8- Also, ryegrass shoots uptake uranium with all application and the best uptake values were accompanied to EDTA concentration of 5 and 7.5 mmol/Kg soil.
9- Uranium uptake also was significantly enhanced by citric acid.
10-EDTA 5 and 7.5 mmol/Kg soil were better than citric acid at the same concentrations with uranium uptake of ryegrass roots, while the reverse was true for indian mustard roots with EDTA application.
11- Citric acid and oxalic acid gave less and similar effect on uranium uptake with ryegrass roots.
12-In general, citric acid and EDTA appeared similarly for uranium uptake by the two plants shoot system but in plants root system EDTA was the most effective followed to citric acid for ryegrass and the reverse was true for indian mustard especially at the two concentrations 5 and 7.5 mmol/Kg soil.
13-Finally, shoots and roots of indian mustard revealed better uranium accumulation than shoots and roots of ryegrass under the different application treatments.
14-All treatments enhanced zinc, copper, manganese, iron and lead uptake in both plants in descending order from EDTA, citric acid to oxalic acid.
15-Translocation of uranium and other heavy metals was investigated in indian mustard only, in order to calculate the metals translocation to used organ as indian mustard yield. Concentration of uranium, lead and copper with citric acid and oxalic acid applications closed to zero.
16-With EDTA application, seeds had concentrations of copper and lead as well as traces of uranium (0.73 – 0.83 ppm).
17-Zinc, manganese and iron are presented in the seed with all applications and their concentrations increased with EDTA application.
For environmental and strategic targets, recovery processes were performed from loaded plants. Plants residue evaporated and identified by EDX analysis for determination residue metals after separation process.
By the end of this work, the achievable data and observations led to formulate the following conclusion
• The indian mustard and ryegrass are promising, environmentally safe, high effective and low cost means for decontamination of polluted soil particularly with radioactive pollutants.
• Indian mustard is recommended to be the first choice for the metal uptake and decontamination of the polluted soil due to its high performance as hyperaccumulator particularly under treatments with the proper amendments and the validity of its seeds for using as oil crop ( except with EDTA treatment).
• Although EDTA behaved great as chelating agent better than both citric acid and oxalic acid, but citric acid is the recommended due to its low passive effect on the plant growth comparing to EDTA, its comparable positive effect on the metal uptake as well as its keeping of the indian mustard seeds free from the pollutants especially uranium.
• To keep the Egyptian agricultural soil safe and within the international permissible levels of pollutants, it is recommend to propose and execute a gradual plan for removing or minimizing the hazards metals from the old agricultural soil which exposed to the phosphatic fertilization on the long term.
• The phytoremediation, as biotechnological mean, exhibits some advantages relative to the traditional methods which employed in the decontamination process especially from the environmental point of view.
• Finally, the author recommends further researches on using the hyperaccumulators, especially indian mustard and ryegrass, as natural and friendship resins for extraction and recovery of uranium and some heavy metals on wide scale.