Evaluation of EDTA and PIOA chelates for phytoremediation of cadmium contaminated soils by Morale (Chenopodium album L.)

Today, soil pollution is one of the important environmental issues that must be taken into consideration. Industrial activities cause pollution and accumulation of heavy metals in the soil. The rate of absorption of pollutants, especially heavy metals, by different plants is different.  If resistant plants can be found that are able to reduce some of the pollution in water or soil, they can be used to remove pollution from polluted sources. Heavy metals are considered as an important environmental problem due to their toxicity, cumulative effects, long persistence time in the environment, carcinogenicity and non-degradability. Chemical phytoremediation is a method in which different chelating agents are used to increase the absorption of metals by the plant. The purpose of this research is to investigate the ability of morale as a weed with a wide geographical spread in the country, to absorb cadmium metal pollution. This research was carried out in the agricultural year of 2018-2019 in the greenhouse of agricultural Research Institute of Zabul University, located in Zahak city, with a geographic location of 61˚ 41' east longitude and 30˚ and 54' north latitude and an altitude of 483 meters above sea level. The research was carried out as a factorial experiment in the form of a completely randomized design with three replications. The experimental treatments include EDTA and PIOA chelate at four levels (0, 0.5, 1 and 1.5 mg/kg of soil) as the first and second factors, respectively, and cadmium at three levels (0, 15 and 30 mg/kg of soil) from the source of cadmium nitrate as the third factor. This research aims to investigate the phytoremediation ability of Morale in the presence of EDTA and PIOA chelating agents in a selected soil from the drainage area of zabol in the form of a pot test on a soil contaminated with cadmium, in the greenhouse of the agricultural research institute was done of the zabol university. In each pot, 4 morale seedlings prepared from the treasury of Zabol University Agricultural Research Institute were planted at a depth of 10 cm. Analysis of data was done using SAS software version 9.1. The mean comparison of the treatments was analyzed using Duncan's multiple range test at the 5% level. The application of chelating agent increased chlorophyll a in all treatments affected by cadmium, so that the highest amount of chlorophyll a (878.33 mg/g) was in the treatment of 1.5 mg/kg EDTA and soil without cadmium, which ratio It showed an increase of about 3.75% compared to the control (without chelating agent and without cadmium). The highest amount of cadmium in aerial parts (8.57 mg/kg) corresponds to the treatment containing 1.5 mg/kg of EDTA chelated and soil with 30 mg/kg of cadmium and the lowest amount of cadmium in aerial parts (0.427 mg/kg) was related to the control treatment (without chelating agent and without cadmium). The application of chelating agent increased root cadmium in all treatments under the influence of cadmium, in a way that showed an increase of about 94.42% compared to the control (without chelating agent and without cadmium). In sum, the results of this research show that the Morale plant is a plant resistant to soil pollution and can tolerate the levels of pollution to a certain extent. Refinement and separation of cadmium metal from the soil was done better by the plant. Due to the high tendency of EDTA to bind to metals, when EDTA is used in high concentrations. It has a potential effect on the release of metals from the solid phase by forming soluble complexes, and the formation of EDTA complexes with metals in the soil solution may advance the balance of precipitation and absorption towards the dissolution of metals.