Effect of biodegradable chelators on induced phytoextraction of uranium

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se unió: 02/05/2021

Effect of biodegradable chelators on induced phytoextraction of uranium

This study investigated the effect of ethylenediamine-N,N′-disuccinic acid (EDDS), oxalic acid (OA), and citric acid (CA) on phytoextraction of U- and Cd-contaminated soil by Z. pendula. In this study, the biomass of tested plant inhibited significantly following treatment with the high concentration (7.5?mmol·kg?1) EDDS treatment. Maximum U and Cd concentration in the single plant was observed with the 5?mmol·kg?1 CA and 7.5?mmol·kg?1 EDDS treatment, respectively, whereas OA treatments had the lowest U and Cd uptake. The translocation factors of U and Cd reached the maximum in the 5?mmol·kg?1 EDDS. The maximum bioaccumulation of U and Cd in the single plants was 1032.14?μg and 816.87?μg following treatment with 5?mmol·kg?1 CA treatment, which was 6.60- and 1.72-fold of the control groups, respectively. Furthermore, the resultant rank order for available U and Cd content in the soil was CA?>?EDDS?>?OA (U) and EDDS?>?CA?>?OA (Cd). These results suggested that CA could greater improve the capacity of phytoextraction using Z. pendula in U- and Cd- contaminated soils.To get more news about Emeramide, you can visit fandachem.com official website.

Uranium (U) is an important radioactive element and widely used in irradiation breeding, insect disease prevention, radiotherapy, nuclear reactor, and other industrial sectors in the form of U compounds and metallic U1. The development of nuclear industry as well as U mineral activities have been affecting the quality of soils in natural environments2. According to a survey, the average content of U in topsoil (0–20?cm) was 3.03?mg/kg in China3; however, the U content in the contaminated soil around U tailings is 3.21–62.37?mg·kg?1 in Hunan Province, China4. Multiple heavy metals (U, Cd, Cr, Fe, Pb, and Cu) have been found in U tailings area5. Meanwhile, Cd has become one of the most severe concerns in U tailings area due to its high mobility and toxicity in the soil environment6. Therefore, U tailing contaminated soils need be paid more attention in certain areas of China because of extensive industry activities of mining7. To date, the remediation technologies of metals contaminated soils, such as adsorption8, electrokinetic remediation9, soil washing10, and phytoextraction11 have been widely applied for reducing the total and/or available metals concentration in soils. Among these, phytoextraction is regarded as one of the most effective treatments because of its simple operation in practical applications. Meanwhile, it is also cost-effective and eco-friendly. However, low shoot uptake and translocation results in a low accumulation capability in plant shoot. Therefore, many methods, including chelators, have been widely applied to accumulate higher quantities of metals in plant shoot, through improving the bioavailability of the metals in soil and stimulating metal uptake in tested plant12,13.

In principle, chelators can be divided into two types: natural and artificial chelators. Natural chelators are mainly low-molecular-weight organic acids (LMWOA) such as, oxalic acid (OA) and citric acid (CA), which can increase the solubility and potential bioavailability of metals in soil, and OA and CA have been widely used in phytoremediation enhancement of metal-polluted soils14,15,16,17. Artificial chelators include diethylenetriaminepentaacetic acid (DTPA), ethyl diglycol acetate (EDGA) and ethylenediaminetetraacetic acid (EDTA), which can chelate insoluble metals to soluble species in soil18. Meanwhile, they usually have stronger capacity to chelate metals in soil compared with low-molecular-weight organic acids19,20. However, DTPA, EDGA, and EDTA have negative impacts that include low biodegradability in soil and increasing the risk of leaching of metals into groundwater21,22. Considering these negative effects, EDDS and CA have been widely used to increase the capacity of metals translocation from contaminated soil to harvestable parts of the tested plant because of strong chelate capacity and good biodegradability23,24. Lan et al. showed that 2?mmol·kg?1 EDDS treatment increased significantly shoot Cd concentrations in Sigesbeckia orientalis L25. The results of Yang et al. indicated that 5?mmol·kg?1 CA had the best effect on U phytoremediation by rye grass26.

Zebrina pendula Schnizl is a fast-growing evergreen herbage found at a uranium tailing site in Hengyang, Hunan province, China. The results of our preliminary experiment have shown that Z. pendula has the higher potential to absorb and accumulate U compared with other tested plants (Table S1). Meanwhile, the species also have advantages of strong tolerance to U, high biomass, and easy management.

In this study, we investigated whether the biodegradable chelators could increase the phytoextraction efficiency of U and Cd from the soil. The specific objectives of this study were to: (1) investigate the influence of three chelators on the biomass production of Z. pendula; (2) analyze the potential of different chelators to improve U and Cd phytoextraction; (3) assess the suitable dosage of chelators for enhancing the effect of U and Cd phytoextraction.

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