Lead Phytoextraction from Contaminated Soil with High-Biomass Plant Species

Inst. of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
Journal of Environmental Quality (Impact Factor: 2.65). 11/2002; 31(6):1893-900. DOI: 10.2134/jeq2002.1893
Source: PubMed


In this study, cabbage [Brassica rapa L. subsp. chinensis (L.) Hanelt cv. Xinza No 1], mung bean [Vigna radiata (L.) R. Wilczek var. radiata cv. VC-3762], and wheat (Triticum aestivum L. cv. Altas 66) were grown in Pb-contaminated soils. Application of ethylenediaminetetraacetic acid (EDTA) (3.0 mmol of EDTA/kg soil) to the soil significantly increased the concentrations of Pb in the shoots and roots of all the plants. Lead concentrations in the cabbage shoots reached 5010 and 4620 mg/kg dry matter on Days 7 and 14 after EDTA application, respectively. EDTA was the best in solubilizing soil-bound Pb and enhancing Pb accumulation in the cabbage shoots among various chelates (EDTA, diethylenetriaminepentaacetic acid [DTPA], hydroxyethylenediaminetriacetic acid [HEDTA], nitrilotriacetic acid [NTA], and citric acid). Results of the sequential chemical extraction of soil samples showed that the Pb concentrations in the carbonate-specifically adsorbed and Fe-Mn oxide phases were significantly decreased after EDTA treatment. The results indicated that EDTA solubilized Pb mainly from these two phases in the soil. The relative efficiency of EDTA enhancing Pb accumulation in shoots (defined as the ratio of shoot Pb concentration to EDTA concentration applied) was highest when 1.5 or 3.0 mmol EDTA/kg soil was used. Application of EDTA in three separate doses was most effective in enhancing the accumulation of Pb in cabbage shoots and decreased mobility of Pb in soil compared with one- and two-dose application methods. This approach could help to minimize the amount of chelate applied in the field and to reduce the potential risk of soluble Pb movement into ground water.

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    • "It has been also reported in many studies that the application of these chemical chelants decrease biomass yields of the plants (Chen and Cutright, 2001; Madrid et al., 2003; Chen et al., 2004). The in situ application of chelants may pose the potential risk of causing groundwater pollution through uncontrolled metal solubilization and migration (Wu et al., 1999; Lombi et al., 2001; Nowack, 2002; Romkens et al., 2002; Shen et al., 2002; Jiang et al., 2003; Madrid et al., 2003; Thayalakumaran et al., 2003; Wenzel et al., 2003; Chen et al., 2004). "
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    ABSTRACT: Phytoremediation is an age old technology. Recently, it has emerged as one of the most accepted, economical, eco-friendly and esthetically important strategy adopted for removal of toxic metals from the contaminated sites. However, it is observed that its application suffers from several imperfections. Edible crops with low biomass and plants having low metal extracting ability have been studied extensively for their use to extract heavy metals. It is found that most of the edible crops are low biomass producing plant with shorter lifespan and sensitive to most of the abiotic and biotic stresses. Several non-edible plants have also been studied for their metal extraction potential. Ricinus communis is a non-edible emerging phytoremediator which is a robust and industrially important oil yielding multipurpose shrub of wild as well as cultivable nature. The application of R. communis for phytoremediation purpose in place of edible as well as non-edible stress sensitive crops/herbs may become a good alternative for the remediation of contaminated land. Its other important uses are biodiesel production, medicinal products, societal development, employment generation to the local peoples, carbon sequestration, reduction in green house gases (GHG), etc. It also increases the fertility of the soil and reduces soil erosion. R. communis has been found to possess excellent ability to extract majority of toxic metals like Cd, Pb, Ni, As, Cu, etc. as well as some organic contaminants like pesticides.
    Ecological Engineering 10/2015; 84:640-652. DOI:10.1016/j.ecoleng.2015.09.038 · 2.58 Impact Factor
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    • "The intense and inadequate use of fertilizers and pesticides in the soil, coupled with the increase in industrial activity and mining are the main reasons for the contamination of soil, waterways and the water table by heavy metals [24]. Among the existing pollutants, Pb is the major contaminant of the soil [25] posing significant environmental problems [26], including the risk of poisoning to human beings and especially the children [27]. Pb absorption is regulated by pH, cation exchange capacity of the soil, as well as by exudation and physicochemical parameters [28] [29]. "
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    ABSTRACT: The levels of lead (Pb) in soils (S), and eight (8) plants (P) growing naturally in a main agricultural activity, semi-arid zone and where there has been a long-term activity of heavy machineries carrying out construction works in the area were de-termined using atomic absorption spectrophotometer (AAS). Their concentration factors (CF) were also calculated. Whole plant parts were used, these include: calotropis procera (P = 4.6012 µg/g, S = 4.8611µg/g, CF = 0.9465). Commelina sp (P = 1.7053 µg/g, S = 1.479 µg/g, CF = 1.153), Colocynthis bulgaris (P = 1.4971 µg/g, S = 1.4231 µg/g, CF = 1.052), cucur-bita pepo (P = 1.754 µg/g, S = 1.342 µg/g, CF = 1.307), haemanthus sp (P = 0.1645 µg/g, S = 0.0164 µg/g, CF = 1 0.03), hibiscus esculenta (P = 0.5357 µg/g, S=0.1759 µg/g, CF = 3.045), mitracarpus scaber (P = 0.3313 µg/g, S=0.85 µg/g, CF = 0.3898) and lactuca taraxacifolia (P = 4.1067 µg/g, S = 4.8913 µg/g, CF = 1.63). The study is important considering the harmful effects of Pb in human and animal physiological systems. Results were significant at 0.05 level.
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    • "Plant species do respond differently to EDTA-enhanced uptake of heavy metals including Pb. Shen et al. (2002) reported that cabbage mung bean and wheat crops accumulated Pb differently when exposed to EDTA at 3.0 mmol EDTA kg −1 of soil. Although all the plants showed increased concentration of Pb in shoots and roots, cabbage plants accumulated higher Pb than other plant species. "
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    ABSTRACT: Heavy metal contamination has become a serious threat to biological systems. Lead contamination can be decreased to acceptable levels through high biomass plants aided with the applied EDTA as an amendment which forms highly soluble and stable metal–EDTA complexes with Pb. A large number of factors affect the efficiency of EDTA-induced metal phytoremediation. A better understanding of soil, plant and climatic factors can help improve the effectiveness of chelant-assisted phytoremediation of Pb. Many concerns have been raised about the adverse impacts of EDTA-assisted phytoextraction. Therefore, it has been advocated to avoid EDTA-assisted phytoremediation. Recently many biodegradable synthetic chelants such as EDDS and NTA have been employed to assist high biomass crops in removing metals from contaminated soils. Although chemically assisted phytoextraction has always shown more disruptive effects on the ecosystem than natural phytoextraction, more research on the role of non-persistent chelants with minimal effects on the environment should be continued under real-field conditions to improve understanding of the mechanisms involved in assisted phytoextraction.
    Soil Remediation and Plants, 1st edited by Khalid Hakeem, Muhammad Sabir, Munir Ozturk, Ahmet Murmet, 01/2015: chapter Phytoremediation of Pb-Contaminated Soils Using Synthetic Chelates: pages 397-414; Sciencedirect / Elsevier., ISBN: 978-0-12-799937-1
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