Phytostabilization of a Metal Contaminated Sandy Soil, I: Influence of Compost and/or Inorganic Metal Immobilizing Soil Amendments on Phytotoxicity and Plant Availability of Metals
Hasselt University, Centre for Environmental Sciences-Environmental Biology, Agoralaan Building D, B-3590 Diepenbeek, Belgium. Environmental Pollution
(Impact Factor: 4.14).
11/2006; 144(2):524-32. DOI: 10.1016/j.envpol.2006.01.038
In a lysimeter set-up, compost addition to an industrial contaminated soil slightly reduced phytotoxicity to bean seedlings. The "Phytotoxicity Index" (on a scale from 1 to 4) decreased from 3.5 to 2.8. The same treatment also reduced metal accumulation in grasses: mean Zn, Cd and Pb concentrations decreased respectively from 623 to 135, from 6.2 to 1.3 and from 10.7 to <6 mg kg-1 dry weight. When combined with inorganic metal immobilizing amendments, compost had a beneficial effect on plant responses additional to the inorganic amendments alone. Best results were obtained when using compost (C)+cyclonic ashes (CA)+steel shots (SS). The "Phytotoxicity Index" decreased to 1.7, highest diversity of spontaneously colonizing plants occurred, and metal accumulation in grasses reduced to values for uncontaminated soils. Based on the first year evaluation, C+CA+SS showed to be an efficient treatment for amendment assisted phytostabilization of the contaminated Overpelt soil.
Available from: Masahiko Katoh
- "On the basis of this study's findings , an inorganic component with a high phosphorus content of 50% or more is required to alter lead phases to be more insoluble and reduce the water-soluble lead level to less than that in the soil without compost, although the microbial activities are not enhanced. The importance of an inorganic component for the immobilization of heavy metals including lead in soil is pointed out by other researchers[21,47,48]. In contrast, 25% inorganic AMC can alter lead phases to be more insoluble and simultaneously enhance microbial activities, whereas the water-soluble lead level is higher than that in the soil without compost during the first 30 days after the application. "
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ABSTRACT: This study aimed to identify how the ratio of inorganic-to-organic components in animal manure compost (AMC) affected both lead immobilization and microbial activity in lead-contaminated soil. When AMC containing 50% or more inorganic fraction with high phosphorous content was applied to contaminated soil, the amounts of water-soluble lead in it were suppressed by over 88% from the values in the soil without compost. The residual fraction under sequential extraction increased with the inorganic fraction in the AMC; however, in those AMCs, the levels of microbial enzyme activity were the same or less than those in the control soil. The application of AMC containing 25% inorganic fraction could alter the lead phases to be more insoluble while improving microbial enzyme activities; however, no suppression of the level of water-soluble lead existed during the first 30 days. These results indicate that compost containing an inorganic component of 50% or more with high phosphorus content is suitable for immobilizing lead; however, in the case where low precipitation is expected for a month, AMC containing 25% inorganic component could be used to both immobilize lead and restore microbial activity.
Available from: Rafaqat Ali Gill
- "Soil pollution by heavy metals has reasonably increased since last few decades due to release of wastewater and waste from anthropogenic and geological activities to these soils (Ghosh and Singh 2005a, b; Ruttens et al. 2006). Among heavy metals, Cd is nonessential and harmful metal which is usually released in soil (Yang et al. 2005; Gill 2011a; Shakoor et al. 2014). "
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ABSTRACT: Performance of B. napus in phytoextraction—an in situ environment friendly technique for the cleanup of contaminated soils—was evaluated through its response to cadmium (Cd) toxicity in combination with a chelator ethylenediamminetetraacetic acid (EDTA) while growing hydroponically in greenhouse conditions under three levels of Cd (0, 10, and 50 µM) and two levels of EDTA (0 and 2.5 mM). Cadmium presence decreased plant growth, biomass and chlorophyll concentrations, while the application of EDTA enhanced plant growth by reducing Cd-induced effects in Cd-stressed plants. Addition of EDTA improved the net photosynthetic and gas exchange capacity of plants under Cd stress. Presence of Cd at 10 and 50 μM significantly increased electrolyte leakage, the production of hydrogen peroxidase (H2O2) and malondialdehyde (MDA) resulting into a significant reduction in the activities of catalase, guaiacol peroxidase, ascorbate peroxidase and superoxide dismutase in Cd-stressed plants. Application of EDTA at the rate of 2.5 mM alone and with combination of Cd increased the antioxidant enzymes activities and reduced the electrolyte leakage and production of H2O2 and MDA. The B.
napus actively accumulated Cd when applied with EDTA in roots, stems and leaves viz. 2817, 2207 and 1238 mg kg−1 DW, respectively, at higher Cd level (50 μM) followed by lower level of Cd (10 μM) viz. 1704, 1366 and 763 mg kg−1 DW, respectively. Results showed that this technique could be useful for the remediation of heavy metal-contaminated agricultural and industrial soils.
Available from: Zhengtao Shen
- "cement, lime and clay) (Du et al., 2012; Jiang et al., 2014), biochar also assists in revegetation and restoration of the treated contaminated land (Beesley et al., 2011). These are critical processes for the stabilisation and sustainable development of the land and reducing further risk to humans and the surrounding ecosystem (Arienzo et al., 2004; Ruttens et al., 2006). Therefore, biochar is a promising material with the potential to be applied in soil remediation for its multiple environmental benefits. "
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ABSTRACT: A field remediation treatment was carried out to examine the long-term effect of biochar on the immobilisation of metals and the revegetation of a contaminated site in Castleford, UK. The extracted concentrations of nickel (Ni) (II) and zinc (Zn) (II) in the carbonic acid leaching tests were reduced by 83-98% over three years. The extracted Ni (II) and Zn (II) concentrations three years after the treatment were comparable to a cement-based treatment study carried out in a parallel manner on the same site. The sequential extraction results indicated that biochar addition (0.5-2%) increased the residue fractions of Ni (II) (from 51% to 61-66%) and Zn (II) (from 7% to 27-35%) in the soils through competitive sorption, which may have resulted in the reduction of leachabilities of Ni (II) (from 0.35% to 0.12-0.15%) and Zn (II) (from 0.12% to 0.01%) in the plots with biochar compared with that without biochar three years after the treatment. The germination of grass in the plots on site failed. Further laboratory pot study suggested that larger amounts of biochar (5% or more) and compost (5% or more) were needed for the success of revegetation on this site. This study suggests the effectiveness and potential of biochar application in immobilising heavy metals in contaminated site in the long term.
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