title: Phytoremediation of Cu and Zn by vetiver grass in mine soils amended with humic acids.
abstract: Phytoremediation of contaminated mine soils requires the use of fast-growing, deep-rooted, high-biomass, and metal-tolerant plants with the application of soil amendments that promote metal uptake by plants. A pot experiment was performed to evaluate the combined use of vetiver grass (Chrysopogon zizanioides) and humic acid for phytoremediation of Cu and Zn in mine soils. Vetiver plants were grown in soil samples collected from two mine sites of Spain mixed with a commercial humic acid derived from leonardite at doses of 0, 2, 10, and 20 g kg(-1). Plant metal concentrations and biomass were measured and metal bioavailability in soils was determined by a low molecular weight organic acid extraction. Results showed that humic acid addition decreased organic acid-extractable metals in soil. Although this extraction method is used to estimate bioavailability of metals, it was not a good estimator under these conditions due to competition with the strong chelators in the added humic acid. High doses of humic acid also promoted root growth and increased Cu concentrations in plants due to formation of soluble metal-organic complexes, which enhanced removal of this metal from soil and its accumulation in roots. Although humic acid was not able to improve Zn uptake, it managed to reduce translocation of Zn and Cu to aerial parts of plants. Vetiver resulted unsuitable for phytoextraction, but our study showed that the combined use of this species with humic acid at 10-20 g kg(-1) could be an effective strategy for phytostabilization of mine soils.
authors.affiliation: Soil Science Department, Agricultural Engineering School, Technical University of Madrid (UPM), Avenida Puerta de Hierro 2, 28040, Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Vargas
authors.affiliation: Soil Science Department, Agricultural Engineering School, Technical University of Madrid (UPM), Avenida Puerta de Hierro 2, 28040, Madrid, Spain. jpereze@madrid.uned.es.
authors.forename: Javier
authors.identifier: http://orcid.org/0000-0003-0996-6795
authors.initials: J
authors.lastname: Pérez-Esteban
authors.affiliation: Organic and Bio-Organic Chemistry Department, Sciences Faculty, National Distance Education University (UNED), Paseo de Senda del Rey 9, 28040, Madrid, Spain.
authors.forename: Consuelo
authors.initials: C
authors.lastname: Escolástico
authors.affiliation: Soil Science Department, Agricultural Engineering School, Technical University of Madrid (UPM), Avenida Puerta de Hierro 2, 28040, Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Masaguer
authors.affiliation: Soil Science Department, Agricultural Engineering School, Technical University of Madrid (UPM), Avenida Puerta de Hierro 2, 28040, Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Moliner
mesh_terms: D001673:Biodegradation, Environmental; D049930:Chrysopogon / Q000378:metabolism*; D003300:Copper / Q000032:analysis / Q000378:metabolism; D006812:Humic Substances / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism; D015032:Zinc / Q000032:analysis / Q000378:metabolism
chemical_list: D006812:Humic Substances; D012989:Soil Pollutants; D003300:Copper; D015032:Zinc
keywords: Heavy metals; Leonardite humic acid; Mine soil; Phytoextraction; Phytostabilization; Vetiver grass (Chrysopogon zizanioides)