title: Stabilising metal(loid)s in soil with iron and aluminium-based products: microbial, biochemical and plant growth impact.
abstract: Four iron and aluminium-based products, including red mud (RM), hematite (Fe2O3), an iron-rich water treatment residual (Fe-WTR) and amorphous Al hydroxide (Al-OH), were evaluated for their effectiveness at stabilising As and heavy metals (i.e. Cd, Cu, Pb, Zn) in a circumneutral contaminated soil [As (2105 mg kg(-1)), Cd (18 mg kg(-1)), Cu (264 mg kg(-1)), Pb (710 mg kg(-1)), Zn (522 mg kg(-1))]. Treatment impacts on soil microbial and biochemical features (i.e. microbial biomass-C, microbial counts, 16S rRNA PCR-TTGE of culturable bacteria, dehydrogenase, urease and β-glucosidase activity, Biolog derived parameters-AWCD and richness) as well as bean (Phaseolus vulgaris) and wheat (Triticum vulgare) growth were also assessed. After 6 months equilibration, all the amendments (application rate 3% w/w) but RM reduced labile As while only Al-OH reduced the concentration of water-soluble heavy metals. Despite the highest bioavailability of contaminants, most of the soil microbial and biochemical features monitored (i.e. microbial biomass-C, total bacterial counts, dehydrogenase activity and AWCD) were significantly higher in the RM-soil. Bean germination was completely inhibited in RM-soil while wheat growth was similar to that of the control. The Al-OH treatment was best overall, promoting microbial abundance, diversity and activity while increasing bean and wheat growth and reducing As accumulated in plant shoots. Results suggest that Al-OH is a suitable candidate for field evaluations while the use of RM in the remediation of circumneutral or subalkaline contaminated soils should be reconsidered.
authors.affiliation: Sezione di Scienze e Tecnologie Ambientali e Alimentari (S.T.A.A.), Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100 Sassari, Italy. Electronic address: ggarau@uniss.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Garau
authors.affiliation: Sezione di Scienze e Tecnologie Ambientali e Alimentari (S.T.A.A.), Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100 Sassari, Italy. Electronic address: silvetti@uniss.it.
authors.forename: Margherita
authors.initials: M
authors.lastname: Silvetti
authors.affiliation: Sezione di Scienze e Tecnologie Ambientali e Alimentari (S.T.A.A.), Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100 Sassari, Italy. Electronic address: castaldi@uniss.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Castaldi
authors.affiliation: Sezione di Scienze e Tecnologie Ambientali e Alimentari (S.T.A.A.), Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100 Sassari, Italy. Electronic address: emele@uniss.it.
authors.forename: Elena
authors.initials: E
authors.lastname: Mele
authors.affiliation: Sezione di Scienze e Tecnologie Ambientali e Alimentari (S.T.A.A.), Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100 Sassari, Italy. Electronic address: pdeiana@uniss.it.
authors.forename: Pietrino
authors.initials: P
authors.lastname: Deiana
authors.affiliation: Sezione di Scienze e Tecnologie Ambientali e Alimentari (S.T.A.A.), Dipartimento di Agraria, University of Sassari, Viale Italia 39, 07100 Sassari, Italy. Electronic address: sadeiana@uniss.it.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Deiana
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry* / Q000633:toxicity; D001151:Arsenic / Q000737:chemistry*; D058491:Bacterial Load; D018533:Biomass; D005290:Ferric Compounds / Q000737:chemistry* / Q000633:toxicity; D007501:Iron / Q000737:chemistry* / Q000633:toxicity; D019216:Metals, Heavy / Q000737:chemistry*; D027805:Phaseolus / Q000187:drug effects / Q000254:growth & development; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000737:chemistry*; D014908:Triticum / Q000187:drug effects / Q000254:growth & development
chemical_list: D005290:Ferric Compounds; D019216:Metals, Heavy; D012336:RNA, Ribosomal, 16S; D012989:Soil Pollutants; C000499:ferric oxide; D000536:Aluminum Hydroxide; D007501:Iron; D001151:Arsenic
keywords: Arsenic-polluted soil; Iron and aluminium-based products; Plant growth; Sequential extraction; Soil enzyme activity; Soil microbial community