title: Radical change of Zn speciation in pig slurry amended soil: Key role of nano-sized sulfide particles.
abstract: Spreading livestock manure as fertilizer on farmlands is a widespread practice. It represents the major source of heavy metal(loid)s (HM) input in agricultural soils. Since zinc (Zn) is present at high concentrations in manure, it poses special environmental concerns related to phytotoxicity, groundwater contamination, and introduction in the food chain. Therefore, investigations on the fate and behavior of manure-borne Zn, when it enters the soil environment, are necessary to predict the environmental effects. Nevertheless, long-term field studies assessing Zn speciation in the organic waste matrix, as well as within the soil after manure application, are lacking. This study was designed to fill this gap. Using SEM-EDS and XAS analysis, we reported the following new results: (i) ZnS made up 100% of the Zn speciation in the pig slurry (the highest proportion of ZnS ever observed in organic waste); and (ii) ZnS aggregates were about 1-μm diameter (the smallest particle size ever reported in pig slurry). Moreover, the pig slurry containing ZnS was spread on the soil over an 11-year period, totaling 22 applications, and the resulting Zn speciation within the amended soil was analyzed. Surprisingly, ZnS, i.e. the only species responsible for a nearly 2-fold increase in the Zn concentration within the amended soil, was not detected in this soil. Based on SEM-EDS and XAS observations, we put forward the hypothesis that Zn in the pig slurry consisted of nano-sized ZnS crystallites that further aggregated. The low stability of ZnS nanoparticles within oxic and complex environments such as the studied soil was the key explanation for the radical change in pig slurry-borne Zn speciation after long-term amendments.
authors.affiliation: Department of Sanitary and Environmental Engineering, Federal University of Santa Maria (UFSM), 97105-900 Santa Maria, RS, Brazil; Department of Hydraulics and Sanitation, Federal University of Parana (UFPR), 81531-980 Curitiba, PR, Brazil. Electronic address: formentini@gmail.com.
authors.forename: Thiago Augusto
authors.initials: TA
authors.lastname: Formentini
authors.affiliation: CIRAD, UPR Recyclage et risque, 18524 Dakar, Senegal; CIRAD, UPR Recyclage et risque, F-34398, Montpellier, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Legros
authors.affiliation: Department of Hydraulics and Sanitation, Federal University of Parana (UFPR), 81531-980 Curitiba, PR, Brazil.
authors.forename: Cristovão Vicente Scapulatempo
authors.initials: CVS
authors.lastname: Fernandes
authors.affiliation: Environmental Engineering Program, Regional University of Blumenau (FURB), 89030-000 Blumenau, SC, Brazil.
authors.forename: Adilson
authors.initials: A
authors.lastname: Pinheiro
authors.affiliation: Aix Marseille Univ, CNRS, IRD, Coll France, CEREGE, Aix-en-Provence, France.
authors.forename: Maureen
authors.initials: M
authors.lastname: Le Bars
authors.affiliation: Aix Marseille Univ, CNRS, IRD, Coll France, CEREGE, Aix-en-Provence, France.
authors.forename: Clément
authors.initials: C
authors.lastname: Levard
authors.affiliation: CAPES Foundation, Ministry of Education of Brazil, 70040-020 Brasilia, DF, Brazil.
authors.forename: Fábio Joel Kochem
authors.initials: FJK
authors.lastname: Mallmann
authors.affiliation: UNOESC, PO Box 250, 89620-000, Campos Novos, SC, Brazil.
authors.forename: Milton
authors.initials: M
authors.lastname: da Veiga
authors.affiliation: CIRAD, UPR Recyclage et risque, F-34398, Montpellier, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Doelsch
mesh_terms: D000383:Agriculture / Q000379:methods; D000818:Animals; D008372:Manure; D053768:Metal Nanoparticles / Q000032:analysis / Q000737:chemistry; D019216:Metals, Heavy / Q000032:analysis / Q000737:chemistry*; D010316:Particle Size; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis; D013440:Sulfides / Q000032:analysis / Q000737:chemistry*; D034421:Sus scrofa; D013552:Swine; D015032:Zinc / Q000032:analysis / Q000737:chemistry*; D017967:Zinc Compounds / Q000032:analysis / Q000737:chemistry*
chemical_list: D008372:Manure; D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D013440:Sulfides; D017967:Zinc Compounds; D015032:Zinc; C031238:zinc sulfide
keywords: Agricultural recycling; Environmental impact; Microscopy; Spectroscopy; Trace elements