Increased zinc and copper availability in organic waste amended soil potentially involving distinct release mechanisms * Marie Tella a, b , Matthieu N. Bravin c , Laurent Thuri  es c , Patrick Cazevieille a , Claire Chevassus-Rosset a , Blanche Collin b, d , Perrine Chaurand b , Samuel Legros a , Emmanuel Doelsch a, * a CIRAD, UPR Recyclage et risque, F-34398, Montpellier, France b Aix-Marseille Univ., CNRS, IRD, CEREGE UMR 7330, F-13545, Aix en Provence cedex 4, France c CIRAD, UPR Recyclage et risque, F-97408, Saint-Denis, R eunion, France d CEA, IBEB, Laboratory of Microbial Ecology of the Rhizosphere and Extreme Environments, Saint-Paul-lez-Durance, F-13108, France article info Article history: Received 21 September 2015 Received in revised form 21 January 2016 Accepted 25 January 2016 Available online xxx Keywords: Bioavailability Metals Municipal solid waste compost Pig manure Sewage sludge abstract This study aimed at determining the fate of trace elements (TE) following soil organic waste (OW) application. We used a unique combination of X-ray absorption spectroscopy analyses, to determine TE speciation, with incubation experiments for in situ monitoring of TE availability patterns over a time course with the technique of the diffusive gradients in thin films (DGT). We showed that copper (Cu) and zinc (Zn) availability were both increased in OW-amended soil, but their release was controlled by distinct mechanisms. Zn speciation in OW was found to be dominated by an inorganic species, i.e. Zn sorbed on Fe oxides. Zn desorption from Fe oxides could explain the increase in Zn availability in OW- amended soil. Cu speciation in OW was dominated by organic species. Cu release through the miner- alization of organic carbon from OW was responsible for the increase in Cu availability. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction The world population has grown substantially over the past century, while becoming more urban. Waste production has in turn risen tenfold and is expected to double again by 2025 (Hoornweg et al., 2013). There is now a global consensus on the necessity to recycle resources to ensure sustainable development (Lehmann, 2013; Schiermeier, 2013). Organic wastes (OW) can be effectively recycled by spreading them on cultivated soils, with many benefi- cial effects, such as: (i) improving the soil physical properties; (ii) providing major nutrients, thereby reducing the use of inorganic fertilizers, and (iii) improving soilborne microflora and fauna ac- tivity by providing organic carbon. These advantages should be assessed together with the potential (eco)toxicological impacts due to the presence of trace elements (TEs) and other contaminants in OW. Many studies have highlighted that OW application in crop fields can drastically boost soil TE levels (Belon et al., 2012; Hargreaves et al., 2008; McBride, 2003; Nicholson et al., 2003). Zinc (Zn) and copper (Cu) account for the highest TE inputs in agricultural soils in many countries. Livestock manure is always identified as the major source of these TEs (Belon et al., 2012). Although the presence of TEs in OW has been demonstrated in many studies, major critical knowledge gaps must be overcome to be able to predict the fate of these potentially toxic compounds following OW application. The first major limitation is the lack of speciation data on TEs in OW. To date, most results concerning TE speciation in OW are inconsistent due to several factors. First, OW are complex matrices composed of different organic and/or inor- ganic phases (solid and liquid for manure) (Tella et al., 2013). Sec- ond, there is still no fully reliable benchmark method available to study TE speciation in such complex materials. Chemical extraction methods are often used but are criticized due their lack of clear chemical selectivity and the variability in the results obtained ac- cording to the protocols used (Doelsch et al., 2006b, 2008; Romeo et al., 2014). In order to overcome this problem, X-ray absorption spectroscopy (XAS) has been used to describe the speciation of target elements. XAS is sensitive to the oxidation state as well as the * This paper has been recommended for acceptance by B. Nowack. * Corresponding author. E-mail address: doelsch@cirad.fr (E. Doelsch). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol http://dx.doi.org/10.1016/j.envpol.2016.01.077 0269-7491/© 2016 Elsevier Ltd. All rights reserved. Environmental Pollution 212 (2016) 299e306