Journal of Hazardous Materials 231–232 (2012) 88–97 Contents lists available at SciVerse ScienceDirect Journal of Hazardous Materials j our na l ho me p age: www.elsevier.com/locate/jhazmat Distribution of bacteria and nitrogen-cycling microbial communities along constructed Technosol depth-profiles Farhan Hafeez a , Aymé Spor a , Marie-Christine Breuil a , Christophe Schwartz b , Fabrice Martin-Laurent a,∗ , Laurent Philippot a a INRA, UMR 1347 Agroécologie, F-21065 Dijon cedex, France b INRA/INPL, Nancy-Université, UMR 1120 Sols et Environnement, BP 172, F-54505 Vandœuvre-lès-Nancy cedex, France h i g h l i g h t s ◮ Microbial structure, abundance and activity were studied along Technosol profiles. ◮ Each layer showed distinct community with diversity decreasing with depth. ◮ Technosols exhibit decrease in microbial activity and abundance with depth. ◮ Nitrification in Technosols is related to the abundance of ammonia-oxidizers. ◮ Technosol properties drive the activity and abundance of N-cycling communities. a r t i c l e i n f o Article history: Received 21 February 2012 Received in revised form 11 May 2012 Accepted 20 June 2012 Available online 1 July 2012 Keywords: Soil depth Contaminated soils Denitrification Nitrification Ammonia-oxidation Quantitative PCR a b s t r a c t Technosol construction through assemblage of treated soil and recycled wastes is an innovative option for the restoration of degraded lands and re-use of industrial wastes. Recent studies have evidenced that Technosols could support soil functions such as primary production but the knowledge about other ecosystemic services, such as nutrient cycling, is limited. We investigated how the total bacterial com- munity and key functional microbial communities involved in nitrogen cycling were influenced by the depth and type of Technosol. We found that despite being artificially constructed, Technosols exhibited a gradual change in microbial activity and abundance along the soil profile. Both nitrification and deni- trification rates decreased with increasing depth as previously observed in other soil systems. Potential denitrification and nitrification were correlated with Technosol physico-chemical properties but also with abundances of nirS denitrifiers and bacterial amoA gene, respectively. The correlation between nitrification rates and bacterial ammonia-oxidizers suggests that bacteria are driving nitrification in Technosols. A-RISA fingerprints showed a distinct community structure along different Technosol layers. Technosol properties affected denitrification strongly than nitrification underlining the importance of better understanding the microbial communities in Technosols to maximize their potential for nutrient cycling, an essential ecosystem function. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Soil degradation has significantly affected the world’s soil resources over the past century and has become one of the great- est socioeconomic and environmental problems facing mankind [1,2]. Indeed, soil is a non-renewable resource and the alteration of soil quality can result in the decrease of its capacity to perform ecosystem services such as plant production, nutrient cycling, and ∗ Corresponding author at: INRA, Université de Bourgogne, UMR 1229 Microbi- ologie du Sol et de l’Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cedex, France. Tel.: +33 3 80 69 34 06; fax: +33 3 80 69 32 24. E-mail address: fmartin@dijon.inra.fr (F. Martin-Laurent). filtering, which has tremendous implications for both the agricul- ture as well as the environment [3–10]. Degradation of soil arises from erosion by wind or water, physical deterioration but also from chemical deterioration by pollutants. Human activities such as agri- culture, urbanization and industrialization are the major causes of soil contamination by pollutants. Among the different strategies used to restore the contaminated lands, construction of Technosols over the polluted sites is an inno- vative technology for ecological reclamation of the contaminated lands. This in-place restoration of the polluted lands is based on the assemblage of treated soil, recycled waste and industrial by- products, which are formulated and staked to build a new soil profile at the contaminated site [11,12]. Along with soil restora- tion, construction of Technosols can also be an efficient technique to 0304-3894/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jhazmat.2012.06.041