Caractérisation des sols urbains formés par remblaiement : approche pédologique intégrant l'étude de la fraction grossière

Abstract

This research project studied the application of a pedological approach to improve the characterization of urban anthropogenic soils. This approach also included the study of the coarse size fraction of the soil and its influence on the soil’s content in metallic elements. The first phase of the project was performed on three soil profiles from an urban contaminated site. The profiles were characterized with pedo-morphological, physicochemical and mineralogical parameters. Sixteen anthropogenic were identified among the three profiles and were made of heterogeneous materials, namely construction debris, slag and rock fragments. The profiles were characterized by large contents of coarse debris, slightly differences in structure, and low contents of organic carbon. Alkaline pH values measured in the anthropogenic horizons were related to total carbonate content. The distributions of metallic elements with depth in the profiles were heterogeneous. Calcite and chlorite appear to be indicators of anthropogenic minerals. The distribution of these parameters in the profiles was strongly related to the sequence of horizons with depth and to the nature of the constitutive materials of each horizon. According to the World Reference Base for Soil Resources (WRB), the studied profiles were classified as urbic garbic Technosols. The second phase of the project showed that the coarse fraction was a significant mass proportion of the studied soils. Moreover, the distribution of metals (Cu, Mn, Pb, and Zn) between fine and coarse fractions was related to the nature of the metals analyzed. The contributions to the mass total of metallic elements from the coarse fractions of anthropogenic horizons were minimal for Pb and Zn, but were maximal for Cu and Mn. Therefore, the coarse fraction should always be considered for the representative assessment of the total contents of metals in urban anthropogenic soils.

Date	4 Jan 2012
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Jean-Sébastien Dubé (Supervisor)