Micropedology to reveal pedogenetic processes in Technosols

Françoise Watteau,Christophe Schwartz,Jean Louis Morel,Hermine Huot,Frederic Rees,Geoffroy Séré,Jean Claude Begin

doi:10.3232/sjss.2018.v8.n2.02

Abstract

Technosols are characterized by the presence of mineral and organic parent materials of technogenic origin (e.g. agricultural or urban wastes, industrial by-products, building materials, transported natural materials). In view of the continual increase of such man-made soils, there is a true need of understanding their functioning and evolution. Micropedology, <em>i.e.</em> morphological and analytical characterization of pedofeatures on soil sections, appears as a relevant approach to take into account the diversity and the specificity of Technosols in the knowledge of their pedogenetic processes. Micropedology was investigated at microscopic and submicroscopic scale on four Technosols. Therefore, it determined specific features of anthropogenic constituents allowing <em>in situ</em> monitoring until the early stages of Technosol pedogenesis. Organic matter dynamics, soil porosity evolution, impact of faunal activity or hydric conditions on Technosol structure were investigated. Moreover, as Technosol components and deposition modes are diverse, one can expect numerous interfaces. In that way, micropedology appeared particularly well adapted to study these local interfaces as sites of favoured pedogenesis. Supplemented with overall physico-chemical soil analyses, characterization of Technosol pedogenic features using micropedology improves the understanding of their functioning and evolution. In addition, according to the environmental context, such data also give useful information for the Technosol management.

Highlights

Technosols are characterized by a significant presence of mineral and organic materials of technogenic origin
We present here the contribution of micropedology to the understanding of Technosol formation and functioning based on the study of 4 different Technosols, with varying parent materials, impact of human activities, vegetation cover and age
Four contrasted Technosols were chosen to illustrate the diversity of such anthropogenic soils: 1. a Constructed Technosol, i.e. Spolic Garbic Hydric Technosol (Calcaric) (IUSS Working Group 2015), comprising from top to bottom : i) green-waste compost horizon (10 cm) from urban trees and grass cuttings, ii) mixture (1:1 v/v) of paper-mill sludge and thermally treated industrial material extracted from a former coking plant (80 cm), and iii) pure papermill sludge (25 cm); this Technosol has been implemented on field tests in 2003 at the GISFI experimental station in the east of France

Summary

Introduction

Technosols are characterized by a significant presence of mineral and organic materials of technogenic origin They have been integrated as a reference in 2006 in the World Reference Base of Soil Resources (IUSS Working Group WRB 2006) at the initiative of the Working Group IUSS SUITMA (Soils of Urban, Industrial, Traffic, Mining and Military Areas). Their diversity, their potential contamination and the significant increase in their presence in the territories justify characterizing their functioning and evolution (Prokof’eva and Poputnikov 2010; Morel et al 2014). Description of soil components or features often helped to identify processes involved in soil evolution during anthropization

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Conclusion