Chapitre 8 : Pharmacologie vasculaire

ISBN 978276062092

A Technosol as archives of organic matter related to past industrial activities

To better understand formation, functioning and evolution of a Technosol developing on a former settling pond of iron industry under forest cover, organic matter (OM) of layers along the soil profile was investigated. Spectroscopic and molecular analyses of extractable OM gave information on OM origin and state of preservation. In the surface layer, OM fingerprints indicated fresh input from vegetation while they revealed well preserved anthropogenic compounds related to industrial processes in deeper layers. OM variability and distribution according to the layers recorded deposition cycles of industrial effluents into the pond. Thus, the Technosol can be considered as archives of past industrial activities. The preservation of anthropogenic OM could be connected with mineralogy, high metal contents and particular physical properties of the Technosol

Are Technosols developing on former settling pond comparable to natural soils?

Pedogenesis of soils developing on human-made substrates is of interest because of the increase of soil anthropisation. Little knowledge is available on these technosols and a better understanding of their evolution is needed and of the fate of the potentially polluting materials they contain. Parent material origin may strongly influence their formation and functioning and the governing processes have to be elucidated. They may be specific or similar to those occurring in natural soils. Our objective is the investigation of a technosol developing on a former settling pond of the steel industry

Combined effects of ionic strength and enzymatic pre-treatment in thermal gelation of peanut proteins extracts

International audiencePeanut proteins are mostly composed of arachins and conarachins, globular proteins that can form gels under thermal denaturation or enzymatic treatment. We explore here how ionic strength (0.5 M or 0.8 M) and gelation process (a thermal treatment preceded or not by an enzymatic pre-treatment) affect peanut protein gel properties. Gel formation and final properties are characterized by rheology, and gel structure by confocal microscopy. We show that the ionic strength imposed during protein extraction determines the arachins/conarachins ratio, and that conarachins-rich samples give stronger gels, which is attributed to their higher content in free thiol groups and lysine residues. The gel storage modulus exhibited a power-law dependence with the protein concentration, which exponent depends on the gelation process. Rheological results, together with confocal microscopy imaging, showed that an enzymatic pre-treatment results in denser structures

Early pedogenesis of a Technosol developing on iron industry deposits

International audienceAs a result of increasing soil anthropisation, large surface areas covered by anthropogenic materials are submitted to environmental factors (e.g. climate, organisms). Pedogenesis of the developing Technosols is often characterized by an intense and rapid weathering (1, 2, 3). However, the nature, localization, and extent of the pedogenetic processes occurring in Technosols are still little known. To assess the soil formation on purely anthropogenic parental materials, a former settling pond of iron industry sludge colonized by vegetation since ca. 50 years was chosen. The soil is composed of contrasted layers, and an organic layer has developed at the surface (4, 5, 6). Composition, mineral and organic components and structure of the soil were studied as tracers of the material origin and indicators of early pedogenetic processes. Also, historical records regarding the industrial operations were analyzed. Twelve layers were sampled in the first two meters of the profile. Mineralogy was determined with XRD, IR, Mössbauer spectroscopy, SEM and TEMEDS. Spectroscopic and molecular analyses were carried out on solvent extractable organic matter. Thin sections were prepared for some layers. Results showed a stratification of the soil profile resulting from successive sludge supplies. Composition, mineralogy, and structure of the layers of the Technosol were derived from the industrial raw materials and processes. Elemental composition reflected the enrichment in volatile elements, and organic analyses the dumping of oil and combustion by-products. Part of the mineral phases was inherited from raw materials, and others resulted from the industrial processes (e.g. high temperature phases). Pedogenetic processes were obvious with the development of an organomineral horizon. In the deeper layers, analysis of microstructure and mineralogy revealed physical (cracks, solute movements) and chemical processes (dissolution, precipitation). These phenomena occurred primarily in cracks and at the interfaces between two layers. Also, roots, which have colonized the whole profile, and developed preferentially in these areas, have induced changes in their rhizosphere (modification of porosity and metal extractability). In conclusion, the Technosol results from successive steps of pedogenesis, driven firstly by drying-wetting cycles and changes of physico-chemical conditions induced by the climatic factor, and finally by biological processes in relation with root development