Relevance of soil mapping criteria to predict geochemical background of trace elements in soils from local to regional scales.

Poster (2006)

Among natural factors driving the soil content in metallic trace elements (MTE), the geochemical background is often deemed as a sound base for the detection of contaminations. Numerous studies have shown ... [more ▼]

Among natural factors driving the soil content in metallic trace elements (MTE), the geochemical background is often deemed as a sound base for the detection of contaminations. Numerous studies have shown the difficulties to take into account the multi-dimensionnality of the spatial variability of most soil properties. As far as a detailed soil map is available for Belgium, the relevance of its information was investigated at various spatial scales in the Walloon Region (Southern Belgium), from the plot to the entire region, to evaluate the feasibility of a multi-scale mapping of geochemical background. A database of soil profiles (gathering both agricultural and forest soils) was used to analyse the relationships between the MTE total content (measured after HF-HClO4-HCl dissolution) and other general characteristics such as pH, Total Organic Carbon content (TOC), Particle Size Distribution (PSD), and cationic exchange capacity (CEC). The factors of MTE spatial distribution inside and between solums were investigated through multivariate statistical analysis. The spatial dependence of these factors was then studied over plot, field, farm, county and region scales, and compared to the spatial structures of the soil map parameters. At the solum level, strong relationships between most of the studied MTE were found, as well as between stone charge and fine earth contents. The PSD is the main driving factor of MTE content in non-carbonated soils, whatever the land use. When considering soil associations, such as catenas, the slope redistribution processes must be taken into account. However, the PSD remains the main driving factors and, as the soil map contains information about that property (mainly the textural class and the profile development), a cartography of the geochemical background based on the use of the soil map and pedotransfer functions or regression models appears relevant. At the regional scale, some long-range spatial structures could be identified. These result mainly from the geological structure of the Walloon region, where the lithological zonation is rather clearly marked. The soil map (texture and nature of stone charge) appears relevant at that scale too but does need a generalization process and fails however to differenciate the intra-type soil spatial variability. Some basic processes of integration of point measurements and qualitative information have been explored. They should be further investigated in the future. [less ▲]

EVALUATION DES RESTAURATIONS DE PELOUSES CALCICOLES EN BELGIQUE : STRUCTURE SPATIALE, DIVERSITE BOTANIQUE ET CONDITIONS DE SOL

Conference (2006)

Contribution to the evaluation of soil quality around the Naivasha lake (Kenya).

Poster (2005, September)

Termites, termitières et bioturbation en région de Cantanhez (Guinée-Bissau).

Report (2005)

Comparaison de différentes méthodes de détermination des teneurs en éléments majeurs et traces dans les sols.

in Actes des 8emes JNES (2004, October)

Intérêt d’une stratification pédologique pour la constitution de référentiels régionaux sur les teneurs en éléments traces métalliques dans les sols de Wallonie.

in Actes du Colloque "Terre wallonne - humains admis" (2004)

A reference soil system for the monitoring of soil nutrient status and metallic trace elements contaminations in agricultural soils.

Conference (2004)

Among other soil characteristics, those related to the nutrient status and the content in metallic trace elements (MTE) originate from both natural factors and land management. A methodological framework ... [more ▼]

Among other soil characteristics, those related to the nutrient status and the content in metallic trace elements (MTE) originate from both natural factors and land management. A methodological framework has thus been set up to evaluate the importance of natural driving factors -the so-called pedo-geochemical background- of the spatial distribution of mineral elements in soils and also to compare the current levels of MTE content in agricultural soils with natural values. References for natural, typical, and suspicious values are stated in a Reference Soil System (RSS) which is based on the identification of relationships between geology, relief, and soil, and on the consideration of soil volumes. It integers the land cover and also takes into account the spatial dependance between measurement points in order to estimate the change detection sensibility. Thanks to a comparison-based methodology, to the existence of a detailed soil map, and to the integration of various spatial representation techniques, an image of the state of the soils has been drawn and can serve as a reference for the prediction and the interpretation of point values, for the evaluation of a particular land utilization type, and as a base for the monitoring of soil quality. The reference values about natural and usual content in MTEs for various soil horizons that are proposed reveal especially a relatively weak level of contamination for agricultural soils. [less ▲]

Eléments traces métalliques dans les sols. Contribution à l'étude de leur déterminisme spatial en Région limoneuse belge.

Doctoral thesis (2003)

The natural background levels of metallic trace elements (MTEs) in cultiva-ted soils should be known in order (i) to understand the processes in which MTEs are involved and (ii) settle a reference system ... [more ▼]

The natural background levels of metallic trace elements (MTEs) in cultiva-ted soils should be known in order (i) to understand the processes in which MTEs are involved and (ii) settle a reference system dedicated to the the ap-praisal of agricultural practices, to the detection of contaminations, or to the time-course follow-up of regional values. A methodological framework has thus been set up to evaluate the importance of natural driving factors, the pe-dogeochemical background, of the spatial distribution of MTEs in soils and also to compare the current levels of MTEs content in agricultural soils from the Loamy Region with natural values. As main results from the study of parent materials, (i) lithological units are now characterized with element content signatures, (ii) the prominent part of clay, total iron, and total aluminium contents as driving factors of the content in MTEs has been measured, and (iii) the geographical homogeneity as well as the absence of spatial continuity of the cover loessic parent material have been showed up. The relations between MTEs and driving variables have been confirmed through the study of the influences of pedogenesis factors on the vertical and lateral differenciations of MTEs content in soils. It was also demonstrated that taking into account the natural volumes of soils when sam-pling facilitates the interpretation of the results and allows finer estimations of the MTEs content, even in homogeneous context. The reference values about natural and usual content in MTEs for various soil horizons that are proposed reveal a relatively weak level of man-made contamination in the Loamy Re-gion. It has also been shown that a regional reference system dedicated to the detec-tion of local contaminations gains in relevance as it integers ancillary datas as well as the local specificities of small natural regions. The spatial variability of MTEs content has been evaluated through various cartographic approaches which led to the conclusion that the Soil Map of Belgium is an extremely worthy document for geochemical mapping. [less ▲]

Contribution à la caractérisation de la distribution spatiale des teneurs en éléments traces métalliques dans les sols en région limoneuse belge

in Actes des 7ème Journées nationales de l'étude des sols (2002)

Importance of pedogenic factors in the spatial distribution of some soil properties in the Belgian loess belt: some loess-substratum contacts.

in Degryse, Patrick; Sintubin, Manuel (Eds.) Contributions to the Geology of Belgium and Northwest Europe. Proceedings of the first Geologica Belgica International Meeting (2002)