doi:10.1016/j.envpol.2007.06.054

Kinetically defined metal fractions mimic mobility aspects of heavy metals. Abstract Kinetic EDTA and citrate extractions were used to mimic metal mobilization in a soil contaminated by metallurgical fallout. Modeling of metal removal rates vs. time distinguished two metal pools: readily labile (Q M1 ) and less labile (Q M2 ). In citrate extractions, total extractability (Q M1 þ Q M2 ) of Zn and Cd was proportionally higher than for Pb and Cu. Proportions of Pb and Cu extracted with EDTA were three times higher than when using citrate. We observed similar Q M1 /Q M2 ratios for Zn and Cu regardless of the extractant, suggesting comparable binding energies to soil constituents. However, for Pb and Cd, more heterogeneous binding energies were hypothesized to explain different kinetic extraction behaviors. Proportions of citrate-labile metals were found consistent with their short-term, in-situ mobility assessed in the studied soil, i.e., metal amount released in the soil solution or extracted by cultivated plants. Kinetic EDTA extractions were hypothesized to be more predictive for long-term metal migration with depth

Soil tillage to reduce surface metal contamination – model development and simulations of zinc and copper concentration profiles in a pig slurry-amended soil

Long-term applications of organic amendments, such as pig slurry (PS), may represent environmental risk of soil and water pollution by trace metals (TM). Our objective was to examine different soil and manure management scenarios that enhance the long-term agricultural use of soils under repetitive PS applications while avoiding environmental risk. Firstly, we developed a new module for simulating the impacts of soil tillage frequencies in Hydrus-1D. Secondly, we used a previously validated modeling approach to predict the surface accumulation and movement of the TM during the next 100-year in the soil under different PS doses (80 and 40m3ha-1cultivation-1) and tillage frequencies (no-tillage and 20, 10, and 5-year tillage). No-tillage simulations revealed consistent TM surface accumulations, reaching the soil threshold value for Cu in the 0-20cm layer after 86 years of PS amendments at high doses, but in layers 0-5, 0-10, and 5-10cm, this concentration was already reached after 17, 38, and 75 years, respectively. While soil tillage reduced TM concentrations over the top 20cm of the soil profile, it increased their transfer to deeper layers. Periodical soil tillage each 5, 10, and 20 years was found to allow PS applications without reaching the Cu threshold value in soil during 100 years. However, soil solution concentrations of Zn reached the threshold values for groundwater. Therefore, the best manure management practice for the long-term PS disposal with respect to Zn and Cu concentrations in soil is the application of moderate PS rates. © 2014 Elsevier B.V

PHYSICO-CHEMICAL AND PHYSICAL PROPERTIES OF HALLOYSITE RICH SOILS IN GUADELOUPE

In Guadeloupe, under moderate humid climatic conditions (1800 - 3000mm.), hydrolysis of young andesitic parent rock lead to the pedogenesis of 1:1 lattice clay (halloysite) rich soils (Rusty brown soils). But in the old, highly weathered north-eastern part of the island, covered by ferrallitic soils, halloysite equally appears to be the major mineral soil constituent. For the latter soils, in addition to the dominant 1:1 lattice clay, the presence of accessory 2:1 clay minerals has been noted. In these highly impoverished soils, the presence of such 2:1 minerals causes an important variability of physico-chemical properties, in particular the cation exchange properties and the occurence of exchangeable aluminium. Soil water properties of halloysite rich soils show remarkable differences with regard to water retention, total porosity and shrinkage. In addition to their minera1ogica1 nature, the morphology and size of the halloysite particles, as well as their spatial arrangement seem to play a leading part with regard to the soil's physical behaviour

Plant available silicon in bare fallow soils after 90 years of annual supplies of manure, lime and fertilizers.

International audienc

Problemes souleves par la caracterisation, a l'echelle de la parcelle, du statut cationique de sols ferrallitiques de Guadeloupe

National audienc

Approche agro-pedologique des zones pastorales sur calcschistes sedimentaires (Beaufortain-Alpes du Nord). II Repartition des sols et des valeurs d'usage pastoral

National audienceThe originality of pedogenesis on calcschist in the Beaufortain mountain pasture region lies in the homogeneity with respect to the size, form and mineralogical nature of the constituents of the decarbonation residue: mica platelets with fine silt particles. In in situ developed soils, the main evolution observed between the weathering horizon and the soil surface is of a physical nature. The physical breakdown of silt particles takes place concomitantly with the disappearance of the pore system inherited from the weathered rock. In the (B) horizon, a microscopy (pore size ≈ 0.6 μm) becomes visible, which is the result of the microdivided mica particle arrangement (particle size < 6 μm). A low water availability and low hydraulic conductivities in this soil horizon with regard to the C horizon therefore occurs. These data have been presented in the first paper. Such soil structure modification produces pertinent repercussions with respect to pasture vegetation. Significant agronomic constraints thus arise in all areas with a flat topography (plateau, fig 1, table II). The uptake of water and nutritious elements (bases) by the root systems of the pasture cover is impeded as the thickness of the (B) horizon with unfavorable physical properties increases (figs 2, 3). In such an environment with a strong tendency to acidification, soil evolution is highly dependent on agronomic farming intensity, both today and in the past (table II, fig 4). As soon as hill slopes get steeper (solifluxion slopes, fig 5, table III), the superficial water movements and topography become major factors explaining soils and vegetations differentiation, often organized in mosaic distribution patterns (table III, IV). Hence, within the same mountain pasture area, calcareous, acid and hydromorphic soils can be observed, each soil type imposing its own specific farming constraints (table IV).L’originalité de la pédogénèse sur calschistes sédimentaires, en altitude (étage subalpin), réside dans l’homgénéité du résidu de décarbonatation (plaquettes de micas de taille limons fins). Au sein des sols développés en place, la principale évolution qui se manifeste entre l’altérite et la surface du sol, est une microdivision de ces particules limoneuses. Celle-ci s’accompagne d’une disparition du système de macroporosité hérité de la décarbonatation de la roche et de l’apparition, dans l’horizon (B), d’un système de micropores. Il s’ensuit une faible disponibilité de l’eau et une vitesse d’écoulement très faible dans cet horizon par rapport à l’horizon C (1 er partie). Cette organisation du sol liée à la pédogénèse, a des répercussions très significatives sur la végétation prairiale et sa dynamique. Elle représente une contrainte agronomique qui s’exprime surtout en situation de plateau. L’approvisionnement en eau et en éléments nutritifs (bases) par le système racinaire du tapis végétal, est alors limité par l’épaisseur de l’horizon (B) et les risques de dégradation de la valeur fourragère sont maximaux. L’évolution pédogénétique et les potentialités dépendent alors étroitement de l’intensité et des modalités de l’exploitation pastorale actuelle et (ou) passée, seuls facteurs susceptibles d’atténuer et de compenser les effets des propriétés physiques défavorables de la couverture pédologique. Au total, sur les plateaux le paysage pastoral porte d’abord la marque des pratiques agricoles. Inversement, dès que la pente s’accentue (situation de versant de solifluxion), la circulation de l’eau et la topographie deviennent les facteurs prépondérants pour expliquer la différenciation en mosaïque des sols et des végétations et révéler les contraintes spécifiques d’entretien des diverses zones

PROBLEMES SOULEVES PAR LA CARACTERISATION , A L'ECHELLE DE LA PARCELLE, DU STATUT CATIONIQUE DE SOLS FERRALITIQUES DE GUADELOUPE

Sur les sols ferralitiques du domaine expérimental INRA de Duclos (Petit- Bourg, Guadeloupe), le Macroptylium atropurpureum cv Siratro subit divers degrés de toxicité aluminique, d'une parcelle à l'autre, comme à l'intérieur d'une parcelle. Les symptômes répondent à la distribution spatiale du rapport de Kamprath (k=»AI saturation»). Cette variabilité permet la mise en évidence d'une loi de comportement unique k=f(pHKCI) sur une même parcelle. Des parcelles de positions topographiques différentes, montrent des lois différentes, k=f(pHKCI), Ca/CEC=g(pHKCI), CEC=h(Matière organique), en réponse à des nuances de composition minéralogique. Une fois déterminées, ces lois permettent de simplifier le diagnostic du chaulage. Au-delà, plus que les valeurs des variables d'état, les véritables caractéristiques physico-chimiques permanentes d'une unité de sol sont les paramètres de ces lois. ----- Grown on oxisols of I.N.R.A.'s experiment station Duclos (Petit-Bourg, Guadeloupe), Macroptylium atropurpureum cv Siratro reveals various degrees of aluminum toxicity. The symptom distribution on field-plots agrees with the spatial distribution of the Kamprath's ratio (k, «Aluminum saturation»). The soil of the field-plot, showing a tilled layer formed by a homogeneous material, display a single behaviour law : k=f(pHKCt). In order to define lime requirement, based on low costing analysis, three laws are established for different soils units : k=f(pHKCI), CA/CEC=g(pHKCl), CEC=h(O.M. content). The differences between parameters of one law, for different soil units, result from slight mineralogical gradations. More than individual state variables values, the behaviour law parameters values are characteristic of a soil-unit

Approche agro-pedologique des zones pastorales sur calcschistes sedimentaires (Beaufortain- Alpes du nord). I. Caracteres de l'alteration, proprietes hydriques et porales associees

National audienceThe weathering of sedimentary calcschist (calcshales) in the Beaufortain mountain pasture region (fig 1), gives rise to soils containing very high amounts of fine (< 5 μm) micaceous silt particles (fig 2; tables II, III). Pedogenesis on this type of parent rock is characterized by a significant argilization (physical breakdown of mica particles) towards the soil surface (table II), causing a total reorganization of solid particle arrangement and corresponding pore geometry (fig 2.2, 2.4, 2.5). A series of physical methods (table I) is used here in order to describe the origin and evolution of the pore geometry during pedogenesis, starting from the pore system inherited from the parent rock after its decarbonization (fig 2.2 and 2.3). These methods enable the observation and the quantification of the porosity in terms of total pore volume, pore size and pore morphology as well as that aspect concerning continuity of the pores. The pore size ranges from the nm to the mm. Analysis of the pore system and the related soil water behaviour (figs 3, 4, 5; table II) performed in different horizons of a representative soil profile indicates the constraints for local agriculture. On hill slopes the superficial water circulation and topography are major factors explaining soil and vegetation differentiation. Such soil-vegetation-land use interactions will be discussed in a second paper considering typical geomorphological land units.En altitude, l’altération des calcschistes sédimentaires (calcshales) conduit à des sols contenant une teneur élevée en limon fin, de composition minéralogique essentiellement micacée. La pédogénèse se caractérise sur ce type de roche, par une argilisation importante due à une microdivision des micas, vers la surface du sol. Ce phénomène entraîne une profonde réorganisation de la phase solide, de l’espace poral et en fin de compte, conditionne les propriétés hydriques des sols. Dans ce premier texte, un ensemble de méthodes de mesure et d’observation est employé pour décrire l’évolution de la géométrie du système de porosité hérité de la roche, après sa décarbonatation. Cette approche permet de visualiser et de quantifier le volume poral total, la taille, la morphologie et la continuité des pores. La gamme de tailles prise en compte s’étend du nm jusqu’au mm. Grâce aux résultats obtenus, il est possible de comprendre les aspects du fonctionnement hydrique qui conditionnent les relations sol-végétation et qui constituent, par conséquent, un facteur clef pour l’exploitation pastorale. Les propriétés du matériau d’altération perdent de l’importance quand la pente s’accentue; la circulation de l’eau et la topographie deviennent alors prépondérantes pour expliquer la différenciation des sols et des végétations prairiales. Ces interactions seront traitées dans une deuxième partie

Origin, mineralogical behaviour and spatial distribution of 2/1 clay minerals in a ferrallitic soil cover on volcanic parent rock of Guadeloupe

Ferrallitic soils in Guadeloupe, covering the older part of the island of Basse Terre, are derived from andesitic pyroclastic deposits. These often heavy textured clay soils are mainly composed of 1 :1 lattice clay minerals with a halloysitic character. Recently, the local occurence of minor amounts of 2 :1 clays has been reported, showing different degrees of alteration. The aim of this paper is to consider several hypotheses about the origin and the spatial distribution of these 2 :1 clay minerals. Their mineralogical characteristics are studied by X-ray diffraction and ТЕМ. Since the degree of alteration of the 2 :1 minerals is closely related to physico-chemical soil behaviour, understanding their spatial distribution is essential to improve agronomic management.van Oort Folkert, Jaunet Anne-Marie. Origin, mineralogical behaviour and spatial distribution of 2/1 clay minerals in a ferrallitic soil cover on volcanic parent rock of Guadeloupe. In: Proceedings of the 9th international Clay Conference, Strasbourg, 1989. Vol I : Clay-organic interactions. Clay minerals in soils. Strasbourg : Institut de Géologie – Université Louis-Pasteur, 1990. pp. 205-213. (Sciences Géologiques. Mémoire, 85