Mass balance of zinc redistribution during the pedogenesis of a soil developed on a natural geochemical anomaly

Pedogenetic processes that redistribute soil elements over time have been considerably investigated and clearly identified. Nevertheless, the quantification of their respective influences on element redistribution is still poorly known, while soil protection requires extensive knowledge of their long-time depending evolution. The quantitative redistribution of elements is of prime importance in polluted soils, since the long-term environmental hazards depend on their potential mobility and biodisponibility, thus speciation. Among the elements frequently encountered in polluted soils and exhibiting a well-established phytotoxic nature, zinc is of great concern. Nevertheless, pollutions are too recent to observe or even predict the long-term behavior of zinc in polluted soils. An alternative approach is to study paleosoil developed on natural geochemical anomalies. Indeed, such paleosoils display zinc concentrations equivalent to those of polluted soils with the advantage to involve long pedological time of contact between the elements and the different soil phases. Our study aims at quantifying the long-term redistribution of zinc during the pedogenesis of a soil developed upon a natural geochemical anomaly. We first determined zinc speciation both in the parental material and in the solum, then quantified redistribution by mass balance calculations. This approach permits to estimate Zn outputs or inputs in the solum and to quantify its redistribution along the profile and among the different mineral phases

O Serviço de documentação textual e iconografia do Museu Paulista

The essay compares the curatorship's works realized during the decade of 1990 by the actual Department of Textual and Iconographical Documentation of Museu Paulista, responsible for the MP Fund / Permanent File (Fundo MP/Arquivo Permanente), hundreds of collections and textual funds and 50.000 iconography pieces, great part of which are gathered in photographic collections. It shows how the documentation work extrapolates the limits of SVDHICO in order to integrate itself with the group activities of the museum and with other research groups. It also points towards new work methodologies which allow to perform the curatorship in an integrated way with the interdisciplinary research and the culture diffusion.O artigo faz um balanço dos trabalhos de curadoria realizados durante a década de 1990 pelo atual Serviço de Documentação Textual e Iconografia do Museu Paulista, responsável pelo Fundo MP/Arquivo Permanente, centenas de coleções e fundos textuais e 50.000 peças de iconografia, grande parte delas reunidas em coleções fotográficas. Mostra como o trabalho de documentação extrapola os limites do SVDHICO para integrar-se com as atividades de conjunto do Museu e com outros grupos de pesquisa. Aponta também para novas metodologias de trabalho com imagens que permitem realizar a curadoria de forma integrada à pesquisa interdisciplinar e à difusão cultural

Zn isotopic fractionation caused by sorption on goethite and 2-Lines ferrihydrite

International audienc

Contrasting isotopic signatures between anthropogenic and geogenic Zn and evidence for post-depositional fractionation processes in smelter-impacted soils from Northern France

Zinc isotopes have been studied along two smelter-impacted soil profiles sampled near one of the largest Pb and Zn processing plants in Europe located in northern France, about 50 km south of Lille. Mean delta Zn-66 values along these two soil profiles range from +0.22 +/- 0.17 parts per thousand (2 sigma) to +0.34 +/- 0.17 parts per thousand (2 sigma) at the lowest horizons and from +0.38 +/- 0.45 parts per thousand (2 sigma) to +0.76 +/- 0.14 parts per thousand (2 sigma) near the surface. The delta Zn-66 values in the lowest horizons of the soils are interpreted as being representative of the local geochemical background (mean value +0.31 +/- 0.38 parts per thousand), whereas heavier delta Zn-66 values near the surface of the two soils are related to anthropogenic Zn. This anthropogenic Zn occurs in the form of franklinite (ZnFe2O4)-bearing slag grains originating from processing wastes at the smelter site and exhibiting delta Zn-66 values of +0.81 +/- 0.20 parts per thousand (2 sigma). The presence of franklinite is indicated by EXAFS analysis of the topsoil samples from both soil profiles as well as by micro-XANES analysis of the surface horizon of a third smelter-impacted soil from a distant site. These results indicate that naturally occurring Zn and smelter-derived Zn exhibit significantly different delta Zn-66 values, which suggests that zinc isotopes can be used to distinguish between geogenic and anthropogenic sources of Zn in smelter-impacted soils. In addition to a possible influence of additional past sources of light Zn (likely Zn-sulfides and Zn-sulfates directly emitted by the smelter), the light delta Zn-66 values in the surface horizons compared to smelter-derived slag materials are interpreted as resulting mainly from fractionation processes associated with biotic and/or abiotic pedological processes (Zn-bearing mineral precipitation, Zn complexation by organic matter, and plant uptake of Zn). This conclusion emphasizes the need for additional Zn isotopic studies before being able to use Zn isotopes to trace sources and pathways of this element in surface environments