High cadmium concentrations in Jurassic limestone as the cause for elevated cadmium levels in deriving soils: a case study in Lower Burgundy, France

Cadmium (Cd) is a highly toxic element and its presence in the environment needs to be closely monitored. Recent systematic surveys in French soils have revealed the existence of areas in eastern and central France, which show systematically high cadmium concentrations. It has been suggested that at least part of these anomalous levels are of natural origin. For the Lower Burgundy area in particular, a direct heritage from the Jurassic limestone bedrock is highly suspected. This potential relationship has been studied in several localities around Avallon and this study reports new evidence for a direct link between anomalously elevated cadmium contents of Bajocian and Oxfordian limestone and high cadmium concentrations in deriving soils. Soils in this area show cadmium concentrations generally above the average national population values, with contents frequently higher than the ‘upper whisker' value of 0.8μgg−1 determined by statistical evaluation. In parallel, limestone rocks studied in the same area exhibit cadmium concentrations frequently exceeding the mean value of 0.030-0.065μgg−1 previously given for similar rocks by one order of magnitude, with a maximum of 2.6μgg−1. Mean ratios between the cadmium concentrations of limestone bedrock and deriving soils (Cdsoil/Cdrock), calculated for different areas, range from 4.6 to 5.7. Calculations based on the analyses of both soils from a restricted area and fragments of bedrock sampled in the immediate vicinity of high-concentration soils are around 5.5-5.7. Cdsoil/Cdrock is useful in determining the potential of soils in Lower Burgundy to reflect and exacerbate the high concentrations of cadmium present in parent bedrock

Origin of high Zn contents in Jurassic limestone of the Jura mountain range and the Burgundy: evidence from Zn speciation and distribution

In order to better understand the origin and enrichment mechanisms leading to elevated Zn concentrations in Jurassic limestone of the Jura mountain range (JMR) and the Burgundy (B), we investigated four locations of Bajocian age (JMR: Lausen-Schleifenberg, Gurnigel; B: Vergisson-Davayé, Lucy-le-Bois) and two locations of Oxfordian age (JMR: Dornach, Pichoux) for their Zn distribution and speciation. Measurements of the acid-extractable and bulk Zn contents showed that Zn is stratigraphically and spatially heterogeneously distributed, in association with permeable carbonate levels. Up to 3,580 and 207mg/kg Zn was detected in Bajocian and Oxfordian limestone, respectively, with numerous limestone samples having Zn contents above 50mg/kg. Using X-ray absorption near edge structure spectroscopy and micro-X-ray fluorescence spectrometry, the speciation and micro-scale distribution of Zn was investigated for selected limestone samples. In Bajocian limestone sphalerite and/or Zn-substituted goethite and a minor fraction of Zn-bearing carbonates were identified. In contrast, Zn-bearing carbonates (Zn-substituted calcite and hydrozincite) were accounting for most of the total Zn in Oxfordian limestone. The micro-scale distribution of Zn for Bajocian and Oxfordian limestone was however similar with localized Zn-rich zones in the limestone cement and at the rim of oolites. The stratigraphic sporadicity and microscale heterogeneity of the Zn distribution together with the Zn speciation results point to a hydrothermal origin of Zn. Occurence of Zn-goethite is probably linked to the oxidative transformation of framboidal pyrite and hydrothermal sphalerite in contact with meteoritic waters. Difference in speciation between Bajocian limestone and Oxfordian limestone may be related to differences in rock permeability and/or to various hydrothermal events. Isotopic dating of the different mineralizations will be needed to decipher differences in Zn speciation and the precise chronology of hydrothermal episode

The environmental setting of Epipalaeolithic aggregation site Kharaneh IV

The archaeological site of Kharaneh IV in Jordan's Azraq Basin, and its relatively near neighbour Jilat 6 show evidence of sustained occupation of substantial size through the Early to Middle Epipalaeolithic (c. 24,000 - 15,000 cal BP). Here we review the geomorphological evidence for the environmental setting in which Kharaneh IV was established. The on-site stratigraphy is clearly differentiated from surrounding sediments, marked visually as well as by higher magnetic susceptibility values. Dating and analysis of off-site sediments show that a significant wetland existed at the site prior to and during early site occupation (~ 23,000 - 19,000 BP). This may explain why such a substantial site existed at this location. This wetland dating to the Last Glacial Maximum also provides important information on the palaeoenvironments and potential palaeoclimatic scenarios for today's eastern Jordanian desert, from where such evidence is scarce

Provenance discrimination of fine sediments by mid‐infrared spectroscopy: Calibration and application to fluvial palaeo‐environmental reconstruction

International audienc

Détermination de la provenance des sédiments fins par Spectroscopie Moyen Infrarouge (SMIR). Application à l'étude de la paléo-dynamique fluviale holocène ello-rhénane (France, Alsace)

International audienc

Mid-Infrared spectroscopic analysis of fine alluvial sediments. Insights for provenance determination of palaeochannel infills

International audienc

Détermination de la provenance des sédiments fins par Spectroscopie Moyen Infrarouge (SMIR). Application à l'étude de la paléo-dynamique fluviale holocène ello-rhénane (France, Alsace)

International audienc