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A new environmentally benign process for producing Fe-based ceramics of variable properties is presented. We have demonstrated that the reaction between lepidocrocite and acetic acid (=AA) in water results in the formation of carboxylate−FeOOH nanoparticles called ferroxane−AA analogous to aluminum-based alumoxanes. The structure of the ferroxane particles consists of an FeOOH core part with the structure of the lepidocrocite (γ-FeOOH), coated with AA. FTIR and EXAFS at the Fe K edge indicates that AA is chemically adsorbed onto the FeOOH core part. The size of these ferroxanes is 0.3 μm composed of nanodomains of 20−30 Å with a γ-FeOOH structure. Thermolysis of the ferroxane−AA yields Fe oxide ceramics. The specific surface area of 134 m2/g does not increase from the initial mineral to the ferroxane while the pore size distribution becomes monodisperse and the diameter of the pore size decreases from 55 to 12 and 13 nm after the firing of the ferroxanes. Moreover, the ferroxane−AA has been successfully doped with metal to form a precursor for Fe mixed-metal oxides. Upon thermolysis the products evolve to homogeneous Fe−metal oxides. A low firing temperature for conversion to ceramic as well as the use of environmentally benign feedstock suggest that the process for creating ferroxane-derived ceramics should have minimal environmental impacts.

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We are evaluating strontium isotopes as alternative tracers of landfill leachate in groundwater. The municipal landfill studied here is located in southeastern France. This landfill has no bottom liner, and wastes are placed directly on the ground. Based on the evaluation of chloride concentration, the plume extends a maximum of 4,600 m. Strontium isotopic composition characterizes two sources: natural groundwater (87Sr/86Sr = 0.708175) and landfill leachate contamination (87Sr/86Sr = 0.708457). The evolution of mixing ratios obtained with strontium reveals a second source of groundwater contamination: fertilizers (87Sr/ 86Sr = 0.707859). These results suggestthat isotopic signatures can be used to provide useful information on sources of groundwater contamination where conventional water quality parameters may yield ambiguous results.

Here we provide evidence of the capability of stable lead isotopes to trace landfill leachate in a shallow groundwater. The municipal landfill we have investigated is located in southeastern France. It has no bottom liner, and wastes are placed directly on the ground. Stable lead isotopes allow the characterization of this landfill leachate signature (206Pb/207Pb = 1.189 +/- 0.004) that is clearly different from that of the local atmosphere (206Pb/207Pb = 1.150 +/- 0.006) and crustal lead (206Pb/207Pb = 1.200 +/- 0.005). Piezometers located in the direct vicinity of the landfill generally display this contaminant imprint. The landfill plume is monitored up to 1000 m downgradient of the landfill, in very good agreement with evaluation from chloride concentration. Meanwhile, 206Pb/207Pb ratios measured at a piezometer located 4600 m downgradient of the landfill suggest a contamination by the landfill plume. This result shows that the complexity of a pollutant plume dispersion in this shallow groundwater system requires several independent tracers to clearly resolve origin and transport pathways for contaminants. Furthermore, seasonal rainfall variation for this Mediterranean mixed Quaternary alluvion reservoir and the use of KCl fertilizers might favor an efficient remobilization of atmospheric lead in plowed soils and its transfer into groundwater as shown by lead isotope systematics.