Actinide-based mineral phases occurring in contaminated soils can be solubilized by organic chelators excreted by plants, such as citrate. Herein, the efficiency of citrate towards U and Pu extraction is compared to that of siderophores, whose primary function is the acquisition of iron(III) as an essential nutrient and growth factor for many soil microorganisms. To that end, we selected desferrioxamine B (DFB) as an emblematic bacterial trishydroxamic siderophore and a synthetic analog, abbreviated (L Cy,Pr )H2, of the tetradentate rhodotorulic acid (RA) produced by yeasts. Firstly, the uranyl speciation with both ligands was assessed in the pH range 2-11 by potentiometry and visible absorption spectrophotometry. Equilibrium constants and absorption spectra for three [UO2(DFB)Hh] (h-1)+ (h = 1-3) and five [UO2(L Cy,Pr )lHh] (2+h-2l)+ (-1  h  1 for l = 1 and h = 0-1 for l = 2) solution complexes were determined at 25.0 °C and I = 0.1 M KNO3. Similar studies for the Fe 3+ /(L Cy,Pr ) 2system revealed the formation of five species having [

To cite this version:Pascale Henner, Félix Bredoire, Antoine Tailliez, Frederic Coppin, Sylvie Pierrisnard, et al.. Influence of root exudation of white lupine (Lupinus albus L.) on uranium phytoavailability in a naturally uranium-rich soil . Journal of Environmental Radioactivity, Elsevier, 2018Elsevier, , 190-191, pp.39-50. 10.1016Elsevier, /j.jenvrad.2018 Influence of root exudation of white lupine (Lupinus albus L.) on uranium 1 phytoavailability in a naturally uranium-rich soil 2 Mechanisms of uranium (U) transfer from soil to plants remain poorly understood. The 35 kinetics of supply of U to the soil solution from solid phases could be a key point to 36 understand its phytoavailability and implications for environmental risk assessment. Root 37 activity, particularly the continuous release of organic acids in the rhizosphere, could have an 38 effect on this supply. We tested the impact of citrate exudation by roots of Lupinus albus, 39 either P-sufficient (P+) or P-deficient (P-), on the phytoavailability of U from a naturally 40 contaminated soil (total content of 413 mg U kg -1 ) using a rhizotest design. Combined effects 41 of P (P-/P+ used to modulate plant physiology) and citrate (model exudate) on the 42 solubilization of U contained in the soils were tested in closed reactors (batch). The batch 43 experiment showed the existence of a low U available pool (0.4% total U) and high 44

This study aimed to determine uranium (U) pollution over time using otoliths as a marker of fish U contamination. Experiments were performed in field contamination (~20 μg L−1: encaged fish: 15d, 50d and collected wild fish) and in laboratory exposure conditions (20 and 250 μg L−1, 20d). We reported the U seasonal concentrations in field waterborne exposed roach fish (Rutilus rutilus), in organs and otoliths. Otoliths were analyzed by ICPMS and LA-ICP SF MS of the entire growth zone. Concentrations were measured on transects from nucleus to the edge of otoliths to characterize environmental variations of metal accumulation. Results showed a spatial and temporal variation of U contamination in water (from 51 to 9.4 μg L−1 at the surface of the water column), a high and seasonal accumulation in fish organs, mainly the digestive tract (from 1000 to 30,000 ng g−1, fw), the gills (from 1600 to 3200 ng g−1, fw) and the muscle (from 144 to 1054 ng g−1, fw). U was detected throughout the otolith and accumulation varied over the season from 70 to 350 ng g−1, close to the values measured (310 ng g−1) after high exposure levels in laboratory conditions. U in otoliths of encaged fish showed rapid and high U accumulation from 20 to 150 ng g−1. The U accumulation signal was mainly detected on the edge of the otolith, showing two U accumulation peaks, probably correlated to fish age, i.e. 2 years old. Surprisingly, elemental U and Zn signatures followed the same pattern therefore using the same uptake pathways. Laboratory, caging and field experiments indicated that otoliths were able to quickly accumulate U on the surface even for low levels and to store high levels of U. This study is an encouraging first step in using otoliths as a marker of U exposure. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

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