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Durum wheat is one of the cereal crops that accumulates the highest concentrations of cadmium (Cd) and deoxynivalenol (DON) mycotoxin in its grains, thereby affecting the safety of products made of durum wheat grains (pasta and semolina). This study investigates

Aerated compost tea (ACT) contains soluble humic substances (SHS) that are expected to alter the dynamics and ecotoxicity of Cu in soil. This study investigated the efficiency of ACT in enhancing the mobility and phytoextraction of Cu in vineyard soil. Crimson clover (Trifolium incarnatum L.) was grown on a vineyard soil at three concentrations of Cu (90, 261 and 432 mg kg

International audience; Speciation of Cd in soil solutions strongly determines the fate of this toxic metal in the environment. Generally, in soil solutions, Cd predominantly binds to the dissolved organic matter (DOM). The determination of the quantity and reactivity of DOM that actually complexes Cd in soil solutions is challenging for operational purposes. Therefore, this study tested whether Cd2+ concentration in soil solutions could effectively be predicted by considering complexation with a single mean organic ligand assumed to be a fraction of DOM of unspecified nature or assumed to be purely fulvic acids (FA) with reactivity as described in WHAM VII. The reactivity of the unspecified ligand and the concentration of FA were modelled and fitted to experimental data from 76 agricultural soils with low Cd contents. The optimal reactivity and FA concentration that minimized the relative error (RE) of predictions of the concentration of Cd2+ in soil solutions were either considered constant across soils or modelled from soil properties by multiple linear regressions (MLR) or random forests (RF), giving 6 models, the predictive value of which was assessed by 10-folds cross-validation. When the reactivity of the mean ligand and the optimal FA concentration were considered constant across soils, the models were biased and 66.9% of predictions had relative errors below a factor of 2. By contrast, if the reactivity of the mean ligand or the optimal FA concentration were allowed to vary with soil characteristics, these performances increased to 95.5%, soil pH being the main predictor and RF being slightly more efficient than MLR. With more than 95% of the relative errors of prediction below a factor of 2, the models developed in this work could be valuable for assessing Cd speciation in the solution of soils having a low Cd content.

The purpose of this study was to assess heavy metal contamination in soil, plants, earthworms, and chicken in farmlands adjacent to an old mining site and to evaluate the potential exposure risks to humans through the consumption of chicken. For this purpose, soil, earthworms, plant, chickens, and eggs were sampled from 5 sites following a gradient of contamination. All samples were analyzed for heavy metals (Pb, Cd, Cu, and Zn). A food chain model was used in order to characterize heavy metal transfer between soil-plant-earthworm and chicken organs. Furthermore, target hazard quotient (THQ), estimated daily intake (EDI), and hazard index (HI) were employed to assess human health risks posed by heavy metal contamination. Despite the higher level of Pb, our data related to the calculation of EDI and THQ suggested that local consumers are more at risk of Cd contamination. The calculated HI showed values ranging from 2.58 to 4.74 for adults, and up to 12.34 for children, indicating a considerable risk to the health of local inhabitants, especially children. This study highlighted the crucial role of diets based on chickens grown in contaminated areas, on health risks especially for children.

Summary Copper-based fungicides are potentially toxic to organisms because of their huge amounts in vineyard soils resulting from almost 150 years of massive use. Dissolved organic matter (DOM) depending on its quality can complex copper and influence its toxicity. DOM quality and quantity are related to soil organic matter (SOM) decomposition under the impact of environmental factors like temperature. We aimed in this study to assess the effect of temperature, depending on soil nature, on the quantity and quality of DOM originating from SOM mineralization. A 60-day incubation at 20°C and 30°C was conducted on two soils differing in type and C/N ratio. DOM absorbance and fluorescence and hydrolytic enzymatic activities were analyzed all along the experiment. The nature of soils affected the measured variables more than the temperature. Nevertheless, in the highest C/N soil, the hydrolytic enzymes activities decreased at t60 for the 20°C temperature suggesting a shift from hydrolytic to oxidative enzymes abundance. It is concluded that the difference between the two studied temperatures was not enough to observe clear changes on DOM properties and SOM decomposition, but that eventual effects could appear in a longer experience and more contrasted temperatures.

Speciation of Cd in soil solutions strongly determines the fate of this toxic metal in the environment. Generally, in soil solutions, Cd predominantly binds to the dissolved organic matter (DOM). The determination of the quantity and reactivity of DOM that actually complexes Cd in soil solutions is challenging for operational purposes. Therefore, this study tested whether Cd

International audience; Mining activity may cause heavy metal accumulation, which threatens human and animal health by their long-term persistence in the environment. This study aims to assess the impact of polymetallic pollution on chicken (Gallus domesticus) from old lead mining sites in northeast of Tunisia: Jebel Ressas (JR). Samples of soil and chickens were collected from five sites being ranked along a gradient of heavy metal contamination. Heavy metal loads were evaluated in soil samples and in chicken liver and kidney. Biochemical evaluation of oxidative stress parameters termed as Catalase (CAT), Glutathione-S-Transferase (GST), and Malondialdehydes (MDA) accumulation was monitored. Metallothionein protein level was assessed as a specific response to heavy metals. DNA alteration was achieved using MNi frequency in the investigated tissues. Finally, the evaluation of gene expression levels of CAT, GST, mt1, mt4, P53, bcl2, caspase3 and DNA-ligase was performed. Our data showed the highest loads of Cd, Cu, Zn and Pb in tissues of animals from site 3, being more pronounced in kidney. Biochemical data suggested a significant increase in antioxidant enzymes activities in all sites respect to control except in site 3 were CAT and GST were inhibited. DNA alteration was observed in all tissues being very pronounced in animals from site 3. Overall, transcriptomic data showed that genes involved in apoptosis were up-regulated in animals exposed to the most contaminated soils. Our data suggest that chicken and selected biomarkers offer a suitable model for biomonitoring assessment of heavy metals transfer through the food web in mining sites. Finally, the obtained results of heavy metals accumulation and related alterations should be carefully considered in view of the controversial relationship between distribution and toxicology of contaminants in exposed organisms.

This study characterizes sunflower response to the levels of Cd encountered in moderately Cd-polluted soils. Two sunflower cultivars differing in their ability to sequestrate Cd in roots were exposed to low concentrations of Cd (0.5 nM or 100 nM) in hydroponics and sampled after 18 days (258 degree-days) when ten leaves were fully expanded. Plant growth, Cd uptake and partitioning among organs were monitored along with the ionomic (ICP-MS) and the metabolic (1H-NMR) composition of the xylem sap. Sunflower tolerance to Cd differed between the two cultivars. The cultivar with the highest ability to sequestrate Cd in roots (Kapllan) was more tolerant to Cd than the one with the lowest ability (ES RICA). The 23% penalization of plant growth observed at 100 nM in cultivar ES RICA was associated with reduced xylem loading fluxes of soluble sugars, perhaps pointing to disruption of carbohydrate metabolism. Retention of Cd in the stem was higher at 100 nM than at 0.5 nM in the Cd-sensitive cultivar ES RICA, which can be seen as a sunflower strategy to restrict the amount of Cd delivered to the leaves under Cd stress. No direct connection was found between the speciation of Cd in the xylem sap and the Cd translocation efficiency, although significant changes in the free ionic fraction of Cd were observed between the two cultivars at 0.5 nM. The relevance of these results in promoting the use of sunflower in phytomanagement of Cd-polluted soils is discussed.

International audience; This study focuses on quantifying the contribution of remobilization to the amount of cadmium accumulated in durum wheat grains. The impact of post-anthesis N supply was tested in two cultivars that differ in their shoot biomass partitioning. Two French durum wheat cultivars were grown hydroponically and exposed to 100 nM Cd. After anthesis, the plants were fed with a solution enriched in the stable isotope Cd-111 to trace the Cd newly absorbed, and subjected or not to nitrogen deprivation. Plants were sampled at anthesis and grain maturity to assess the post-anthesis fluxes of Cd and N among organs. Cd remobilized from pre-anthesis stores contributed to more than half of the Cd accumulated in mature grains. Cd was mainly remobilized from stem and poorly remobilized from leaves. Stopping N supply during grain filling enhanced N remobilization but had no impact on post-anthesis uptake and remobilization of Cd, and thereby, on Cd concentration in grains. No difference was observed between the two cultivars in the contribution of Cd remobilization and its dependence toward post-anthesis N supply. Cd remobilization significantly contributes to the accumulation of Cd in durum wheat grains. Cd remobilization is not tightly linked with N remobilization and behaves like a senescent-independent process in durum wheat.

National audience

This study aims to characterize the response of durum wheat to different concentrations of Cd found in agricultural soils. One French durum wheat cultivar (i.e. Sculptur) was exposed to low concentrations of Cd (5 nM or 100 nM) in hydroponics. After anthesis, the plants were fed with a solution enriched with the stable isotope 111Cd to trace the newly absorbed Cd. Plants were sampled at anthesis and grain maturity to assess how plant growth, Cd uptake and partitioning among organs, as well as Cd remobilization, differed between the two Cd exposure levels. Durum wheat did not show any visual symptoms of Cd toxicity, regardless of which Cd treatment was applied. However, post-anthesis durum wheat growth was 14% penalized at 100 nM due to the large transpiration-based accumulation of Cd in leaves at this stage. The allocation of Cd to the grains was not restricted but enhanced at 100 nM compared to 5 nM. Both the root-to-shoot Cd translocation and the fraction of aboveground Cd allocated to grains were higher in plants exposed to 100 nM. Cadmium was remobilized exclusively from roots and stems, and remobilized Cd contributed on average to 40–45% of the Cd accumulated in mature grains, regardless of which Cd treatment was applied. The relevance of these results to decreasing the concentration of Cd in durum wheat grains is discussed.

International audience; Aims This study investigated the possible source organs delivering several trace elements to seeds (root uptake versus net remobilization), by studying changes in biomass and element contents in the plant organs. Methods Sunflowers were grown in a greenhouse using a nutrient solution enriched with Cd. Four samplings were performed from the early flowering to the seeds physiological maturity. Results The low grain Ca indicated that phloem was likely the main route for transporting the elements to seeds. Excluding roots, the mass balance of the elements indicated the following contribution of the net remobilization to the total quantities in seeds at maturity: Mg = 50%, Cd = 14%, Cu = 35%, Fe = 29%, Mn = 19%, Zn = 12%. Source organs were mainly the receptacle and the stem. No significant net remobilization was observed for Ca, K and Mo. Conclusions The amount of trace elements accumulated in vegetative parts can be redistributed to seeds in an extent that depended on the element. Due to the important contribution of root uptake to the content in seeds at maturity, the availability of elements in soil during the reproductive stages is an important point to consider.

Aims Varietal screening was conducted to characterize how French durum wheat lines (Triticum turgidum L. subsp. durum) differ in the concentration of cadmium (Cd) in their grains and to identify the main (eco) physiological processes behind these differences. Methods Eight French and two Canadian durum wheat lines were grown hydroponically in a nutrient solution with a low concentration of Cd (2 nM). At maturity, the partitioning of biomass and Cd among organs was analyzed and elemental profiles of the grain were obtained. Results Grain Cd concentration ranged from 0.03 to 0.08 mu g g(-1) and was thus in the same range as that measured in field trials. The level of Cd in the grain was correlated with levels of P, Mn and Zn. French lines behaved like high-Cd cultivars. A 2.4-fold variation in grain Cd was observed within French lines, which was not explained either by a difference in uptake or by a difference in the root sequestration of Cd. One important finding is that the leaf biomass was the most influential variable explaining the genotypic variation in grain Cd observed within French lines. Conclusions The partitioning of aboveground biomass may influence the concentration of Cd in grain, in addition to the sequestration of Cd in roots.

Aims. This work concentrated on understanding the allocation of Cd recently taken up between the organs of sunflower at early and middle reproductive growth stages. The roles of transpiration and allometry were investigated. Methods. Sunflowers were grown hydroponically in greenhouse, being exposed to low concentrations of Cd (pCd2+ = 11.03). At flower bud and grain filling stages, plants were exposed for three days to 111Cd and at the same time, subjected or not to fans to increase the transpiration. The partitioning of 111Cd between plant organs measured by high resolution ICP-MS was then modelled. Results. Although the use of fans increased the plant water uptake and transpiration by about 20%, there were no significant effects on the partitioning of recent Cd. Most of the recent Cd was recovered in roots (60%) and only 2.8% were found in seeds (0.8% for the husk and 2.0% for the almonds). The sequestration of recent Cd in a plant organ was successfully explained by its biomass and except for leaves, by the biomass of other organs acting as competitive sinks. Conclusions. This work proposes a modelling approach for the partitioning of the labelled Cd between plant organs in sunflower.

International audience; Aim To characterize the response of sunflower to the low levels of Cd exposure encountered in agricultural soils. Methods Plants were exposed in hydroponics to low concentrations of Cd (2.5 nM or 20 nM) and sampled at four vegetative stages (6, 9, 14 and 19 expanded leaves). Plant growth, root Cd absorbing properties and Cd partitioning between organs were monitored along with Cd content in the xylem sap. Results Sunflower growth was not limited when exposed to 20 nM Cd. The amount of Cd taken up by the plant roots as well as the rate of Cd loading in xylem sap increased in direct proportion to the concentration of Cd2+ in the nutrient solution, suggesting that neither the root Cd absorbing capacities nor the root-to-shoot translocation of Cd were impacted by the level of Cd exposure. The partitioning of Cd between stem and leaves followed that of dry matter, regardless of the Cd treatment. The root-to-shoot partitioning of Cd at early growth stages differed from that prevailing later on. Conclusions In an agricultural context, the partitioning of Cd between sunflower organs does not appear to be affected by the level of Cd exposure during vegetative growth.