Eisenia andrei earthworms were exposed for 7 and 14 days to six samples of soil taken from around an abandoned lead (Pb) mine and characterized by different levels of metal contamination (S6-S1, this latter being the most contaminated soil). The organisms were analyzed for metal bioaccumulation and for biological parameters as biomarkers of stress (lysosomal membrane stability; lipofuscin lysosomal content; lysosomal/cytoplasmic volume ratio) and genotoxicity (Micronucleus frequency). Chemical analysis showed the loads of Pb, Cd, Zn, and Cu in the worms following exposure. Among the stress biomarkers, lysosomal membrane stability was significantly affected in the coelomocytes of the earthworms exposed already 7 days to different contaminated soils. Organisms exposed for 14 days to S1 showed in the cells of the chloragogenous tissue, a particularly relevant increase in lipofuscin, a biomarker of oxidative stress, and an increase in the lysosome/cytoplasm volume ratio, indicating stressful condition at the tissue level. Moreover, in the same conditions, a decrease in total body weight was observed. At the longer exposure time, the coelomocytes of worms exposed to S1, S2, and S3 (soils with higher metal concentrations) showed a significant increase in micronuclei (MNi) frequency. Expressions of the P21 and topoisomerase genes, which are involved in DNA repair, showed significant up-regulation in the cells of worms exposed to S1, S2, S3, S4 and to a less extend S6. This may indicate that the worms were only able to successfully reduce the level of DNA damage in S4 and S5 if considering MN frequency data. The biomarker data was integrated by the Earthworm Expert System, allowing an objective interpretation of the complex biological data and clearly defining the areas in which the presence of chemicals is toxic for the edaphic organisms.

International audience | A lysimeter approach (under natural climatologic conditions) was used to evaluate the effect of four metal immobilizing soil treatments [compost (C), compost + cyclonic ashes (C + CA), compost + cyclonic ashes + steel shots (C + CA + SS)) and cyclonic ashes + steel shots (CA + SS)] on metal leaching through an industrially contaminated soil. All treatments decreased Zn and Cd leaching. Strongest reductions occurred after CA + SS and C + CA + SS treatments (Zn: -99.0% and -99.2% respectively; Cd: -97.2% and -98.3% respectively). Copper and Pb leaching increased after C (17 and > 30 times for Cu and Pb respectively) and C + CA treatment (4.4 and > 3.7 times for Cu and Pb respectively). C + CA + SS or CA + SS addition did not increase Cu leaching; the effect on Pb leaching was not completely clear. Our results demonstrate that attention should be paid to Cu and Pb leaching when organic matter additions are considered for phytostabilization of metal contaminated soils

Physicochemical and biological characterisation of different dredged sediment deposit sites in France

International audience | Metal(loid)s found at many sites as a result of human activities induce contamination of ecosystems, which threatens the environment and public health. Several approaches can be used in order to reduce such negative impacts of pollutants, and among them, phytoremediation has gained attractive attention. The objective of the present study was to assess the capacity of Populus euramericana, Dorskamp cultivar, for the phytoremediation of metal(loid)s on a technosol (former mining site) highly contaminated mainly with Pb and As, and amended with biochars having different particle sizes. In a 46-day mesocosm glasshouse pot experiment, technosol was mixed at three ratios (0, 2, or 5% w/w) with four different hardwood-derived biochars (with various particle sizes) in order to study the biochar application rate and particle size effects on soil pore water (SPW) characteristics, on poplar growth, and on metal(loid) distribution and concentrations in the plant organs. The results showed that all biochars tested had a significant impact on several SPW physico-chemical parameters. Especially, biochar additions reduced available Pb concentrations but with no effect on As. In such conditions, Populus growth in amended technosol increased whatever rate and particle size of biochar used. Metal(loid) concentrations and repartition in plant organs showed the following: (1) for Pb, a higher root concentration with low aerial part translocation, which depended on biochar used, and (2) for As, mainly a root sequestration. We identified biochar with the finest particle size and combined with P. euramericana, Dorskamp, was the most suitable as remediation tools for Pb stabilization in post-mining contaminated soils.

International audience | Metal(loid)s found at many sites as a result of human activities induce contamination of ecosystems, which threatens the environment and public health. Several approaches can be used in order to reduce such negative impacts of pollutants, and among them, phytoremediation has gained attractive attention. The objective of the present study was to assess the capacity of Populus euramericana, Dorskamp cultivar, for the phytoremediation of metal(loid)s on a technosol (former mining site) highly contaminated mainly with Pb and As, and amended with biochars having different particle sizes. In a 46-day mesocosm glasshouse pot experiment, technosol was mixed at three ratios (0, 2, or 5% w/w) with four different hardwood-derived biochars (with various particle sizes) in order to study the biochar application rate and particle size effects on soil pore water (SPW) characteristics, on poplar growth, and on metal(loid) distribution and concentrations in the plant organs. The results showed that all biochars tested had a significant impact on several SPW physico-chemical parameters. Especially, biochar additions reduced available Pb concentrations but with no effect on As. In such conditions, Populus growth in amended technosol increased whatever rate and particle size of biochar used. Metal(loid) concentrations and repartition in plant organs showed the following: (1) for Pb, a higher root concentration with low aerial part translocation, which depended on biochar used, and (2) for As, mainly a root sequestration. We identified biochar with the finest particle size and combined with P. euramericana, Dorskamp, was the most suitable as remediation tools for Pb stabilization in post-mining contaminated soils.

International audience | no abstract

International audience | no abstract