Altered fungal communities in contaminated soils from French industrial brownfields.

Polycyclic aromatic hydrocarbons (PAHs) and metals are contaminants of industrial brownfield soils. Pollutants can have harmful effects on fungi, which are major actors of soil functioning. Our objective was to highlight fungal selection following long-term contamination of soils.

DNA stable isotope probing reveals contrasted activity and phenanthrene-degrading bacteria identity in a gradient of anthropized soils.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous soil organic pollutants. Although PAH-degrading bacteria are present in almost all soils, their selection and enrichment have been shown in historically high PAH contaminated soils. We can wonder if the effectiveness of PAH biodegradation and the PAH-degrading bacterial diversity differ among soils.

Soil Properties and Multi-Pollution Affect Taxonomic and Functional Bacterial Diversity in a Range of French Soils Displaying an Anthropisation Gradient.

The intensive industrial activities of the twentieth century have left behind highly contaminated wasteland soils. It is well known that soil parameters and the presence of pollutants shape microbial communities. But in such industrial waste sites, the soil multi-contamination with organic (polycyclic aromatic hydrocarbons, PAH) and metallic (Zn, Pb, Cd) pollutants and long-term exposure may induce a selection pressure on microbial communities that may modify soil functioning.

Metal release from contaminated leaf litter and leachate toxicity for the freshwater crustacean Gammarus fossarum.

Industrialization has left large surfaces of contaminated soils, which may act as a source of pollution for contiguous ecosystems, either terrestrial or aquatic. When polluted sites are recolonized by plants, dispersion of leaf litter might represent a non-negligible source of contaminants, especially metals. To evaluate the risks associated to contaminated leaf litter dispersion in aquatic ecosystems, we first measured the dynamics of metal loss from leaf litter during a 48-h experimental leaching.

Litter chemistry prevails over litter consumers in mediating effects of past steel industry activities on leaf litter decomposition.

Soil pollution has adverse effects on the performance and life history traits of microorganisms, plants, and animals, yet evidence indicates that even the most polluted sites can support structurally-complex and dynamic ecosystems. The present study aims at determining whether and how litter decomposition, one of the most important soil ecological processes leaf, is affected in a highly trace-metal polluted site. We postulated that past steel mill activities resulting in soil pollution and associated changes in soil characteristics would influence the rate of litter decomposition through two non-exclusive pathways: altered litter chemistry and responses of decomposers to lethal and sub-lethal toxic stress.

Impact of carbohydrate supply on stem growth, wood and respired CO2 delta13C: assessment by experimental girdling.

The present study examines the impact of the C source (reserves vs current assimilates) on tree C isotope signals and stem growth, using experimental girdling to stop the supply of C from leaves to stem. Two-year-old sessile oaks (Quercus petraea) were girdled at three different phenological periods during the leafy period: during early wood growth (Girdling Period 1), during late wood growth (Girdling Period 2) and just after growth cessation (Girdling Period 3). The measured variables included stem respiration rates, stem radial increment, delta(13)C of respired CO(2) and contents of starch and water-soluble fraction in stems (below the girdle) and leaves.

Seasonal changes in optically assessed epidermal phenolic compounds and chlorophyll contents in leaves of sessile oak (Quercus petraea): towards signatures of phenological stage.

Seasonal patterns of dry mass invested in chlorophyll and epidermal phenolic compounds (EPhen) were investigated in vivo using optical methods, in leaves of 2-year-old oaks (Quercus petraea Matt. (Liebl.)) grown under semi-controlled conditions.

Is there any 12C/13C fractionation during starch remobilisation and sucrose export in potato tubers?

The delta(13)C (carbon isotope composition) variations in respired CO(2), total organic matter, proteins, sucrose and starch have been measured during tuber sprouting of potato (Solanum tuberosum) in darkness. Measurements were carried out both on tubers and on their growing sprouts for 23 days after the start of sprout development. Sucrose was slightly (13)C-depleted compared with starch in tubers, suggesting that starch breakdown was associated with a small isotope fractionation.

Biochemical composition is not the main factor influencing variability in carbon isotope composition of tree rings.

From June to December, we determined the effects of variations in biochemical composition on delta(13)C of tree rings of 2-year-old oaks (Quercus petraea (Matt.) Liebl.) growing under semi-natural conditions, and the dependence of these effects of water stress during the growth season.