Litter breakdown as a tool for assessment of the efficiency of afforestation and ash-aided phytostabilization on metal-contaminated soils functioning in Northern France

Impact of Anthropic Activities on Soil Quality under Different Land Uses

Anthropization often leads to land use transformation, causing deep changes to soil properties and its quality. Land use change could be an environmental and socioeconomic problem, as it impacts soil quality and ecosystem services. There is an urgent need to understand the pressures affecting soil quality. The aim of the work is to quantify the impact of different land uses on soil abiotic and biotic properties and on its quality. To achieve the aims, soils from different land uses (forest, urban and agricultural) were collected in the surroundings of Naples and analyzed for pH, water content, contents of C and N, C/N ratio and total and available concentrations of Cu, Ni and Pb, microbial and fungal biomasses, basal respiration and metabolic quotient. Then, a soil quality index (SQI) was calculated for each land use. The results showed that soil abiotic and biotic properties of the agricultural sites differed from those of forest and urban sites. At agricultural sites, microbial abundances decreased due to low amount of C and N and to high amount of Cu and Pb. This caused low use efficiency of energetic substrates and a reduced soil quality of agricultural sites as compared to forest and urban sites.

Effect of Miscanthus × giganteus ash on survival, biomass, reproduction and avoidance behaviour of the endogeic earthworm Aporrectodea caliginosa

To achieve the EU's targets for reducing energy production from fossil fuels, the use of energy crops, such as Miscanthus × giganteus, is increasing resulting in a corresponding increase in waste ash from incineration. The chemical properties of Miscanthus ash (e.g. phosphorus and potassium content) may allow this waste material (currently landfilled) to be used as a fertiliser, but no information exists on the effect of the ash on the biological properties of soil. The main aim of this study was to determine the potential impact of Miscanthus ash on earthworms by assessing the effect on survival, change in biomass, reproduction and avoidance behaviour of the geophagous, soil dwelling earthworm, Aporrectodea caliginosa. Tests utilised a range of Miscanthus ash doses from 0 to 50 t ha^-1 (0, 1, 2.5, 5, 10, 25, 50). Results showed that Miscanthus ash had no significant impact on A. caliginosa survival, biomass and reproduction, but negative trends were observed for biomass from 2.5 t ha^-1 and for reproduction from 10 t ha^-1. In contrast, a significant avoidance response was observed in the 25 and 50 t ha^-1 treatment and according to ISO guideline 17512 there is a negative impact of the Miscanthus ash on soil habitat function at 25 t ha^-1 and above as more than 80% of earthworms were in the control soil. It is suggested that this negative effect on soil habitat function could be attributed to a range of factors including the presence of heavy metals in the ash and a change in substrate pH, texture and/or osmotic stress. Further laboratory-based studies conducted over extended time periods with a more refined range of ash doses and associated field-based studies are required to validate the results and determine a more precise assessment of the threshold ash value inducing a loss of soil habitat function.

Adverse effects of fly ashes used as immobilizing agents for highly metal-contaminated soils on Xenopus laevis oocytes survival and maturation-a study performed in the north of France with field soil extracts

Amphibians are now recognized as the most endangered group. One of this decline causes is the degradation of their habitat through direct contamination of water, soil leaching, or runoff from surrounding contaminated soils and environments. In the North of France, the extensive industrial activities resulted in massive soil contamination by metal compounds. Mineral amendments were added to soils to decrease trace metal mobility. Because of the large areas to be treated, the use of inexpensive industrial by-products was favored. Two types of fly ashes were both tested in an experimental site with the plantation of trees in 2000. Aim of the present work was to investigate the effects of extracts from metal-contaminated soils treated or not for 10 years with fly ashes on Xenopus laevis oocyte using cell biology approaches. Indeed, our previous studies have shown that the Xenopus oocyte is a relevant model to study the metal ion toxicity. Survival and maturation of oocyte exposed to the soil extracts were evaluated by phenotypic approaches and electrophysiological recordings. An extract derived from a metal-contaminated soil treated for 10 years with sulfo-calcic ashes induced the largest effects. Membrane integrity appeared affected and ion fluxes in exposed oocytes were changed. Thus, it appeared that extracted elements from certain mineral amendments used to prevent the mobility of metals in the case of highly metal-contaminated soils could have a negative impact on X. laevis oocytes.