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Rees F.,CNRS Soil and Environment Laboratory | Simonnot M.O.,University of Lorraine | Morel J.L.,CNRS Soil and Environment Laboratory
European Journal of Soil Science | Year: 2014

Biochar, the solid product of biomass pyrolysis, can be used as a soil amendment to stabilize metals in contaminated soils. The effects of biochar on the mobility of metals in soils are, however, poorly understood. To identify the predominant processes, we focused on (i) a possible kinetic limitation by transport in biochar particles, (ii) the evolution of biochar mineral phases and (iii) the effect of biochar on soil pH. Batch experiments were conducted to measure the sorption kinetics of copper (Cu), cadmium (Cd) and nickel (Ni) and the sorption-desorption isotherms for lead (Pb), Cu, Cd, zinc (Zn) and Ni in a wood-derived biochar. Sorption data were then compared with extraction test results using biochar with one acidic and one basic soil contaminated by Zn, Cd and Pb. Kinetic results showed that biochar particle sizes controlled metal sorption rate despite a similar specific surface area, which indicated a limitation by intra-particle diffusion. Isotherms showed a partially reversible sorption to biochar following the order Pb>Cu>Cd≥Zn>Ni, which we explained primarily by the (co)precipitation of metals or their adsorption on specific biochar mineral phases. Effective metal immobilization was observed with biochar in both contaminated soils but could not be predicted from the sorption isotherms. This immobilization appeared to be governed by the soil pH increase, which induced a greater retention of metals on soil particles. Short-term effects of biochar on contaminated soils may therefore be controlled by diffusion in biochar particles and by soil alkalinization processes. © 2013 British Society of Soil Science. Source

Watteau F.,CNRS Soil and Environment Laboratory | Villemin G.,CNRS Soil and Environment Laboratory | Villemin G.,University of Lorraine
Bioresource Technology | Year: 2011

A microstructure characterization study using transmission electron microscopy (TEM) was conducted to specify organic matter dynamics during the co-composting process of sewage sludge, green waste and barks. TEM results showed that ligneous and polyphenolic compounds brought by barks were not biodegraded during composting. Green waste brought more or less biodegraded ligneous constituents and also an active microbial potential. Chloroplasts and sludge flocs appeared to be relevant indicators of green waste and sewage sludge in composted products, as they were still viewable at the end of the process. TEM characterization of the final product highlighted two main fractions of organic matter, one easily available and a more recalcitrant one, and also a remaining microbial activity. Thus microstructure characterization appeared to be an appropriate way of taking the heterogeneity of the organic constituents' size and composition into account when attempting to specify such compost quality parameters as maturity and stability. © 2011 Elsevier Ltd. Source

Bartoli F.,CNRS Soil and Environment Laboratory | Dousset S.,University of Lorraine
European Journal of Soil Science | Year: 2011

Organic inputs were used for 10 years on a French vineyard topsoil to improve structural stability and thus to protect against erosion. The three types of organic inputs (mulches) included: conifer compost, CC (100 m3 ha-1 every 3 years); conifer bark, CB (300 m3 ha-1 every 5 years); and cereal straw, S (10 t ha-1 every 2 years). The other two types of organic inputs were cover crops of clover (C) and fescue (F). The impacts of these organic inputs on soil organic carbon (SOC) content, wettability (capillary rise and X-ray photoelectron spectroscopy (XPS)) and structural stability were studied. The SOC content was twice as large in the CC, C and F topsoils (SOC content of 2.56-3.24%) as in the reference (R) topsoil (SOC content of 1.39%). Both apparent contact angle (θ) and surface OH:C mass ratio indicated that the R and S topsoils were hydrophilic (θ of 27.4-33.4°, surface OH:C ratio of 3.20-4.41), whereas the CB, C and F topsoils were partially hydrophobic (θ of 69.1-79.8°, surface OH:C ratio of 1.36-2.86), and the CC topsoil had intermediate values (θ of 46.9°, surface OH:C ratio of 2.43-2.81). Moreover, the greater the θ value, the smaller the water sorptivity value and the greater the proportion of water-stable aggregates, Agw. The increase in SOC content had beneficial effects on Agw, particularly for the partially hydrophobic C and F topsoils (Agw of 22.3-44.5%) against the hydrophilic R and S topsoils (Agw of 8.2-12.7%). Development of hydrophobicity, correlated with the decrease in the surface OH:C ratio and the increase in the C-O, C-N proportion on surface C, should be attributed to humified organic matter or/and to plant and microbial polysaccharides. As the XPS and aggregate stability data describe soil physical processes at small scales (nm to mm), we suggest an experimental and modelling framework for upscaling these results for practical improvement and management of vineyard soils. © 2010 The Authors. Journal compilation © 2010 British Society of Soil Science. Source

Pelosi C.,French National Institute for Agricultural Research | Joimel S.,CNRS Soil and Environment Laboratory | Makowski D.,French National Institute for Agricultural Research | Makowski D.,Agro ParisTech
Chemosphere | Year: 2013

Pesticide risk assessments include experiments designed to measure the effect of pesticides on earthworms using the Eisenia fetida fetida or Eisenia fetida andrei species. There is no clear consensus in the literature on the sensitivity of different earthworm species to pesticides. We performed a meta-analysis on the sensitivity of several earthworm species to pesticides to determine the most sensitive species, and to discuss their suitability for European homologation tests. A dataset including median lethal dose (LC50) values reported in 44 experimental treatments was constructed and then analyzed in order to compare the sensitivity levels of E. fetida with that of other earthworm species. Results showed that LC50 values reported for Lumbricus terrestris and Aporrectodea caliginosa were on average significantly lower than for E. fetida. Considering the relatively high LC50 values reported for E. fetida and the absence of this species from zones where pesticides are usually applied, the relevance of using E. fetida for pesticide homologation tests is questionable and we advise risk assessors to use A. caliginosa as model species. A new protocol based on this species could be proposed for European homologation tests but its implementation will require the definition of a new standard and take time. In the meantime, the results obtained with E. fetida should be interpreted with caution taking into account the low sensitivity of this species. Our study illustrates the value of the meta-analysis approach for comparing the sensitivity of different earthworm species to pesticides. It would be useful to extend the dataset presented in this paper in order to analyze the sensitivity of other aquatic or terrestrial organism groups used for pesticide homologation or ecotoxicology tests. © 2012 Elsevier Ltd. Source

Morel J.L.,CNRS Soil and Environment Laboratory | Chenu C.,Agro ParisTech | Lorenz K.,Institute for Advanced Sustainability Studies | Lorenz K.,Ohio State University
Journal of Soils and Sediments | Year: 2015

Purpose: The sustainable use and management of global soils is one of the greatest challenges for the future. In the urban ecosystem, soils play an essential role with their functions and ecosystem services. However, they are still poorly taken into consideration to enhance the sustainable development of urban ecosystems. This paper proposes a categorization of soils of urbanized areas, i.e., areas strongly affected by human activities, according to their ecosystem services. Materials and methods: Focus is put first on ecosystem services provided by non-urban soils. Then, the characteristics and number of services provided by soil groups of urbanized areas and their importance are given for each soil group. Results and discussion: Soils of urbanized areas are here defined as SUITMAs, because they include soils of urban, sensu stricto, industrial, traffic, mining, and military areas. This definition refers to a large number of soil types of strongly anthropized areas. SUITMAs were organized in four soil groups, i.e., (1) pseudo-natural soils, (2) vegetated engineered soils, (3) dumping site soils, and (4) sealed soils. For each soil group, examples for ecosystem services were given, evaluated, and ranked. Conclusions: This proposal contributes to foster the dialogue between urban spatial planning and soil scientists to improve both soil science in the city and recognition of SUITMAs regarding their role for the sustainable development of urban ecosystems and, in particular, to enhance multifunctional soils in urban areas. © 2014, Springer-Verlag Berlin Heidelberg. Source

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