PhD position open at ECOLAB & CIRIMAT (Toulouse, France). Influence of the physico-chemical properties of carbon nanotubes on their impact on plants.

- LAB PRESENTATION

The PhD project will be carried out jointly between EcoLab (laboratory for functional ecology and environment) and CIRIMAT (Interuniversity Center for Research and Materials Engineering), in Toulouse (France).

Research at EcoLab (more than 150 people) takes place in the field of ecology and environmental sciences at the interface between life science, earth science and social science, in the context of sustainable development. The aim of the laboratory is the combined study of the functioning of communities and ecosystems, their relationships at different spatial and temporal scales and their response to external forcings. It also develops applied research to meet society's expectations, particularly in the assessment of the state of the environment, defining new standards and indicators of ecosystem health. EcoLab facilities are both located on the Toulouse University campus and at the National School of Agronomy of Toulouse at Castanet-Tolosan.

The CIRIMAT Carnot Institute gathers more than 200 people working in the field of material science and engineering. Physico-chemists, material scientists, pharmacists, polymer physicians unite their expertise in this future-oriented institute aiming at providing new answers to nowadays challenges.

Divided into 7 research groups, dedicated to complementary aspects of material science and engineering, CIRIMAT's research concerns all families of materials : metals/alloys, ceramics, polymers and composites ; and in link with a wide range of applications.

- THESIS PRESENTATION

For over a decade, nanotechnology has attracted interest of industrials and scientists and was even described as the "new industrial revolution" by the French government1. Among the most produced nanomaterials are carbon nanotubes (CNT). In the world, the demand is estimated to reach 2000 tons per year by 2018. In Europe, production capacity is 800 tons / year (Arkema France, Nanocyl Belgium). These CNTs are particularly interesting for their strength, lightness, elasticity as well as electrical and thermal conductivities. They are mainly used in energy storage and composite materials (automotive, sport equipment).

This strong growth leads to nanomaterial release into ecosystems and in particular in soils. Nowadays a major problem limiting our understanding of CNT fate in the environment and the associated risks is the lack of in situ characterization techniques. Qualitative and quantitative analysis of carbonaceous nanomaterials in matrices themselves mainly made of carbon is very challenging. Quantities of nanomaterials in the environment are only estimated from modeling results. For CNTs, the estimation is between 1.10-2 and 10 µg/kg soil2. These concentrations may be locally much higher in the case of soils amended with sewage sludge, the use of nanopesticides3 or in scenarios of nanoremediation4. Because of this technological barrier, CNT ecotoxicity has been much less studied than that of TiO2 or Ag nanoparticles. Some articles are available on CNT fate in aquatic ecosystems5,6 but very little is known about their fate in terrestrial ecosystems. The published studies show a limited mobility of CNTs in soils7,8, toxicity towards bacteria9 and soil invertebrates10.

In this context, plants are particularly interesting because they are at the interface between the three compartments (water-soil-air) and at the base of the food chain. Preliminary studies carried out in the laboratory have demonstrated the internalization of multiwall CNTs in crop plants (wheat and rapeseed) after exposure in hydroponic conditions11. These experiments have also highlighted different impacts of CNTs depending on their external diameter. Moreover, recently (May 2014) the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) has recommended to stimulate research on the risks of CNTs to reduce scientific uncertainties through the implementation of multidisciplinary projects12.

The aim of the present project is to go beyond the preliminary studies carried out in simplified conditions (exposure in ultrapure water at high concentrations) that is to say to go towards more environmentally realistic exposure conditions (lower concentrations in soil). In addition, following the recommendations of ANSES, the project will benefit from a multidisciplinary approach at the interface between physics, chemistry and biology. The PhD project will be divided into three main research questions :

- What is the influence of the physico-chemical characteristics of CNTs on their fate ?

- Are these CNTs transferred to the plants and to their edible parts ?

- What are the consequences of such exposure at the physiological level ?

Several types of CNTs will be synthesized with different lengths, diameters and surface functionalization. Their mobility in soil will be studied on sand column. Later plants will be grown in contaminated soil. At the end of the growth cycle, CNT concentrations in the different organs will be assessed (stem, leaf, seed/fruit) and CNT distribution will be investigated.

The impact of exposure on the development of plants will be monitored as well as CNT impact on plant metabolism (chlorophyll, bio-macromolecules, oxidative stress) and genome (DNA damage).

- CANDIDATE PROFILE

Candidates should have a master degree in ecology, plant biology or agronomy, and a strong interest in chemistry. Knowledge in statistics (using R software) will be appreciated. Previous experience in nanomaterial ecotoxicity would be an asset. If the candidate does not speak French, she/he should be fluent (speaking/writing) in English (mandatory).

Applications will be open until June 5th, and interview (video conference possible) will take place in late June.

Other personal skills :

- Sense of organization, discipline

- Ability to communicate and work in team

- Excellent relationship quality

- Proactive behavior

- Ability to write reports and scientific papers in English (and French for some parts of the PhD thesis)

You can send your application to camille.larue@ensat.fr and flahaut@chimie.ups-tlse.fr with CV and application letter.

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PhD position Toulouse

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