Troposphere

Troposphere / Biogenic ecosystems

The work deal with the investigation of the impact of global changes (pollution, exploitation of environments, climate) on the biogeochemical functioning of natural and anthropogenic ecosystems and the  emissions of Greenhouse Gas (GHG) and other Volatile Organic Compounds (VOC) by these ecosystems. The aim is to better appreciate the feedbacks on the chemical composition of the atmosphere, on the air quality, and the evolution of the future climate. The main ecosystems studied are sphagnum type peatlands (carbon sink function, CO2 and CH4 emissions) highly vulnerable to global changes (PEATWARM, CARBIODIV, CliMireSiber, CAREX projects) and agricultural fields (N2O emissions) strongly linked to nitrogen and carbon amendments, and agricultural practices (SPATIOFLUX project).

These studies are part of LABEX VOLTAIRE and of the PIVOTS project (PESA and PRAT Platforms). SPIRITS instruments developed at LPC2E for GHG measurement, one of which is sold and used at INRA (soil science team in Ardon) in collaboration, contributes mainly to these studies

 Investigation of GHG exchanges from sphagnum type peatlands: C balance and impact of global changes

Seasonal and daily cycles of CO2 exchange and CH4 emissions monitored at the m2 scale (with IR sensors among them SPRIT-LPC2E and manual chambers) on the 4 sites of the SNO Tourbières (label INSU-SIC) and on mesocosms extracted in la Guette peatland enabled us to determine the major controlling factors of GHG fluxes. Thus, empirical and mechanistic models for production-exchange of GHG were developed (D’Angelo et al., 2016; Leroy et al., 2017). Carbon balance is investigated in la Guette peatland before and after water table restoration initiated by the installation of a dam upstream the peatland in the frame FEDER-EU, Région CVL :  CARBIODIV (2013-16) and CAREX (2017-21) projects. Gap filing for missing data at different scales (spatial and temporal) could be achieved to estimated C balance for peatlands of the SNO tourbières. First results had underlined that la Guette peatland operates as a source of C to the atmosphere before water table restoration (220 gC.m-2.year-1) (d’Angelo et al., in prepration).

To improve C balance investigation, ecosystem level observations in the frame of the French Peatland Observation Service (SNO Tourbières, CNRS/INSU) are studied since 2017 by the installation of an eddy covariance flux station on la Guette peatland supported by the project PIVOTS Région CVL (ARD2020, FEDER, CPER)

The field and experiment observations (GHG fluxes) obtained and the peat GHG production-transport model under developed at OSUC will be used in the emission surface ORCHIDEE model for a future coupling with atmospheric chemistry and climate (LMDz) models.Modeling work, included DOC dynamics, is carried out in coll. with the IPSL-LSCE, Gif / Yvette.

 N2O emissions to the atmosphere from cultivated lands

N2O fluxes monitored at different scales (chambers and/or micro-meteorology, with the SPIRIT-INRA) on croplands (OS2 site in Beauce-Chartraine, mainly, where the location is shown in Fig. 6 Ib 1, and CEH-Scotland site of the EU project INGOS once) improved the understanding and modelling of the spatial variability of N2O fluxes at the intra-plot (Grossel et al., 2014) or landscape scale (Grossel et al., 2016, Bureau et al., 2017). As a prospective, indirect emissions of N2O will be investigated in more details such as N2O released by N or N2O transport from water streams.

References

Publications et communications associées  (à corriger aussi en version française)

D’Angelo et al., Carbon balance and spatial variability of CO2 fluxes in a disturbed peatland in temperate climate, in prep. to Biogeosciences

Leroy F. et al, Biogeosciences, under minor revision
Leroy F. et al, submitted to Journal of Environmental Sciences, 2018
Bureau J. et al, Submitted to Agriculture, Ecosystems and Environment, 2017
Leroy F. et al, submitted to Soil Biology and Biochemistry, 2017
Grossel A. et al, Agriculture, Ecosystems and Environment, 2016
D’Angelo B. et al, Agricultural and Forestry Meteorology, 2016.
Guimbaud C. et al., Journal of Environmental Sciences, 2016.
Grossel A. et al., Ecological Modelling, 2014.
Guimbaud, C. et al., Meas Sci Technol, 2011.
Gogo, S. et al., Journal of Soils and Sediments, 2011.

CAREX (2017-22) : Peatland restauration, Carbone balance and biodiversity, from experimental investigation (FEDER-EU, Region Centre Val de Loire)

CAREX (2017-22) : Validation d’indicateurs de restauration du fonctionnement des tourbières (carbone, hydrologie, biodiversité) pour leur gestion durable sous l’effet du changement climatique. Le projet CAREX s’inscrit dans la continuité logique du projet CARBIODIV.

Bio-décontamination of gasoline hydrocarbons contaminated soils

A non-destructive new methodology for aerobic bio-treatment in situ monitoring of hydrocarbons contaminated aquifers was developed in the frame of the ANR-ECOTECH BIOPHY with the support of Labex Voltaire (PhD and postdoc grants : C. Noël, 2011-2015). Geophysical methods (Electrical Resistivity and Induced Polarization) combined with gas analyses with SPIRIT-LPC2E (CO2 flux with 13C/12C isotopic ratio determination) was used on a BTEX polluted site from a gasoline station (Guimbaud et al., 2016 and in Preparation, Noël et al. 2016a, 2016b). The investigated site is an old gasoline station near Paris contaminated by BTEX hydrocarbons remaining from tanks leak. A bioactive barrier has been set to stimulated aerobic biodegradation by H2O2 liquid injection in the aquifer.

Results

Gegeophysical measurements (2D tomography), have shown that an active depollution of a contaminated site with hydrocarbons is characterized by a zone of high conductivity (or low resistivity) due to the formation of conductive metabolites (ions in solution) resulting from the biodegradation of hydrocarbons (Technique : Electrical Resistivity Tomography or ERT) and of high chargeability due to the presence of many bacteria behaving like induced dipoles and often present in the form of biofilms (Technique : Time Domain Induced Polarization or DIP) (Noel et al., 2016 a,b)

Geochemical measurements (Flux and δ13C) have shown a good cartographic correlation observed from upstream to downstream the depollution plume between (i) the CO2 flux emitted at soil surface and the BTEX concentration in the aquifer and (ii) the δ13C/12C of CO2 emitted and the underground δ13C/12C of BTEX, with some fractionation factor. Results demonstrate the effectiveness of monitoring a stimulated bio-depollution in real time without excavation of soil matter by measurements of the surface CO2 emission fluxes with δ13C/12C characterization. For the first time, the dynamic of bio-depollution could be quantified from the Rayleigh equations applied on the monitoring of δ13C/12C of the CO2 released at ground surface. CO2 monitoring at ground surface could be a cost effective way to monitor real time biological or chemical treatments of depollution in order to optimize soil bio-treatment (Guimbaud et al., 2016 and in preparation to EST, 2018)

Prospective:

Reduction of the costs could be achieved to follow-up studies of depollution from CO2 gas surface analysis and 2D tomography, compared to existing conventional methods using isotopic analysis of pollutants in subsoils by excavation. These new technics could be improved by more investigation on well characterize soils such as the experimental platforms PIVOTS-PRIME (join Region Centre – Europe funded project ARD2020) under construction at BRGM.

Publications

Guimbaud C., C. Noel, E. Verardo, A. Grossel, F. Jégou, Z. Hu, C. Robert, J. Jacob, I. Ignatiadis, J.C. Gourry, A new approach to quantify the dynamics of in situ biodegradation of hydrocarbons in a contaminated aquifer by CO2 d13C monitoring at ground surface, in preparation to “Environmental Science & Technology”.

Noel C., J.C. Gourry, J. Deparis, M. Blessing, I. Ignatiadis, C. Guimbaud. Combining geoelectrical measurements and CO2 analyses to monitor the enhanced bioremediation of hydrocarbon-contaminated soils: a field implementation; Applied and Environmental Soil Science, special issue “Integrated Approaches to Soil Contamination Monitoring”, Volume 2016, Article ID 1480976, 15 pages, 2016.

Noel C., J.C. Gourry, J. Deparis, I. Ignatiadis, F. Battaglia-Brunet, C. Guimbaud, Suitable real time monitoring of the aerobic biodegradation of toluene in contaminated sand by Spectral Induced Polarization measurements and CO2 analyses, Near Surface Geophysics, 14 (3), 263-273, 2016.

Guimbaud C., C. Noel, M. Chartier, V. Catoire, M. Blessing, J.C. Gourry, C. Robert, A quantum cascade laser infrared spectrometer for CO2 stable isotope analysis: field implementation at a hydrocarbon contaminated site under bio-remediation; Journal of Environmental Sciences, special issue “Changing complexity of air pollution”, 40, 60-74, 2016.

Guimbaud C., C. Noel, E. Verardo, A. Grossel, F. Jégou, Z. Hu, C. Robert, J. Jacob, I. Ignatiadis, J.C. Gourry, A new approach to quantify the dynamics of in situ biodegradation of hydrocarbons in a contaminated aquifer by CO2 d13C monitoring at ground surface, in preparation to “Environmental Science & Technology”.

ANR ECOTECH BIOPHY 2010 (mars 2011-Juillet 2015) : Optimisation de procédés de BIOdépollution des eaux souterraines contaminées par des hydrocarbures par un monitoring géoPHYsique et analyse de gaz en ligne :   Coord. J.C. Gourry (BRGM)