Project title and acronym: Ecotoxicology approaches in a context of global changes: from knowledge to action - CONNEXION.
Resulting from the 2016 call for emerging projects of the LabEx BASC, the CONNEXION project lasted 2 years (2017-2019).
Project leader: Isabelle Lamy (ECOSYS)       Partner in BASC: LSCE (Bertrand Guenet).

This project was born from three observations: 1) Ecotoxicology (study of toxic pollutants in ecosystems), in particular that of diffuse, low-dose and chronic contamination, is a scientific field that is still little known by decision-makers, particularly in the field of land use planning, 2) Global change poses many questions to ecotoxicology, which are still little addressed (are contaminated soils and environments more vulnerable? ...) and 3) Although they are at the interface between water and air, there is still no framework directive for soils allowing them to be managed sustainably, and their degradation is of less concern to citizens.

In order to put forward low-contaminated ecosystems in the management of spaces by considering the long term and to better appeal to citizens, we have worked on two axes: i) to create an interdisciplinary dynamic of rapprochement between scientists on the one hand, and scientific decision-makers on the other hand, and ii) to cross prospective studies on the evolution of contaminated soils in a context of global change with scenarios of climate evolution, which are themselves, very meaningful to the general public.

Diagram: Interactions between soil, climate and contamination: soil contamination impacts its functioning, which can increase or decrease its greenhouse gas emissions. These modifications lead to climate variations (T°C, precipitations...) which can in turn impact the processes taking place in the soil, or the dynamics of contamination.

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From a "proof of concept" perspective, we worked on two major issues of the project:

• The vulnerability of contaminated soils to climate change
• The participation of contaminated soils in greenhouse gas emissions, with the aim of studying the feedbacks on the climate

Experimental data were used to quantify, under double stress conditions (Cu + drought), the impact of a contaminant on soil nitrification with a bioassay. On the other hand, a meta-analysis of literature data allowed us to quantify in a generic way the impact of copper on soil organic carbon mineralization. The equations defined for nitrogen were implemented in the DNDC module of the ORCHIDEE model to determine the greenhouse gas emissions of contaminated soils according to different scenarios over the long term, and to discuss the change of scale of ecotoxicological approaches, rather at the spatial scale of the plot, versus climate models, rather at the scale of continents.

The results show that the vulnerability of soils for a contaminant is a function of its dryness state, and that contaminated soils emit greenhouse gases in inverse proportion to the contamination, this particularity is however not sustainable in time. Thanks to global contamination maps, these data can be extrapolated and discussed depending on the reliability of the input data and the nature of the models.

This project allowed to finance part of the operation of a thesis financed by the ENS in the framework of the ABIES doctoral school (Laura Sereni) on the problematic 'Ecotoxicology and Climate', to initiate collaborations on this theme between communities which did not know each other, to pose a subject of project of students to the master INGS (Paris Saclay University/AgroParisTech) on "the stakes and expectations in ecotoxicology in Ile de France" with written report and oral defense.

Following this project, many perspectives have emerged on the interactions between soil, greenhouse gas emissions and contaminants, including plants and soil organisms as levers for system disturbances.

The project leader explains the project and its RESULTS in VIDEO (LabEx BASC scientific days, February, 2021)

Publications

Article :

> L. Sereni, B. Guenet, I. Lamy, 2021. Does copper contamination affect soil CO2 emissions? A literature review. “Frontiers in Environmental Science,-Toxicology, Pollution and the Environment” on line

(+ 2 articles in prep)

Book chapter :

> I. Lamy, L. Sereni & B. Guenet. 2020 '
Contaminated soils, soil organic carbon and climate disruption: what relationships? 'In "Are urban soils arable? "', Eds C. Mougin, F. Douay, M. Canavese, T. Lebeau, E. Rémy Part 4 'Urban and peri-urban soils in the hands of research' Chapter 1, Quae editions, Versailles