Environmental Dynamics and Impacts of contaminant cocktails originating from Plastics in soil ecosystems – e-DIP

While most persistent pollutants are present in molecular or ionic forms, commercial plastics include a wide variety of polymers (PE, PP, PLA…) and additives (e.g., phthalate, bis- and nonyl-phenol) and produce thousands of NIAS (e.g., butyl-benzene or phenol), of which only a few are known and monitored in soils. While some of these plastics, like PLA, are biodegradable and might contribute to C cycle, they still contain additives, which effects are unknown. This project will develop a novel approach to address this issue through the use of well-defined contaminant cocktails produced in controlled conditions and realistically representing commercial plastics.
This project will explore several scenarios of exposure of soil organisms to controlled plastics, to assess their toxicity in different compartments (rhizosphere, microorganisms, mesofauna, plastisphere), their impacts on soil functions and biogeochemical cycles, their dynamics and that of associated microorganisms, and the physico-chemical and microbial feedbacks of the soil on the plastics.
We will consider the interplay of physical, chemical and biological processes for environmental dynamics and impacts of cocktails of plastic contaminants in soils, considering both the action (toxicity and transfer) and retroaction (biodegradation, physico-chemical interactions) between plastics and soil biosphere compartments.

The project will
1) define a holistic approach to the environmental dynamics of cocktails of plastic contaminants in soils, considering the interplay of physical, chemical and biological processes to better understand their impacts and transfer between soil compartments;
2) assess methods and provide recommendations with regards to methodologies to be used for the analyses of plastics with different additives in contrasting environmental matrices;
3) overcome the current bottlenecks in the direct quantification of polymers and additives in complex matrices, by comparing controlled experiments with and without well-characterized custom-made plastics;
4) propose an innovative approach including back and forth collaboration between polymer chemistry and soil ecology, to adapt, during the course of the project, the study to situations where effects or feedbacks would occur.

The results of the project will help prioritizing which compounds need to be directly monitored in the soil matrix and advise the use and further the development of dedicated new analytical methods.
The project will provide objective scientific evidence on environmental threats of plastic production, for decision-makers to decide whether the benefit of using plastics outweighs the danger posed by the presence of additivated polymers (plastics) in soils. The e-DIP project will be an important contribution to this societal debate that will transform the way we live in the next 20 years and can be a lever to change consumer practices.
The e-DIP project will federate a french multidisciplinary scientific team capable of tackling the different issues paving the way to a complete understanding concerning plastic fate in terrestrial environments.

Several scientific articles will be published in high impact international journals, some in open access journals to reach a large scientific audience (the full texts will be deposited in HAL). A publication, coordinated by the project coordinator, will show the synergy between all the WPs and highlight the integrative character of the project. The results will be presented at scientific conferences in the different fields covered by e-DIP. In order to build and strengthen the leadership role of France in plastic pollution research, project partners will organize special sessions at international meetings such as EGU and AGU. The results will also be disseminated to socio-economic actors concerned with plastic use and waste treatment through workshops, working groups or awareness seminars.
Short summaries will be produced based on published and validated data to be shared with a wider audience through the project website, social networks (LinkedIn and Twitter), citizen cafés, Science Festivals and organizations to inform and raise awareness on plastic environmental issues.

Plastic pollution might lead to the degradation of soils, with major environmental and economical costs for agriculture. Considering the multiple facets of plastic pollution (contaminant cocktails including additives and non-intentionally added substances NIAS, added alone in mulching or closely entangled with residual organic matter in amendments), this project will take a lead in assessing the extent of this threat and propose ways to remediate it. With a novel methodology based on a back and forth collaboration between polymer chemistry and soil ecology we will explore several exposure scenarios of soil organisms to custom-made plastics, deciphering their toxicity in different environmental compartments (rhizosphere, microorganisms, mesofauna, plastisphere), their impacts on soil functions and on biogeochemical cycles, their dynamics and that of plastic-associated microorganisms and the physico-chemical and microbial retroactions of soils on plastics.