Claude Grison, European Inventor Prize 2022: “We can clean up soil and water with plants”

80%: this is the share of soils contaminated in France, in particular by heavy metals. Pollution with particularly high risks for biodiversity and human health. Rarely mentioned in the media, soil pollution does not seem to be on the agenda of political authorities. However, it is the primary Source of pollution, even ahead of air and water pollution. For chemist Claude Grison, “preserving soil quality should be a priority”. A priority that is all the more urgent as it threatens global food and nutritional security. European Inventor Award 2022 for her soil decontamination method, the chemist insists on the need to develop inventive and effective technologies for restoring polluted sites, areas and terrestrial ecosystems.

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Soil pollution, an underestimated but significant phenomenon

France has more than 310,000 industrial sites, in operation or not, some of which generate significant pollution by hydrocarbons, heavy metals or solvents. The main Source of pollution, soil contamination remains underestimated, no doubt because its consequences are poorly understood and less tangible than others. They are no less famous. Indeed, pollution by heavy metals or metallic pollution leads to soil erosion, i.e. degradation due to the displacement of materials on the surface of the outermost layer of the earth’s crust, or even to a ” phytotoxicity” of soil systems, making them toxic to the plant environment.

This soil erosion leads to a migration of metallic elements in the soil-water systems and with them, a contamination of the rivers. Results ? A drastic reduction in soil fertility and the contamination of agricultural and food products. Added to this dangerous pollution are the harmful effects of climate change such as severe droughts, intense but short rains, and the global warming of a planet (part of the population of which overconsumes limited resources). Combined effects which “raise fears in the short term of a scarcity of vital resources”, is alarmed by chemist Claude Grison.

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Soil quality, a major challenge for global food security

Industrialization, wars, mining activities and the intensification of agriculture are all phenomena that contribute to soil contamination throughout the world. At the same time, the galloping urbanization of cities is transforming and destroying land surfaces. However, this deterioration in the quality of soils and arable land is worrying in more ways than one, particularly for world food security, for which it constitutes a major challenge. A challenge that is all the more urgent as food security is already subject to growing constraints, including:

  • A demographic challenge : the growth of the world population should reach 9 billion inhabitants in 2050 with an increased urbanization of this population;
  • climate change : which multiplies extreme events and increases the pressure on agricultural yields;
  • Globalization of the world marketl agricultural and food products, coupled with a negative change in eating habits;
  • Increased pressure on resourcesin quantity and quality: decrease in the availability of drinking water accentuated by unequal distribution, depletion of mineral resources, decrease in the availability of arable land, evolution of ecosystem services, conversion of land use.

Soil pollution affects the food we eat, the water we drink, the air we breathe and the health of our ecosystems“, already alerted the Deputy Director-General of the FAO in 2018. “The ability of soils to cope with pollution is limited, preventing soil pollution should be a priority worldwide“, she concluded. How can we remedy this in practice? Claude Grison, the researcher who has developed an effective, innovative and ecological means of depollution, helps us to see things a little more clearly.

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How does depollution by plants work, and besides which plants are capable of extracting metals from the soil?

Given their phytotoxicity, metalliferous soils exert strong selection pressure and generate special habitats for plant species and associated microorganisms. The result is a unique biological resource, metallophytes. These metallophytes are defined as plant species capable of tolerating high concentrations of metallic elements, of surviving and of reproducing on such sites. Some of these metallophytes not only tolerate pollution, but are able to extract metallic elements through their roots and then transfer them to the aerial parts where they are stored. This is called phytoextraction. Phytoextraction is thus an ecotechnology of partial depollution of soils and sediments by accumulation of metallic elements in the aerial parts of hyperaccumulating plants. The phytoextracted metallic elements are mainly zinc, nickel, manganese.

What does the innovative concept of eco-catalysis that you have developed consist of?

Eco-catalysis is an unprecedented development of phytoptechnologies for the restoration of terrestrial (phyoextraction) and aquatic (rhizofiltration, biosorption) ecosystems and for the preservation of wetlands. The plant waste generated is recovered through an innovative concept of ecological recycling. Taking advantage of the remarkable adaptive capacity of certain plants to phytoaccumulate metallic elements, eco-catalysis is based on the direct use of metallic species of plant origin as reagents and catalysts for fine organic chemical reactions. It allows the preparation of biomolecules according to an eco-responsible and bio-inspired approach.

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You rightly underline the urgency of taking an interest in water depollution in a context where the resource is showing its limits more than ever. Does your decontamination method work in the same way for aquatic environments?

Phytotechnology for depolluting water works on a different principle, called biosorption. The process is based on the construction of filters made of plant powder from aquatic plants and wetlands. The origin of plant raw materials is twofold:

  • The production of native aquatic plants such as water mint;
  • The harvesting and processing of invasive exotic aquatic plants as part of the control of their development such as water primrose and Japanese knotweed.

Biosorption makes it possible to respond to very different scenarios of metal pollution:

  • – strategic metals: platonoids (Pd, Pt, Rh), rare earths (Ce, Eu, Yb, Sc, etc.)
  • – primary metals: Zn, Mn, Ni, Cu, Fe
  • – toxic metals: Cd, Pb, Co, Cr, As, Sb,…

As a “citizen researcher” who has been studying the question of depollution for more than a decade, what do you think is essential to implement at the national level to fight against the disaster promised by global warming?

I think it is urgent to take into account the work resulting from research which constitutes many avenues for reflection and action to meet the challenges of climate change, the erosion of biodiversity, the degradation of terrestrial ecosystems and aquatic species, or the uncontrolled multiplication of invasive animal and plant species.

Many researchers want to become actively involved in current environmental challenges, relying on solid knowledge, supporting the transfer of their innovations to the socio-economic sphere, working with local authorities and associations that are structured around these issues, with the curious and nature enthusiasts, with the many young people who are very willing on these aspects. It is still necessary to help and support them in their efforts. Finally, it is also a question of developing our collective culture towards more humble relationships with nature.

Read also :

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Tropical plants to clean up soil contaminated with heavy metals

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What are the most polluted and least polluted coastal regions in Europe?

>>>Orléans: a life-size laboratory to decontaminate the soil>>>

Orléans: a life-size laboratory to decontaminate the soil

The article is in French

Tags: Claude Grison European Inventor Prize clean soil water plants

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