Contributions to plant ecophysiology under heavy metals stress and to scaling for phytoremediation in contaminated areas

The habilitation thesis with the title "Contributions to the ecophysiology of plants under heavy metal stress and to scaling for phytoremediation in contaminated areas" consists of an extensive synthesis of my scientific and didactic activity performed after obtaining the title of doctor in natural sciences (rerum naturalium, 1999) and contains the last chapter the evolution and development plan of the scientific and teaching career, as well as future perspectives. The purpose of this thesis is to present the evolution of scientific research activities from the simple classic approach, which focused on a single objective (e.g., phytoextraction, phytoremediation, etc.), to a complex approach with a multi-objective focus (e.g., besides phytoremediation, the focus was also on several other ecosystem services). If before the start of the doctoral program and during its development the focus was on the field of the biogeochemical cycles of nitrogen and heavy metals, and only in the initial phase on the subfield of remediation of areas polluted with both organic and inorganic compounds, later I deepened the circulation of heavy metals and developed after an original, objective method, the remediation of metal-polluted areas making a valuable contribution also in the field of plant ecophysiology. This activity was carried out within the framework of two post-doctoral fellowships, three reintegration projects, and several international and national fundamental and applied research projects. After a general description of the approach, the working method consisted in the presentation of the scientific activity in section B: Scientific achievements, which in turn are grouped into Theoretical Contributions, Methodological Contributions, Results obtained as investigations directly in the field, and as ex-situ and in-situ experiments, and the Technological Development subsection, Section C: Plans for scientific and teaching career evolution and developmentwith the subsections C.1 The development coordinates of the research activities carried out until now, and C2 The development coordinates of the didactic activities carried out until now, the last section D being the references subchapter. Methodological development started with simple pot-scale experiments in plant growth chambers or greenhouses, at at ex-situ zero-tension or light-tension lysimeter scale up to plot scale (experimental plots from 2x2 m x 35plots up to 5x5 m x 10 plots). The proposal in the following research project application is at a scale of 25 x 25 m. The experimental design and the research hypotheses were formulated according to the scientific interest, both in fundamental and applied research. In terms of basic research, a current area of interest of great complexity has been found in exploring how the amount and stoichiometry of elements in the soil and the temperature control the traits space of grassland plants, and then, in turn, some of these traits control the elemental fluxes by runoff and leaching, their stoichiometry, and in the long term the stocks and stoichiometry of elements in the soil. This research had three primary objectives: to test four hypotheses about the effects of heavy metals and time on the C:N:P stoichiometry in field conditions, to test six hypotheses about the effects of heavy metals (HMs) and temperature on the C:N:P stoichiometry at the ex-situ microcosm and mesocosm scales, to test three hypotheses about the effects of HMs and temperature on the structure of traits space and to disentangle the significance of the results about the effects of complex stress on the production of ecosystem services. This research was possible within the exploratory research project no. 156 of 16/02/2021, PN-III-P4-ID-PCE-2020-0494) with the title: "Exploring the effects of metals and temperature on the functional traits săace of grassland plants, coupled to water-mediated element fluxes” - METTELFLUX) (some findings can be found in the last part of chapter B2, Theoretical contributions, and more details in the article by Iordache and Neagoe 2023, published in the Journal of Environmental Management). The significant conceptual advance is the link between the biogeochemical niche and ecological stoichiometry bodies of knowledge and the eco-hydrological one (extended with elemental fluxes) by key plant traits common to both fields. The methodology uses three heavy metal contaminated sites already intensively characterized and multi-scale experiments. This has immediate applications in bio(eco)-technologies used in environmental restoration/ remediation. Its importance from a socio-economic or cultural point of view is by the concept of ecosystem services: it provides a deep understanding of the value of functional biodiversity for the production of regulation services inside, and especially outside of the protected area. It has the potential to improve the attitudes of the public towards biodiversity. Regarding applied research, I briefly presented in subchapter B5 the transition methodology from TRL2 to TRL6, which has been possible until now in two stages: in 2014-2017, we went from TRL2 to TRL3 within the partnership project no. 98 of 01/07/2014 (PN-II-PT-PCCA-2013-4-2171) with the title "Tools for the integrated management of mining areas and rivers basins" - TIMMAR). During 2020-2022, we upscaled from the TRL3 to TRL4 in the experimental-demonstration research project no. 453 of 23/10/2020 (PN-III-P2-2.1-PED-2019-2584) with the title: " TRL4 Remediation eco-technology of tailing dams in function of geochemical, geomorphological and ecological setting" - TIMMAR- RESET)". The transition from TRL4 to TRL6 was proposed in the technology transfer project application PN-IV-P7-7.1-PTE-2024-0762 with the title: "TRL6 eco-technology for the remediation of tailings dams in function of geochemical, geomorphological and ecological settings" - TIMMAR 2-RESET". This application is under evaluation, the proposed eco-technology being of importance both globally as evidenced by the ecological stability standards recommended by the International Commission on Large Dams in Bulletin 153 on the sustainable design and post-closure performance of tailings dams (ICOLD Tailings Dam Committee 2013), as well as on a European and national level where two facts of high public visibility pointed out the importance of the technology proposed for maturation at the TRL6 stage: the first is the situation of supply chains with critical materials. The second is the consequence of the lack of correlation in public policies in the case of Roșia Montana gold mining project. Note: the defended form of this thesis in PDF format was corrected for sevaral typing mistakes occuring in the Summary.