UMBRELLA: “Using MicroBes for the REgulation of heavy metaL mobiLity at ecosystem and landscape scAle: an integrative approach for soil remediation by geobiological processes
ENV.2008.3.1.2.1; Irene Lichtscheidl (2009-2012); "Recovery of degraded soil resources”. Coordinated by E. Kothe from Jena/Germany.
Periodic Report Summary - UMBRELLA (Using microbes for the regulation of heavy metal mobility at ecosystem and landscape scale: An integrative approach for soil remediation by geobiological processes)
The overall goal of UMBRELLA was to use microorganisms to develop cost efficient and sustainable measures for soil remediation at heavy metal contaminated sites throughout Europe.
This was facilitated by research in microbiology, plant uptake and (hydro)geochemistry that focussed on the study of microbial influence on biogeochemical cycling of metals and their impact for use in soil and water protection. Modelling of the processes occurring and their influence on large-scale landscape levels provided the basis to modulate the impact on downstream river systems. The transfer of technologies developed provided a speed-up of existing bioremediation techniques and a tool box to end users was provided with microbes for remediation actions in different European climatic, geological and biological settings that would allow low cost, sustainable, on-site bioremediation of metal contaminations. Dissemination of results was ensured through participation in international congresses and publications. At the same time, the introduction of a concerted, internationalised education of interdisciplinary trained PhD students across Europe ascertained a long-lasting, sustainable education profile with relevance to soil remediation. The involvement of government agencies was chosen to provide governments with data to develop integrated guidelines based on the suggested guidelines and rules of best practise derived from UMBRELLA.
The project focussed on ecotoxicological risks resulting from metal contamination on-site as well as by transport through water paths in ground water and international water ways and provided rules to overcome the current practise of regulation by individual European agencies for soil and water protection. The management of an integrative, multi-partner consortium ensured the applicability by combination of six sites across Europe in one modelling approach that covered northern, southern, middle and eastern European sites, guaranteeing future applicability across the entire Europe. On this background, the UMBRELLA project used an integrative approach including microbiology, botany and (hydro)geochemistry as modelling input. The concept was tested with input from socioeconomic partners and, in the second phase of the project, from government agencies in a combined effort to provide an integrated version for the European Community to develop regulations for soil remediation, reducing the risk for mankind and nature.
Within the work package (WP) of microbiology, four groups worked on the development of plant growth promoting microbial consortia, physiological and molecular characterisation of microbial communities and biofilms, development of microbially controlled remediation processes and isotope fractionation to follow metal uptake into living systems which was closely interlinked by working on the same samples to find microbial populations from different sites with applicability to different European settings. The utilised methods were inter-dependent to optimally describe microbial strains and communities for remediation purposes. The research was cutting-edge with the use of tools like CHIP technology, high-throughput cultivation and physiological screening and molecular identification of heavy metal retention molecules. All methods were highly advanced and oriented towards molecular understanding of processes. The WP of applied botany was involved in establishing plant uptake of heavy metals and the response of plants to stressors like heavy metals in the presence of rhizosphere microbes. The microbial strains provided from WP 1 were evaluated for the effects on plant growth on contaminated substrates. Plant selection was established based on each site's inventory of plant communities in the contaminated catchment and detailing the structure of the community in the contaminated areas. Plant growth promoting rhizobacteria and mycorrhizal fungi were studied; however, their influence was not fully exploited for the use in bioremediation and biomonitoring. Four groups with expertise in plant uptake of heavy metals, mycorrhizal alteration of heavy metal uptake, heavy metal response in plants and investigation of speciation of metals in soil and in plant biomass participated to achieve a molecular understanding of metal uptake and plant response in phytoremediation approaches. The data was planned to be used to extrapolate these results to ecosystem and catchment levels.
In the WP (hydro)geochemistry, the water as a transport medium was investigated with respect to flow paths of heavy metal contaminated acid mine drainage waters and the importance of such transport paths for uptake into the biopath. Thus, the experimental sites were characterised and waters sampled from soil, surface and ground water wells in dependence of microbial inoculation (WP1) were investigated for metal content, speciation, reactive transport and mineralisation and mineral solution processes. The objective was to combine different approaches, i.e. the water ways and the use of rare earth elements to define sources and sinks, the use of radioisotope probing to follow water paths in the scale of catchment areas, the characterisation of mineral dissolution and precipitate formation and the investigation of mineral phases developing under microbial impact, with microbiological experiments to understand the impact of microbes on mobilisation and immobilisation from single sites to large catchment areas.
The general objective of WP4 was to develop contaminant dispersal models. According to the goal of the project, modelling involved scales from plant to catchments in order to link local remediation measures with their regional consequences and not only separately describe them. Within this WP, a nonlinear correlation model at the landscape level on the impacts of contamination on soil and water ecosystems was developed and long-term distributions of contaminants at catchment scale were predicted for use by stakeholders and the European Community. Two major targets were defined, namely the incorporation of the knowledge gained in this project to establish a tool box for use in remediation actions and proof of concept.
Mycorrhizal fungi are commonly occurring soil fungi that colonise the roots of most terrestrial plants including various crops. The benefits of the symbiosis include improved uptake of immobile soil mineral nutrients, water relations, disease resistance and increased stability of soil aggregates. The utilisation of the mycorrhizal symbiosis was defined an important tool not only in sustainable agricultural systems but also in ecosystem restoration. There were two ways for the utilisation of these fungi. The first was to stimulate the indigenous population already present in the soil. The second was to inoculate plants with effective isolates of arbuscular mycorrhiza fungi.
The socioeconomic impact was underlined by the involvement of two small and medium enterprises (SMEs) which were able to use the results. In addition, guidelines and rules of best practise were established for use by public entities and government agencies.
The inoculation of former mine sites could already lead to better bioremediation successes, especially since metal contaminated environments generally suffer from low microbial activities. The baseline from which the project started thus addressed several shortcomings of current techniques, namely the following:
1. the role microbes played in the phytoextraction of metals was still underestimated
2. there was very little use of microbial biocurtains and natural attenuation for immobilisation of heavy metal contaminants in sites with moderate contamination
3. secondary mineral formation, weathering and mineral dissolution were scarcely investigated with respect to biotic influences
4. the risk of contaminated soils for other environmental compartments, such as water and wildlife, occurred both on-site and at the scale of the landscape via fluvial dispersion, but remediation was usually estimated only at a site scale
5. the geological, mineralogical and geomorphological parameters influencing the distribution of metals were investigated on site or for immediate catchment areas and were not related to the downstream impact tributaries had on the coastal and marine environment
6. there was a lack of mathematical models with European level applicability dealing with the remediation of sites contaminated with metals.
The baseline data impinged on the creation of effective bioremediation techniques for sites contaminated by mining activities, as well as on our ability to develop generic methodologies that went beyond application to a single site. Progressing beyond the current state of understanding and application, the following ideas were tested:
1. to identify appropriate strains of microorganisms across European contaminated sites and use them in combination with plant species for optimising either phytoextraction or phytostabilisation
2. to set up methodologies for characterising the geochemical risk, integrating across the landscape levels to evaluate the efficiency of microbially enhanced bioremediation
3. to produce mathematical models of key ecosystem and landscape scale processes relevant to the risk assessment and remediation
4. to use the results from the previous ideas in designing a bioremediation methodology for land influenced by mining activities.
To achieve these goals, six study sites were selected by combination of different geomorphological and hydrological settings, different climates and different ecosystems leading to an integrated scheme of remediation actions that were site specific and yet allowed for generalised application for different regions across Europe. The results of the biogeological research programme would be widely applicable and representative as they included an assessment of microbiological ecosystems in their relation to pollution and re-establishing of reference conditions. Each site was approached at two hierarchical levels, namely at ecosystem, i.e. contaminated land, and at the integrating low order catchment. Both primary and secondary contaminated areas would be considered, because the ecosystems function either as main source of metals or as buffer for metal fluxes.
The innovative approach of the project was to combine the site specific knowledge from each site with large scale modelling and thus provided stakeholders, end users such as companies active in remediation, as well as governments with knowledge on successful combination of tools for remediation. The UMBRELLA tool boxes were applicable for different requirements across Europe. Companies were supplied with the tool box for remediation of metal contaminations and the governments would gain knowledge to find regulation for soil and water protection.
One major outcome of the project was the education of young scientists in different European countries which had already established a network of expertise. Since the applicants were both universities and non-university research institutions, the PhD students of this project visited other sites and partner laboratories. Thereby, the scientists leaving this programme were well trained on one specific topic of their expertise, but at the same time developed a broad knowledge on trans-disciplinary topics relevant for soil science and soil protection. These scientists were able to serve in government units, find jobs in remediation related companies and act as multipliers for the knowledge gained in the newly developing, interdisciplinary field of biogeosciences. Further information could be obtained at 'www.umbrella.uni-jena.de'.