Projects / Programmes
From hazardous waste to living soils ? microbial communities and plant-soil feedbacks in heavy metal contaminated soil before and after remediation
| Code |
Science |
Field |
Subfield |
| 4.03.01 |
Biotechnical sciences |
Plant production |
Agricultural plants |
| Code |
Science |
Field |
| B003 |
Biomedical sciences |
Ecology |
| Code |
Science |
Field |
| 4.01 |
Agricultural and Veterinary Sciences |
Agriculture, Forestry and Fisheries |
contaminated soil, remediation, soil revitalization, heavy metals, soil microbial communities, plant-soil interactions, soil biodiversity
Researchers (15)
Organisations (3)
Abstract
Soil is a finite resource; its preservation is essential for food security and our sustainable future. Soil contamination, caused by the large amounts of pollutants, is becoming a major problem on a global scale. In particular heavy metals are a big concern as they are non-degradable and persist in soil. Soil contaminated with heavy metals is referred as a hazardous waste. All around the world urban agriculture, even on contaminated soil, is booming fulfilling diverse functions including food production, community building, and reducing socio-economic tensions. However, samples from inner city and urban gardens are frequently reported to exceed safety standards for HM concentration in food crops thus it is of great importance to find good solutions for efficient restoration of degraded areas.
Recently we demonstrated the technical and economic feasibility of the novel chelant-based soil washing technology for remediation of heavy metal contaminated soils. In this inovative technology the chelant (ethylenediamine tetraacetate, EDTA) and process water recycling relies on a combination of substitution/precipitation reactions in an imposed pH gradient for EDTA recovery, and on electrochemical polishing of process waters for total water recycle in a closed loop. The innovative procedure is a good solution for cleaning heavy metal contaminated soils, and has a potential to return the valuable resource – fertile soil – back into function. However, the harsh treatment eliminates most of the microbial life in the remediated soil, and significantly reduces its biological activity.
Increasing evidence show that only living soil can perform ecosystem services such as sustainable food production, nutrient cycling, and others. However, there is practically no knowledge on the composition, succession, function, or dynamics of microbial communities in remediated soil and the proposed project would bridge this gap. We propose a study of compositional and functional aspects of microbial communities (archaea, bacteria and fungi), and related plant-soil feedbacks after revitalizing the remediated soil with microbial inocula. Two distinct soil types will be used for remediation (1) calcareous soil from Slovenia, and (2) acidic soil from Austria. As a result a custom soil-type specific microbial inoculua of a well characterised microbial communities will be produced for more efficient revitalisation of larger quantities of remediated soil. For the first time the innovative remediation technology will be connected to recently developed metagenetic (e.g. next generation sequencing with Illumina MiSeq) approaches to follow those communities. Integration of the role of microbial community ecology in environmental sciences is urgently needed to improve our understanding of the determinants of the survival of introduced microbial inocula, the role of adaptability and diversity of soil microbes and whether inoculation has a direct or indirect effect on plant production.
To be able to observe the changes among the communities before and after remediation we will also characterise the communities in the contaminated sites. However, in addition to have a reference state for the original community, we will also address some important fundamental questions in microbial ecology like 'How soil microbes respond to long-term disturbance or environmental change?', addressing the stability of the community composition, and 'What are the main environmental predictors in microbial community composition?'. Extreme, persistent and directed abiotic pressures (heavy metal contamination as a long-term disturbance) may result in a more stable system with highly specific microbial communities, dominated by the adapted heavy metal tolerant taxa consistently present in high abundance in the contaminated soils. Questions on the long-term (press) related changes in soil microbial communities are relevant to many human drivers with the long-term nature like climate chan
Significance for science
Only recently the new molecular tools (NGS - next generation of sequencing) have enabled studies of spatial and temporal dynamics in the composition of soil microbial communities in more detail, thus we can address dynamics and stability of microbial communities in different environments, including heavy metal (HM) contaminated soil. This sheds some light on the important questions in soil microbial ecology like Which are the main environmental predictors in the microbial community composition? (O1, assoc. hypoth.), important also in the light of other long-term environmental changes (e.g. climate, land-use).
We can only culture about 1% of soil microbes. Extreme environments can serve as novel study systems to examine microbial evolution that can result in new, adapted extremophilic taxa (e.g. Maček et al. 2011, Šibanc et al. 2014). Within the project, potentially new species (e.g. AM fungi) can be isolated, identified, and stored in international collections (e.g. the Swiss Collection of AM Fungi at Agroscope). Those taxa have a huge potential also for use in biotechnology and other applied fields. O1, assoc. hypoth.
The innovative remediation procedure is a good solution for eliminating accumulation of hazardous waste, and has a potential to return the valuable resource – fertile soil – back to life. Increasing evidence show that only living soil contributes to ecosystem services. There still is little knowledge on the composition, establishment, succession, function and dynamics of microbial communities in remediated soil and the proposed project will bridge the gap. O2, O3, O4, assoc. hypoth.
Indigenous inocula will be applied to the remediated soils. We will test if inoculation results in a faster development of complex and functional microbial communities compared to the no-inocula treatment. As a result a custom soil-type adapted microbial inoculum with a well characterised microbial community composition will be produced for efficient revitalisation of larger quantities of remediated soil. O4, assoc. hypoth.
The innovative remediation technology will be connected to metagenetic (NGS) approaches for the first time. Integration of the role of microbial community ecology in environmental sciences and soil remediation is urgently needed to improve our understanding of the determinants of the survival of introduced microbial inocula, the role of adaptability and diversity of soil microbes and whether inoculation has a direct or indirect effect on plant production in those soils.
Finally, suitability of remediated soil to serve as a plant substrate and plant-soil feedbacks, including establishment of mycorrhizal symbiosis will be evaluated. O5, assoc. hypoth.
Significance for the country
Our innovative remediation procedure has potential application to a wider stakeholder community as model system that enables clean-up of larger quantities of contaminated soil. Our data will be of use to researchers and policy makers assessing the value of this technology, and will inform the design of future experiments and models.
According to EU legislation HM polluted soils exceeding HM critical values are considered as hazardous waste that has to be subjected to remediation treatment before landfilling (Directive 1999/31/EC). Innovative technologies have to prove their applicability at the lab, pilot, and demonstration scales. However, despite all these efforts, very few receive recognition at the EU market, while in practice, conventional non-sustainable soil remediation technologies (i.e. “dig & dump”) still prevail.
The novel technology can be regarded as green and sustainable remediation method. Apart from the contaminated Meza Valley, included in the study, the Slovenian government is (under the pressure of civil movements and NGOs) preparing legislature to proclaim also the wider area of city Celje as environmentally degraded because of the same problems. The industrial cities of Jesenice and Litija are facing similar problems. Hot spots of Pb contamination can be find in urban areas with the intensive traffic. This is not limited only to Slovenia, but is a global problem in many inhabited areas with a big health concern, especially for children.
The main barriers to the uptake of alternative soil remediation technologies are cost, lack of confidence in their effectiveness and a lack of general understanding. The results of the project will rise the confidence in the novel soil washing technology through demonstrational pilot-scale remediation and revitalisation of two different soil types. As a result a custom soil-type adapted microbial inoculum will be produced for revitalisation of larger quantities of remediated soil.
Availability of efficient soil remediation technologies and reclamation of contaminated land is a powerful tool to revitalize urban degraded areas. Regeneration of physical environment reinforces also the social cohesion and can be used for integration of minorities and (increasingly) older urban population (e.g. urban gardens). The results of the project will give the opportunity to further explore soil remediation as an instrument to achieve social cohesion and economic inclusion of disadvantaged groups (e.g. green economy, social innovation, environmental entrepreneurship).
Extreme environments can be source of specific organisms that can be used in biotechnology. HM polluted sites represent a big potential for isolation of HM tolerant species for application in industry and revitalisation/remediation of contaminated sites as components of commercial inocula.
Within the project scope, a web page will be constructed. Public will be informed about our results with lectures, publications and presentations in public media.
Most important scientific results
Interim report,
final report
Most important socioeconomically and culturally relevant results
Interim report,
final report
