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HEP Project Nanomaterials in Soil ©Copyright: Dr. Schymura, Stefan

HEP Project Nanomaterials in Soil

Foto: Stefan Schymura

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Helmholtz European Partnering - WP2 Nanomarterials in Soil

The sensitive and selective quantification of nanoparticles (NPs) in environmental samples such as water, soil and organisms at environmentally relevant concentrations remains the overwhelming challenge for a robust risk assessment of manufactured nanomaterials (MNMs). This is especially true in the case of soil-MNM interactions. Despite soil being a major sink for MNMs released into the environment, studies on NPs reactivity in soil are still very limited and critical questions remain unanswered. A robust risk assessment needs to be based on detailed mechanistic insight on the microscopic interaction processes that determine NP fate in soils that allows upscaling and quantitative pre­dictability of processes on the macro­scale, such as overall NP mobility and retention.

Soil is composed of organic and inorganic substances as well as organisms amongst which the most active are bacteria. On the one hand, interactions of MNMs with bacteria and crystal surfaces control MNM mobility in soil, on the other hand MNMs can have significant impact on soil microorganisms by changing their community structures or physiology.  

We focus on the systematic analysis of MNM mobility as modified by microbial activity and physicochemical properties of soil component surfaces. JSI provides a strong background in environ­mental and analytical chemistry, molecular microbial ecology, soil-microbes interaction [1] and weathering/dissolution of inorganic material by microbes [2], as well as geochemical elemental cycles and risk and environmental im­pact assessment [3]. In combination with the competence of HZDR in radiolabeling of NPs for most sensitive detection in complex media [4, 5], the analysis of crystal surface reactivity [6], as well as analytical reactive transport analysis using radionuclide tracers [7] provides the necessary tools to achieve this goal of linking microscopic understanding to macroscopic outcome. Thus, the proposed work package has two main foci:

a)    On the microscale, interactions of MNMs with major soil constituents (minerals, organic constituents, microbes) are to be investigated using AFM / colloidal probe techniques and X-ray spectroscopy to extract the key surface po­tentials driving MNM-mineral interactions. This is followed by targeted variation of these sur­face potentials by chemical and biological variation of the mineral substrate and surrounding medium to­wards increasingly complex systems, reflecting natural soils. Complementary, the impact of MNMs on microbial activity in soils, will be analyzed by using transcriptomics approaches on individual microbes as well as in biofilms and aggregated communities, thus providing a bridge to the macroscale.

b)    On the macroscale this is accompanied by mobility and fate studies extracting macroscopic key parameters for MNM retention and mobility with a similar escalation of system complexity which can then be linked to the microscopic factors comprising them. Here, the use of radio­labeled MNMs enables the use of environmentally relevant concentra­tions. The effects on microbial communities associated with soil will be determined by using metagenomic approaches.

The combination of innovative radiolabeling strategies and state-of-the-art environmental analy­tical tools for mutual validation and development of robust measurement procedures for MNMs in soil will provide a significant impact to the field allowing the process validation and extraction of meaningful data from transport and extraction experiments using environmentally relevant con­centrations linked to and based on a profound microscopic process understanding.

[1]   Rijavec, T., Lapanje, A. Frontiers in microbiology 2016. 7: 1785-1-1785-14.

[2]   Lapanje, A. et al. Microbial ecology 2012. 63: 865-882.

[3]   Vidmar, J. et al, Microchemical Journal 2017. 132: 391– 400.

[4]   Schymura, S., et al, Angewandte Chemie International Edition 2017. 56(26): 7411-7414.

[5]   Hildebrand, H., et al. Journal of Nanoparticle Research, 2015. 17(6): 278.

[6]   Fischer, C. and A. Luttge, Proc. of the National Academy of Sciences, 2018. 115(5): 897-902.

[7]   Kulenkampff, J., et al., Solid Earth, 2016. 7(4): p. 1217-1231.