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Mechanisms and rates of asbestos weathering in the environment

The asbestos lab
Plant experiments: Poa Pratensis cv. Baron on Santomera soil
Plant experiments: Lupinus albus cv. Multitalia in bloom
Working in the asbestos lab
Asbestos: Spin trapping EPR measurement (sample)
Dissolution experiment: Fe mobilization by Dfob as a function of pH
Soil experiments: Fibers incubated in a “cement” bag in the acidic Schrems Podzol

Asbestos cement was used as building material until it was banned in the late 1980s due to the carcinogenicity of asbestos. Before its ban, asbestos containing waste had been used as recycling material in road construction and had been deposited in the environment. After the public health risk resulting from these activities had been recognized, large scale remediation programs were initiated, e.g. in the Netherlands and in Israel, with the aim of removing asbestos from the environment. However, remediation of asbestos contaminated field sites is challenging particularly in case low levels of asbestos containing wastes are dispersed in soils and other terrestrial systems. Recent findings of asbestos waste in agricultural fields in Austria demonstrate the ubiquity of this problem. Our research group assesses natural attenuation of asbestos waste contamination in soils. We examine how weathering of asbestos minerals depends on the conditions in the soil and we investigate if plants can accelerate these weathering processes through the chemical compounds they release from their roots.


Our research focuses on the asbestos mineral that has been most commonly used in construction work: chrysotile. The fibrous habit of this mineral allows it to become airborne easily, and to remain in the lungs for a long period of time upon inhalation. Due to their small size the asbestos fibers can penetrate deeply into the lungs where they are efficiently trapped. They are however too large to be encapsulated and eliminated from the body, which results in long-term inflammation of lung tissue. The carcinogenicity of asbestos is related to the iron in the mineral structures. This iron undergoes Fenton-like redox cycles which generate radicals that can damage DNA. Hence, the structural iron content of asbestos fibers strongly affects their carcinogenicity. Apart from Fe, also other hazardous metals like Cr and Ni are present in high concentrations in such fibers.
Our main hypothesis is that chrysotile asbestos weathers and eventually disintegrates in natural environments;  its fibrous habit diminishes and its Fe-related reactivity decreases over time in a soil system as a result of weathering processes. For testing this  hypothesis we follow an approach, in which we stepwise increase the level of complexity of the examined system: first we explore the weathering of chrysotile fibers in ligand solutions, then in soils and finally in soil-plant systems.


At a molecular level we are investigating the mechanisms of proton-promoted and ligand-promoted dissolution of chrysotile asbestos as a function of various geochemical variables, such as pH and ionic strength. We are assessing inhibitory and promoting effects on the dissolution of the main constituents (Mg and Si) and minor constituents (particularly Fe) of chrysotile asbestos in batch and flow through experiments. The dissolution behavior is examined by incubating asbestos fibers under various conditions. The effect of plant-exuded ligands on the dissolution of chrysotile constituents, particularly Fe, is explored. In another experimental approach, we are determining the radical forming potential of both pristine and altered chrysotile asbestos fibers by means of EPR (electron paramagnetic resonance) spectroscopy by applying a spin trapping technique. Furthermore, paramagnetic centers in chrysotile fibers are measured by means of solid EPR spectroscopy. By applying Mößbauer spectroscopy, we are determining the Fe(II)/Fe(III) ratio of pristine and altered fibers, the crystallographic site of Fe (in octahedral Mg- and tetrahedral Si layers) and secondary Fe phases formed during dissolution.


In our soil and plant experiments, the complexity of our experimental systems increases more towards environmental systems. We are examining the effect of soils with different soil properties (pH, soil organic matter content, clay content, etc.) on both weathering rates and radical forming potential of chrysotile asbestos fibers. Furthermore, we are examining if plants (white lupine (Lupinus albus), Kentucky bluegrass (Poa pratensis) and red sorrel (Rumex acetosella)), which are known to exude large amounts of Fe binding ligands into the rhizosphere, accelerate chrysotile weathering and decrease the residual reactivity of asbestos fibers.


We are working to extend the scientific knowledge on chrysotile asbestos fibers and to create a basic scientific framework for the behavior of chrysotile asbestos in environmental systems. The outcomes of this research will greatly contribute to the knowledge required for future decision making concerning environmental asbestos remediation.  

 

Researchers involved:

Univ. Prof. Dr. Stephan Kraemer (head), Department of Environmental Geosciences, University of Vienna

Dr. Walter Schenkeveld, Department of Environmental Geosciences, University of Vienna

Martin Walter MSc, Department of Environmental Geosciences, University of Vienna

Ao. Univ. Prof Dr. Lars Gille, Institute of Pharmacology and Toxicology, Veterinary University of Vienna

Mag. Gerald Pichler, Institute of Pharmacology and Toxicology, Veterinary University of Vienna

Ao. Univ. Prof. Dipl.-Ing. Dr. techn. Michael Reissner, Institute of Solid State Physics, Technical University of Vienna

 

 

In media and public:

 

Falter Heureka 2/16

https://www.falter.at/heureka/search/201620/2

 

Die Presse, 04. März 2016

http://diepresse.com/home/science/4910092/Sauerampfer-und-Lupinen-gegen-Asbest?_vl_backlink=/home/science/index.do

http://diepresse.com/home/panorama/wien/4939648/Die-sauberste-Baustelle-der-Welt?from=gl.home_panorama

 

Uni Wien, uni:view Magazin, 15. Dezember 2015

https://medienportal.univie.ac.at/presse/aktuelle-pressemeldungen/detailansicht/artikel/mit-pflanzen-gegen-asbest-in-boeden/

 

Falter, “JungforscherInnen”, 05. November 2014

https://www.falter.at/heureka/search/201445/5?cnt=10

 

Lungenärzte im Netz, 25. Jänner 2016

http://www.lungenaerzte-im-netz.de/news-archiv/meldung/article/pflanzen-beschleunigen-abbau-von-asbest-in-boeden/

 

Hitech, 16.Dezember 2015

http://www.hitech.at/2015/12/16/pflanzenpower/

 

Materialsgate, 16. Dezember 2015

https://www.materialsgate.de/de/mnews/62036/Bauwesen+Mit+Pflanzen+gegen+Asbest+in+B%C3%B6den.html

 


Deutsche Botanische Gesellschaft, 15. Dezember 2015

http://www.deutsche-botanische-gesellschaft.de/no_cache/article/mit-pflanzen-gegen-asbest-in-boeden.html?back=290

 

“Umweltschutz: Servicemagazin für Entscheider in Ökologie und Wirtschaft”, 15. Dezember 2015

http://www.umweltschutz.co.at/item/article/mit-pflanzen-gegen-asbest-in-boeden/

 

Garten+Haus, 17. Dezember 2015

http://www.garten-haus.at/?+Mit+Pflanzen+gegen+Asbest+in+Boeden+&id=2500%2C5480734%2C%2C%2CY2Q9Ng%3D%3D

 

Umwelt-Dienstleister, Magazin für Deutschland, Österreich, Schweiz, 17. Dezember 2015

http://umweltdienstleister.de/2015/12/17/asbest-in-boeden-beschleunigt-beseitigen/

Department of Environmental Geosciences
University of Vienna

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