Research Focus

Environmental Chemistry

Exploring the pathways of HEAVY METALS as pollutants in aquatic environments:

Heavy metals are pollutants of major concern in the aquatic environment globally. They are toxic even at low concentrations, they are persistent and they tend to bio-accumulate. Although they are natural components of the aquatic environment and some of them, for example, Zn and Cu, are essential for most biota in certain concentrations, human activities have led to their multiple remobilization and distribution in the environment.

Exposure to elevated levels poses a threat to wildlife health in many regions of the world. The main anthropogenic sources for pollution are domestic and industrial emissions through waste effluents and emissions caused by mining, energy production, and agricultural activities. Four out of the six top contaminants in the world reported by Pure Earth in 2015 belong to the class of heavy metals Pb, Hg, Cr, and Cd. Many of these elements such as Pb or Hg have long been known for their toxic properties, and therefore, worldwide enormous efforts have been taken to decrease their release into the environment.

Amongst others, the European Union has set maximum levels for Cd, Pb, Hg, and Ni as priority substances regarding aquatic environments in the directive on environmental quality standards in the field of water policy. In many European countries, the criteria demanded in this law have already been met. With regard to human food safety, the European Union added the ALARA (as low as reasonably achievable) principle for Pb—in addition to the maximum allowed levels in food for human consumption to their regulation—to further reduce Pb uptake. Canada is working on a similar regulation. However, millions of people’s health is threatened by the known toxic effects of contamination with trace elements, mostly in low- and middle-income countries. This is because precautionary measures to diminish contamination with trace elements are inadequate. On the contrary, the novel use of Ag is currently booming in high-income countries due to increasing applications in many aspects of daily life, commonly in the form of nanoparticles, with rarely known consequences for aquatic environments. There is nearly no control of Ag emissions into the environment, which may evolve into a serious problem even in high-income countries in the near future.

In our group we are specialized in analyzing heavy metals and other trace elements in environmental samples such as water, sediments, plants, animals and food stuff. In following the levels of food webs and other ways of possible (bio) concentration of these elements, we are able to not only evaluate the concentrations of these elements but also calculate possible risks for the environment and the biotic community including the human consumer. In our works, we have discovered novel insights in the trace metal content of biotic and a-biotic compartments from Europe and Africa. We could show, that although there is a general trend in melioration of pollution, we are far away of being able to lean back and stop being concerned, but rather are encouraged to continue to take a close look on the development within this filed.
          

NOVEL COMPOUNDS under development: IONIC LIQIDS

On the search for environmental friendly and cost effective substances to remove metals from aqueous solutions – in cooperation with Bioinorganic group.

A new class of chemical compounds has been discovered as suitable alternative for traditional chemical treatment of polluted water: Ionic liquids (ILs). ILs are per definition salts with melting points below 100°C and might be green alternatives for the extraction of heavy metals due to their favorable environmental and physico-chemical properties. These characteristics include, among others, a very low vapor pressure and recyclability. Partial solution during extraction, so-called leaching, however, limits their applicability. By introducing metal-chelating functional groups to hydrophobic ions, we have accomplished to synthesize novel ILs with improved stability during extraction while still achieving high selectivity towards metals such as lead, cadmium and mercury or emerging pollutant silver. These ILs are tested in extraction experiments using metal-spiked water samples of varying composition, including natural drinking water and seawater. Furthermore, we evaluate their toxicity on aquatic organisms and develop methods for the extraction of heavy metals based on their immobilization on solid supports.

Radiochemistry

The main interest of our group is the development of new methods for the measurement of natural and anthropogenic radionuclides in environmental samples. Modern ion exchange methods are used for pre-concentration and separation of the nuclides of interest before appropriate radiometric measurement. The investigated samples are e.g. water, aerosol and soil samples, or animal bones and thyroids.

Anthropogenic nuclides widely investigated in our environment during the last years were the fission products Cs-137 and Sr-90 as well as the activation products Pu-238 and Pu-(239+240). Natural radionuclides like Rn-222, Ra-226, Ra-228, Pb-210, Po-210 and the uranium isotopes are measured in Austrian tap-waters as well as in mineral waters to get an overview about the exposure to the public due to drinking water uptake. On aerosols the long-lived radon progeny Pb-210 and its daughter products were measured in order to calculate aerosol residence times. Pb-210 was also successfully used for dating of lake sediments.

Beyond the measurement of these “classical” radionuclides the determination of nuclides with very low natural abundance is of growing interest. We measure the distribution of the long-lived uranium fission product I-129 in the environment and plan to use the I-129/U ratio for dating of samples which represent a closed system. Another important topic is the determination of the long-lived uranium isotope U-236 and its applications in geoscience, nuclear safeguards and environmental protection. These investigations are done in cooperation with VERA, the Vienna Environmental Research Accelerator, Faculty of Physics, University of Vienna.