Contamination of surface and subsurface environment by heavy metals and radionuclides is one of worldwide concern problems. The manufacturing and the use of synthetic products can result in heavy metal contamination of urban and agricultural soils. Therefore, research on various geochemical and biogeochemical processes that control the concentrations, fate, and transport of heavy metal and radionuclide contaminants in subsurface environments is of particular importance.
The research group lead by Prof. Wang in Institute of Plasma Physics, Chinese Academy of Sciences, achieved great progress in the research work about the species and microstructures of heavy metal ions and radionuclides in the natural environment. The researchers used extended X-ray absorption fine structure (EXAFS) technique at the National Synchrotron Radiation Laboratory (NSRL, China) to study the microstructures and interaction mechanism of heavy metal ions with clay minerals as different experimental conditions such as pH, contact time, temperature and humic substances. The results indicate that the species and microstructures of heavy metal ions are changeable with increasing contact time at molecular level, although the amount of heavy metal ions adsorbed on clay minerals does not change with increasing contact time from the batch investigations. The species and interaction mechanisms of heavy metal ions with clay minerals are also affected by other experimental conditions. Also they have clarified the species and interaction mechanisms of Ni with minerals at different experimental conditions, and the model fitting results of Ni(II) sorption on montmorillonite at different environmental conditions. The results are much more important to understand the physicochemical behavior of heavy metal ions with clay minerals in the natural environment. The relative results are published in international journals such as Geochimica Cosmochimica Acta (2011, 75: 6520); Environmental Science & Technology (2011, 45: 7718); and Dalton Transactions (2011, 40: 10953).

The species and interaction mechanisms of heavy metal ion (Ni) with diatomite at different experimental conditions.