Results from a UK e-Science project are helping to solve two pressing environmental problems. One finding could help to avoid arsenic contamination of drinking water extracted from man-made wells. Another could lead to improved methods of removing the now-banned industrial chemical, dioxin, from soil. The results were obtained using e-Science techniques and grid computing to simulate all the possible interactions between these contaminants and rock or soil.
Arsenic often appears in minerals rich in iron and sulphur, such as pyrite (fools gold). Scientists working as part of eMinerals, a major project funded under the Natural Environment Research Councils e-Science programme, have found out precisely how arsenic is taken up and held in the pyrite structure and the factors likely to lead to its release. We now know that arsenic replaces the sulphur in pyrite rather than the iron, and that pyrite is likely to dissolve more easily when arsenic is present, says Dr Kate Wright, who worked on the project. Further work could identify ways of stabilising arsenic-containing iron sulphide rock by introducing additives that slow the rate at which it dissolves.
The eMinerals project found that a dioxin molecule will bind more strongly to clay surfaces the more chlorine atoms it contains, irrespective of the position of the chlorine atoms in the dioxin molecule. It also found that binding is stronger the greater the electrical charge on the surface. However, water competes with dioxin to bind to surfaces and, in practice, a dioxin molecules ability to bind to a surface is a balance between the binding strength of the dioxin to the surface, the water to the surface, and the dioxin to the water.
Both examples involved performing numerous simulations of the interactions between the different minerals in soil and rock with all the known variants of the contaminants. For example, there are 76 different variants of the dioxin molecule and numerous m
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Research Councils UK