Shedding New Light on Environmental Pollutants and Processes Using Synchrotron Radiation
Environmental pollutants are receiving increasing attention in the news media and in scientific publications because of their widespread occurrence and their potential harmful effects to humans and other organisms. Almost every day we see new reports about environmental pollutants such as arsenic pollution in drinking water in Bangladesh and in mine tailings in the Sierra Nevada foothills, selenium in agricultural soils of the Central Valley of California, mercury in San Francisco Bay fish and in mine tailings of the California Coast Range, chromium in some of the drinking water of Los Angeles, lead in house paint, and plutonium and uranium in soils at some DOE laboratories. Two of the key pieces of information needed to assess the potential danger of such pollutants is their chemical speciation at the molecular level and how they react with the surfaces of natural solids. Synchrotron x-ray absorption spectroscopy (XAS) can provide this information for a wide range of heavy metal and metalloid pollutants in complex environmental samples. Examples of synchrotron-based XAS studies at SSRL of a number of environmental pollutants will be discussed and used to illustrate some of the important environmental issues faced by modern society.