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Press Release July 10, 2006

Surprising Discovery Leads to New Understanding of Water Quality

CHICAGO, July 10 /PRNewswire/ -- Scientists at the U.S. Department of
Energy's Argonne National Laboratory have discovered new ways that ions
interact with mineral surfaces in water, opening a door to new knowledge on
how contaminants travel in the environment. The insight, published in
today's issue of Physical Review Letters, leads to a better understanding
of the factors that determine water quality.

Water -- colorless, odorless and tasteless -- may seem simple, but its
interaction with minerals can be difficult to study. Ions (ranging from
nutrients such as calcium, to contaminants such as lead) are present in
natural waters, but their transport is often limited by adsorption to
mineral surfaces. The more scientists can understand about the interaction
of minerals with water and ions, the more effectively they can control
water quality in our environment, and Argonne's research in this area is
making a leading contribution to the field.

Contrary to generally held scientific assumptions, the simple textbook
description of how ions adsorb to mineral-water interfaces has been shown
to not be universally true. Argonne Physicist Paul Fenter stated, "Ions are
known to carry a hydration shell in water. Previously, it was thought that
ions either adsorb to a mineral surface with this shell intact as an outer-
sphere ion, or remove part of this shell to directly bind to the mineral as
an inner-sphere ion. We now know that this is not just a black and white
difference, but have discovered new shades of gray by showing that outer-
sphere and inner-sphere species of the same ion can co-exist."

This revelation was the outcome of a new element-specific method
developed to understand the behavior of ions at the interface between
minerals and liquids, like water. According to Argonne Chemist Changyong
Park, "Conventional methods provided no direct sensitivity to observing
this behavior. Outer-sphere species were almost invisible and extremely
difficult to identify. There was just no way to see the co-existence of
both species previously."

Using the Advanced Photon Source (APS) at Argonne, which provides the
western hemisphere's most brilliant x-ray beams for research, the team was
able to make this new discovery. These x-rays enabled scientists to pursue
new knowledge about the structure and function of materials -- and develop
new methods for scientific study. Using the APS, the team was able to take
advantage of the technique's spectroscopic sensitivity to identify the way
specific ions interact at mineral-water interfaces and visualize the
phenomena directly.

The findings built on earlier work on cation adsorption using
traditional x-ray scattering techniques. The Argonne scientists, working
together with researchers from the University of Illinois at Chicago
Department of Earth and Environmental Sciences, previously discovered an
anomaly in the way that ions adsorb. The team collaborated again with the
new element-specific technique which led to this new discovery, central to
understanding the behavior of ions at solid-liquid interfaces.

Water is the "universal solvent," dissolving more substances than any
other liquid. This means that wherever water goes, either through the
ground or through our bodies, it takes ions along with it. A general
understanding of this behavior and the development of a new scientific
method for studying this phenomenon may lead to better understanding of
various other processes that take place at solid-liquid interfaces,
including corrosion, erosion, catalysis, and even the biological behavior
of cell membranes.

The Chemistry Division at Argonne National Laboratory conducts
strategic research at the frontiers of chemistry, promoting the exchange of
great scientific minds and tools to answer complex questions for a brighter
future. Research areas include geochemistry, radiation and photochemistry,
photosynthesis, metal clusters, nanoclusters, chemical dynamics of gases,
chemical transformations, heavy-element separations, and computational and
electrochemical processes.

This research is funded by the Geosciences Research Program of the
DOE's Office of Basic Energy Sciences.

The nation's first national laboratory, Argonne National Laboratory
conducts basic and applied scientific research across a wide spectrum of
disciplines, ranging from high-energy physics to climatology and
biotechnology. Since 1990, Argonne has worked with more than 600 companies
and numerous federal agencies and other organizations to help advance
America's scientific leadership and prepare the nation for the future.
Argonne is managed by the University of Chicago for the U.S. Department of
Energy's Office of Science.