Messenger - Vol. 3, No. 3, Page 10
Spring 1994
On Research
Researcher tracks metals on the move

     Buried deep beneath the Earth's surface, metals pose no threat to
human health or the environment. A common caveat holds that when such
metals are set free, however, they can wreak havoc in water and soil.
     That's not necessarily true, says Herbert E. Allen, professor of
civil engineering. Allen and his colleagues study the "speciation," or
transformation, of metals, as they move through soil, water and
     To prevent environmental damage, regulatory authorities set
maximum limits for lead, silver, copper and other metals in the
environment. For example, silver used in photography, printing,
dentistry and radiology is thought to be harmful to aquatic
organisms-even at levels of less than 1 microgram per liter of water.
Trace amounts of copper can also cause problems, and lead poisoning
from paints, water pipes and gasolines has been well-documented in
     Yet, according to Allen, restrictions on metals in water are
often based on "erroneous data."
     Current water-quality criteria set by federal and state officials
reflect toxicity tests performed on aquatic organisms in a laboratory
setting, he explains. Yet, metals may be far less toxic in natural
waters, where they can be imprisoned by particles that help prevent
biological damage.
     "While it is absolutely essential to protect our environment,"
Allen says, under the existing regulatory system, taxpayers shell out
millions of dollars to protect aquatic life that isn't in any danger.
"With limited funds available to clean up so many environmental
problems, it's also important to spend money wisely," Allen says. In
his view, more cost-effective regulations would be based on an
understanding of the chemical processes that transform metals as they
move from place to place.
     "The total amount of metal in water isn't all that important,"
says Allen. "We should be more concerned about the specific chemical
forms of metals present in water-the amount of bioavailable metals in
water-and the chemical changes those metals undergo."
                                                    -Ginger Pinholster