Scientists have found a way to use hair to figure out where a person is from and
where that person has been. The finding could help solve crimes, among other
useful applications. Water is central to the new technique. Our
bodies break water down into its parts: hydrogen (氢) and oxygen. Atoms (原子) of
these two elements end up in our tissues and hair. But not all
water is the same. Hydrogen and oxygen atoms can vary in how much they weigh.
Different forms of a single element are called isotopes (同位素). And depending on
where you live, tap water contains unique proportions of the heavier and lighter
isotopes of hydrogen and oxygen. Might hair record these watery
quirks (古怪举动；怪癖)? That's what James R. Ehleringer, an environmental scientist at
the University of Utah in Salt Lake City, wondered. To find
out, he and his colleagues collected hair from barbers and hair stylists (发型师)
in 65 cities in 18 states across the United States. The researchers assumed that
the hair they collected came from people who lived in the area.
Even though people drink a lot of bottled water these days, the scientists found
that hair overwhelmingly (压倒性的) reflected the concentrations of hydrogen and
oxygen isotopes in local tap water. That's probably because people usually cook
their food in the local water. What's more, most of the other liquids people
drink including milk and soft drinks contain large amounts of water that also
come from sources within their region. Scientists already knew
how the composition of water varies throughout the country. Ehleringer and
colleagues combined that information with their results to predict the
composition of hair in people from different regions. One hair sample used in
Ehleringer's study came from a man who had recently moved from Beijing, China,
to Salt Lake City. As his hair grew, it reflected his change in
location. The new technique can't point to exactly where a
person is from, because similar types of water appear in different regions that
span a broad area. But authorities can now use the information to analyze hair
samples from criminals or crime victims and narrow their search for clues
(线索).
单选题
Which of the following is NOT correct about tap water of writer's view
point?
A.Tap water reflects the concentrations of hydrogen and oxygen isotopes in
different regions.
B.Tap water is a kind of soft drink in the United States.
C.Tap water contains unique proportions of isotopes of hydrogen and
oxygen.