Man-Made and Half-Lives of Some Unstable Isotopes Used in Dating Parent Isotope Daughter Product Half-Life Value Thorium 232 Lead 208 14.0 billion years Rubidium 87 Strontium 87 48.8 bil
Trang 1beled and unlabeled analytes compete
for limited amounts of a molecule that
binds the analyte very specifically RIA
is used worldwide in the
determina-tion of hormones, drugs, and viruses
The technique is so specific that
con-centrations in the picomolar region
can be measured Another major use
of radioisotopes is as tracers that
de-termine metabolic pathways, transport
processes, and reaction mechanisms
A compound labeled with a
radioac-tive isotope is introduced into the
pro-cess, and the radioactivity allows the
compound to be followed through the
mechanism
Pharmacokinetics is the study of the rates of
move-ment and biotransformation of a drug and its
metabo-lites in the body Many kinetic parameters, such as a
drug’s half-life in the body, can be determined by
us-ing radiolabeled drugs and measurus-ing radioactivity
after some type of chromatographic separation of the
parent drug from its metabolites
Radiopharmaceuticals are substances labeled with
radionuclides that are used in the visualization of
or-gans, the location of tumors, and the imaging of
bio-chemical processes This usage is based on the fact
that a substance that is found in a healthy cell at a
cer-tain concentration has a different concentration in
damaged cells The particular isotope used depends
on the organ or biochemical process under study
Radioisotopes are used in many ways in industry
Gamma rays from cobalt 60 are used to examine
ob-jects for cracks and other defects Radioisotopes can
be used to measure thickness of all types of rolled
ma-terials and as tracers in locating leaks in pipes
carry-ing liquids or gases The fill level of closed containers
is monitored by absorption or scattering of radiation
In the chemical industry radioisotopes are used to
indicate the completeness of a precipitation reaction
A radioisotope of the element to be precipitated is
added to the solution to be precipitated When the
fil-trate is free of radioactivity, precipitation is complete
Radioisotopes are used in dating ancient rocks and
fossils Carbon is used in dating fossils All living
or-ganisms are assumed to be in equilibrium with their
environment, taking in carbon in food and expelling
it through respiration and other processes A living
or-ganism is assumed, when it dies, to have a certain
per-centage of carbon 14, radioactive carbon As the fossil
ages the carbon 14 decays by beta emission, and its percentage is reduced Since the decay rate is known,
a reasonable age estimate can be obtained by measur-ing the rate of radioactive emission (proportional to percentage carbon 14) from the fossil Uranium is used in a similar way to date rock samples that contain
a mixture of uranium and lead, which is at the end of its decay chain
Grace A Banks
Further Reading
Billington, D., G G Jayson, and P J Maltby Radioiso-topes Oxford, England: BIOS Scientific Publishers
in association with the Biochemical Society, 1992 Choppin, Gregory R., Jan-Olov Liljenzin, and Jan
Rydberg Radiochemistry and Nuclear Chemistry 3d
ed Boston: Butterworth-Heinemann, 2002 Dragani6, Ivan G., Zorica D Dragani6, and Jean-Pierre
Adloff Radiation and Radioactivity on Earth and Be-yond 2d ed Boca Raton, Fla.: CRC Press, 1993 Ehmann, William D., and Diane E Vance Radiochem-istry and Nuclear Methods of Analysis New York:
Wiley, 1991
Faure, Gunter, and Teresa M Mensing Isotopes: Princi-ples and Applications 3d ed Hoboken, N.J.: Wiley,
2005
Henriksen, Thormod Radiation and Health New York:
Taylor & Francis, 2003
Serway, Raymond A., Chris Vuille, and Jerry S
Faughn College Physics 8th ed Belmont, Calif.:
Brooks/Cole Cengage Learning, 2009
Thornburn, C C Isotopes and Radiation in Biology New
York: Halstead Press Division, Wiley, 1972
Tykva, Richard, and Dieter Berg, eds Man-Made and
Half-Lives of Some Unstable Isotopes
Used in Dating
Parent Isotope Daughter Product Half-Life Value
Thorium 232 Lead 208 14.0 billion years Rubidium 87 Strontium 87 48.8 billion years Potassium 40 Argon 40 1.25 billion years Samarium 147 Neodymium 143 106 billion years
Source: U.S Geological Survey.
Trang 2Natural Radioactivity in Environmental Pollution and
Radiochronology Boston: Kluwer Academic, 2004.
Umland, Jean B., and Jon M Bellama General Chemistry.
3d ed Belmont, Calif.: Thomson/Brooks Cole, 1999
Web Sites
World Nuclear Association
Radioisotopes in Industry
http://www.world-nuclear.org/info/
default.aspx?id=548&terms=radioisotopes
World Nuclear Association
Radioisotopes in Medicine
http://www.world-nuclear.org/info/
default.aspx?id=546&terms=radioisotopes
See also: Atomic Energy Commission; Isotopes,
sta-ble; Manhattan Project; Nuclear energy; Nuclear
Reg-ulatory Commission; Plutonium; Radium; Thorium;
Uranium
Isotopes, stable
Category: Mineral and other nonliving resources
Where Found
Stable isotopes comprise the bulk of the material
uni-verse Some elements are found in only a single form,
while others have several isotopes For study and
ap-plication, it is necessary to separate the various
iso-topes from one another A number of methods have
been developed to accomplish isotope separation
Primary Uses
Analysis of stable isotopes and isotopic composition is
used extensively in a wide variety of fields These
in-clude soil and water analysis, plant tissue analysis,
de-termination of metabolic pathways in plants and
ani-mals (including humans), archaeology, forensics, the
geosciences, and medicine
Technical Definition
An isotope is one of two or more species of atom that
have the same atomic number (number of protons)
but different mass numbers (number of protons plus
neutrons) Stable isotopes are those which are not
ra-dioactive Because the chemical properties of an
ele-ment are almost exclusively determined by atomic
number, different isotopes of the same element will exhibit nearly identical behavior in chemical reac-tions Subtle differences in the physical properties of isotopes are attributable to their differing masses Description, Distribution, and Forms
There are approximately 260 stable isotopes While most of the eighty-one stable elements that occur in nature consist of a mixture of two or more isotopes, twenty occur in only a single form Among these are sodium, aluminum, phosphorus, and gold At the other extreme, the element tin exhibits ten isotopic forms Two elements with atomic numbers less than
84, technetium and promethium, have no stable iso-topes The atomic weight of an element is the weighted average of its isotope masses as found in their natural distribution For example, boron has two stable iso-topes: boron 10 (an isotope with mass number 10), which accounts for 20 percent of naturally occurring boron, and boron 11, which accounts for 80 percent The atomic weight of boron is therefore (0.2) × (10) + (0.8) × (11) = 10.8 In those elements that have natu-rally occurring isotopes, the relative abundance of the various isotopes is found to be remarkably constant, independent of the source of the material There are cases in which the abundances are found to vary, and these are of practical interest
History
In the early part of the twentieth century, the discov-ery of radioactivity, radioactive elements, and the many distinctly different products of radioactive de-cays showed that there were far more atomic species than could be fit into the periodic table Although possessing different physical properties, many of these species were chemically indistinguishable
In 1912, Joseph John Thomson, discoverer of the electron, found that when a beam of ionized neon gas was passed through a properly configured electro-magnetic field and allowed to fall on a photographic plate, two spots of unequal size were exposed The size and location of the spots were those that would be ex-pected if the original neon consisted of two compo-nents—about 90 percent neon 20 and 10 percent neon 22 Later Francis William Aston improved the experimental apparatus so that each isotope was fo-cused to a point rather than smeared out The device
he developed, known as a mass spectrograph, allows much greater precision in the determination of iso-tope mass and abundance
Trang 3Obtaining Isotopes
All methods for separating stable isotopes are based
on mass difference or on some isotopic property that
derives from it The difficulty of isotope separation
depends inversely upon the relative mass difference
between the isotopes For example, the two most
abundant isotopes of hydrogen are ordinary hydrogen
(hydrogen 1) and deuterium (hydrogen 2) These
iso-topes have a relative mass difference of (2-1)/1 = 1, or
100 percent The mass difference between chlorine 35
and chlorine 37, by contrast, is only (37-35)/35 = 0.057,
or 5.7 percent
There are two types of separation methods The
only single-step method is electromagnetic
separa-tion, which operates on the principle that the
curva-ture of the path of a charged particle in a magnetic
field is dependent on the particle mass This is the
same principle on which the mass spectrograph is
based Though it is a single-step technique, the amount
of material that can be separated in this way is
ex-tremely small All other processes result in a
separa-tion of the original material into two fracsepara-tions, one
slightly enriched in the heavier isotope To obtain
sig-nificant enrichment the process must be repeated a
number of times by cascading identical stages Such
multistage methods include gaseous centrifugation,
aerodynamic separation nozzles, fractional
distilla-tion, thermal diffusion, gaseous diffusion,
electroly-sis, and laser photochemical separation For example,
in centrifugation a vapor of the material to be
sepa-rated flows downward in the outer part of a rotating
cylinder and upward in the center Because of the
mass difference, the heavier isotope will be
concen-trated in the outer region and can be removed to be
enriched again in the next stage
Uses of Stable Isotopes
Most stable isotope applications are based on two
facts First, isotopes of a given element behave nearly
identically in chemical reactions Second, the relative
abundances of isotopes for a given element are nearly
constant The three principal types of applications are
those in which deviations from the standard
abun-dances are used to infer something about the
environ-ment and/or history of the sample, those in which the
isotopic ratio of a substance is altered so that the
sub-stance may be traced through a system or process, and
those in which small differences in the physical
prop-erties of isotopes are used to understand process
dy-namics
As an example of the first type of application, con-sider that the precise isotopic composition of water varies with place and time as it makes its way through the Earth’s complex hydrologic cycle Knowledge of this variation allows for the study of storm behavior, identification of changes in global climatic patterns, and investigation of past climatic conditions through the study of water locked in glaciers, tree rings, and pack ice The cycling of nitrogen in crop plants pro-vides an example of stable isotope tracer methods Fertilizer tagged by enriching (or depleting) with ni-trogen-15 is applied to a crop planting Subsequent analysis makes it possible to trace the quantities of fer-tilizer taken up by the plants, remaining in the soil, lost to the atmosphere by denitrification, and leached into runoff water
Michael K Rulison
Further Reading
Asimov, Isaac The History of Physics New York: Walker,
1984
Bransden, B H., and C J Joachain Physics of Atoms and Molecules 2d ed New York: Prentice Hall, 2003 Clayton, Donald D Handbook of Isotopes in the Cosmos: Hydrogen to Gallium New York: Cambridge
Univer-sity Press, 2003
Ehleringer, James R., and Thure E Cerling “Stable
Isotopes.” In The Earth System: Biological and Ecologi-cal Dimensions of Global Environmental Change,
ed-ited by Harold A Mooney and Joseph G Canadell
Vol 2 in Encyclopedia of Global Environmental Change.
New York: Wiley, 2002
Fry, Brian Stable Isotope Ecology New York: Springer,
2006
Hobson, Keith A., and Leonard I Wassenaar, eds
Tracking Animal Migration with Stable Isotopes
Am-sterdam: Academic Press, 2008
National Research Council Separated Isotopes: Vital Tools for Science and Medicine Washington, D.C.:
National Academy Press, available from Office of Chemistry and Chemical Technology, National Re-search Council, 1982
Web Site Northern Arizona University, Colorado Plateau Stable Isotope Laboratory What Are Stable Isotopes?
http://www.mpcer.nau.edu/isotopelab/
isotope.html
Trang 4See also: Biotechnology; Hydrology and the
hydro-logic cycle; Isotopes, radioactive; Nitrogen cycle;
Nu-clear energy; Soil testing and analysis
Italy
Categories: Countries; government and resources
Italy is one of the world’s leading producers of wine,
ol-ive oil, and cheese Olol-ive trees and vineyards can be
found throughout the country The town of Carrara is
world famous for the quality of its marble deposits.
The Country
A founding member of the European Union, Italy
be-came a nation-state in 1861 and a republic in 1946
It-aly is a peninsula that extends into the Mediterranean
Sea in southern Europe The country comprises a
boot-shaped mainland, the islands of Sicily and
Sar-dinia, and several smaller islands Italy shares borders
with Austria, Switzerland, France, San Marino, and
Slovenia Natural threats to the nation include
earth-quakes, volcanic eruptions, mudslides, and avalanches,
along with land subsidence in Venice Three-quarters
of the country is mountainous; the Alps stretch across
the northern region, and the Apennines run
south-ward along the peninsula The southern area of the
country has four active volcanoes, including Mount
Vesuvius and Mount Etna In 2008, Italy’s economy
was the fourth largest in Europe and seventh
world-wide The country is known for its cuisine, wine,
cheese, olive oil, and marble Italy has played a large
role in European and global history Home to
Etrus-cans and later the Romans, Italy has been influential
in the fields of architecture, literature, painting,
sculp-ture, science, education, government, philosophy,
mu-sic, and fashion
Olive Oil
Italy is one of the top-two leading producers of olive
oil in the world Fossils of olive trees have been found
in Italy dating back 20 million years The culture of
producing olive oil, however, did not emerge in the
area until much later The spread of the Greek empire
brought olives to southern Italy in the eighth century
b.c.e The Romans planted olive trees throughout
the Mediterranean region Ancient historians wrote
about Italian olive oil as being reasonably priced and
the best in the Mediterranean Olive oil was a main ingredient in various ointments and was believed to increase strength and youthfulness Leading produc-ers of extra virgin olive oil are the regions of Liguria, Tuscany, Umbria, and Apulia One-third of Italy’s olive oil trees are in the Apulia region The taste and quality of the oil is affected by the type of olives, climate and conditions where they are grown, the method of harvest, and the production process The Italian government strictly controls the extra virgin olive oil industry; in order to earn the distinc-tion of extra virgin the oil must have an acidity level of less than 1 percent In 1998, the United States im-ported 131 million liters of olive oil from Italy Olive oil from Italy is among the highest priced and most in demand This has led companies to mix lower quality oil with Italian oil in order to produce a cheaper prod-uct The oil is then labeled as being imported from It-aly In March, 2008, the Italian government arrested twenty-three people and shut down eighty-five farms involved in schemes to sell counterfeit Italian olive oil The following month, the government arrested forty people who were adding chlorophyll to sun-flower and soybean oils The oil was then sold through-out Italy and around the world as extra virgin olive oil Twenty-five thousand liters of the counterfeit oil were confiscated before it could be exported
Marble Carrara, located in the Apuan Alps in northwestern Tuscany, is the marble capital of Italy It produces one-third of all the marble quarried in Italy The area was first mined by the Romans, who used slaves and con-victs to extract the rock They would insert damp wooden wedges into existing cracking in the rock face; the wood would then expand, loosening the marble In 1570, gunpowder was first used in Carrara
to extract marble from the mountainside Explosives drastically changed the landscape of the area as more quarries opened and larger chunks of marble were ex-tracted A hydroelectric plant was built nearby in
1910, which allowed the quarries to use electricity for the first time This technology is used in the nearly three hundred active marble quarries in Carrara Several varieties of marble are mined in the area, including the uncommonly white, flawless marble for which the town is famous The port of Marina di Car-rara is one of the most famous in Italy and is known worldwide for loading and unloading marble and granite During the early sixteenth century, sculptor
Trang 5642 • Italy Global Resources
Italy: Resources at a Glance
Official name: Italian Republic Government: Republic
Capital city: Rome Area: 116,314 mi2; 301,340 km2
Population (2009 est.): 58,126,212 Language: Italian
Monetary unit: euro (EUR)
Economic summary:
GDP composition by sector (2008 est.): agriculture, 2%; industry, 27%; services, 71%
Natural resources: coal, mercury, zinc, potash, marble, barite, asbestos, pumice, fluorspar, feldspar, pyrite (sulfur),
natural gas and crude oil reserves, fish, arable land
Land use (2005): arable land, 26.41%; permanent crops, 9.09%; other, 64.5%
Industries: tourism, machinery, iron and steel, chemicals, food processing, textiles, motor vehicles, clothing,
footwear, ceramics
Agricultural products: fruits, vegetables, grapes, potatoes, sugar beets, soybeans, grain, olives, beef, dairy products,
fish
Exports (2008 est.): $546.9 billion
Commodities exported: engineering products, textiles and clothing, production machinery, motor vehicles, transport
equipment, chemicals, food, beverages and tobacco, minerals and nonferrous metals
Imports (2008 est.): $546.9 billion
Commodities imported: engineering products, chemicals, transport equipment, energy products, minerals and
nonferrous metals, textiles and clothing, food, beverages, and tobacco
Labor force (2008 est.): 25.11 million
Labor force by occupation (2005): agriculture, 4.2%; industry, 30.7%; services, 65.1%
Energy resources:
Electricity production (2007 est.): 292.1 billion kWh
Electricity consumption (2006 est.): 316.3 billion kWh
Electricity exports (2007 est.): 1.916 billion kWh
Electricity imports (2007 est.): 34.56 billion kWh
Natural gas production (2007 est.): 9.706 billion m3
Natural gas consumption (2007 est.): 84.89 billion m3
Natural gas exports (2007 est.): 68 million m3
Natural gas imports (2007 est.): 73.95 billion m3
Natural gas proved reserves ( Jan 2008 est.): 94.15 billion m3
Oil production (2007 est.): 166,600 bbl/day Oil imports (2005): 2.223 million bbl/day Oil proved reserves ( Jan 2008 est.): 406.5 million bbl
Source: Data from The World Factbook 2009 Washington, D.C.: Central Intelligence Agency, 2009.
Notes: Data are the most recent tracked by the CIA Values are given in U.S dollars Abbreviations: bbl/day = barrels per day;
GDP = gross domestic product; km 2 = square kilometers; kWh = kilowatt-hours; m 3 = cubic meters; mi 2 = square miles.
Rome
Italy
Austria
France
Hungary
Greece Albania Yugoslavia Bosnia Croatia Slovenia Switzerland
Algeria Tunisia
A
d r i a tic
S e a
I o n i a n
S e a
M e d i t e r r a n e a n S e a
T y r r h e n i a n
S e a
Trang 6Michelangelo (1475-1564) traveled often to the
quar-ries to pick out marble for his projects, including
Da-vid Carrara marble was used to build the Pantheon,
Trajan’s Column in Rome, the Marble Arch in
Lon-don, and the Cathedral of Siena The stone is also used
as a facade for buildings worldwide Carrara is home
to many fairs that celebrate marble and quarrying In
1982, the town opened the Marble Museum of Carrara
to preserve the history of marble and the marble
indus-try in the area The museum has several sections,
in-cluding archaeological relics, drawings, photographs,
plaster casts, sculptures, and industrial artwork It also
tells the history of marble quarrying and has
machin-ery, technical diagrams, and photographs The
gal-lery contains more than three hundred samples of
marble, granite, and rock from Italy and elsewhere
Feldspar
Feldspar is a group of minerals that compose up to 60
percent of the Earth’s crust The mineral can be
found as crystals in granite or other igneous rock, in
sedimentary rocks, in metamorphic rocks, or in veins
Feldspars are often pink, white, gray, or brown The
color varies with the chemical composition of the
mineral Feldspars are used in glassmaking, tile,
ce-ramics, abrasive cleaners, and many other products
Italy was the leading feldspar producer throughout
the 1990’s, vastly outmining the rest of the world By
1998, Italy was producing almost 2.1 million metric
tons of feldspar At that time, Italy’s tile industry was
among the top in the world, and the ceramics
indus-try was among the leaders in Europe
The Maffei Sarda company began mining feldspar
in northern Sardinia in 1989 In the late 1990’s, the
company began producing a soda-potash feldspar that
is unusually white in color and has been used to make
bone china At the time, another mining company
de-veloped a process to extract feldspar from granite that
it recovered from a mining dump in Italy’s Lake
Maggiore region Italy’s yearly production of feldspar
continues to increase; in 2008, the country mined 4.2
million metric tons In 2008, Italy continued to be the
top producer of feldspar, followed by Turkey, China,
and Thailand That year, Italian feldspar accounted
for almost one-quarter of the total world production
Metal and Mineral Resources
Italy mines a variety of metals, including copper, lead,
zinc, gold, and mercury The majority of mining
com-panies and mines are government controlled Some
privatization of the industry began during the 1990’s During the 1970’s, Italy was a leading producer of py-rites, fluorite, salt, and asbestos The country also mined enough zinc, sulfur, lead, and aluminum to meet its own demand However, less than two decades later, Italy had drastically depleted these resources and was no longer self-sufficient
One-half of the country’s iron production is from Elba Island The last iron cave was closed there in
1981 The island is also home to the Mining Museum The museum has more than one thousand rocks and minerals on display and allows visitors to tour a mine The majority of Italy’s metals are found on its islands; the decline of mining and depletion of the deposits have severely impacted their economies
The world’s second largest mercury mine is lo-cated in Idrija, Slovenia The region has been con-trolled by a number of different European nations; it was controlled by Italy between World Wars I and II The Idrija mine was in operation by the time Christo-pher Columbus set sail for the West Indies in 1492 Mercury was first exported through Venice, followed
by Amsterdam in 1659 After more than five hundred years in operation, the mine was shut down because of declining mercury ore prices Mercury is still found in the Lake Maggiore region of Italy
Coal The island of Sardinia has a long history of coal min-ing During the fascist period, a large number of the island’s swamplands were drained to produce farm-able land Several agrarian communities began to form in these areas At this time, the city of Carbonia was also established, which became the mining center
of Sardinia Tourism increased on the island by the early 1950’s, which led to a decrease in coal mining
By 2007, the Miniera Monte Sinni mine, located in the Sulcis basin in southwestern Sardinia, was the only ac-tive underground coal mine in Italy It produced on average only 90,000 metric tons of coal each year Italy, however, has large coal reserves: an estimated 544 mil-lion metric tons, of which 30.8 milmil-lion metric tons are minable, according to a 2007 study A 2003 estimate placed the country’s reserves at more than 900 mil-lion metric tons The study also estimated that the Sulcis basin had produced 72.6 million metric tons of coal Production of lignite from Italy’s only lignite mine declined drastically between 1998 (141,500 met-ric tons) and 2002 (9,000 metmet-ric tons) The Tuscan mine was shut down in 2003
Trang 7Italy was fourth among energy consumption in
Eu-ropean countries This growing demand for power
sources has increased Italy’s dependence on coal The
use of coal has met some political opposition but is
aided by advances in the “clean coal” industry In
2008, Italy’s largest power company, Enel, converted a
large power plant from oil to coal The plant is located
northwest of Rome, in Civitavecchia The company
defends this move as a means to lower costs; fuel costs
have risen 151 percent since 1996 Italy has the
high-est electricity prices in Europe The country plans to
produce 33 percent of its power from coal, more than
double the 14 percent it produced prior to 2008
Wine
The Etruscans, who were located in what is now
north-ern Italy, and the Greek colonists to the south began
Italy’s long history with winemaking After taking
con-trol of the area, the Romans started their own
vine-yards Winemaking in the Roman Empire was a large
enterprise and pioneered mass production storage
methods like barrel making and bottling The
Ro-mans operated several vineyard plantations manned
with slave labor on much of the coastal area of the
re-gion The plantations were so extensive that in 92 c.e
the emperor had to shut down a number of them in
order to use the land for food production
Today, Italy is one of the two leading wine
produc-ers in the world In 2005, Italian wine accounted for
20 percent of the world’s wine The United States
im-ported nearly one-third of the total from Italy (36
per-cent by dollar value) Italy produces wines of many
flavors, colors, and styles There are approximately
one million vineyards throughout modern Italy The
country has twenty wine regions, which are also its
po-litical districts The economy of the Apulia region is
based primarily on wine, with 106,712 hectares of
grapes and a yearly output of approximately 723.7
million liters of wine The islands of Sardinia and
Sic-ily are also major wine producers Tuscany is famous
for its red wines About 70 percent of the 216 million
liters produced there each year are red wines The
re-gion has more than 63,537 hectares of vineyards
Starting in 1968, winemakers began producing “super
Tuscans,” wines that are not mixed according to the
traditional blending laws of the area During the
1970’s, Tignanello became one of the first super
Tus-cans by eliminating the white grapes from a recipe for
chianti Piero Antinori replaced them with red
Bor-deaux grapes in order to produce a richer wine The
new wines do not fit into any of the four traditional categories in which Italian wine is classified However, winemakers throughout the country continue to ex-periment and create new wines
Fish Even though the majority of fish and seafood con-sumed in Italy is imported, fish production in the country has risen since the 1960’s During the mid-1980’s the European Union passed the Common Fish-eries Policy The policy is designed to eliminate over-fishing and maintain a competitive fish and seafood industry within Europe In 2002, a European Union commission reduced the catch limits on the number
of cod and other species of fish that had dwindling numbers In 2004, subsidies for fisherman to help procure new vessels were eliminated Because of this, the number of Italian fishing ships has decreased, leaving mostly small-scale fishing operations In 2003, Italian fishermen caught 26 percent less fish than the previous year The northern region of Italy houses 62 percent of the country’s fish farms; 22 percent are found in central Italy, and 16 percent in the southern region These fisheries produced $405 million worth
of fish in 2003 Canada is a large importer of fish to It-aly, but retailers face a tough obstacle: Italian consum-ers are used to purchasing fresh goods, not canned or frozen These companies may be added by the grow-ing demand for value and the convenience of ready-made food
Other Resources
In addition to olives and grapes, Italy is famous world-wide for its cheeses The country produces more than four hundred different varieties of cheese In 2008, the government purchased 200,000 wheels of cheese (29.9 kilograms each) to help feed the poor, as food lines and the number of needy grew in the major cit-ies Italy is also a major exporter of rice and tomatoes During the late twentieth century, tomato farms dou-bled in size, and production quadrupled Northern It-aly grows three times the amount of wheat as the southern regions, which is used to make pizza crusts and pasta The country consumes a large portion of the agricultural products that it produces Eighty per-cent of Italy’s citrus fruit is grown in Sicily Italy is also
a leading producer of apples, oranges, lemons, pears, and other fruits as well as flowers and vegetables Potash can be various chemical compounds, mostly potassium carbonate Potassium oxide potash is used
Trang 8in fertilizer The town of Agrigento in southern Sicily
has an economy that is largely based on potash and
sulfur mining The nearby harbor is Italy’s principal
sulfur port
Jennifer L Campbell
Further Reading
Clark, Martin Modern Italy: 1871 to the Present New
York: Pearson Longman, 2008
Davis, John Anthony Italy in the Nineteenth Century,
1796-1900 New York: Oxford University Press,
2001
Duggan, Christopher A Concise History of Italy
Up-dated ed New York: Cambridge University Press,
2006
Knickerbocker, Peggy Olive Oil: From Tree to Table San
Francisco: Chronicle Books, 2007
Leivick, Joel Carrara: The Marble Quarries of Tuscany.
Palo Alto, Calif.: Stanford University Press, 1999
Lintner, Valerio A Traveler’s History of Italy 8th ed.
Northampton, Mass.: Interlink, 2008
Romaneili, Leonardo Olive Oil: An Italian Pantry San
Francisco: Wine Appreciation Guild, 2003
Scigliano, Eric Michelangelo’s Mountain: The Quest for
Perfection in the Marble Quarries of Carrara New York:
Free Press, 2005
See also: Agricultural products; Agriculture
indus-try; Coal; Feldspars; Fisheries; Marble; Potash; Wheat
Ivory
Category: Plant and animal resources
Where Found
Ivory is obtained from the large teeth and tusks of
sev-eral mammals, including the elephant,
hippopota-mus, walrus, extinct wooly mammoth, and narwhal
In these animals, an upper incisor grows throughout
life into a large tusk In elephants, for example, the
av-erage tusk weighs 7 kilograms, but in large males the
weight might be much more A major factor
endan-gering the continued existence of these extant
mam-mals has been the value of their ivory
Primary Uses
Ivory has been used by humans for thousands of years,
often as a medium for carving The art of scrimshaw
makes use of ivory, and many other ornamental ob-jects are carved from ivory In the past, most ivory was used in the manufacture of piano keys, but billiard balls, bagpipes, flatware handles, and furniture inlays were other products made from ivory Today, most ivory is used for the Chinese, Japanese, and Korean
seals known as hankos; these small seals are used on
of-ficial business documents
Technical Definition Ivory is the hardened dentine of the teeth and tusks of certain large mammals In both male and female ele-phants, one incisor on each side of the upper jaw grows throughout life In females, growth of the tusks tends to slow after age thirty, but in males both the length and bulk of the tusks increase through the life span, thus making old male elephants prime targets for ivory poachers In walruses, the tusks form from upper canines and grow throughout life in both sexes Narwhals have only two teeth, both in the upper jaw; these lengthen to become long, straight tusks, usually only one in males and sometimes two in females Hip-popotamuses have tusks of ivory that do not yellow with age, as elephant tusks tend to do
Description, Distribution, and Forms
Both the Asiatic elephant, Elephas maximus, and the African elephant, Loxodonta africana, have been
ex-tensively exploited for the ivory in their tusks Asiatic elephants are now restricted in range to southern Asia, although historically they had a much larger dis-tribution, from Syria to northern China and south to Sri Lanka, Sumatra, and perhaps Java According
to 2008 population estimates, only 34,000 to 54,000 wild Asiatic elephants remain throughout the present range of the species Approximately 17,000 to 23,000 are found on the Indian subcontinent, 11,000 to 20,000 in continental Southeast Asia, and 6,000 to 11,000 in Sri Lanka, Sumatra, and Borneo
The African elephant includes two major kinds, which some experts consider subspecies: the forest
elephant, Loxodonta africana cyclotis, of west and cen-tral Africa, and the savanna or bush elephant, Loxo-donta africana africana, of the savanna areas of
sub-Saharan Africa Intense pressure from both legal and illegal ivory hunters caused the entire African ele-phant population to fall from around 1.3 million in
1979 to 625,000 in 1989 More recent estimates place the population throughout Africa to be no more than 500,000 In 1990, the United Nations Convention on
Trang 9Trade in Endangered Species of Wild Fauna and
Flora (CITES) put a ban on the international trade of
ivory, and this slowed to some extent the killing of
ele-phants
A now-extinct relative of the elephant, the woolly
mammoth, Mammuthus primigenius, once ranged
throughout the cold, northern areas of Asia and
por-tions of North America Global climate change has
ex-posed the bodies of many mammoths and their tusks
have been gathered, mostly by Russian workers, as a
source of ivory
The walrus, Odobenus rosmarus, occurs in coastal
ar-eas of the Arctic Ocean and adjoining sar-eas This
spe-cies has been heavily exploited for the ivory of its large
upper canines, which may be more than 100
centime-ters long in males and about 80 centimecentime-ters in
fe-males Biologists are concerned that with the decline
of the African elephant population as a source of
ivory, poachers will turn to the killing of walruses
Narwhals, Monodon monoceros, are found in the
Arc-tic Ocean and nearby seas, primarily between 70° and
80° north latitude Their normal range is entirely
above the Arctic Circle Narwhals have two upper-jaw
teeth; in males, one of these remains embedded while the other erupts and grows in a spiral pattern to form
a long, straight tusk This tusk may be about one-third
to one-half of the animal’s total body length, some-times becoming as long as 300 centimeters with a weight of 10 kilograms Occasionally, one or two tusks are grown by a female narwhal Most researchers be-lieve that the narwhal uses the tusk as a defensive weapon, because extensive scarring is often found on the heads of males
The hippopotamus, Hippopotamus amphibius,
oc-curs throughout Africa in suitable waterways south of the Sahara Desert and also in the Nile River to its delta It has disappeared throughout most of western and southern Africa, partially because it is killed for its ivory tusks Some of the lower canine tusks of male hippos are just as large as many elephant tusks enter-ing the ivory market, causenter-ing the hippo to be a target for illegal trafficking in ivory
History The trade in ivory is thought to date to the time of Cro-Magnon man, approximately thirty-five thousand years ago The Asiatic elephant has been ex-ploited for ivory for at least four thousand years; upper classes in both Asia and the Mid-dle East greatly desired items made of ivory Ivory demand in Europe in the 1600’s drove the killing of many thousands of elephants around the Cape of Good Hope From 1860 to
1930, 25,000 to 100,000 elephants were killed each year for the ivory trade, mostly to obtain material for piano key manufacture By the early nineteenth century, the ivory-carving in-dustry in India was being supported by im-ported African elephant tusks, as the Asiatic el-ephants had already been seriously depleted The overall number of elephants in Africa in the early 1900’s was still several million and re-mained so until after World War II
The mid-twentieth century had a lag in commercial ivory hunting, but in the 1970’s hunting resumed in earnest as the raw ivory price increased from five to one hundred dol-lars per kilogram The African elephant was placed on appendix 2 of CITES in 1979, listed
as vulnerable by the International Union for Conservation of Nature, and listed as threat-ened by the United States Department of the Interior However, these listings did little to
This Asian elephant displays tusks of ivory that are 2.5 meters long The
il-licit ivory trade is an endangerment to elephants (©iStockphoto.com)
Trang 10prevent poaching, and the African elephant
popula-tion plummeted to 600,000 by 1997 In 1990, CITES
banned the international trade of ivory, but in 1997,
the convention approved the sale of more than 54
metric tons of ivory from Botswana, Namibia, and
Zimbabwe This stockpiled ivory was sold to Japan
CITES reinstated a trade ban again in 2000, then once
more allowed an exception in 2002 for Botswana,
Na-mibia, and South Africa In 2004, Namibia’s proposal
to allow tourist trade in ivory carvings was approved;
many conservationists believe that CITES’ imposing
and then temporarily lifting ivory bans has
encour-aged poaching in the African countries where larger
populations of elephants still exist In 2007, in
re-sponse to public pressure on the ivory trade issue,
eBay banned all international sales of elephant ivory
products and in 2009 disallowed any sales of ivory by
users of its Web site
China’s growing economy has driven illegal trade
in ivory as well as attracted organized crime related to
its sale A kilogram of ivory brings about $750
Esti-mated illegal shipments to China total approximately
218 metric tons, an amount that would cause the
deaths of at least 23,000 elephants
One tool available to conservation law
enforce-ment is DNA testing A genetic test developed by
Sam-uel Wasser of the University of Washington helps to
track illegal shipments to their source For example,
an extremely large illegal shipment of 532 tusks and
42,000 hankos was seized in Singapore in 2002
Ge-netic testing traced this ivory to Zambia, and the tusks
in the shipment weighed approximately 11 kilograms
each, indicating that they came from old elephants
Obtaining Ivory
Generally, ivory is obtained by the killing of the
ani-mals that possess ivory teeth and tusks As mentioned
above, these include elephants, hippopotamuses,
nar-whals, and walruses
Mammoth ivory is obtained primarily in Russia by
those who find recently thawed mammoth carcasses
Because of global climate change, this has become a
more common occurrence Mammoth ivory has been
used by Russian merchants in the manufacture of
items to sell to Asia About 90 percent of mammoth
ivory exported to Asia is used to make hankos for
Chi-nese, JapaChi-nese, and Korean markets This ivory,
be-cause it comes from an extinct mammal, can be legally
imported into the United States More than 46 metric
tons were imported in 2007 Dealers in Moscow
re-port that they can sell mammoth ivory for three hun-dred to four hunhun-dred dollars per kilogram in Russia;
in western markets it sells for up to sixteen hundred dollars per kilogram
Native subsistence hunting of walruses, by har-pooning or clubbing, has been occurring for thou-sands of years and probably had little negative impact
on populations of the species However, with the hunting of walruses by Europeans for ivory, hides, and oil, beginning in the sixteenth century, numbers of the animals on both sides of the North Atlantic de-clined dramatically The last large populations in the Canadian Arctic were gone by the 1930’s, and only about 25,000 of the Atlantic population remain Re-cent surveys of the Pacific population indicate that some 200,000 walruses are present, but there is con-siderable concern among biologists that ivory de-mand in Asia will drive poaching of the remaining ani-mals
Hippopotamuses have been extensively killed for hundreds of years for meat, hides, and ivory As popu-lations of African elephants have steadily declined, there has been increased pressure on hippos for their ivory The lower canine tusks of males are often as large as elephant tusks now entering the illegal mar-ket, and a sharp rise in the export of hippo ivory coin-cided with the placing of the African elephant under the more protective listing of appendix 1 of CITES The Vikings were probably the first culture to ex-ploit the narwhal extensively for its tusk, which sold for high prices as early as the tenth century The tusks were also in great demand in Asia, where they were used for carving and as medicine During the late 1900’s, narwhal tusks were sold for as much as forty-five hundred dollars The annual kill of narwhals in Canadian waters is estimated to be approximately one thousand The species has received little firm protec-tion from any conservaprotec-tion law
Uses of Ivory For many years, the use of ivory centered around dec-orative items, such as carved figurines and various gewgaws, primarily for customers in Europe, Asia, and the United States The manufacture of ivory piano keys and billiard balls was a major factor in the demise
of both Asiatic and African elephants Estimates indi-cated that consumption of ivory—for the making of piano keys—in Great Britain in 1831 accounted for the deaths of four thousand elephants More modern uses of ivory have been for flatware, jewelry, and