"From the Iliad to Earth and Environmental Engineering
Through Chemistry"
Nicholas Turro © 1999
"From the Iliad to Earth and Environmental Engineering
Through Chemistry"
Nicholas Turro © 1999
THE ANCIENT GREEKS, MINING, THE ENVIRONMENT AND CHEMISTRY: ALL CONNECTED IN THE STORY OF LAVRION.
Mining: An Ancient Art. Silver: The Stuff of a War Chest
Lavrion is a Greek city of 10,000 inhabitants which is situated
about 60 km south of Athens, and 20 km north of Sounion, an important
tourist and archaeological site. In the areas around Lavrion, considerable
ore deposits of lead and silver exist. These deposits were exploited for
their minor silver content from the 14th century BC, and reached a peak
during the Golden Age of Athens (5th century BC). It is estimated that the
ancient Athenians developed ingenious techniques to process the ore
deposits in the area around Lavrion to produce over 3500 tons of silver
(worth over $1,000,000,000 at today's value of silver) together with a
staggering 1,400,000 tons of lead. It has been estimated that 70% of the
silver was produced during the 4th and 5th centuries BC. The silver from
the mines of Lavrion served as the "dollar" of the age and may have been
the basis of the "war chest" for financing the Trojan wars. In modern
times lead mining was resumed in the late ninetieth century by a French
company that marketed the extensive lead deposits created by the Greek
mining. This lead to the creation of a small city built on the tailings
and slags of centuries of mining. The mines were closed permanently
around 1980.
The Chemical Issues.
The intensive past mining and metallurgical activities in the area of Lavrion have resulted in the generation of huge amounts of waste rock (so called tailings, metallurgical slags, dust and by-products). The modern city of Lavrion has actually been built around and on top of these waste materials, which are rich in heavy, hazardous and toxic metals such as lead, zinc, cadmium and arsenic. Over the centuries, the action of natural forces, such as wind and water erosion and chemical leaching due to the "in-situ" formation of sulfuric acid from oxidation of the lead sulfide (overall eq. 1), have caused the wide migration of toxic metals and resulted in widespread contamination and an enormous environment problem that must be addressed. The sulfuric acid is produced by the natural oxidation of lead sulfide by the oxygen of air.
H2SO4 + PbO (eqn. 1)The Environmental Issues.
Chemical analysis of earth, road and house dust samples from Lavrion have revealed that the levels of toxic metals in the soils in the area are excessively high and indicate that a severe environmental problem and health problem exists for the citizens of Lavrion. For example, the lead in the blood of the children of Lavrion is well above acceptable levels set by the World Health Organization: the current recommendation for lead levels is that no more than 2% of a population have a lead content of greater than 20 micro gram per milliliter of blood. However, in Lavrion, 50% of the population examined were found to exceed the recommended level.
The situation in Lavrion is typical of the environmental problems that have been created by the mining of minerals, metals and coal all over the world throughout the centuries. Remedial action and rehabilitation of the area around Lavrion is an important environmental issue and is representative of the many other examples of environmental problems that exist all over the globe as the result of centuries of mining. The solutions to these problems will require a knowledge of chemistry, chemical engineering, and particularly of a new engineering discipline, EARTH AND ENVIRONMENTAL ENGINEERING.
A Plan for Environmental Remediation of Lavrion. An Application of Earth and Environmental Engineering.
With regard to the plan for remediation of Lavrion, earth and environmental engineering projects are in place which have the following goals:
(1) evaluation, in detail, of the current status of the soil environmental
contamination in the Lavrion area;
(2) selection and application of method that will prevent further
contamination of the soils by applying preventive measures at the source
of pollution;
(3) development and application of remediation techniques that will
decontaminate the polluted soils or will render them harmless;
(4) development of an integrated environmental management scheme for the
Lavrion area.
The Environmental Lessons from Lavrion and Mining the Earth
The Lavrion story demonstrates how human activities that are
deemed to be very beneficial in a period of great intellectual and
cultural development (the Greek Civilization was fuelled partly by the
silver produced at Lavrion), can nonetheless have adverse effects on
generations hundreds and even thousands of years into the future. Our
present civilization still depends greatly on "mining" the earth and its
oceans and irreversibly exploiting its hidden treasures: Fossil fuels,
metals, industrial minerals and construction minerals. In fact, the
consumption of such non-renewable materials in the twentieth century by
far exceeds their use in the previous six thousand years of human history.
As an example, the annual consumption of solid materials, i.e. excluding
all fossil fuels, in the U.S. amounts to nearly six tons per person, or
1.5 billion tons overall.
Therefore "mining" the Earth for solid materials is as essential to the future of humanity as air and water. Two actions that will decrease the necessary amount of mining are a) reducing the amount of materials used for a particular service, e.g. smaller automobiles or mass transport systems, and b) intelligent recycling of materials after use, i.e. resource recovery. But even with 100% implementation of these measures, "mining" will still take place, to make up for materials lost irretrievably and to provide coal to heat humanity till alternate sources of energy have bloomed.
Since mining will continue because of the dependence on the treasures of the earth, it is essential to ensure that mining practices are carried out in an environmentally sound manner. Governments in the developed countries are establishing stringent guidelines for mining the Earth, such as ensuring that the initial mining plan contains sufficient provisions and funding a) to avoid short and long term contamination of air and water, either during mining or further processing of the ores to metals b) when mining stops, to restore the outer surface of the land to as good or better condition.
Earth and Environmental Engineering at Columbia.
Earth and Environmental Engineering at Columbia brings together mining, chemical and environmental engineers, as well as chemists, Earth scientists, materials scientists and industrial ecologists. The principal goals are to develop educational and research programs that will train professionals who can lead in
a) environmentally conscious mining and mineral processing;One of the leaders in this new way of thinking of solutions of environmental problems was Prof. Antonis Kontopoulos, of the University of Athens. In 1997, Prof. Kontopoulos and his wife Nanda (an archeologist), guided Prof. Turro through Lavrion in 1997 and inspired him to consider coupling the story of the ancient Greeks with the current environmental problems of Lavrion resulting from mining. Dr. Kontopoulos, who was planning to come to Columbia University as a visiting Professor during the 1998-1999 academic year, suffered an untimely death in the spring of 1998. This tragedy was a bitter disappointment, abroad and here, but Columbia University will continue to follow his lead in honor and memory of his pioneering efforts in Earth and Environmental Engineering.
Related Links:
The Lavrion Mines (copyrighted material is restricted to Columbia domain)
Acid/Base Reactions in the Environment