MERCURY ENDANGERS RIVER-EDGE DWELLERS
More than a million people in Brazil are submitted to mercury contamination every day — this metal is liquid and highly toxic, and presently used as gold separator by gold miners, without any control.
Mining at the river edges has led many ecological areas to complete destruction, and now it is considered a severe threat to the health of many of those river-edge dwellers (that is, people who live by the river) in Amazonia, Goias, Minas Gerais and the pantanal in Mato Grosso; the natural inhabitants, the Brazilian indians, do not escape from this menace. This mercury contamination is one the most hazardous forms of pollution which is in course in Brazil nowadays. Some researchers claim that almost all of the hydrographic reservoirs of the country have a slight trace of mercury.
The contamination route follows some definite phases. The gold miner takes out the limestones and little rocks from the river edge, and those are mixed up with mercury. In case there is any powdered gold in the water and limestone, this is immediately joined with the metal. The next step is to throw the remaining limestone away, take the set of mercury, gold and rock and submit it to directed high-temperature fire. As heat is increased, the metal, which is highly volatile, evaporates. Gold, free from any litter, remains pure. We could only take about 10% of the gold in the limestone if mercury wasn’t used.
Health is damaged by the mercury gases, which is breathed by the gold miner. When this gas is burnt, it produces pollutant and toxic residues. Some part of the gas is spread into the atmosphere and eventually goes back to the soil and water, brought by rain drops, polluting them. Liquid metal is thrown into the water, where it will be swallowed by fish and other animals, making contamination even more dangerous to the ecosystem and to the people who feed on river plants and animals.
Mercury effects in the organism are accumulative and methods to depollute waters are considered inefficient. In some areas in Mato Grosso, where gold mining has long been abolished, animals still die after having drunk water from the river; this is a real proving that mercury has dangerous and long term effects.
In our body, mercury and its derivatives may attack the central nervous system, the kidneys and the lungs, including also congenial problems in other generations.
1. Explain the process of separating mercury from limestone, as it is written in the text.
2. Which is the route mercury takes after having been used by the gold miners?
3. Why does the author use the phrase "Mercury effects in the organism are accumulative and methods to depollute waters are considered inefficient"?
4. Make a sketch in which you show a way of fighting against mercury. Consider the affirmation that the author makes about the hydrographic reservoirs in Brazil.