VCE Environmental Science

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There is a good chance you will get a question about this heavy metal on the exam. Mercury and sulphur dioxide (as well as one other pollutant that you have done a case study on) are pollutants that you will have to know about in a good deal of detail – their sources (point and/or diffuse and/or fugitive), transport mechanisms and sinks. Also, what are the human and environmental effects of exposure to these toxic chemcials? Are they likely to cause acute or chronic toxicity and at what levels? How can the efects of these pollutants be minimised to reduce harmful human and environmental health risks?

Article in the Melbourne Age about disposal of mercury in fluorescent light tubes.

“The nervous system is very sensitive to all forms of mercury. Exposure to high levels of any types of mercury can permanently damage the brain, kidneys, and developing foetus. Effects on brain functions may result in irritability, shyness, tremors, changes in vision or hearing and memory problems. High exposures of mercury vapour may cause chest pain, shortness of breath, and a build up of fluids in the lungs (pulmonary oedema) that can be fatal. Methyl mercury and mercury metal vapours are especially harmful, because more mercury reaches the brain. Long term exposures may cloud the eye. Contact with mercuric chloride can cause burns to the skin and permanent damage to the eyes. Mercury also accumulates in the body.

Mercury and mercury containing products will enter the body if we breathe in contaminated air, drink contaminated water, eat contaminated food, or have our skin come into contact with it. Mercury may be absorbed through the skin. Mercury released into the environment is converted into methyl mercury by bacteria. The methyl mercury will then build up in the tissues of fish and shellfish. Humans (and other animals) may also be poisoned by eating these fish or shellfish.”

National Pollutant Inventory – Mercury Fact sheet

Our task on Wednesday was to prepare sulphur dioxide gas, investigate it’s properties and it’s effect on various substances, including printed fabric, newspaper, leaves, metal foils, marble chips, limestone and concrete. We found that sulphur dioxide reacts with air and water to form an acidic environment. The universal indicator showed a decrease in pH. Sulphur dioxide is known as a primary and secondary pollutant because it has detrimental health and enironmental effects in itself, as well as reacting with other chemicals to form other pollutants – sulphur trioxide and sulphuric acid, which causes acid rain.