Mercury Pollution-Sources, Effects and Control.

Mercury is an element with symbol Hg and atomic number 80. It is commonly known as quicksilver. A heavy, silvery element, mercury is the only metallic element that is liquid at standard condition of temperature and pressure; the only other element that is liquid under these conditions is bromine. Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulfide). The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide.

Anthropogenic Sources of mercury in soil, water and air:

Mercury is used in-

• various medical devices like- Thermometers, Sphygmomanometers, that measures blood pressure.
• Manometers- This device indicates the difference between two pressures (differential pressure),
• Barometers ( is a scientific instrument used in to measure atmospheric pressure.
• Float Valves ( which are necessary in water supply system in order to regulate the flow of water and to minimize the wastage of water).
• Mercury switches and relays
• Fluorescent lamps (Electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light, which then causes the phosphor in the tube to fluoresce, making visible light)
• Batteries-
• Dental amalgams
• The chlor alkali industry to make chlorine
• Production of zinc, steel and other metals
• Cement production
• Coal burning and gold mining
• Medical waste incinerators

Natural Sources of mercury in soil, water and air:

  Natural processes include

• volcanic activities  Volcanoes release mercury from the underground reservoirs upon eruption.
• Land emissions are usually observed in the regions where soils are enriched with minerals such as cinnabar containing Mercury Sulphide (HgS). This mercury is released by either natural weathering of the rocks or by geothermal reactions.
• Degradation of minerals

Mercury is useful in various ways. Here only few are mentioned. Since its uses are many, the contamination pathways are also many. Once mercury is inhaled in its vapor form or ingested through skin or contaminated food and water, the manifestation of its toxic effect starts. Mercury poisoning  can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methyl mercury), by inhalation of mercury vapor, or by ingesting any form of mercury.

Mercury cycles through atmosphere, water, and soil in various forms to different parts of the world. Due to this natural cycle, irrespective of which part of the world releases mercury it could affect an entirely different part of the world making mercury pollution a global concern. Mercury pollution is now identified as a global problem and awareness has been raised on an international action plan to minimize anthropogenic mercury emissions and clean up mercury pollution.

Mercury is poisonous in all forms-inorganic, organic or elemental. Methyl mercury is neurotoxin: it can damage the developing brain as it crosses the placental and blood- brain barrier easily. The fetus , if exposed to mercury will show autism when born.The symptoms of mercury poisoning depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashes, anxiety, memory problems, trouble speaking, trouble hearing, or trouble seeing. High level exposure to methylmercury is known as Minamata Disease. Signs and symptoms of minamata

include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms. A congenital form of the disease can also affect fetuses in the womb. Methylmercury exposure in children may result in acrodynia (pink disease) in which the skin becomes pink and peels. Methylmercury is formed from inorganic mercury by the action of microbes that live in aquatic systems including lakes, rivers, wetlands, sediments, soils and the open ocean. Long-term complications may include kidney problems and decreased intelligence. The effects of long-term low-dose exposure to methylmercury are unclear.

 Mercury can also trigger depression, suicidal tendency, paralysis and kidney failure, Alzheimer’s disease, speech and vision impairment, allergies, infertility etc. Even a minuscule increase  in methyl mercury exposures may adversely affect the cardiovascular system. It is also a possible carcinogen for humans.

Control:

Though concerns about the element’s toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alternatives such as alcohol- or galinstan-filled glass thermometers and thermistor- or IR based electronic instruments. Likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers.

Oceans and river water are highly polluted with mercury leading to the fishes contaminated with methyl mercury. To reduce this poisoning, a huge awareness drive about mercury pollution is needed.

Education is the best way to fight the evil. The more articles are written on mercury pollution, the more the people will be knowing about it and the more controlling methods will be generated.

We must reject the use of mercury in various industries. The batteries which uses Hg must be replaced by less harmful materials. Only the awareness and research can reduce the spread of mercury in the atmosphere.

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