Environment / General / Science

Mercury, the metal


Mercury is a word we hear often in various contexts, as a planet, metal and there is even an insurance company with this name. However, for this article we will be discussing liquid metal. As a child I was fascinated by this metal due to its shiny lustre, fluidity and no matter how hard you try, you just can’t catch and hold it 🙂

Volcanic eruption

Mercury is often referred to as a quicksilver and  is naturally found in earth’s crust. It reaches the surface of the earth via volcanic eruptions and gets embedded in rocks. When the rock weathers, the atmosphere gets exposed to mercury, thus entering the ecosystem. Apart from this, several human activities have also led to mercury entering the ecosystem such as coal mining, improper disposal of equipment containing mercury, excess use in agriculture. Mercury is usually found in liquid form at room temperature and has the symbol ‘Hg’ in the periodic table with atomic number of 80. For the most part it is found as a part of compounds such as cinnabar, metacinnabar and as impurities in some minerals and in such states it is called ‘inorganic mercury’ and it is rarely found in its pure form. And in it’s pure form it can render to be very toxic.  It is used in several medical/scientific equipment such as thermometers, barometers, blood pressure cuffs. Its properties such as liquid at room temperature, non sticky nature, high coefficient of expansion made it an ideal candidate for measurement in these devices. In fact, this metal is very much a part of our daily lives as it is added to topical antiseptics, skin lightening cosmetics and in dental fillings.


Exposure to mercury is shown to have harmful effects on the development of fetuses and young children as it can affect vision, hearing and also lead to brain damage.  Therefore,  there has been an initiative by WHO to phase out mercury from medical equipment to reduce the risk of its exposure. Mercury in its pure form is not allowed on aircrafts too as it readily combines with aluminium and corrodes it, equivalent to iron rusting, thus damaging aircrafts which is mainly made of aluminium. Mercury is also used extensively as disinfectants, fertilizers and herbicides and excessive exposure to plants is shown to cause phytotoxicity in plants. Some of the effects include reduced photosynthesis, water uptake and transpiration. Even though there is so much bad news about mercury, not all living things face it’s wrath. Scientists have discovered a new type of bacteria in Antarctic sea ice named Nitrospinia which converts mercury into a more toxic form called methlymercury. Environmental pollution is a big contributor to mercury found in the sea ice as well as our oceans as a result of which high levels of mercury are found in fish and other marine organisms.

Fortunately, not all is bad news when it comes to mercury pollution. Scientists from Inter American University in Puerto Rico have created a strain of bacteria which not only can tolerate high levels of mercury and were also able to remove mercury from their growth solution. Which just goes on to show that no matter how intelligent and evolved we humans are, we still have to depend on mother nature to get us out of trouble!

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