MERCURY – A SOLUTION TO OUR ECONOMY AND A THREAT TO OUR ENVIRONMENT? 

Naturally found in the Earths’ crust as a compound, mercury is essential yet toxic, a metal yet liquid, at room temperature. It is formerly known as hydrargyrum (Hg), a Latin word meaning water silver, derived from its shiny liquid metallic form. It has a high density with a high rate of thermal expansion which makes it useful for weather forecast by detecting weather using a barometer and medical examination by testing body temperature using a thermometer.

Mercury easily blends with gold to form amalgam making it suitable for gold mining as it easily recovers fragments of gold from the soil and sediments. About 25 tonnes of mercury per year is being used in Zimbabwe due to the rise of gold mining which is growing in the country and significantly contributing to the economy. The sector contributes between 10% and 60% of the country’s Gross Domestic Product and exports respectively. Despite its usefulness, mercury is a heavy metal and persistent. It does not easily degrade in the environment, rather it interacts with other compounds, micro-organisms, plants and animals resulting in negative effects.

The United Nations Environment Programme, Global Mercury Assessment of 2018 revealed that globally, artisanal and small-scale gold mining is the largest source of human activities mercury emissions with a contribution of about 37%, followed by stationary combustion of coal, non-ferrous metals production, and cement production each contributing about 21%, 15% and 11% respectively. This significant release of mercury into our environment is alarming, but time is still on our side to call for action to save our planet before we destroy it to a point of no return.

In Zimbabwe, women have taken a step in the gold mining business as it pays hard cash in USD dollar currency. Due to gender equality being applied in all sectors, women are now actively engaging in gold mining processes where they are concentrating and crushing ore. To make extra cash, women are re-processing the dumped tailings to extract traces of gold left in them. This act is putting women’s health at risk as they usually operate without sound control measures and personal protective wear. 

Mercury has various sources, naturally it comes from weathering of mineral rocks during soil formation, natural disasters through volcanoes and wild forest fires. As humans, our business-as-usual model contributes to mercury pollution by burning of coal at our power plants and industries for energy and electricity which vapours traces of mercury into the atmosphere. Mining gold to produce jewellery and electronic devices generates waste rock (tailings), and disposing off waste at dump sites and landfills especially electronic waste releases certain amounts of mercury into the soil, surface and ground water.

The high density of the mercury, gives it precedence in weather forecasting purposes that is why we get to watch the weather forecast to stay informed. Doctors use thermometers to test our body temperature before diagnosis, the red liquid which fluctuates in the thermometer is mercury, credit to its high rate of thermal expansion which is fairly constant over a wide range of temperatures. In recent years, digital thermometers are being preferred over mercury thermometers. The sun provides us with natural light but when it is at night, we need alternative sources of light. Batteries and fluorescent lights use mercury to store energy and generate light.

Mercury was known to the ancient Chinese, Egyptians and Hindus and it has been found in Egyptian tombs dating back to about 1500 B.C. The resource application is old as time and so are its impacts, despite being recognised and reported in 1865. Gold is a precious and valuable metal, it is blended with mercury to remove impurities and then boiled to extract pure gold releasing mercury as vapour into the atmosphere. The separation of mercury and gold require physical interaction. Most artisanal miners usually do not make use of applicable personal protective clothing. This behaviour puts them at great risk. Being exposed to mercury for long periods leads to mercury poisoning which has potential damage to key organs such as the eyes, ears and kidneys. Mercury is also known for impairing the health balance of unborn babies harming their developing brains and nervous systems when a pregnant woman is exposed.

On a daily basis, we use tools with mercury such as thermometers or fluorescent bulbs, they are hazards and they need to be handled with care. However, if a fluorescent bulb breaks, it releases mercury as vapour which can be inhaled. Inhaling mercury can damage the nervous system, disrupt kidney functions and cause eye irritation. That’s why florescent bulbs are fragile and require cation. Mercury has a number of effects on human health such as; DNA and reproductive system distortion, allergic reaction and brain functions damage just to mention a few. Mercury also has effects upon the environment by accumulating in plants and polluting water and soil.

Mercury in soils and water is transformed by micro-organisms into methyl-mercury, a highly toxic organic molecule. The organic molecule is absorbed by mushrooms, algae or phytoplankton or fish resulting in bioaccumulation. Bioaccumulation is the accumulation of a toxic chemical in the tissue of a particular organism. The contaminated plants and fish are then eaten by animals the same process is done on each level of the food chain which adds up the concentration of mercury on each food chain level resulting in biomagnification. Biomagnification is the increase in concentration of a toxic chemical in the tissue of a particular organism. The higher an organism is on the food chain, the more deadly it is. Acceptable recommended levels of mercury should not exceed 5.0 ug/L in a person’s whole blood.

Our business-as-usual model will land us in unfavourable conditions. We need to steer our ways towards sustainable mining and production in order to save our planet. The Minamata Treaty is a legislation body with 128 signatories which provides guidelines on mercury emissions controls. Its implementation drives mercury pollution control by mining sustainably to attain high gold production without damaging the environment. Our planet’s fate lies in our hands, think globally, act locally.