Mercury in the environment

Mercury is a naturally occurring element. However, human activities have increased atmospheric mercury concentrations 450% above natural levels, with a similar increase in rivers and oceans. This is a problem because mercury is highly toxic.

Here, we give a brief overview of how mercury gets into the environment, and the effects it can have on the animals, plants, and people that live in it. Because of these effects, it is critical to monitor mercury. Fortunately, at Enviro Technology, we have a range of solutions to help you with this – speak to our experts today.

How does mercury get into the environment?

• Natural sources – Mercury is naturally present in the Earth’s crust and is released through volcanic and geological activity. It cycles naturally through the environment, although humans have impacted this cycle.
• Combustion – Mercury is released into the atmosphere from thermal power stations, cement manufacture, metal production, waste incineration, and domestic heating.
• Industrial waste – Historically, mercury was central to the production of sodium hydroxide, chlorine, and hydrogen (the “chlor-alkali” process), but this use has since been prohibited. However, industry (such as the chemical industry) is still responsible for releasing hundreds of kilograms of mercury into waterways per year, including following wastewater treatment.
• Household waste – Mercury has had many product applications, including in measuring devices, electrical switches, lamps, and batteries; although these uses are increasingly restricted. When these products become waste, mercury can be released during incineration, or through volatilisation or leaching from landfill. Dental practices must also comply with hazardous waste regulations as dental fillings can contain mercury.
• Mining – Mercury is used in gold extraction. Artisanal and small-scale gold mining was responsible for 38% of global total mercury emissions in 2015. However, this mainly takes place in Sub-Sharan Africa and South America and so environmental impacts are most critical in these regions. Nevertheless, wherever they are in the world, anyone who purchases gold should be conscious of its environmental and social footprint.

Image source: The Environment Agency

Mercury’s effects in the environment

Animals

Mercury associates readily with tiny particles, meaning that it accumulates in marine and riverine sediment, either settling on the sea- or riverbed or dispersing itself within the water column. The mercury is then taken up by plants or microscopic organisms, which are then themselves consumed by larger animals. Alternatively, fish may intake mercury directly through their gills. The toxic effects of mercury in fish include impaired reproduction and growth, as well as behavioural issues, such as an inability to capture prey. This can impact commercial fish stocks and jeopardise fishermen’s livelihoods. However, critically, the accumulation of mercury in seafood poses serious risks to the health of humans too, and was demonstrated, devastatingly, in Minamata, Japan, last century.

Image source: United Nations Environment Programme

Plants

Evidence suggests that mercury in plant tissues comes mainly from the atmosphere, as it is difficult for the roots to absorb it from the soil. Mercury has no biological role in plants (or animals); indeed, it is incredibly harmful. In plants, mercury disrupts proteins and causes chemical stress, leading to inhibited growth and photosynthesis, as well as damaging DNA and structures such as membranes.

Because plants are integral to most habitats, experts say that mercury toxicity can compromise the viability of whole ecosystems. For example, in a Portuguese marsh heavily contaminated by mercury from a local chlor-alkali factory, diversity of plant species was reduced, and the marsh came to be dominated by a single plant type. This will have had a knock-on effect on the number of animals that could live there.

What about crops? Compared to fish, mercury accumulation in crop plants has received relatively little attention. However, one study found that 90% of rice samples from 32 Chinese sites that had been heavily polluted by local mercury mines had mercury concentrations that exceeded the maximum value for consumption, as defined by the country’s government. The standing water conditions of rice paddies are the ideal environment for the bacteria which metabolise mercury into its most toxic forms; nevertheless, given that rice is a staple food for billions of people worldwide, accumulation of mercury in rice is a concern and should be further investigated.

Mercury monitoring is essential

Humans have used mercury in many ways. However, a consequence of this is that the element has found its way into all corners of the environment, where it can harm plants, animals, and humans. Indeed, mercury pollution is a prime example of how human and environmental health are closely interlinked. This is why, if activities might involve mercury, monitoring is essential to protect people and ecosystems. At Enviro Technology, we can provide systems for this, including continuous emissions monitoring; trace mercury detection; and environmental sample analysis.

Get in touch with Paul Keeling  to find your mercury monitoring solution.