What is heavy metal bioaccumulation?

What is a heavy metal?

A heavy metal is a metal that is dense (is thick), or has a high atomic weight, and is poisonous or toxic in large amounts. Some examples are cadmium, beryllium, mercury, lead and copper.

What does bioaccumulation mean?

Bioaccumulation is when a substance accumulates (builds up) in a living organism. The substance accumulates faster than it is broken down.

What is the cause of the problem in Australia?There are no causes of heavy metal bioaccumulation that are specific to Australia, but the causes of it are:

• industrial production (eg. Pesticides production, smelters, and oil refineries).• acid rain breaking down soil and releasing the heavy metals into a water source• mining• disposal of electronic waste (eg. Computers and mobile phones) • and the disposal of other waste. • untreated sewage sludge• consumer and industry waste.

Industries linked to the problem:

• The coal industryCoal plants emit mercury. Ash and sludge is also produced from coal plants. This ash and sludge has things like lead and mercury in it.

• Natural GasThe Natural Gas industry produces heavy metals like arsenic, lead and mercury.

• The Chlor-Alkali industry The chlor-alkali industry produces waste like mercury and calcium.

• MiningThe mining industry produces arsenic, lead, cadmium, copper and manganese.

Environmental effects

Heavy metals have a negative effect to the environment in large amounts. Heavy metals can contaminate soil, and that affects crops. They can also contaminate water sources, which affects marine life. It accumulates inside the marine life, and has a negative effect. For example, mercury in fish, and other animals, can cause damage to the kidneys and nervous system, slow growth, or even result in death.

Heavy metals that contaminate water and accumulate inside marine life, can also then spread through the food chain and reach more creatures, including land animals. Heavy metals in animals can cause bone defects, such as osteoporosis . High amounts of heavy metals in the air are toxic to birds.

Effect on society

Heavy metal bioaccumulation affects society in a number of ways. Bioaccumulation in and poisoning of marine life can cause a decline in the fish population, which affects the fishing industry, because there are less fish for fishermen to catch. This lack of fish can also raise the price of fish and other sea creatures.

Heavy metals can reach humans, through the food chain, and are very toxic.

• Lead exposure in humans can cause damage to the central nervous system• Cadmium in humans can possibly cause lung cancer.• Copper in high amounts can cause anemia, and kidney and liver damage.• Mercury can cause damage to the central nervous system and brain.

What's being done about it?

The use of heavy metals, such as mercury and lead has been stopped, and there are laws and regulations about those heavy metals and other ones.

There are many conventions about heavy metal bioaccumulation and pollution. A few are:

The Cartagena convention. The convention aims to reduce heavy metal pollution. Governments that agree to the protocol have to set up monitoring programs, conduct environmental impact assessments, and promote education and awareness about pollution.

The convention on Long-Range Transboundary Air Pollutants. This convention is trying to reduce, and eventually stop air pollution – in particular mercury, lead, and cadmium.

The Basel Convention. This convention aims to protect humans and the environment from the effects of moving, management, and disposal of dangerous wastes, which includes heavy metals.

Image showing how mercury can reach humans through the food chain. Mercury, a heavy metal.

Image showing heavy metal sources.