Lead & compounds: Environmental effects
Description
Lead occurs naturally in the environment. Lead itself does not decompose, however lead compounds are changed by sunlight, air and water. Lead usually adheres to the soil. Movement to groundwater will depend on the type of lead compound and characteristics of the soil. Over time, lead accumulates in living tissues (a process called bioaccumulation) and is persistent in water.
As with humans, exposure to lead can lead to death of animals, birds or fish and death or low growth rate in plants. In soft water, lead is highly poisonous to plants, birds or land animals, long term effects on animal life are shortened lifespan, reproductive problems, lower fertility and changes in appearance or behavior. As lead bioaccumulates, it is expected that fish tissues will contain lead from polluted waters.
Entering the environment
Lead occurs naturally in the earth's crust. It is also found in combined form in several minerals: galena, anglesite, pyromorphite and mimetite.
Lead may be released as particles into the atmosphere or as dissolved compounds in water. Lead is also released from natural sources such as windblown dusts and forest fires.
Lead usually attaches to particles of organic matter, clay, soil or sand.
Where it ends up
Lead, as the element, does not break down in the environment. Lead compounds are affected by sunlight, air or water. If released to the air from industry or from burning fossil fuels or waste, lead may remain airborne for approximately 10 days. Most lead released to air, water, sediment, and soil strongly attaches to other particles, and may remain there for many years.
Environmental guidelines
The following ambient air quality standards were established a maximum of 0.50 micrograms of lead per cubic metre of air, averaged over one year, no exceedances allowed. Lead sampling must be carried out for a period of 24 hours at least every sixth day. Measurement of lead must be carried out on Total Suspended Particles (TSP) or its equivalent.
In 2000, the Australian and New Zealand Environment and Conservation Council (ANZECC) and the Agriculture and Resource Management Council of Australia and New Zealand (ARMCANZ) established trigger levels of 1.0-9.4 micrograms of lead per litre of fresh water and 2.2-12 micrograms of lead per litre of marine water.
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