Manganese is a pinkinsh-gray, chemically active element. It is a hard
metal and is very brittle. It is hardly melt, but easily oxidized.
Manganese is reactive when pure, and as a powder it will burn in Oxygen,
it reacts with water (it rusts like Iron) and dissolves in dilute acids.
Manganese is essential to Iron and steel production. At present steel
making accounts 85% to 90% of the total deman, most of the total demand.
Manganese is a key component of low-cost stainless
steel formulations and certain widely used Alumimum alloys. Manganese
dioxide is also used as a catalyst. Manganese is used to decolorize
glass and make violet coloured glass. Potassium permanganate is a potent
oxidizer and used as a disinfectant. Other
compound that find application are Manganese oxide (MnO) and Manganese
Carbonate (MnCO3): the first goes into fertilizers and ceramics, the
second is the starting material for making other Manganese compounds.
Manganese in the environment
Manganese is one of the most abundant metals in soils, where it
occurs as oxides and hydroxides, and it cycles through its vaious
oxidation states. Manganese occurs principally as pyrolusite (MnO2),
and to a lesser extent as rhodochrosite (MnCO3). More than 25
million tonnes are mined every year, representing 5 million tons of the
metal, and reserves are estimated to exeed 3 billion tonnes of the
metal. The main mining areas for Manganese ores are South Africa,
Russia, Ukraine, Georgia, Gabon and Australia.
Manganese is an essential element for all species. Some organisms, such
as diatoms, molluscs and sponges, accumulate Manganese. Fish can have up
to 5 ppm and mammals up to 3 ppm in their tissue, although normally they
have around 1 ppm.
Manganese is a very common compound that can
be found everywhere on earth. Manganese is one out of three toxic
essential trace elements, which means that it is not only
necessary for humans to survive, but it is also toxic when too
high concentrations are present in a human body. When people do
not live up to the recommended daily allowances their health will
decrease. But when the uptake is too high health problems will
The uptake of Manganese by humans mainly takes place through food,
such as spinach, tea and herbs. The foodstuffs that contain the
highest concentrations are grains and rice, soya beans, eggs,
nuts, olive oil, green beans and oysters. After absorption in the
human body Manganese will be transported through the blood to the
liver, the kidneys, the pancreas and the endocrine glands.
Manganese effects occur mainly in the respiratory tract and in the
brains. Symptoms of Manganese poisoning are hallucinations,
forgetfulness and nerve damage. Manganese can also cause
Parkinson, lung embolism and bronchitis. When men are exposed to
Manganese for a longer period of time they may become impotent.
A syndrome that is caused by Manganese has symptoms such as
schizophrenia, dullness, weak muscles, headaches and insomnia.
Because Manganese is an essential element for human health
shortages of Manganese can also cause Health effects. These are
the following effects:
- Glucose intolerance
- Blood clotting
- Skin problems
- Lowered cholesterol levels
- Skeleton disorders
- Birth defects
- Changes of hair colour
- Neurological symptoms
Chronic Manganese poisoning may result
from prolonged inhalation of dust and
fume. The central nervous system is the chief site of damage from
the disease, which may result in permanent
disability. Symptoms include languor,
sleepiness, weakness, emotional disturbances, spastic gait,
recurring leg cramps, and paralysis. A high
incidence of pneumonia and other upper
respiratory infections has been found in workers exposed to
dust or fume of Manganese compounds. Manganese
compounds are experimental equivocal
Manganese compounds exist naturally in the
envIronment as solids in the soils and small particles in the
water. Manganese particles in air are present in dust particles.
These usually settle to earth within a few days.
Humans enhance Manganese concentrations in the air by industrial
activities and through burning fossil fuels. Manganese that
derives from human sources can also enter surface water,
groundwater and sewage water. Through the application of Manganese
pesticides, Manganese will enter soils.
For animals Manganese is an essential component of over thirty-six
enzymes that are used for the carbohydrate, protein and fat
metabolism. With animals that eat too little Manganese
interference of normal growth, bone formation and reproduction
For some animals the lethal dose is quite low, which means they
have little chance to survive even smaller doses of Manganese when
these exceed the essential dose. Manganese substances can cause
lung, liver and vascular disturbances, declines in blood pressure,
failure in development of animal foetuses and brain damage.
When Manganese uptake takes place through the skin it can cause
tremors and coordination failures. Finally, laboratory tests with
test animals have shown that severe Manganese poisoning should
even be able to cause tumor development with animals.
In plants Manganese ions are transported to the leaves after
uptake from soils. When too little Manganese can be absorbed from
the soil this causes disturbances in plant mechanisms. For
instance disturbance of the division of water to
Hydrogen and Oxygen, in which Manganese plays an important part.
Manganese can cause both toxicity and deficiency symptoms in
plants. When the pH of the soil is low Manganese deficiencies are
Highly toxic concentrations of Manganese in soils can cause
swelling of cell walls, withering of leafs and brown spots on
leaves. Deficiencies can also cause these effects. Between toxic
concentrations and concentrations that cause deficiencies a
small area of concentrations for optimal plant growth can be