There Are Two Sources Of Molybdenum in The Environment

(1) Weathering releases molybdenum from rocks. It is estimated that 1,000 tons of it enters water bodies and soils every year and migrates through the environment. Uneven distribution of molybdenum causes "soil and water diseases" in some areas due to lack of molybdenum, and "gout diseases" (e.g. Armenia) in some areas due to high molybdenum content.
(ii) The wider application of molybdenum in human activities and the burning of molybdenum-containing fossil fuels (e.g., coal) have increased the amount of molybdenum circulating in the environment. Worldwide production of molybdenum is 100,000 tons per year, and 800 tons of molybdenum are burned and released into the environment each year. The amount of molybdenum added to the cycle by human activities exceeds the natural cycle. The industries that use molybdenum the most are metallurgy, electronics, missiles and space, atomic energy, chemistry and agriculture. Molybdenum pollution has not been studied enough.

The transport of molybdenum in the environment is related to the oxidizing and reducing conditions, acidity and alkalinity of the environment and the influence of other media. The more oxidizing and alkaline the water and soil, the easier it is for molybdenum to form MoO ions; plants can take up molybdenum in this state. The acidity of the environment increases or reducibility increases, molybdenum is easily converted into complex ions, and eventually forms MoO; this state of molybdenum is easily fixed by clay and soil colloids and humic acid and becomes inactive, and cannot be absorbed by plants. In the ocean, the reducing environment of the deep sea causes molybdenum to be adsorbed by organic substances and then wrapped in colloids containing manganese, eventually forming nodules that sink to the bottom of the sea and are removed from the cycle of the biosphere.
Molybdenum has a low impact on warm-blooded animals and fish. High levels of molybdenum has a negative impact on plants, tests show that: molybdenum concentration of 0.5 ~ 100 mg / liter when the growth of flax will have varying degrees of impact; 10 ~ 20 mg / liter when the growth of soybeans have a harmful effect; 25 ~ 35 mg / liter when the growth of cotton is mildly harmful; 40 mg / liter when the growth of sugar beets have a harmful effect. When the concentration of molybdenum in water reaches 5 mg/l, the biological self-purification of water will be inhibited; when 10 mg/l, this effect will be inhibited even more, and the water has a strong astringent taste; when 100 mg/l, the microbial growth of the water body slows down, and the water has a bitter taste. China stipulates that the maximum permissible concentration of molybdenum in ground water is 0.5 mg/l, the maximum permissible concentration of soluble molybdenum in workshop air is 4 mg/m3; and insoluble molybdenum is 6 mg/m3.