Molybdenum (Mo) is a transitional metal and a rather rare element. Molybdenum occurs in oxidation states ranging from Mo3+ to Mo6+. The most common solid and aqueous species are Mo4+ or Mo6+. In oxidizing condition, the predominant form of Mo is Mo6+ in water. At low pH (<2), the predominant species is H2MoO4 (undissociated form). Between pH 2 and 5 the oxyanion HMoO4- ion is the predominant form. At higher pH (>5), the main form is MoO42-. Molybdenum generally has a high geochemical mobility and tends to enter aqueous solution.
Mo is measured by inductively coupled plasma mass spectroscopy (ICP-MS) or inductively coupled plasma optical emission spectroscopy (ICP-OES).
Mo may be a potential residence time indicator in some groundwaters.
References and Further Reading
- Dalai, T.K., Nishimura, K. and Nozaki, Y., 2005. Geochemistry of molybdenum in the Chao Phraya River estuary, Thailand: Role of suboxic diagenesis and porewater transport. Chemical Geology, 218(3-4): 189-202.
- Edmunds, W.M. & Smedley, P.L. (2000). Residence time indicators in groundwaters: The East Midlands Triassic Sandstone aquifer. Applied Geochemistry, 15, 737-752.
- Kaback, D.S. and Runnells, D.D., 1980. Geochemistry of Molybdenum in Some Stream Sediments and Waters. Geochimica Et Cosmochimica Acta, 44(3): 447-456.
- Kuroda, P.K. and Sandell, E.B., 1954. Geochemistry of Molybdenum. Geochimica Et Cosmochimica Acta, 6(1): 35-63.