The relationship in Eq. (5) results in a k0 value higher than 6.2 × 10− 4 μM− 3 year− 1at depths above 300 m and lower than 6.2 × 10− 4 μM− 3 year− 1 at depths below 300 m. The low k0 value in the deep ocean may be due to low temperature, high pressure or the presence of inert forms (such as organic complexes or colloids) of dissolved Mn in the deep ocean. Although Mn(II) oxidizing bacteria are known to substantially increase Mn(ll)
Delanzomib rate ( Hastings and Emerson, 1986, Tebo and Emerson, 1986, Sunda and Huntsman, 1987 and Sunda and Huntsman, 1990), bacterial activity should not influence our model calculation at depths below 300 m because the k0 value of 6.2 × 10− 4 μM− 3 year− 1 at 300 m is already equal to the value for inorganic homogeneous Mn(II) oxidation and the values below this depth are lower. Von Langen et al. (1997) also showed that open ocean bacteria do not rapidly utilize low levels of Mn(II) and they suggest that inorganic reactions may play the
dominant role in Mn(II) oxidation in the ocean. Brewer et al. (1980) also estimated that the removal residence time of Mn is 20 year in the deep North Atlantic. This value is in good agreement with inorganic oxidation removal of Mn calculated via Eq. (2) rather than bacteria-enhanced oxidation residence time.
