109
Minor Elements in Seawater
3.4 Biological Interactions
The interactions of trace elements with marine organisms have been studied by many
workers. Bowen (1966) has summarized these interactions, which are outlined next, in
terms of concentration factors (concentration in the organism relative to a given volume
of seawater).
1. Cl – is rejected by organisms.
2. Na + , Mg 2+ , Br – , F – , and SO 4
2– have concentrations in organisms similar to seawater
(concentration factors of 1.0).
3. Most of the other elements, with the exception of the noble gases, are strongly
concentrated in living tissue.
4. The order of affinity of organisms for cations is
4+ > 3+ > 2+ transition > 2+ group IIA > 1+ group I metals.
For plankton, the order is
Fe 3+ > Al 3+ > Ti 3+ > Cr 3+ > Ga 3+ > Zn 2+ > Pb 2+ > Cu 2+ > Mn 2+ > Co 2+ > Cd 2+
This order does not agree with the Irving- Williams order. The formation of complexes with surface ligands does not control the uptake by plankton.
Mn, nmol kg
–1
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
Depth, m
0
1000
2000
3000
4000
5000
Pacific
Atlantic
Figure 3.14
Profiles of Mn in the Atlantic and Pacific Oceans.