Trace Metals & Phytoplankton Gert Vlaming 24-01- 2003
Dec 20, 2015
Recycled elements
• Low concentrations in the surface layer
• Enhanced concentrations in the deeper water
• Residence time: intermediate (103 – 105 yrs)
• Concentrations: 10-12 – 10-5 M
Element Atlantic -
Surface
Atlantic -
Deep
Pacific -
Surface
Pacific -
Deep
Fe 3+ 2.0 *10-9 7.0*10-9 0.2*10-9 2.0*10-9
Cu2+ 1.3*10-9 2.0*10-9 1.3*10-9 4.5*10-9
Ni2+ 2.0*10-9 7.0*10-9 2.0*10-9 10*10-9
Cd2+ 0.1*10-10 3.5*10-10 0.1*10-10 10*10-10
Zn2+ 1.5*10-10 1.6*10-9 1.5*10-10 8.2*10-9
Mn2+ 1.9*10-9 1.8*10-9 1.9*10-9 8.0*10-10
Co2+ 2.7*10-11 1.5*10-11 2.3*10-11 1.5*10-11
Concentrations
mol/l
Concentrations II
• Atlantic ocean receives a greater flux of windborne dust and atmospheric contaminants than the Pacific
• Accumulated elements released from the decaying particulate matter
• Mn and Co: adsorption onto particles
Biochemical functions
Fe • nitrogen fixation• transport of oxygen• protection
Zn • Food digestion
Ni • hydrolysis of urea
• reactions with H2
And many enzymatic reactions
Availability
• > 97% of the total metal in solution is held in strong organic complexes
• These complexes are not available for phytoplanktonic uptake
The essential trace metals have very low concentrations
Recycling ratio
flux circulating within the ecosystem flux circulating through the environment
R =
Cd 494
P 214
C 54
N 33
Cu 2.2
Zn 1.9
Fe 1.8
Mn 1.4
R R
Recycling ratio II
• The inability of phytoplankton to exercise absolute discrimination
• Phytoplankton are capable of actively regulating their internal economy
• For most essential trace metals the cells are at, or close to, their nutrient limitation levels
Adaptations
• Internal
• External
• Interspecific
• Collective
There’s a “chemical war” going on ...
Organic complexation
• Cells release organic complexing agents
• Beneficial for Fe, Cu en Mn
• Enabling large pool of Fe to be maintained
• Maintaining concentrations below toxic levels
Conclusions
• Availability of trace metals is a significant factor regulating primary production
• Phytoplankton is strongly effecting the concentrations of trace metals