12.755 Lecture 05 Biogeochemical Aspects of Aluminum, Lead, Copper, Cadmium, and Zinc

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12.755 Lecture 05Biogeochemical Aspects of
Aluminum, Lead, Copper, Cadmium, and Zinc
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Readings

• L05, L06, L07 will all be posted shortly
• Read Nealson, both Johnson papers (Mn L06, Fe
  L07) for Thursday
• Browse Weber for Thursday
• Read all Iron fertilization policy papers (esp
  Boyd 2009) for next Tuesday
• Also read Frew for next Tuesday
• Next Tuesday we will have a discussion on iron
  fertilization and climate mitigation after Phoebe
  Lams guest lecture.

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Dust deposition is a key source for many metals
(and macronutrients)Figure from Fung et al, 2000
GBC. Also see work by Jickells, Duce, Mahowald,
Sedwick, Sholkovitz, Church, Measures, Landing
and others.
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North Atlantic Aluminium DistributionsMeasures,
Geotraces Document
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PNAS 2009
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Paytan et al is inconsistent with Mann et
al.Prochlorococcus is more sensitive to copper
than Synechococcus in careful laboratory
studiesSpecies shift effects the control
decreases in chlorophyll by gt3-fold, not a
healthy experiment, light levels are
highEukaryotes are increasing massively in cell
number , known to be less sensitive to metal
toxicityProchlorococcus doesnt decrease in cell
number but should be contributing a significant
component of Chlorophyll, implying their pigment
per cell has decreased significantly (which is a
sign of stress).
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Moffett et al., 1997, Limnol Oceanogr
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Solubility of anthropogenic dust is much higher
than natural dust
Sholkovitz, Sedwick, Church GCA 2009
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Potential use of Vanadium as a proxy for iron
solubility
Sholkovitz, Sedwick, Church GCA 2009
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Summary and Future issues from Mahowald et al
Annual Review Marine Science 2009
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Correlations with NutrientsMicronutrient
influences on oceanographic distributions
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Cadmium and Zinc Oceanographic
ObservationsNutrient-like profiles and
correlations with phosphate or silicic acid

• Boyle , Sclater and Edmond. 1976 On the Marine
  Geochemistry of Cadmium. Nature
• Bruland , K. Knauer, Martin. 1978 Zn in Northeast
  Pacific Waters. Nature

Boyle 1988 Paleoceanography
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Bruland , K. Knauer, Martin. 1978 Zn in Northeast
Pacific Waters. Nature

• ALMOST all lead data for the marine environment
  are inaccurate, contends Patterson1, because of
  gross contamination from faulty sampling and
  analytical procedures. Most marine chemists
  assume that similar problems are associated with
  other trace elements as well. Hence, clean
  sampling and analytical techniques have been
  adopted. These procedures, in conjunction with
  the improvement of analytical instrumentation,
  have resulted in reports on Cu, Ni and Cd (refs
  24 3, 5 and 3, 68 respectively) levels in
  seawater that are at least an order of magnitude
  lower than those previously thought to exist. We
  report here that Zn concentrations (10600 ng
  l-1) are also considerably lower than previously
  published estimates of 130 g l-1 and that its
  vertical distribution (surface depletion, deep
  enrichment) is very similar to that of a major
  plant nutrient that is, silicate.

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Why is there a kink in the CdP relationship?
An unresolved matter.

• Analytical issues
• Province differences, mechanism unknown (Atlantic
  is distinct, DeBaar 1994)
• Biodilution effect of iron limitation on CdP
  (Lane, Cullen, Maldonado, 2009)
• Zn biochemical substitution influences (Zn, Co,
  Cd interactions Sunda and Huntsman 2000)
• Zn preference, as Zn becomes depleted, Cd uptake
  increases
• Zn abundance falls below ligand concentration
• Figure from DeBaar 1994

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Zinc correlates well with silicic acid But Zn
is not particularly enriched in diatom frustrules
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Nickel nutrient like similar to phosphate, with
caveats
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Copper evidence of scavengingThere is
clearly more to learn about copper scavenging
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Nutrient like metals are strongly controlled by
biological uptake and remineralization (diagonal
vectors)Metals with strong dust and scavenging
show no correlation (vertical vectors)What
controls the slope?
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The hybrid-types can also have correlations
CoP correlation exists - but only in surface
waters due to scavenging. (Saito et al., 2004
GBC Noble et al., 2008 DSR Saito et al in prep
Noble et al in prep).
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Downward scavenging vector evident when all
depths are included
Data from Martin et al., 1989
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Biogeochemical Provinces for Cobalt (and
Zn/Cd)? CoP correlations in the upper water
column are a global phenomenon But have a much
higher slope in surface waters of oligotrophic
regions
Relative utilization of cobalt and phosphate (
Co vs PO4, mmol mol-1)
Location Depth range Co (pM) DCo/DP mmol mol-1 r2
South Atlantic (CoFeMUG) 0-200 0-100 7-130 7-37 46 300 0.85
Peru Upwelling Region (Saito, Moffett DiTullio, 2004) 8m 21-315 248 0.83
Equatorial Atlantic (Saito and Moffett, GCA 2002) 5m 5-87 560 0.63
NE Pacific (Martin et al., DSR, 1989) 50-150m 7.9-32 39.8 0.98
NE Pacific (Martin et al., DSR, 1989) 50-150m 28-40 35.5 0.99
NE Pacific (Martin et al., DSR, 1989) 8-50m 25-55 38.4 0.97
Central N Pacific (Saito et al., August 2003, unpublished) 15-150m 13-150 67 0.86
Ross Sea, Antarctica (Saito and Noble, 2006 unpublished) 10-300m 21-65 27 0.83
cyanobacteria
cyanobacteria
cyanobacteria
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Cd and Zn are used as paleotracers of phosphate
and silica By analysis of CdCa and ZnCa in
foraminfera shells (Figures by Boyle or
Marchitto, see Boyle for development of Cd
method Marchitto et al. for Zn method Boyle,
Oppo, Curry, Elderfield, Rickaby, Marchitto and
others for application).
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