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

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 Lam’s guest lecture.

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.

North Atlantic Aluminium Distributions Measures, Geotraces Document

PNAS 2009

Paytan et al is inconsistent with Mann et al. Prochlorococcus is more sensitive to copper than Synechococcus in careful laboratory studies Species shift effects: the control decreases in chlorophyll by >3-fold, not a healthy experiment, light levels are high Eukaryotes are increasing massively in cell number, known to be less sensitive to metal toxicity Prochlorococcus doesn’t 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).

Moffett et al., 1997, Limnol Oceanogr

Solubility of anthropogenic dust is much higher than natural dust Sholkovitz, Sedwick, Church GCA 2009

Potential use of Vanadium as a proxy for iron solubility Sholkovitz, Sedwick, Church GCA 2009

Summary and Future issues from Mahowald et al Annual Review Marine Science 2009

Correlations with Nutrients: Micronutrient influences on oceanographic distributions

Cadmium and Zinc: Oceanographic Observations: Nutrient-like profiles and correlations with phosphate or silicic acid Boyle, Sclater and Edmond On the Marine Geochemistry of Cadmium. Nature Bruland, K. Knauer, Martin Zn in Northeast Pacific Waters. Nature Boyle 1988 Paleoceanography

Bruland, K. Knauer, Martin Zn in Northeast Pacific Waters. Nature ALMOST all lead data for the marine environment are inaccurate, contends Patterson 1, 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 2–4; 3, 5; and 3, 6–8 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 (10–600 ng l -1 ) are also considerably lower than previously published estimates of 1–30 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.

Why is there a kink in the Cd:P relationship? An unresolved matter. 1.Analytical issues 2.Province differences, mechanism unknown (Atlantic is distinct, DeBaar 1994) 3.Biodilution effect of iron limitation on Cd:P (Lane, Cullen, Maldonado, 2009) 4.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

Zinc – correlates well with silicic acid But Zn is not particularly enriched in diatom frustrules

Nickel – nutrient like similar to phosphate, with caveats

Copper – “evidence of scavenging” There is clearly more to learn about copper scavenging

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?

The hybrid-types can also have correlations: Co:P 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).

Downward scavenging vector evident when all depths are included Data from Martin et al., 1989

Relative utilization of cobalt and phosphate ( Co vs PO 4,  mol mol -1 ) LocationDepth range Co (pM)  Co/  P  mol mol -1 r2r2 South Atlantic (CoFeMUG) Peru Upwelling Region (Saito, Moffett DiTullio, 2004) 8m Equatorial Atlantic (Saito and Moffett, GCA 2002) 5m NE Pacific (Martin et al., DSR, 1989) m NE Pacific (Martin et al., DSR, 1989) m NE Pacific (Martin et al., DSR, 1989) 8-50m Central N Pacific (Saito et al., August 2003, unpublished) m Ross Sea, Antarctica (Saito and Noble, 2006 unpublished) m Biogeochemical Provinces for Cobalt (and Zn/Cd)? Co:P correlations in the upper water column are a global phenomenon But have a much higher slope in surface waters of oligotrophic regions cyanobacteria

Cd and Zn are used as paleotracers of phosphate and silica By analysis of Cd:Ca and Zn:Ca 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).