1 / 28

Lecture 3 Trace Metals in Seawater

Lecture 3 Trace Metals in Seawater. What are trace elements? Why are they important? Principal of Oceanographic Consistency. Profiles shapes as clues for controlling processes. A first look at spatial variation. What are the different “ types ” of elements?. Trace elements in seawater

Audrey
Download Presentation

Lecture 3 Trace Metals in Seawater

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Lecture 3 Trace Metals in Seawater What are trace elements? Why are they important? Principal of Oceanographic Consistency. Profiles shapes as clues for controlling processes.

  2. A first look at spatial variation What are the different “types” of elements?

  3. Trace elements in seawater Definition: Those elements that do not contribute to salinity All elements less than 1 mg kg-1. Why are they important? 1. many are micronutrients (e.g. Fe, Cu) – speciation is important 2. others are toxic (e.g. Cu, Hg) 3. some are tracers for redox conditions (Mn, Fe, Cr, I, Re, Mo, V, U) 4. some are enriched in economic deposits such as manganese nodules (e.g. Cu, Co, Ni, Cd) 5. some have man made sources and are tracers of pollution (e.g. Pb, Pu, Ag) ** Difficult to collect samples for without contamination and difficult to analyze.

  4. Shapes of Profiles – clues for controls Conservative- Cesium (Cs); Molybdenum (Mo) - under oxic conditions Nutrient Like – Biological control Shallow (soft parts) and Deep (hard parts) Regeneration Zinc Cadmium Nickel Copper Barium Surface Enrichment – Atm input, River/Coastal inputs Lead Manganese Mid-depth Maximum – Hydrothermal inputs, Oxygen minimum Manganese Iron Near Bottom Enrichment – sediment source North Sea Metals (Cd, Cu, Mn) Deep Depletion - scavenging Lead-210 Aluminum Manganese

  5. Nutrient Like Profiles Superposition of vertical biological flux on horizontal circulation Results in low surface water and high deep water concentrations. Results in higher concentrations in the older deep Pacific than the younger deep Atlantic

  6. Example: Comparison of vertical profiles of nutrients from the Atlantic and Pacific PO4 Si

  7. Nutrient Like Examples Cd, Zn, Cu, Ni But what about Mn, Pb ??

  8. Ba Nutrient Like- Deep Regeneration- Hard Parts Ba and Si strongly correlated. But Why??

  9. Cd Nutrient Like- Shallow Regeneration- Soft Parts Cd and PO4 strongly correlated. But Why??

  10. Modern Data Use the Cd-PO4 correlation as a tool to determine paleo PO4 concentrations. Paleo Reconstruction

  11. Al Atmospheric Input and Scavenging Al profiles Mediterranean to Atlantic to Pacific

  12. Mid-depth Maximum (~200 – 1000m) Mn Depth (km) Depth (km) Total Dissolved Oxygen Minimum Zone - ETNP Murray et al (1981)

  13. MOR Hydrothermal System – Mid-Depth Maximum and Scavenging

  14. Mid-Depth Maximum (~2000m) Fe and Mn Hydrothermal plume from the Juan de Fuca Ridge T anomaly particles Mn Fe Coale et al (1991) Nature, 352, 325

  15. Pb Atmospheric input Pb in Greenland snow

  16. Atmospheric Input Anthropogenic Origin Pb Surface Maximum Flegal and Patterson, 1983

  17. Pb – Ocean Profiles

  18. Sediment Source High Trace Metal Concentrations on the Continental Shelf S PO4 Si Cd Cu Mn Kremling (1983) Nature 303, 225

  19. Ocean Periodic Table (from Ken Johnson, MBARI) http://www.mbari.org/chemsensor/pteo.htm Then click on any element of interest for example profiles.

  20. Metal Limitation and Toxicity – Cu – Role of Free Metal Ion Cu Speciation and Plankton Growth pCu = - log Cu2+ Cutotal = Cu2+ + inorganic complexes + organic complexes

  21. Cu Speciation – Ocean Distributions Total Copper Strong Organic Ligands Free Cu2+ Total Cu

  22. Oceanographic consistency • Acceptance of data must satisfy two criteria: • Vertical profiles should be smooth, not spiky. • Ocean mixing produces smooth profiles • 2. Correlations should exist with other elements that • share the same controlling mechanisms. First Example – Cu in surface waters south of New Zealand (Boyle and Edmond, 1975, Nature, 253, 107) PO4 NO3 Si - SST

  23. Mn Multiple Controls

  24. Vertical profile of PCu

  25. Classification of elements Conservative (or “bio-unlimited”) Bio-limiting (and “biointermediate”) Scavenged Some have a style of their own (e.g. O, Ar, Bi, Hg)

More Related