1 / 17

Lead Concentrations and Isotopes in Corals and Water near Bermuda, 1780-2000

Lead Concentrations and Isotopes in Corals and Water near Bermuda, 1780-2000. Amy E. Kelly, Matthew K. Reuer , Nathalie F. Goodkin , Edward A. Boyle (2009) Earth and Planetary Science Letters 283, 93-100.

oleg
Download Presentation

Lead Concentrations and Isotopes in Corals and Water near Bermuda, 1780-2000

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. Lead Concentrations and Isotopes in Corals and Water near Bermuda, 1780-2000 Amy E. Kelly, Matthew K. Reuer, Nathalie F. Goodkin, Edward A. Boyle (2009) Earth and Planetary Science Letters 283, 93-100

  2. MIT Pb concentration data (Boyle) from US GT NAT-2010 transect compared to MIT data from nearby stations from 1989 and 1999.

  3. Background • A certain amount of lead (Pb) naturally occurs in the oceans • Human industry has increased the concentration of Pb in the earth’s oceans since the Industrial Revolution. Sources have different ratios of stable isotope (204Pb, 206Pb, 207Pb, 208Pb). 204Pb is primordial. • Back-dating Pb deposits in coral can tell us about historic Pb levels in the ocean • The amount of Pb that corals incorporate into their calcium (Ca) structures is proportional to the Pb concentration in the water where they live. First order removal process!

  4. Fig 1: Location of Study • Bermuda • Coral atoll (North Rock, 11m; Smith’s Bay, 15m) • Atlantic Ocean (BATS) • Westerly winds carry aerosols with Pb from the US. • (some) European Pb aerosols are carried there as well. • Residence time in surface SW ~ 2 years

  5. Types of Coral used • Diploriastrigosa • Diplorialabyrinthiformis http://www.reefcolors.de/Galleries/2006_Varadero/index.html http://www.dcbiodata.net/explorer/results/detail/5258

  6. 2 Key Questions: • What are the pre-anthropogenic Pb concentration and Pb I.R. (isotope ratios) of corals and seawater? • How has the anthropogenic Pb component evolved isotopically through time?

  7. Fig 2: Pb/Ca ratios in coralraw data: note JSB higher than NR Range is 4 to 80 nmolPb/mol Ca Average JSB to 1938 = 5.0 (using Dp = 3.6; [Pb] = 15 pmol kg-1)

  8. Partition Coefficients (Dp) Controls: thermodynamics and crystal chemistry but also coral species, temperature, growth rate Casw = 10.3 mmol kg-1

  9. Fig 3: Inferred Pb Concentrations from North Rock (best record for North Atlantic) Leaded gasoline coal + ore 15 to 80 pM

  10. Fig 4: Inferred Pb Concentrations from John Smith’s Bay 15% higher than NR

  11. Lead Isotope Ratios (I.R.s) • When the earth was formed, mineral deposits formed with different I.R.s in different places (especially 206Pb/207Pb and 208Pb/206Pb) • By looking at the I.R.s present in the Bermudan corals over time, we can infer where the Pbcame from

  12. Fig 5: 206Pb/207Pb from John Smith’s Bay UMV US Europe Ratio of 1.20 similar to NW Atlantic sediments and manganese nodules. Nature lead.

  13. Fig 6: 206Pb/207Pb from North Rock

  14. Fig 7: 208Pb/207Pb from North Rock

  15. Fig 8: 206Pb/207Pb from Both Sites UMV

  16. 208Pb/206Pb vs. 206Pb/207Pb Over Time

More Related