3. … however, abundance of organic carbon in biosphere/soil/ocean reservoirs is too small to control atmospheric O 2 levels
4. SLOW OXYGEN CYCLE: ATMOSPHERE-LITHOSPHERE O 2 CO 2 Compression subduction Uplift CONTINENT OCEAN FeS 2 orgC weathering Fe 2 O 3 H 2 SO 4 runoff O 2 CO 2 Photosynthesis decay orgC burial SEDIMENTS microbes FeS 2 orgC CO 2 orgC: 1x10 7 Pg C FeS 2 : 5x10 6 Pg S O 2 : 1.2x10 6 Pg O O 2 lifetime: 3 million years
5. OXIDATION STATES OF NITROGEN N has 5 electrons in valence shell 9 oxidation states from –3 to +5 (nitrate radical in oxidation state +6) Decreasing oxidation number (reduction reactions) Increasing oxidation number (oxidation reactions) -3 0 +1 +2 +3 +4 +5 +6 NH 3 Ammonia NH 4 + Ammonium R 1 N(R 2 )R 3 Organic N N 2 N 2 O Nitrous oxide NO Nitric oxide HONO Nitrous acid NO 2 - Nitrite NO 2 Nitrogen dioxide HNO 3 Nitric acid NO 3 - Nitrate ion N 2 O 5 Dinitrogen pentoxide NO 3 Nitrate radical
6. THE NITROGEN CYCLE: MAJOR PROCESSES ATMOSPHERE N 2 NO HNO 3 NH 3 /NH 4 + NO 3 - orgN BIOSPHERE LITHOSPHERE combustion lightning oxidation deposition assimilation decay nitrification denitri- fication biofixation burial weathering fixation SOIL/OCEAN
7. BOX MODEL OF THE NITROGEN CYCLE Inventories in Tg N Flows in Tg N yr -1
8.
9. N 2 O versus depth in the Greenland Ice sheet. Constraints on N 2 O budget changes since pre-industrial time from new firn air and ice core isotope measurements S. Bernard, T. R¨ockmann, J. Kaiser, J.-M. Barnola, H. Fischer, T. Blunier, and J. Chappellaz, Atmos. Chem. Phys., 6, 493–503, 2006 N 2 O in the atmosphere
10.
11. OXIDATION STATES OF SULFUR S has 6 electrons in valence shell oxidation states from –2 to +6 Decreasing oxidation number (reduction reactions) Increasing oxidation number (oxidation reactions) -2 +4 +6 FeS 2 Pyrite H 2 S Hydrogen sulfide (CH 3 ) 2 S Dimethylsulfide (DMS) CS 2 Carbon disulfide COS Carbonyl sulfide SO 2 Sulfur dioxide H 2 SO 4 Sulfuric acid SO 4 2- Sulfate
12. THE GLOBAL SULFUR CYCLE SO 2 H 2 S volcanoes coal combustion oil refining smelters SO 2 CS 2 SO 4 2- OCEAN 1.3x10 21 g S 10 7 years deposition runoff SO 4 2- plankton COS (CH 3 ) 2 S microbes vents FeS 2 uplift ATMOSPHERE 2.8x10 12 g S 1 week SEDIMENTS 7x10 21 g S 10 8 years (sources in Tg S y -1 ) 20 60 10
13. RISING MERCURY IN THE BIOSPHERE 3000-yr record in Swiss bog Roos-Baraclough and Shotyk, ES&T 2003 Mercury in polar bear fur up 5-12X since 1890 Dietz et al., ES&T 2006 States with fish mercury advisories
15. GLOBAL MERCURY CYCLE (NATURAL) Inventories in Mg Rates in Mg y -1 Selin et al. [2007]
16. GLOBAL MERCURY CYCLE (PRESENT-DAY) Inventories in Mg Rates in Mg y -1 Selin et al. [2007]
17. Africa Tons y -1 Asia Australia Europe N. America S. America Figure 2. Global trend in mercury anthropogenic emissions by continent, 1990-2000. Data from Pacyna et al. [2006a].
19. CONTRIBUTIONS TO N. AMERICAN MERCURY DEPOSITION FROM THE GLOBAL vs. REGIONAL POLLUTION POOL Hg(0) Hg(II) N. American boundary layer Hg(0) emission (53%) Hg(II) Global pool (lifetime ~ 1 y) Regional pollution pool Hg(II) emission (47%) reduction External anthropogenic Oceans Land N. America accounts for only 7% of global anthro. emission (2000) NORTH AMERICA cycling and re-emission
20. SOURCE ATTRIBUTION FOR U.S. MERCURY DEPOSITION % contribution of N. American sources to annual total mercury deposition Natural (32%) North American anthropogenic (20%) Rest of world anthropogenic (31%) – half cycled through ocean on annual time scale Legacy anthropogenic re-emitted from soil on centurial time scale (16%) Selin et al. , 2007
Editor's Notes
Big imbalance, small change due to long lifetime. Big inertia/momentrum
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