1. Biogeochemical Cycles Carbon Cycle

2. Announcements Midterm is WED. Review materials: are posted on website. Review session: in sections this week * reminder: Bring your books to section.

3. Announcements: Midterm: You will need pink scantron & #2 pencil You will not need a calculator People with accommodations please see me at break

4. “Biogeochemical Cycles”? Biogeochemical cycles: The interlinked cycling of matter (and energy) between geosphere and biosphere.

5. “Biogeochemical Cycles”? “Only in recent decades have scientists begun to fathom the extremely complex interplay of biological, geological and chemical processes by which materials and energy are exchanged and reused at the Earth's surface. These intermeshed processes, known as biogeochemical cycles, operate on timescales of microseconds to eons and occur within domains that range in size from a living cell to the entire atmosphere-ocean system.” “ Driven by solar or geothermal energy, these cycles are concentrated at interfaces where living organisms catalyze chemical reactions…”

6. Biogeochemical Cycles The flow of matter & ways in which it is recycled

7. Sedimentation and burial 0.05 Weathering 0.05 Maybe a better picture : understand biogeosphere as a system

8. “Biogeochemical Cycles”? Three interlocking elements: 1) Chemistry 2) Biology 3) Geological or atmospheric processes (e.g. weathering, sedimentation, dust transport etc)

9. 1) The Basics What is “organic” carbon? C-C-C CH 2 -CH 2 -CH 2 ?

10. 1) The Basics Life (biosphere) transforms and recycles carbon Inorganic matter (oxidized carbon) CO 2 Organic matter (reduced carbon) CHO

11. Organic Matter Based on reduced carbon (C-H) Carbohydrates (sugars and starches - CHO) Fats and Oils (CH) Proteins (contain N too) Inorganic Matter 1)Oxidized carbon CO x 2) Macro Nutrients –Nitrogen –Phosphorus –Sulfur –Potassium 3) Trace Nutrients –ie, Iron, Cobalt, Selenium, etc. Matter: Building Blocks of Life

12. 1) Autotrophs (plants): Fixation of elements into “organic matter” 2) Heterotrophs: return elements to geosphere via breakdown of organic matter Inorganic matter (oxidized carbon) CO 2 Organic matter (reduced carbon) CHO autotrophs heterotrophs

13. Carbon & nutrients Captured by Autotrophs Autotrophs get carbon & nutrients from environment in inorganic form (ie nitrogen as NO2, Phosphorous as PO4) Figure 6.1

14. PRIMARY PRODUCERS autotrophs or green plants use energy from the sun to turn nutrients into organic compounds: PHOTOSYNTHESIS CO 2 + H 2 O ==> CH 2 O + O 2 carbon dioxide + water becomes organic tissue + oxygen

15. What controls this process? First: actually, there’s more happening: CO 2 + PO 4 + NO 3 + H 2 O ==> CH 2 O,P,N + O 2 carbon dioxide + phosphate + nitrate + water becomes organic tissue + oxygen

16. OrganicMatter Carbohydrates Fats and Oils Proteins Pigments, etc Inorganic Carbon (Co2) Macro Nutrients –Nitrogen –Phosphorus –Sulfur –Potassium Trace Nutrients Think of all living things : a basic “recipe” x y z

17. Typically, it’s the thing you are short of.. “Limiting Nutrient” –Liebig’s law of the minimum: growth rate of plants is determined by the least abundant nutrient relative to the needs of the plant

18. Heterotrophs Heterotrophs or Consumers: get their energy from their food Cannot “fix carbon” = make organic compounds from only inorganic nutrients

19. DECOMPOSERS (“remineralization”) Also Heterotrophs - such as fungi and bacteria Convert organic molecules to inorganic nutrients, usually using oxygen RESPIRATION CH 2 O + O 2 ==> CO 2 + H 2 O Organic tissue + oxygen becomes carbon dioxide + water

20. DECOMPOSERS (“remineralization”) Heterotrophs such as fungi and bacteria Again, there’s more happening: CH 2 O,P,N + O 2 ==> CO 2 + PO 4 + NO 3 + H 2 O organic tissue + oxygen becomes carbon dioxide + phosphate + nitrate + water

21. The Basic Carbon Cycle (short term) *CO2 from the atmosphere is fixed into organic matter Organics Matter (OM) is stored, transported Ultimately it is respired- back to CO2… CO 2 OM CO 2

22. Problem: How to be quantitative? Understand biogeochemical system so can make predictions? (ie, a perturbation will do..what..? )

23. 2) BOX MODELS The basic modeling tool used to study biogeochemical systems Goal: Parameterize a system as reservoirs and fluxes

24. 2) BOX MODELS A simple box model of “reservoirs” of carbon- ( approximately to scale..) What about fluxes? ATM CO2

25. Example: “ Pools” & Fluxes of Carbon in Atmosphere and Ocean Example: “ Pools” & Fluxes of Carbon in Atmosphere and Ocean DIC: 37,000

26. Sedimentation and burial 0.05 Weathering 0.05 “Pools and fluxes” working of the whole system depends on 1) size of reservoirs 2) rates of transfer

27. Sedimentation and burial 0.05 Weathering 0.05 Key additional concept: Is the system in equilibrium? =“steady state”

28. Box Model Box represents a RESERVOIR Amount of substance in reservoir is INVENTORY Arrow represents a FLOW or FLUX IF in STEADY - STATE INVENTORY remains CONSTANT FLUX IN = FLUX OUT FLUX INFLUX OUT

29. Box Model Box represents a RESERVOIR Amount of substance in reservoir is INVENTORY Arrow represents a FLOW or FLUX RESIDENCE TIME = INVENTORY / FLUX = average time one molecule spends in reservoir WHY IS RESIDENCE TIME IMPORTANT? Tells 1) how long it would take to significantly affect the INVENTORY if the FLUX IN or OUT is altered 2) how quickly will something can change. (Start seeing changes in inventory ~half of a residence time) FLUX INFLUX OUT

30. Residence Time Concept Residence time = Inventory / Flux “Inventory” = mass (g) “flux” = mass/ time ( g/ yr) Residence time = (g ) / (g/yr) = yr (time)

31. Residence Time Inventory (total amount in ocean) Total Fluxes Out Residence time = Inventory / Flux = The average amount of time one atom of constituent spends in ocean Also = Approx. amount of time it takes for the concentration of a constituent to significantly change Total Fluxes In Amount / time =

32. Residence time Example My assistant will now conceptually demonstrate:

33. Baxter The Dog.

34. Note Relative Hair Length: Long Hair or Short Hair?

35. “Fur Inventory”: (?) Would you thus estimate the total amount (“inventory”) of Dog-Hair to be on Baxter: a) relatively LARGE b) Relatively SMALL (vs other dogs)

36. What about Bax-Fur “Residence time”? IF you guessed that the inventory of Baxter-fur is relatively SMALL… What would you GUESS the residence time is (short or long)? What other information would you need to really find out?

37. Recall: Residence time = Inventory / FLUX How can we measure FLUX?

38. 1 Month Yield from Electronic Hair Isolation/ concentration Device: 1 Month Yield from Electronic Hair Isolation/ concentration Device: * ~ 3lbs total mass !!!

39. ~90 % Dog Hair!!!

40. FLUX is HIGH !! Mass: 3 lbs * 90% = 2.7 LB Dog Hair. 2.7 lbs* 0.45 (Kilo/ Lb) = 1.22 Kilos * 1000 (g/Kg) = 1222 grams Dog Hair!!

41. if FLUX = mass/time Mass: = 1222 grams Dog Hair Experiment TIME: 30 days FLUX = 40 grams/Day!! (That, my friends, is a LOT of dog hair.)

42. Key Concept: Inventory and Flux are NOT necessarily related! Ie: If you know inventory- tells you NOTHING about flux (and vice versa) *can easily have very small inventory- BUT high flux (or small flux, but Huge inventory..)

43. So: can we get a real number for Bax-fur residence time? What would we need? 1. ASSUME STEADY STATE

44. Can we get a number for residence time? 2. Need a Good estimate for Hair INVENTORY in g’s..but how..

45. Real Example: What is res time of water in ocean? RESERVOIR is the OCEAN INVENTORY is 1350 X 10 6 km 3 FLUX IN (river flow from continents into ocean) FLUX OUT (evaporation and transport of water to continents) FLUX INFLUX OUT

46. What about water in atmosphere? RESERVOIR is the ATMOSPHERE INVENTORY is 0.013 X 10 6 km 3 FLUX IN (evaporation of water from Earth’s surface) FLUX OUT (precipitation) FLUX INFLUX OUT

47. The Atmospheric Carbon Reservoir In the absence of fossil fuel burning and other human activities, the atmospheric carbon reservoir would be in steady state.. Atm carbon reservoir example: inventory  = _______ = ____ ___________ 12 Years flux 760 Gton 60 Gton/Yr

48. RESIDENCE TIME = INVENTORY / FLUX Fluxes are due to evaporation and precipitation Fluxes are due to photosynthesis and respiration

49. 3) FOCUS on MODERN CARBON CYCLE

50. Biogeochem. Cycle where Carbon is “currency” Carbon cycle” most commonly studied biogeochemical cycle “Currency” (=what you are modeling in fluxes and reservoirs) is CARBON Q: Why carbon?

51. “Cartoon” of overall carbon cycle

52. Fig. 6.6 Biota Carbon Balance: Gross primary production (GPP) (carbon flux in) Respiration + Death (carbon flux out) NET primary production (NPP) = (GPP - Respir) (120 - 60 = 60 Pg/yr) Biota Balance

53. Fig. 6.6 ATMOSPHERE (a reservoir NOT in steady-state) Fluxes in: 0.1 + 5.3 + 2.0 + 4 + 60 + 55 + 88 = 7.4 + 207 = 214.4 Pg/year Fluxes out: 120 + 90 = 210 Pg/year (Fluxes in > Fluxes out by ~ 4 Pg/yr) Atmospheric reservoir of C is growing ~ 4 Pg/year! Human emissions: ~7.4 ± 1.0 Pg/year. If 4 Pg/year is accumulating in the atmosphere, where are the other 3.4 ± 1.0 Pg/year going? Atmosphere: not in balance!

54. We emit about 7.4 ± 1.0 Pg/yr We measure atmosphere gaining 4.0 Pg/yr Calculation 3.4 ± 1.0 Pg/yr missing from the atmosphere

55. Fig. 6.6 BIOTA & SOILS Reservoir size: 2000 Flux in: 120 Flux out: 4+60+55 = 119 120 - 119 = 1 Pg/yr BIOTA & SOILS are gaining ~ 1 Pg/yr Is it going into Biota? Some..

56. Fig. 6.6 OCEAN Reservoir size: 38000 Flux in: 90 Flux out: 88+0.2=88.2 90 - 88.2 = 1.8 Pg/yr OCEAN is gaining 1.8 Pg/yr Is it going into Ocean?.. A lot more!

57. Sources & Sinks of Anthropogenic carbon BIOTA & SOILS Flux in: 120 Flux out: 4+60+55 = 119 Net SINK: 1 Pg/yr OCEAN Flux in: 90 Flux out: 88+0.2 = 88.2 Net SINK: 1.8 Pg/yr Human SOURCES: 7.4 ± 1.0 Pg/yr Measured Atmospheric increase:4.0 Pg/yr CALCULTED Carbon SINKS: 3.4 ± 1.0 Pg/yr Measured carbon SINKS:2.8 Pg/yr Calculated and Measured SINKS are equal within error SOURCE: where atmospheric carbon is coming from SINK: where atmospheric carbon is going

58. Ocean currently taking up ~ 2x more than land.. Ocean currently takes up ~ 2x more than land.. But also.. Ocean uptake each year is 50% what’s going into the atmosphere.  our problems would be MUCH MUCH worse if ocean uptake slowed down.. Much better if speeded up..  Key to understand ocean C uptake mechanisms!

59. 4) Some FEEDBACKS in C-CYCLE

60. 1. CO2 fertilization: higher CO2 causes faster plant growth, more carbon uptake Fossil Fuel use increase CO 2 increases Plant growth increases CO 2 decreases (-)

61. 2. warming also causes faster plant growth, more carbon uptake Fossil Fuel use CO 2 increases Global warming Plant growth increases CO 2 decreases

62. Fixed Nitrogen* Plant growth increases CO 2 decreases 3. Nitrogen fertilization: faster plant growth, more carbon uptake * Via fertilizer production

63. Fossil Fuel use CO 2 increases Global warming Decay increases CO 2 increases 5. BUT: warming causes faster decay, carbon release

64. Fossil Fuel use CO 2 increases Global warming Decay increases Nutrients increase Plant growth increases CO 2 decreases 4. BUT faster decay, also means more nutrients for plant growth, carbon uptake

65. Overall: to understand system- must explore, parameterize & test all feedbacks.. Create enormous super-computer models..

66. End Next : Focus on Ocean’s Role in Atm CO2 regulation

67. Sources & Sinks of Anthropogenic carbon BIOTA & SOILS Flux in: 120 Flux out: 4+60+55 = 119 Net SINK: 1 Pg/yr OCEAN Flux in: 90 Flux out: 88+0.3 = 88.3 Net SINK: 1.7 Pg/yr Human SOURCES: 7.4 ± 1.0 Pg/year Atmospheric increase:4.0 Pg/year Carbon SINKS: 3.4 ± 1.0 Pg/year SOURCE: where carbon is coming from SINK: where carbon is going

68. Two Mechanisms for ocean to take up carbon: 1.Increase in ‘biological pump’ 2.Increase in carbon dissolving in ocean (“buffering”), causes ocean acidification! “BIOLOGICAL PUMP”: -primary producers use inorganic nutrients and carbon to form organic matter -organic matter is exported out of surface ocean into deep ocean -carbon is stored in deep ocean for 100’s of years “OCEAN BUFFERING” CO 2 + CO 3 2- + H 2 O ==> 2 HCO 3 --

69. Surface versus Deep Dissolved Nutrients Surface Ocean (light in upper ~100 m) –Photosynthesis dominates –carbon/nutrient concentrations are LOW Organic particles formed in surface ocean fall into deep ocean (exporting nutrients out of surface) Deep Ocean (dark below ~100 m) –Respiration of organic particles –carbon/nutrient concentrations are HIGH CO 2 + PO 4 + NO 3 + H 2 O CH 2 O,P,N + O 2 photosynthesis respiration

70. 1 mole = 6.023 X 10 23 molecules molecular mass = grams/mole µmol/kg = 1 x 10 -6 moles per kg O2O2 PO 4 At surface: Photosynthesis Uses PO 4 Produces O 2 Photosynthesis Falling Particles of Dead Organic Matter Respiration Uses O 2 Produces PO 4

71. Dissolved Inorganic Carbon in the Ocean High dissolved Carbon in the Surface Higher dissolved Carbon in the Sub-surface WHY ISN’T CARBON IN THE SURFACE USED UP?

72. Two Mechanisms for ocean to take up carbon: 1.Increase in ‘biological pump’ 2.Increase in carbon dissolving in ocean (“buffering”), causes ocean acidification! “BIOLOGICAL PUMP”: -primary producers use inorganic nutrients and carbon to form organic matter -organic matter is exported out of surface ocean into deep ocean -carbon is stored in deep ocean for 100’s of years “OCEAN BUFFERING” CO 2 + CO 3 2- + H 2 O ==> 2 HCO 3 --

73. Regions with HIGH Nitrogen, but LOW biological production (where biological growth is limited by IRON) IRON FERTILIZATION: An idea for increasing the biological pump in regions that are iron-limited.

74. END

75. Box model review OCEAN Land (via rivers) hydrothermal atmosphere Ocean Salt is in “Steady State” Chemistry of ocean is not changing Input fluxes = Output fluxes OR Sources = Sinks Sediments

76. “Greening” of the plantet

77. Quiz Questions

78. Question #1 Autotrophs –A. only need sunlight to grow –B. get their nutrients from eating complex organic molecules –C. get their nutrients from inorganic compounds –D. need all the elements found on earth

79. Question #2 Heterotrophs –A. only need sunlight to grow –B. get their nutrients from eating complex organic molecules –C. get their nutrients from inorganic compounds –D. need all the elements found on earth

80. Question #3 The residence time of a constituent in a reservoir is approximately equal to the amount of time: A. it takes to fill the reservoir with input fluxes B. it takes to empty the reservoir with output fluxes C. it takes to significantly alter the inventory of the reservoir D. all of the above Today’s fluxes of carbon into and out of various reservoirs indicates that the Global Carbon Cycle is: A.Well-balanced and in steady-state B.Imbalanced and not in steady-state C.About to achieve steady-state soon

81. Question #4

82. Question #5 Which of these are currently causing the flux of carbon INTO the biosphere to increase: A.more CO2 is slowing plant growth B.more nitrogen is increasing plant growth C.global warming causes more respiration and release of CO2 from soils D.global warming is slowing plant growth

83. NOT USED SLIDES

84. Carbon Dioxide (was mixed in biogeochem cycle section- no explanation text)