1. Coupled Biogeochemical Cycles William H. Schlesinger Millbrook, New York

2. 1. Some basic stoichiometry for life―in biomass First articulated by Liebig (1840) and later advanced by Redfield (1958), Reiners (1986), Sterner and Elser (2002), and Cleveland and Liptzin (2007)

3. Complementary Models for Ecosystems Reiners, W.A. 1986

4. 145 100 + ?Δ 121 40 The Global Nitrogen Cycle - Modern 48-59 18 <5

5. IF NPP = 60 x 10 15 g C/yr 60X 10 15 g C x 1 N = 1.2 x 10 15 g N 50 C = 1200 x 10 12 g N/yr

9. From: Magnani et al. 2007

10. Townsend et al. 1996. Ecological Applications 6(3):806-814. Spatial Distribution of the 1990 Carbon Sink Resulting from Fossil-fuel N Deposition between 1845 and 1990

11. Coupling of biogeochemical cycles, due to: 2.The flow of electrons in the oxidation/reduction reactions― First articulated by Kluyver (1926), and later advanced by Morowitz, Nealson, Falkowski, and many others

12. Schlesinger, W.H. 1997

13. Table 1. Matrix of redox reactions via microbial metabolisms as updated and modified from Schlesinger et al (2011).

14. Mikucki et al. 2009

15. Coupled Metabolism & The Sulfur Wars Howarth and Teal 1979 report 75 moles/m 2 of sulfate reduction annually 2H + + SO 4 = + 2CH 2 O2CO 2 + H 2 S + 2H 2 O implies 150 moles of C is oxidized 150 mols C= 1800 g C/m 2 /yr Howes et al. 1984 NPP nowhere near that high!

16. 145 100 + ?Δ 121 40 The Global Nitrogen Cycle - Modern 48-59 18 <5

17. Denitrification 5CH 2 O + 4H + + 4NO 3 - → 2N 2 + 5CO 2 + 7H 2 0 Intermediates include NO and N 2 O

18. Hirsch et al. 2006

20. ∆ N 2 0 = TOTAL N 2 0 __________________ N 2 + N 2 0

21. Schlesinger 2009

22. Calculation of change in denitrification from N 2 O 124 Tg (0.37) + 110 Tg (0.082) = 234 Tg (0.246) 4 TgN 2 O/yr / 0.25 = 17 TgN/yr

23. 145 116-124 121 40 The Global Nitrogen Cycle - Modern 48-59 18 150 +9 <5 Land-sea Transport 48

24. 3. Coupling of biogeochemical cycles to carbon through chelation

26. Fig. 2. The fractional amount of Pb loss calculated over the study period is significantly correlated with the thickness (cm) of the forest floor at each site. A logarithmic fit to these data give r 2 = 0.65. Kaste et al. 2006.

27. Principles of coupled biogeochemical cycles apply to geo-engineering

30. For example, if we wanted to sequester a billion metric tons of C in the oceans by enhancing NPP with Fe fertilization Current marine NPP = 50 x 10 15 g C/yr F-ratio of 0.15 means that 7.5 x 10 15 g C/yr sinks through the thermocline An additional 1 x 10 15 g C/yr sinking would require ~7 x 10 15 g C/yr additional NPP, so 7 x 10 15 g C x 23 x 10 -6 Fe/C = 1.6 x 10 11 g Fe (Lab uptake), or x 6 x 10 -4 = 4.2 x 10 12 (Field observation) Buesseler & Boyd (2003) Versus, the global production of Fe annually (1900 x 10 12 g Fe/yr)

31. For example, to provide a sink for 1 x 10 15 gC/yr in the world’s soils by fertilizing them: Current terrestrial NPP = 50 x 10 15 g C/yr Preservation ratio of 0.008; i.e., global NEP – 0.4 g C/yr (Schlesinger 1990) To store an additional 1.0 x 10 15 g C in soils would require adding 125 x 10 15 g C/yr to terrestrial NPP 125 x 10 15 g C/yr x 1 N/50 C = 2.5 x 10 15 g N as fertilizer each year 2.5 x 10 15 g C @ 0.857 g C released as CO 2 per g N = 2.14 x 10 15 g C/yr released in fertilizer production

32. The Global Phosphorus Cycle

33. Natural Biogeochemical Cycle in Surface Biosphere (terrestrial & oceanic) ElementFlux (10 12 g/yr)Biospheric Flux/Sedimentary Flux C107000446 N9200368 P1000500 S4505.6 Cl1200.46 Ca23003.7 Fe405.3 Cu2.523.6 Hg0.0034.3

34. Comparison of Biogeochemical Cycle to Anthropogenic Cycle (Flux in 10 12 g/yr) ElementBiospheric FluxAnthropogenic FluxAnthro/SedimentaryAnthro/Biospheric C107000870036.30.081 N92002218.80.024 P10002512.50.025 S4501301.60.29 Cl1201700.651.42 Ca2300650.100.028 Fe401.10.140.028 Cu2.51.514.30.60 Hg0.0030.00233.30.77

35. My final message today: There is an increasing role for biogeochemists to contribute to the understanding and fruitful solutions to global environmental problems.

36. www.caryinstitute.org