Implication of biogeochemical change driven by global warming in the East Sea

1. EAST SEA STUDY Implication of biogeochemical change driven by global warming in the East Sea Il Nam Kim Department of Marine Science University of Texas at Austin

2. INTRODUCTION • BACKGROUND • MATERIAL & METHOD • RESULTS • CONCLUSION

3. INTRODUCTION

4. ■ The East Sea ▲ Study area depth (m) • 17 June – 21 July • 22 July – 11 August ▲ a semi-closed marginal sea ▲ frequently referred to as ‘ miniature ocean ’ ▲ The maximum depth – 4,049m average depth – 1,600m

5. ■ Dissolved Oxygen distribution at 1000m [Talley et al. 2006]

6. ■ Warming evidences ▲ Temperature changes Sea Surface Temp. Vladivostok [Min and Kim, 2006] [Kim et al., 2004]

7. ▲ Oxygen changes box modeling [Kim et al., 2001] [Kang et al., 2004]

8. BACKGROUND

9. ■ Denitrification ▲ In the presence of oxygen ☞ nitrification (NH4+ → NO2- → NO3-) ▲ In the absence of oxygen ☞ denitrification (NO3- → NO2- → N2O/N2) [Sarmiento and Gruber, 2006]

10. In the eastern tropical North Pacific In Saanich Inlet FIG. 4 ▲ The major areas The Arabian Sea [Devol, 1978] [Hupe and Karstensen, 2000]

11. MATERIAL

12. ■ Study Map •≥ 200 m •≥ 300 m ▲ Cruise: CREAMS II expedition (1999) ▲ Parameters used : T, S, DO, nutrients, TAlk, DIC lat, long, depth (≥300m)

13. METHOD

14. T : Temperature • S : Salinity • DO : Dissolved Oxygen • P : Phosphate • N : Nitrate • Si : Silicate • TALK : Total Alkalinity • DIC : Dissolved Inorganic Carbon ■ Linear Inverse Mixing Model ▲ Model equations [Hupe and Karstensen 2000]

15. ▲ Matrix form A x d R - = • Kim and Lee (2004) TMW (Tsushima Middle Water) LCW (Liman Cold Water) ESIW (East Sea Intermediate Water) ESPW (East Sea Proper Water) known known unknown unknown • A : source water types • x : mixing ratio • d : observed data • R : residual ※ rD (Gruber and Sarmiento 1997)

16. ▲ Redfield ratios ▲ Solution ※ MATLAB is available to calculate non-negative solutions ☞ function of NNLS ▲ Weights

17. RESULTS I - some evidences

18. ■ N:P ratio

19. ■ Vertical profiles of NO3-, NO2-, O2, and N/P ratio

20. RESULTS II - linear inverse modeling

21. ■ Expected denitrification locations ▲ CASE 1 ▲ CASE 2 ▲ CASE 3 ▲ CASE 4

22. ■ Vertical profiles of ∆Ndeni ▲ CASE 1 ▲ CASE 2 ▲ CASE 3 ▲ CASE 4

23. ■ How to derive the unit of time ? ▲ Estimation of pseudo-age using oxygen ▲ Example

24. ■ Horizontal distributions of ∆Ndeni - CFCs ▲ CASE 1 ▲ CASE 2 (µmol/m2day) ▲ CASE 3 ▲ CASE 4

25. ■ Horizontal distributions of ∆Ndeni - MBBM ▲ CASE 1 ▲ CASE 2 (µmol/m2day) ▲ CASE 3 ▲ CASE 4

26. SUMMARY Area = 7.0926e+3 km2

27. RESULTS III - feedback loop

28. ■ The feedback loop based on biogeochemical changes Global Warming ↑ Water formation ↓ SST ↑ Gamo (1999) Gamo (1999) Gamo et al. (2001) Min and Kim (2006) Kang et al. (2003b) Chae et al. (2005) Postlethwaite et al. (2005) POSITIVE N2O ↑ Denitrification ↑ low Oxygen Environment ↑ Kim and Kim (1996) ? Chen et al. (1999) Kim et al. (2001) Kang et al. (2004) Kim et al. (2004)

29. CONCLUSION

30. The denitrification in the East Sea is estimated approximately to be 9 to 16 µmol·m-2·d-1 through the linear mixing inverse model. • New finding ? vs Warming event ? • Therefore, we need to have deep concern about the phenomenon that is occurring though the oxygen content high. It might be a signal of global warming.

31. Thank you for your time !