1. Bess Ward Department of Geosciences Princeton University

3. Weddell Sea Ross Sea Palmer Peninsula

5. Pine Island Glacier breaks away from the Palmer Peninsula -- global warming at work?

6. Cooling Trend in Antarctica -- warmer in polar seas Doran et al., 2002

8. Weddell Sea Ross Sea Palmer Peninsula

10. Doran et al., 2002

12. Antarctic Continental Cooling u Climate indicators u Reduced T, decreased wind, increased sunshine u Reduced river flow, thicker ice u Ecosystem effects u Less primary production u Fewer nematodes

13. Conflicting Signals of Climate Change in Antarctica u Indications of global scale change? u Feedback effects of global climate? u Ecological consequences?

15. The Mystery of the Dysfunctional Nitrogen Cycle Taylor Glacier South Pole West LB East Lake Bonney

16. West LB East Lake Bonney STRANGE… N cycle non functional: Way too much nitrous oxide (N 2 O) and nitrate (NO 3 ) West Lake Bonney NORMAL N cycle functional: Very little nitrous oxide (N 2 O) and nitrate (NO 3 ) One lake, two lobes connected at the surface WHY????

17. N 2 O = Greenhouse gas UV radiation Ozone layer N 2 O involved in Catalytic ozone destruction NO 3 bacteria Nitrous oxide (N 2 O): intermediate in denitrification N2N2

18. Nitrogen Concentrations (µM) NORMAL Depth (m) West Lobe ammonium nitrate East Lobe STRANGE ammonium nitrate

19. Nitrogen Concentrations (µM) East Lobe STRANGE ammonium nitrate

20. Nitrogen Concentrations (µM) East Lobe STRANGE ammonium nitrate (Priscu et al., 1996; LTER) nitrous oxide Depth (m) East Lobe REALLY STRANGE

22. First, drill a hole….

23. Weather port, West Lobe Lake Bonney

24. Sampling Hole through the Ice Cover

25. “Lab” inside the weather port

26. Isolate denitrifying bacteria and detect them in the lake Species- specific immunofluorescence

27. Distribution of strain ELB17 (Marinobacter) in Lake Bonney (counted by immunofluorescence) East Lobe

28. Optimal growth conditions for strain ELB17

29. Nitrite reductase (nirS) genes in Lake Bonney u Central enzyme in denitrificaiton encoded by nirS u nirS genes found in both lobes Chris Francis

31. Sharon Harris: Teacher Experiencing Antarctica Measuring denitrification rates based on N 2 O production

32. Depth (m) West Lobe Denitrification rate

33. Depth (m) East Lobe Denitrification rate

34. Denitrification does not occur in the East Lobe… but all the ingredients are present u Denitrifiers can be isolated from the lake u The strains survive under in situ conditions u Denitrifying cells are detected in the lake u Denitrifying genes are detected in the lake u Denitrification happens in the bags, not in the lake u So what is the #?@@*#&^&*$ problem??

35. Nitrogen Concentrations (µM) East Lobe STRANGE ammonium nitrate (Priscu et al., 1996; LTER) nitrous oxide Depth (m) East Lobe REALLY STRANGE

36. EastWest Copperlowhi Silver low Mark Wells

37. Nitrite Reductase, Nitrous Oxide Reductase NO 3 NO 2 NON2ON2O N 2 Inducible, conserved, gas metabolism (Cu, heme) (Cu)

38. The Copper Hypothesis u Cu u Cu is required for denitrification u AgCu u Ag substitutes for Cu in denitrification enzymes, and makes them nonfunctional u AgCu u Ag toxicity or competition with Cu inhibits denitrification in the East AgCu u But how did the two lobes end up with such different Ag / Cu ratios?

39. LTER East Lobe West Lobe Taylor Glacier

40. Blood Falls, West Lake Bonney

42. Cross section of Lake Bonney today W E Taylor Glacier

43. Lake Bonney 3000 years ago “cold-dry” period W E Taylor Glacier

44. W E

45. W E

46. W E

47. W E

48. Lake Bonney 1200 years ago Hypersaline pool in the East Lobe W E Taylor Glacier

49. W E

50. W E

51. Cross section of Lake Bonney today W E Taylor Glacier

52. Geochemical Evidence u West and East Lobes have different histories u History reflected in chemical composition of the water u Modern biogeochemistry depends on past climate change u Future climate change depends on current biogeochemistry

53. Bonney Hoppers

54. Sunrise at McMurdo, 11 July 2001