1. Reactor 3 (Mox, a blend of Pu, and U fuel) after explosion - Reactor 1 at bottom - Reactor 2 in between which is said to be in full melt down. Copyright © 2010 R. R. Dickerson1

2. Do Japanese Reactor Breakdowns pose a threat to us? Chernobyl released massive amounts of radioactive material: – 131 I halflife 8 d Mixed gaseous and particulate phases. Particles 0.1 – 1.0  m last the longest. Bioaccumulates in milk and caused thyroid cancer in the Ukraine. Treatable with 150 mg KI (RDA 150  g) – 137 Cs halflife 30 yr Particulate Phase Copyright © 2010 R. R. Dickerson2

3. –One Bq is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. –Plutonium ( 239 Pu), an  emitter, and toxic. Unknown amounts emitted. Ingestion. bio clearance time: months. –Annual Limit of Intake = 3E5 Bq (8  Ci) Inhalation. Small particles stick to the lung alveolae. –Annual Limit of Intake = 300 Bq = 0.0081  Ci = 0.13  g 239 Pu. Ultimately, Chernobyl caused only local problems. Copyright © 2011 R. R. Dickerson3

4. Gamma Ray Spectrometers. Copyright © 2011 R. R. Dickerson4

5. Forward Trajectories from Japanese Nuclear Reactor Fires Copyright © 2011 5

6. Chernobyl Results Barely detectable over N. Dakota after 10 d. 1% of release deposited (wet and dry) onto UK. Not a major health threat. Local effects serious. 6000 cases of thyroid cancer in Ukraine. Copyright © 2011 R. R. Dickerson6

7. Forward Trajectories today, 17 March. Copyright © 2010 R. R. Dickerson7

8. 8 Stratospheric Ozone Lecture AOSC/CHEM 637 Atmospheric Chemistry Russell R. Dickerson

9. Copyright © 2010 R. R. Dickerson9

10. 10 Cholesterol photolysis to Vitamin D h →

11. Copyright © 2010 R. R. Dickerson11 Folate, vitamin B-9

12. Copyright © 2010 R. R. Dickerson12

13. Copyright © 2010 R. R. Dickerson13 VII. STRATOSPHERIC POLLUTION Without ozone in the atmosphere there could be no life as we know it on the surface of the Earth. All of the atmospheric ozone, that is the “ ozone column ” is only about 0.3 atm cm. In other words, if all the air were squeezed out of the atmosphere, and the remaining ozone were brought to STP, it would be only 0.3 cm thick. –Murphy ’ s Law is strictly obeyed by NOx pollution in the atmosphere. –Chemistry of the stratosphere different from troposphere. (VIEWGRAPH) Table 15.1 Solar intensity at the Earth ’ s surface assuming 0.30 atm cm (300 D.U.) ozone. Note that the maximum flux is about 7x10¹ ⁵ (photons/(cm²s)/10 nm). See Limb Image

14. Copyright © 2010 R. R. Dickerson14 Actual depth of atmospheric layers.

15. Copyright © 2010 R. R. Dickerson15 Where O ₃ stops absorbing, sunlight begins to reach the surface of the Earth. Hartley (1880) measured the ozone spectrum. Fabry and Buisson (1913) measured the solar spectrum at the Earth ’ s surface and concluded that the UV radiation reaching the surface of the Earth must be controlled by ozone in the upper atmosphere, they even made an accurate estimate of the amount of ozone! Today we will examine the various catalytic cycles that control the level of ozone in the stratosphere. We will calculate the O ₃ abundance for a highly simplified atmosphere containing only O ₂ and N ₂. λ (nm) σ (atm ⁻ ¹cm ⁻ ¹) I/Io 250305 1.0x10 ⁻⁴⁰ 275162 1.0x10 ⁻ ²¹ 3009.5 6.0x10 ⁻ ² 3250.27 9.2x10 ⁻ ¹

16. Copyright © 2010 R. R. Dickerson16

17. Copyright © 2010 R. R. Dickerson17 VII. A) OZONE CATALYTIC CYCLES 1)Chapman Reactions (1931) O ₂ + h → 2O(1) O + O ₂ + M → O ₃ + M † (2) O ₃ + h → O ₂ + O(3) O + O ₃ → 2O ₂ (4) By way of qualitative analysis, Reactions (1) plus (2) produce ozone. O ₂ + h → 2O(1) 2 x ( O + O ₂ + M → O ₃ + M )(2) 3 O ₂ + h → 2 O ₃ NET

18. Copyright © 2010 R. R. Dickerson18 While Reactions (3) plus (4) destroy ozone. O ₃ + h → O ₂ + O(3) O + O ₃ → 2O ₂ (4) 2O ₃ + h → 3 O ₂ NET Reactions (3) plus (2) add up to a null cycle, but they are responsible for converting solar UV radiation into transnational kinetic energy and thus heat. This cycle causes the temperature in the stratosphere to increase with altitude. Thus is the stratosphere stratified. O ₃ + h → O ₂ + O(3) O + O ₂ + M → O ₃ + M*(2) NULLNET By way of quantitative analysis, we want [O ₃ ] ss and [O] ss and [Ox] ss where “ Ox ” is defined as odd oxygen or O + O ₃. The rate equations are as follows.

19. Copyright © 2010 R. R. Dickerson19 (a) (b) (a+b) From the representation for O atom chemistry: In the middle of the stratosphere, however, R ₃ >>2 R ₁ and R ₂ >> R ₄ thus: (I) This does not mean that R ₄ is unimportant, but it can be ignored in an approximation of [O]ss at the altitude of the ozone layer. The ratio of [O] to [O ₃ ] can also be useful:

20. Copyright © 2010 R. R. Dickerson20 (II) Reactions 2 and 3 set the ratio of O to O ₃, while Reactions 1 and 4 set the absolute concentrations. Now we will derive the steady state ozone concentration fro the stratosphere. From the assumption that Ox is in ready state we know: R ₁ = R ₄ Thus j(O ₂ )[O ₂ ] = k ₄ [O][O ₃ ] Substituting from (I), the steady state O atom concentration: or

21. Copyright © 2010 R. R. Dickerson21 SAMPLE CALCULATION At 30 km (VIEWGRAPH)

22. Copyright © 2010 R. R. Dickerson22 In any good experiment you check ratios of variables first, to avoid errors or bias. Lets look at the O/O 3 ratio. Then we’ll consider the absolute concentration of ozone.

23. Copyright © 2010 R. R. Dickerson & Z.Q. Li 23

24. Copyright © 2010 R. R. Dickerson & Z.Q. Li 24

25. Copyright © 2010 R. R. Dickerson & Z.Q. Li 25 O/O 3 = j(O 3 )/(k 2 M O 2 ) Beautiful agreement!

26. Copyright © 2010 R. R. Dickerson & Z.Q. Li 26 What is the observed O 3 mixing ratio? 2x10 12 molecules cm -3 /2.7x10 19 (P 30 /P 0 *298/T) P 30 ~ P 0 exp(-30/7) = 0.014 atm [O 3 ] = (2E12/3E19)/0.014 ~ 5E-6 = 5 ppm

27. Copyright © 2010 R. R. Dickerson27 We calculated almost a factor of ten above the true concentration! What is wrong? There must be ozone sinks missing. 2) Bates and Nicolet (1950) “ HOx ” Odd hydrogen “ HOx ” is the sum of OH and HO ₂ (sometimes H and H ₂ O ₂ are included as well). HO ₂ + O ₃ → OH + 2O ₂ (5) OH + O ₃ → HO ₂ + O ₂ (6) 2O ₃ → 3O ₂ NET The following catalytic also destroys ozone. OH + O ₃ → HO ₂ + O ₂ (6) HO ₂ + O → OH + O ₂ (7) O + O ₃ → 2O ₂ NET

28. Copyright © 2010 R. R. Dickerson28 The second catalytic cycle speeds up Reaction 4, that is it effectively increases k ₄. Note that any loss of odd oxygen is the same as loss of ozone. These catalytic losses are still insufficient to explain the observed ozone concentration. 3) Crutzen (1970); Johnston (1971) “ NOx ” Odd nitrogen or “ NOx ” is the sum of NO and NO ₂. Often “ NOx ” is used as “ odd nitrogen ” which includes NO ₃, HNO ₃, 2N ₂ O ₅, HONO, PAN and other species. This total of “ odd nitrogen ” is better called “ NOy ” or “ total reactive nitrogen. ” N ₂ and N ₂ O are unreactive. NO + O ₃ → NO ₂ + O ₂ O + NO ₂ → NO + O ₂ O + O ₃ → 2O ₂ NET This is the major means of destruction of stratospheric ozone. The NOx cycle accounts for about 70% of the ozone loss at 30 km. We will calculate the implied steady ozone concentration later.

29. Copyright © 2010 R. R. Dickerson29 4) Stolarski & Cicerone (1974) “ ClOx ” Cl + O ₃ → ClO + O ₂ ClO + O → Cl + O ₂ O + O ₃ → 2O ₂ NET This reaction scheme is very fast, but there is not much ClOx in the stratosphere … yet. Today ClOx accounts for about 8% of the ozone loss at 30 km. If all these catalytic destruction cycles are added together, they are still insufficient to explain the present stratosphere O ₃ level. The general for of a catalytic ozone destruction cycle is: X + O ₃ → XO + O ₂ XO + O → X + O ₂ O + O ₃ → 2O ₂ NET

30. Copyright © 2010 R. R. Dickerson30 Molina, M.J., and Rowland F. S., Stratospheric sink for chloroflurormethanes – chlorine atomic-catalyzed destruction of ozone, Nature, 249 (5460): 810-812 1974. CCl x F y + h → CCl x-1 F y + Cl CFC ’ s do not decompose in the troposphere.

31. Copyright © 2010 R. R. Dickerson31 Table 15.2 Stratospheric ozone destruction cycles CycleSourcesSinksReservoirs HOx H ₂ O,CH ₄,H ₂ HNO ₃ · nH ₂ O H ₂ SO ₄ · nH ₂ O H ₂ O,H ₂ O ₂ NOx N ₂ O + O(¹D)HNO ₃ HO ₂ NO ₂,ClO NO ₂ ClOx CH ₃ Cl,CFC HClHCl, HOCl The sinks involve downward transport to the troposphere and rainout or other local loss. Note that some sinks are also reservoirs: HCl + OH → H ₂ O + Cl

32. Copyright © 2010 R. R. Dickerson32 Antarctic Ozone Hole In the Antarctic winter there is no sunlight and even in the spring there is too little UV to generate enough O atoms to destroy ozone. The annual loss of ozone over Antarctica is driven by heterogeneous chemistry and visible radiation. A good current review Is provided by Solomon Nature, 1990, and “ Scientific Assessment of Ozone Depeation :1991 ” (WMO). The destruction of ozone is usually moderated by the production of chlorine nitrate, an important reservoir species. NO ₂ + ClO + M → ClONO ₂ + M In the Antarctic winter, heterogeneous reactions “ denitrify ” the stratosphere (Molina et al., Science, 1987). Molecular chlorine is only weakly bound, and can be dissociated by visible radiation.

33. Copyright © 2010 R. R. Dickerson33 Cl + O ₃ → O ₂ + ClO ClO + ClO + M → (ClO) ₂ + M (ClO) ₂ + hv → Cl + ClOO ClOO + M → Cl + O ₂ + M 2O ₃ → 3O ₂ NET Two types of Polar Stratospheric Clouds (PSC ’ s) exist. Type I = HNO ₃ · 3H ₂ O Nitric acid trihydrate, formed at T ≤ 195K Type II = H ₂ O Ice formed at T ≤ 190K They move NOy species from the vapor phase to the condensed phase as HNO ₃. The are involved in catalytic cycles with chlorine and bromine compounds that speed the reaction of ozone with itself to form oxygen. They move chlorine from the reservoir species HCl and ClONO ₂ to ClOx.

34. Copyright © 2010 R. R. Dickerson34 OTHER STUFF McElroy et al. (1986) Cl + O ₃ → ClO + O ₂ Br + O ₃ → BrO + O ₂ ClO + BrO → Cl + Br + O ₂ 2O ₃ → 3O ₂ NET twice (Cl + O ₃ → O ₂ + ClO) ClO + ClO + M → (ClO) ₂ + M (ClO) ₂ + hv → Cl + ClOO ClOO + M → Cl + O ₂ + M 2O ₃ → 3O ₂ NET

35. Copyright © 2010 R. R. Dickerson35 ClO + ClO + M → Cl ₂ O ₂ + M Cl ₂ O ₂ + M → Cl ₂ + O ₂ + M Cl ₂ + hv → 2Cl etc. Note HCl is a reservoir, not a stable sink: HCl + OH → H ₂ O + Cl Solomon et al. (1986) OH + O ₃ → HO ₂ + O ₂ (6) Cl + O ₃ → ClO + O ₂ HO ₂ + ClO → HOCl + O ₂ HOCl + hv → OH + Cl 2O ₃ → 3O ₂ NET Crutzen and Arnold (1986)

36. Copyright © 2010 R. R. Dickerson36 1.Remove NOx via reactions on particles 2.Condensation of HNO ₃  3H ₂ O at higher temperatures than pure H ₂ O. 3.Cosmic ray induced OH – not a big deal. 4.HCl + OH → ClOx HBr + OH → BrOx