Generalized Ozone Balance

Above 40 km, the catalytic cycles involving hydrogen free radicals represent a very rapid loss process for odd oxygen (Nicolet, 1970)  

With some algebraic manipulation, the chemistry of these hydrogen catalyzed reactions can be included in the equation for the photochemical equilibrium ozone abundance between about 50 and 80 km to yield the following simple formulas at various altitudes (Allen et al, 1984)  

The important role of odd hydrogen catalyzed destruction of odd oxygen is illustrated by comparing these expressions to Eq. (5.43), which presents the analytic expression for the equilibrium ozone density assuming only pure oxygen chemistry. 

The hydrogen radicals also participate in the following cycle  

This process dominates the odd oxygen destruction near the tropopause because it is the most effective catalytic cycle involving only ozone as the reactive odd oxygen species. Most of the other HOx, NOx, and C10x cycles (see below) also require reaction with atomic oxygen, which is present only in very small amounts at low altitudes. For example, the following cycles are important in the middle and upper stratosphere, and in the mesosphere 

---

The general mass balance for each phase at nonsteady state, considering convection, mass transfer and reaction (e. g. ozone decay), can be written ... 

The role of reaction (21) in atmospheric chemistry is now well recognized, and general agreement upon the value of its rate constant, of critical importance for modelling calculations of the stratospheric ozone balance, now appears to be... 

These effects of ozone on the permeability of this algal system may be sximmed up as follows during exposure, K" " leaks out of the cell and cannot be pumped back in even when exposure is discontinued and the K" " leak has ceased, the cell is still unable to restore the lost K+ if a critical level of cellular K+ has been lost at this point, turgor pressure and water content become depressed, the metabolic control provided by ionic balance is lost and general metabolic alterations should be observed (17). 

A very simple type of a bubble column, which was not mentioned above is a gas-wash bottle. This very small-scale system (VL = 0.2-1.0 L) may be used for basic studies, in which general effects (e. g. influence of pH and/or buffer solutions specific ozone dose) are to be assessed. Its use is not recommended for detailed studies, because the mass-transfer coefficient is often low and its dependency on the gas flow rate is unknown or difficult to measure. Often there is no possibility to insert sensors or establish a reliable measuring system for exact balancing of the ozone consumption. An optimal mode of operation would comprise treatment of the (waste-)water for a certain period of time, preferably without withdrawal of solution during the ozonation. In this way different ozonation conditions can be tested by varying the ozonation time or the ozone gas concentration. A variation of the gas flow rate is not recommended. 

---