1.

A coal-fired electric power plant is located close to an urban area. Emissions from

its smokestack contain sulfur dioxide concentrations of 100 ppm at a discharge rate of

10,000 ft²/sec. The height of the smokestack is 150 ft.

a) Assuming an average wind velocity of 10 mph and homogeneous, anisotropic

diffusion E, = E,= 10 ft²/sec, E=3 ft²/sec, compute the concentration at ground level down-

wind from the plant. In particular, if an ambient air pollution standard of 30 ppb applies

for SO2, will the standard be violated and over what distance? Where does the maximum

ground level concentration occur? Assume zero decay. Assume disc diffusion if reasonable

(What is disc diffusion? See in-class discussion and handout notes on solutions to the

advective diffusion equation. Also, Fischer, H. B. et al. (1979) Mixing in Inland and Coastal

Waters, Academic Press, NY. pp. 53, 54, 109 may be helpful.). 5 pts

b) If SO2 undergoes the following reaction

SO₂ + H₂O → H₂SO₂

H₂SO3 + 1/2O₂ → H₂SO4

SO₂ + H₂O + 1/2 O₂ → H₂SO4

(i.e., leading to acid rain formation) and if the reaction is assumed to be first order with

respect to SO₂ i.e.,

dSO₂

= -K (SO₂)

dt

where K=1000 day¹, find the effect on the ground level concentration. 5 pts

c) Evaluate the effect of variable wind velocities by considering the extremes of 0

mph and 40 mph. Discuss whether the solution equations you have used for a) and b) are

applicable in these cases. Discuss the relative effects of advection and decay for varying

wind velocities. Any other comments? 5 pts