Environmental Effects of Fossil Fuel Use - Energy and the Environment - page 265

of 45 ◦ gm − 3 )ata toward the highway, stability category C. Calculate the CO concentration ( µ

receptor 100 m downwind from the highway.

Problem 9.9
Using the EKMA plot of Figure 9.6, assuming the peak afternoon concentration of O 3 is 200 ppbV,
estimate the percentage of the necessary reductions of initial concentrations of VOC and NO x to
achieve an afternoon peak concentration of O 3 of 120 ppbV for an urban (VOC:NO x = 4:1), sub-

urban (VOC:NO x = 16:1) environment. Estimate the concentration

reductions in two ways: VOC only and NO x only. Explain why in one environment it is more effec-
tive to reduce VOC concentrations, whereas in another environment it is more effective to reduce
NO x concentrations. Is it possible to achieve in a certain environment the 120 ppbV concentration
by actually increasing morning NO x concentrations? In which environment is that possible, and
what would that do to downwind locations?

8:1), and rural (VOC:NO x =

Problem 9.10
Measurements show that in an environmentally sensitive area the average sulfate ion concen-
tration in precipitation is 25

µ mol/L and the nitrate ion concentration is 15 µ mol/L. Using the

approximation equation (9.20), calculate the pH of precipitation.

Problem 9.11
The state of Ohio emits about 2.5 million tons per year of SO 2 . The emission centroid of Ohio is about
1000 km from the center of Massachusetts. Ohio is exactly upwind from Massachusetts. (a) Using
the transfer coefficients plotted in Figure 9.12, estimate the annual rate of wet deposition of sulfate
ions (kg ha − 1 y − 1 ) in Massachusetts arising from Ohio SO 2 emission sources. (b) Massachusetts
receives on the average 25 kg ha − 1 y − 1 wet sulfate deposition. What percentage of that does
Ohio contribute? Note that the molecular weight of sulfate is 1.5 times the molecular weight
of SO 2 .

Problem 9.12
The annual average airborne sulfate particle concentration in Massachusetts is 7 gm − 3 , the dry µ

deposition time constant of sulfate is τ ds = 2E(5) s, and the average mixing height is 1000 m. What

is the dry deposition rate (kg ha − 1 y − 1 ) of sulfate particles in Massachusetts. Compare this with

the wet deposition rate of sulfate.

Problem 9.13
(a) Estimate the maximum visibility distance (km) for a polluted atmosphere with b ext = 4) m − 1 6E( −

5) m − 1 . (b) If the maximum visibility is 6 km, what and for a clean atmosphere with b ext = 6E( −

is the extinction coefficient (m − 1 )?