31 August 1998
Independent Mathematical Contractors, Inc.
Suite 2, Strawmarket Business Plaza
Lonlinc, SK 04685
Dear IMC:
As you know, the Lonlinc(, Skanebra) Council on the Protection of the Environment (CPE) is charged with the evaluation of all things environmental that may have an impact on the continued health of the residents, animal and human, of the thriving city of Lonlinc. Currently boasting a population of 200,000 and growing at an annual rate of 7%[1], Lonlinc is regarded by some as increasing in size sufficiently fast as to demand appropriate consideration of the environmental impact of such things as the increased traffic attendent with this growth.
One effect of this increase in traffic is an increase of exhaust pollutants in the air, which increase may lead to the phenomenon known as ``acid rain.'' This occurs when NOx from car exhaust combines with atmospheric water to create nitric acid (NO3), rendering any precipitation that might fall acidic. In an effort to determine if this is likely to soon be a problem in the Lonlinc area, we have over the past three years monitored the rate of precipitation and the concentration of NO3 in that precipitation, which data appears in tables 1 and 2 below.
Table 1: Average monthly precipitation (mm)
| month | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 |
| avg precipitation | 17.3 | 20.6 | 60.0 | 70.5 | 109.8 | 114.0 | 99.9 | 98.7 | 101.6 | 62.3 | 35.1 | 26.0 |
| month | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 |
| avg. precipitation | 17.7 | 21.8 | 59.6 | 75.0 | 110.9 | 108.8 | 100.4 | 102.8 | 96.5 | 59.3 | 36.9 | 25.5 |
| month | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 |
| avg. precipitation | 17.3 | 20.9 | 56.7 | 13.4 | 108.9 | 105.5 | 92.8 | 103.3 | 98.3 | 60.9 | 53.9 | 25.1 |
Table 2: Average NO3 concentration in precipitation (g/ml)
| month | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| NO3 conc. | 0.4003 | 0.4033 | 0.4060 | 0.4078 | 0.4100 | 0.4124 | 0.4136 | 0.4171 | 0.4184 |
| month | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | NO3 conc. | 0.4214 | 0.4248 | 0.4255 | 0.4282 | 0.4307 | 0.4331 | 0.4356 | 0.4380 | 0.4409 |
| month | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | NO3 conc. | 0.4440 | 0.4454 | 0.4490 | 0.4513 | 0.4532 | 0.4567 | 0.4587 | 0.4603 | 0.4638 |
| month | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 |
| NO3 conc. | 0.4658 | 0.4700 | 0.4715 | 0.4743 | 0.4772 | 0.4805 | 0.4834 | 0.4852 | 0.4879 |
The critical factor in determining the severity of the acid rain is, of course, the amount of NO3 that is deposited on the surfaces on which it falls. We therefore need to establish, based on the data we have collected, how the monthly rate of chemical deposition is changing in time, and to predict when (if ever) this is likely to exceed 11.5g/month on a given 1 cm2 area.
We appreciate your prompt attention to this matter, and look forward to receiving your final report of 3--5 pages on or before the 21st of September. To assure your success in the endeavor, our department's scientific expert, Dr. Gavin LaRose, will be available to answer any questions that you might have in the course of your investigation. He will, however, be unavailable to assist with this project over the weekend of the 18th--20th. You should also plan on meeting with him during the week of the 7th of September to verify your initial progress towards completion of the project. We have made available, through him, a number of sample reports that may prove useful as you develop your formal response.
Sincerely
Jack C. Ousteaux
Director, Lonlinc CPE
jco:glr