1-B

2-D

3-A [we covered the “troposphere” part of this question in Wednesday’s lecture, but have not yet got to the stratosphere, but you know it now]

4-D

5-C [we have not covered this yet in lecture, but sulfur-rich coals contribute more in Northeast and NOx gases from prevalence of auto transportation in the west; so you know it now]

6-D (not much N in fossil fuels, but a lot of N in the air that gets burned at high temperature)

7-B

8-B (Chlorine is not one of the answers but would be at the top of the list; as it turns out NOx is the next biggest culprit contributing to ozone layer destruction) [not yet covered in lecture but see sample question #3]

9-C

10-C

11-B

12-G

13-B

14-C, Agriculture is a human activity that impacts soils.

15-D

16-B

17-D

18-A, Subsidence is a natural event that impacts soils.

19-K

20-F

21-G

22-H

23-J (ozone would have been an even better answer, but it is not in the list)

24-No, the primary pollutant SO₂ (converted to the secondary pollutant sulfuric acid) is not the only contribution to acid rain (more correctly, "acid precipitation"). If all SO2 was removed from the pollution stream, there are plenty of sources of the primary pollutant NOx (to form nitric acid as secondary pollutant) throughout the US to make acid rain (but generally not as acid as if SO₂ is also present).

25- Erosion would be low in the naturally forested landscape before 1900. The conversion to farm would increase erosion, as agricultural processes commonly leave bare plowed fields for some part of the year, which invites high rates of erosion. With abandonment, natural vegation would begin to re-invade the farm and the land would be covered all year round, thereby reducing erosion. As the land was converted to city, erosion rates would likely be very high when the land was first cleared for construction, but after the construction phase was over, the erosion late would be very low as much of the original soil area becomes covered by buildings and roads.

26- The solution to pollution is "DILUTION". Architects and engineers dealing with outflows of water- or air-borne pollution came up with designs that would assist in more rapidly mixing the pollution stream with clean air (or water). Hence very tall smokestacks are built for power plants and smelters to help the polluted air mix with the cleaner air higher above the surface. Dilution does result, but frequently the problem is just transferred to some locality downwind.

27- CO₂, CH₄, N₂O, CFCs (“others” would include SO₂, O₃)

28- "normally" temperature decreases as you go upward in the troposphere. An "inversion" is opposite to the norm, and temperature increases as you go upward (ie, warm air overlies cold air). Temperature inversions represent extremely stable atmospheric conditions in which vertical movement is inhibited (inversions act like a lid keeping in pollution), thereby preventing air close to the ground (where pollution originates) from mixing with cleaner air above. (The stratosphere is highly stable because temperature increases as you go upward in that layer).

29- Strong oxidizer: Damage to sensitive lungs and respiratory system, degrading of materials made of rubber (gaskets, tires, belts, electrical cords, etc); damages chlorophyll in plants

30- higher incidence of melanoma (skin cancer) and cataracts in humans, damage to autotrophs (reductions of productivity, damage to DNA)- [we did not yet cover this in lecture, see corresponding MacKenzie readings]

31. The “Green Revolution” began in the early to mid-1900s, and has greatly increased agricultural production in the face of rising population (and even diminishing cropland) by: mechanization, pesticides, herbicides, irrigation, new crop strains (breeding and now genetic engineering), fertilizers. In the 1950s, the green revolution was applied to the farming in the tropics. The billion dollar question is whether it can be successfully sustained and adopted by poorer and developing countries, many of which are in tropical locations (because of cost of fertilizers and pesticides, soil degradation, continued loss of farmland, loss of water for irrigation, and loss of genetic variability/variety). Even in developed countries, available land for agriculture is declining.