Just what is Acid Rain?

Transcription

1 Acid Rain

2 Just what is Acid Rain? Acid Rain is the term used to describe the ways in which acid precipitates out of the atmosphere. Acid Rain is more accurately termed acid deposition. There are two types of acid deposition: wet and dry. The types of wet deposition are: acidic rain, fog, and snow. The types of dry deposition are: acidic gases and particles.

3 Normal rain is weakly acidic Normal rain is weakly acidic with a ph of about 5.6 to 6 This is due to carbon dioxide in the air mixing with water in the air CO 2 + H 2 O > H 2 CO 3

4

5 The contributors Factories give off sulfur dioxide and nitric oxide. The exhaust from the car contains a lot of nitric oxide.

6 Acid deposition Acid deposition also occurs by dry deposition in the absence of precipitation. This can be responsible for as much as 20 to 60% of total acid deposition Occurs when particles or gases stick to the ground, plants, buildings, etc

7 Mechanism of acid depostion Compounded by ozone, O 3 Ozone reacts with water to form hydroxyl radicals, OH These radicals can then react with nitrogen oxides or sulfur oxides to produce acid

8 SOx : sulfur oxides Sulfur oxides SO 2 and SO 3 come from the burning of fossil fuels rich in sulfur. Coal has a lot of sulfur. Oil and gas are refined and have little or no sulfur.

9 Nitrogen oxides: NO and NO2 Nitrogen oxides are produced whenever a high energy spark is used to burn fuel. Ex. Spark plugs of engines In addition to burning fuel, nitrogen in the air will react with oxygen to produce a mixture of nitrogen oxides

10 Nitrogen oxides from cars In Jan. 1982, fog near the Rose Bowl in Pasadena was found to have a ph of 2.5; In Dec. 1982, fog at Corona del Mar, on the coast south of LA, registered a ph of 1.5

11 How could SO x, NO x, and CO 2 be considered acids? These gases are called acid anhydrides, meaning they are acids without water. When dissolved in water, they form aqueous acids: SO 3(g) + H 2 O (l) -----> H 2 SO 4(aq) 4NO 2(g) + 2H 2 O (l) + O 2(g) -----> 4HNO 3(aq) CO 2(g) + H 2 O (l) ----> H 2 CO 3(aq)

12 Ammonia and ammonium Ammonia NH3 enters the atmosphere by industrial burning or agriculture Ammonia, a weak base reacts with acids in the air To produce ammonium salts And increase the rate of conversion of sulfur oxides to acid

13

14 Effects of Acid Rain

15 Water and Aquatic Animals Lakes and streams become acidic when the natural buffers in the water and surrounding soil cannot neutralize the acid rain. A low buffering capacity allows aluminum, which is toxic to many aquatic organisms, to leach into the water.

16 Acid rain may not be the direct factor that kills fish. There is enough evidence that acid rain dissolves the granite found in lakes releasing high concentrations of aluminum, causing a thick mucous on the gills and the fish literally suffocate; Remember, normal aquatic life is between ph of Affect on fish gills

17 Plants and Forests Acid rain causes slower growth, injury, and death to plants. Acid rain damages the leaves of plants, leaches important nutrients (calcium, potassium, and magnesium) from the soil, and increases the level of toxic aluminum in the soil.

18

19 Fig Acid rain damage Smoky mountains.

20

21 Limestone CaCO 3 (s) + H 2 SO 4 (aq) CaSO 4 (aq) + CO 2 (g) + H 2 O (l) Acid rain can cause the corrosion of metals and the deterioration of stones like limestone. Reaction with limestone (calcium carbonate) The calcium sulfate is soluble in water which causes the stone to crumble.

22

23 Fig acid rain damage to limestone New York City, 1944.

24 Copper Copper naturally oxidizes to form a protective coating that protects the metal from corrosion Acid rain can cause copper to corrode before this coating can form A_ID=526

25 Effects on Human Health Acid rain itself is not harmful to humans, but the pollutants that cause it are The sulfur dioxide and nitrogen oxide can cause respiratory problems such as asthma and bronchitis

26 Solutions 1. Scrubbers, fluidized beds 2. Reduce the amount of electricity we use 3. Use renewable energy like wind power, solar panels, tidal power, Hydroelectricity, and geothermal energy. 4. Fit catalytic converters to vehicle exhausts which remove the nitrogen oxides. 5. Limit the number of vehicles on the roads and increase public transport. 6. Use cleaner coal with less sulfur