Acid Deposition Topic: 5 A.S: N – R

What is Acid Deposition? Primary pollutants such as sulfur dioxide (SO2)from factories and nitrogen oxides (NOx) from cars form secondary pollutants that are acidic.

Acid Formation These primary pollutants mix with water to form acids! These can fall as: Wet deposition- (Acid Rain) precipitation Dry deposition- particles and gases, which can become wet deposition when they encounter any water. If not in the atmosphere, where might this happen?

Acid Rain? Normal rain has a pH of 5.6 This is because the precipitation (water) mixes with CO2 to make dilute carbonic acid. Average pH of rain in the Eastern United States is 4.2-4.7! 10 times as acidic as normal rain! Some California fogs, though, have pH’s as low as 2.3 This is the same as lemon juice!

Wet Deposition SO2 reacts with O2 and water vapor to form dilute sulfuric acid. NOx react with O2 and water vapor to form dilute nitric acid. Resulting precipitation has pH of 5.5 or lower.

Direct Effects of Acid Deposition Dry particles can cause human respiratory problems when inhaled Property damage Marble and limestone dissolve easily in very weak acids Acid rain can even damage the clear coat on cars Acidification can slow or inhibit decomposition. How? It can also cause an overproduction of mucus within fish gills, leading to suffocation. Coniferous forests are most vulnerable to acidification because it decreases the waxy cuticle on the needles that protects the trees from excess water loss. KILLS BACTERIA & FUNGI

Coniferous Trees

Indirect Effects of Acid Deposition Acid water leaches toxic metals, such as mercury, aluminum, and lead out of rocks and soil. It then runs off into water, which is then absorbed by producers. What happens after this? POISONS PLANT LIFE Leaches nutrients out of soil, which decreases productivity of crops and forests. Weakens trees and makes them more susceptible to severe cold, diseases, and insect attacks

Below 4.5, most lakes are devoid of fish!

Why is Acid Rain a Regional Problem?

Regional Problem – Not Global Acidic components only remain in the atmosphere for a short while before they are grounded weather patterns. Areas that are most effected are near industrial areas or areas with high traffic (emissions). Some soils are made up of bases (limestone) and salts that can act as buffers to acid deposition. Sensitive soils do not have these natural buffers

Preventing Acid Rain Altering Human Activities: Stop burning coal! Change from using coal to cleaner burning natural gas and/or renewable energy sources. Removal of sulfur from coal (scrubbers) before it is burned. Ie: “clean coal”…expensive, not efficient Regulations: Filters on smokestacks….who regulates? Removal of Nitrogen Oxides from automobile exhaust. How is this regulated? EMISSIONS TESTING

Restoring Acidified Soils and Water Liming Large amounts of crushed limestone can be deposited to neutralize lakes and soils, however: Costly to do all areas Can be harmful to plankton and aquatic plants if overdone. Only a Temporary Remedy - must be done annually.