Acid deposition_by Rajkumar

THE ACID DEPOSITION

……………………………. RBMahajan

1. Dry deposition- Acidic gases and particles

2. Wet deposition- Acidic rain, fog and snow

ACID DEPOSITION Acid deposition refers to the process by which acidic particles, gases and precipitation leave the atmosphere

THE ACID RAINRain is naturally acidic, (pH 5.6) b/c of dissolved CO2

What is Acid rain?- Acid rain is rain, snow or fog that is polluted by acid in the atmosphere and damages the environment.

ACID RAIN DROP

• Sources of primary pollutants • Deposition of secondary pollutants

Formation of Acids

Produced by natural phenomena and anthropogenic activities [like combustion of fossil fuels , oxidation of organic material in soils , volcanic eruptions, biomass burning]

It is soluble in water It can be oxidised within airborne water

droplets producing sulphuric acid

Sulphur dioxide (SO2)

Produced by Combustion Of Fuels Residential, cars , commercial

Industrial furnaces, electrical-utility boilers, Engines, other equipment

It is soluble in water It can be oxidised within airborne water

droplets producing nitric acid

Nitrogen Oxide [ Nox ]

Acid Rain

(Acid Precipitation)

                                                       Any precipitation carrying dissolved acids from natural or man made causes.Examples; a. CO2 dissolves in H2O---------> Creates carbonic acid (H2CO3)b. Sulfur dioxide (from internal combustion) mixes with H2O ---------> Sulfuric Acid (H2SO4)c. Nitrogen oxides (from internal combustion) mixes with H2O ---------> Nitric Acid (HNO3)

 *Acid precipitation may have a pH as low as 3. Very Acidic!

*Acids in the air may be carried thousands of miles from their source, polluting soil & water in pristine areas!

marble and limestone are calcium carbonate (2CaCO3 + 2SO2 + O2 --> 2CaSO4 + 2CO2);

sulfur dioxide in dry deposition increases metal corrosion (Fe + SO2 + O2 --> FeSO4);

protective oxide layer removed from metals (Al2O3 + 3H2SO4 -->Al2(SO4)3 + 3H2O

Effects of acid deposition on materials

• Depends on– Transport downwind– Buffering in soils

(alkalinity)• On thin, non-buffering soils• On buffers

– carbonate rocks, limestone often used for buildings,

• Limestone and concrete structures

Effects of Acid Deposition

Leaching (washes) out essential nutrients from soil like;Mg(2+), Ca(2+), K(+) ions

Damages roots by releasing Al(3+) ions from rocks;

SO2 blocks stomata and prevents photosynthesis;

Leaves are damaged by acidity.

Effects of acid deposition on plant life

• Forests

Effects of Acid Deposition

aluminum oxide trapped in rocks can be released and Al(3+) interferes with gills' ability to take in O2; (Al(OH)3 + 3H(+) --> Al(3+) + 3H2O)

nitric acid can cause eutrophication (plant deaths, anaerobic decomp, etc)

destruction of food chain pH 4 is dead lake

Effects of acid deposition on aquatic life

• Lakes, rivers - Deduced diversity and abundance of aquatic ecosystems

Effects of Acid Deposition

Effects of acid deposition on human life-

acid gases irritate respiratory tract; increased risk of asthma, bronchitis, emphysema;

poisonous metal ions released from pipes are tied to some diseases (Alzheimer's)

Effects of acid deposition

DAMAGES THE ENVIRONMENT

reduce industrial emission levels, alternative energy sources, reduced demands for fossil fuels, reduce acid rain damage in lakes by adding

lime/calcium hydroxide to neutralize acids (CaO + H2SO4 --> CaSO4 +H2O)

Methods to control acid deposition

Problem- In this experiment, you will,1. Generate three gaseous oxides, CO2, SO2, and NO2.

2. Simulate the formation of acid rain by bubbling each of the three gases into water and producing three acidic solutions.

3. Measure the pH of the three resulting acidic solutions to compare their relative strengths

You can use data logger. You will be assessed for DCP and CE

Lab. Acid Rain

Acid Formation Equation Explanation

Sulfurous Acid

Sulfuric Acid

Sulfuric Acid #2

Nitrous Acid

Nitric Acid

Acid Deposition work sheet

1.What is acid deposition?2.How is carbonic acid a natural contributor to acid rain? Provide equations to support your response:3.There are four common routes for Wet Acid Deposition, complete the table:

Environmental Effect on Detailed information regarding effect

Appropriate Equations

Explanation of Process

Limit the Production

Neutralize the effects

1.What are the five environmental effects of acid rain? Explain each below::

1. There are two generic methods to counter acid deposition, describe each method below: