ACID DEPOSITION AND FOREST ECOSYSTEMSChapter 3.11

Acid Deposition

Technology is great but it also contributes to acid deposition.

Coal-burning plants, cars, and trucks, metal smelters, and oil refineries provide energy, transport, and materials for the industrial world, but at the same time produce oxides of sulfur and nitrogen, among the most dangerous of air pollutants.

The Problem of Combustion

Sulfur dioxide (SO2) and Nitrogen oxides (NOx) are released into the atmosphere by burning fossil fuels.

Sulfur and Nitrogen enter the atmosphere they may combine with water droplets to form acids.

The acids return to the surface of the Earth in the form of snow or rain, called ACID PRECIPITATION.ACID PRECIPITATION.

ACID PRECIPITATION KILLSACID PRECIPITATION KILLS: Fish Soil Bacteria Aquatic Plants Terrestrial Plants

The sulfur and nitrogen oxides released from tailpipes and smokestacks do not always enter the water cycle in the atmosphere.

Sulfur and nitrogen compounds may remain airborne and settle out in the dry state – DRY DEPOSITIONDRY DEPOSITION

Dry Deposition enter the water cycle and form acid as it combines with moisture

CAN BE FOUND:Dew on lawnsSurface of lakesWater inside your respiratory tract

THE EFFECTS OF ACID PRECIPITATION

Direct effects on Humans:Medical effects

Accelerated respiratory problems Examples: Asthma, bronchitis

Cause eyes to waterIrritate skin

Dissolving marble statuesCorroding metalDulling car finishesDamage to buildings

Effects on Ecosystems

Damage to leavesDamaged to tissues of trees become more

susceptible to fungal or bacterial infections.

EFFECTS OF ACID RAIN

Acid Falls to SoilAcid falls to Soil

Kills Bacteria Promotes growth of Moss

Releases Aluminum in the soil

Reduces Nutrients in Trees

Damage tree Roots

Important to

Nitrogen Cycle

pH – Potential Hydrogen A measure of the acidity or alkalinity (basic) in

the solution Measured using pH meter

pH is a scale from 0 – 14 where: 0 – 6.9 = Acidic 7.0 = neutral 7.1-14 = Basic

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

A pH of 3 is 10 times more acidic than pH of 4

More Acidic More Basic

pH of Normal rain water pH of 5.6

pH of Acid RainRange from 4.5 to 5.6; average 5.0

pH corresponds to the

concentration of Hydrogen

Ie. Low pH = high H

HOMEWORK

Read page 116 -118 Fill in handoutAnswer Questions #1-4 page 118