Soil & Acid Precipitation

What is Soil?

Soil is … a mixture of minerals (rocks), organic matter, gases, liquids, and countless organisms what supports life on Earth!

What defines “healthy soil” ? To evaluate soil quality, we must consider: Soil Profile Soil Type Acidity

Soil Profile There are 3 distinct layers to the make-up of soil: 1. Topsoil – O and A layers. - made mostly of humus, which is decaying organic matter - has rocks, organisms like bacteria, fungi, insects, worms 2. Subsoil – B layer - very compact - has little/no organic matter except bacteria and roots of large trees 3. Regolith and bedrock – C and R layers - made of of large chunks of rock - bedrock is solid rock - water cannot pass through so it accumulates here  this is where aquifers (groundwater) are located

What is the healthiest soils made of? 50% pore space 48% solid material 25% air 25% water 45 to 48% mineral matter 2 to 5% organic matter What is the healthiest soils made of? Not all healthy soil has this balance – only the most desirable soils.

Soil Particles All soil originated from bedrock, therefore all soil is made up chipped rock pieces called minerals or soil particles 4 types of soil particles (largest to smallest) sand, silt, and clay loam (various sizes)

4 Types of Soil Particles (largest to smallest) sand silt clay loam

Sand: 4 Types of Soil larger, feels coarse and gritty creates large spaces that allows root growth and air pockets for plants water drains too easily which takes nutrients away from roots of plants

Silt: 4 Types of Soil fine particles, muddy texture easily transported by water, found in or along rivers and wetlands soil drains slowly which helps plant grow, but soil also erodes away easily human activities (ie: logging) results in silt being washed into rivers, acts as a pollutant

Clay : 4 Types of Soil very fine particles dense; particles are packed tight together, so there are no air pockets traps water = often very wet and sticky plant growth in clay is difficult

4 Types of Soil Loam: contains sand, silt and clay of different sizes which creates pockets that hold air or water has lots of humus (decaying organic matter) drains well without drying out plants grow easily in loam dark brown or black

Which soil type is best for farming? sand silt clay loam

Negative Human Impacts on Soil

Negative Human Impacts on Soil Soil Erosion soil is washed away by wind or water occurs when soil is ploughed or overgrazed by livestock if the top soil is gone, nutrients are gone too!

Fertilizers Negative Human Impacts on Soil farmers add manure, nitrogen and/or phosphorus to soil to make plants grow bigger and faster these fertilizers are washed away from the soil by water and pollute local water bodies resulting in in excessive algae growth called eutrophication

Algae Bloom in Lake Erie https://www.youtube.com/watch?v=gMwQaHtK904

China’s Yellow Sea Turns Green! https://www.youtube.com/watch?v=RFd_jadmaR4

Leaching Negative Human Impacts on Soil occurs when soil is over-water and nutrients in the topsoil wash downward, making them unavailable to plants

Crop Rotation planting a different kinds of crops every other season allows soil nutrients to be replenished if crops are not rotated, the certain soil nutrients will get used up and crops will no longer grow well planting legumes helps to put nitrogen back into the soil since they have nitrogen-fixing bacteria

Acids in Soils

Acidity is another factor in soil quality and it is measured using the pH scale

pH Scale

soil pH for humid environments soil pH for drier environments pH Scale for Soils soil pH for humid environments soil pH for drier environments

Acidity of Soil Most plants prefer a somewhat neutral environment (around pH 7) If soil is too acidic or basic (alkaline) it can harm plants: damages roots  can’t absorb soil nutrients damages waxy coating on leaves  infection worm skin is burned  no recycling of nutrients

What is Acid Precipitation? any form of rain or snow with high levels of nitric acids and sulfuric acids (from pollution) up to 40X more acidic than normal precipitation causes soils to become acidic too

SO2 NO2 When humans burn fossil fuels, sulfur dioxide and nitrogen dioxide are released into the atmosphere, which react with water, oxygen, and other substances to form sulfuric acid and nitric acid. SO2 NO2

Sources of Sulfuric Acid and Nitric Acid NO2 coal burning factories metal extraction factories called smelters oil refining factories to make gasoline burning fuels by cars (biggest cause!)

A forest affected by acid precipitation

Impacts to Lakes, Streams, Rivers & Wetlands acidic water tends to absorb aluminum from soil which will then spread to other lakes and streams acidic aluminum-contaminated water is toxic to crayfish, clams, and other aquatic animals – it weakens their hard shells.

What can we do to fight acid rain? laws that limits of factory emissions “scrubbers” placed in factory smoke stacks to filter out most chemicals before gases are released into the air

Is acid precipitation a local or global problem? Pollution is carried by wind, acidic waters continuously move so problems associated with acid rain is global problem!

Read pages 70-75 Soil pg. 75 Q’s #1-5 pg 85 Q’s #3, 13, 14 Acid Rain