U1: Ecosystems

“Environmental science is the study of the effects of natural and unnatural processes, and of interactions of the physical components of the planet on the environment.” - environmentalscience.org

Geologic Scale

The image to the right is a Geologic Scale. It is used to explain the types of organisms that have inhabited the earth over its 4.5 to 4.8 billion years. The categories are Era, Period, Epoch and then the smaller category of ages. We are currently in the Holocene Epoch. The next Epoch is the Anthropocene due to humankind’s impact in speeding up extinction.

The Spheres of Earth

● Lithosphere: Earth’s solid and rocky outer layer, interacts with other spheres the most.

● Atmosphere: Sphere of gases that surround Earth.

● Hydrosphere: Earth’s oceans and bodies of freshwater.

● Pedosphere: Most commonly known as soil.

● Biosphere: Living organisms on Earth.

Lithosphere

● There are Three Centric Zones of Rock, which are made of solid or molten rock.

● Inner Core: The innermost layer composed of nickel and iron; solid

● Outer Core: Mostly iron but also nickel and other elements; semi-liquid.

● Mantle: Last layer; made mostly of solid rock

○ The Mantle is split into three pieces:

■ Lithosphere: Thin, rigid layer, Earth’s outer shell

■ Crust: Solid surface

■ Asthenosphere: A layer of slow flowing liquid rock

Tectonic Plates

● Roughly, around the time of the Paleozoic and Mesozoic Eras (Refer back to geologic scale chart), the continents were joined together; this is referred to as Pangea. About an estimated 200 million years ago, Pangea started to split apart due to tectonic plates.

● Tectonic Plates: large pieces of the Lithosphere that move slowly across Earth’s mantle.

● There are two kinds of plates, Continental and Oceanic. When these plates interact, it creates different scenarios.

● Plate Boundaries: The edges of a tectonic plate. This is where the plates interact.

● Convergent Boundary: Two plates are pushed towards each other, causing one plate to slide underneath the first and get pushed into the mantle.

● Divergent Boundary: Two plates move away from each other and create a small gap. allowing magma to rise to the surface and make a new crust.

● Transform Fault Boundary: Boundaries that rub against one another. Also called transform boundaries.

● Subduction: When an Oceanic-Oceanic boundary or an Oceanic-Continental boundary converge, the ocean plate is pushed below the other into hot magma, causing it to melt.

● Orogeny: Convergent continent-continent boundaries push up the plates until they form chains of mountains.

Volcanoes and Earthquakes

● There are three kinds of Volcanoes:

○ Active Volcanoes have erupted during recorded history, about 10,000 years.

○ Dormant Volcanoes have not erupted in that period.

○ Extinct Volcanoes will never erupt again.

● The tectonic movement involved categorizes active volcanoes: the Subduction Zone at convergent boundaries, the Rift Valleys at divergent boundaries, and Hot Spots, which form in the middle of tectonic plates.

● Volcanoes can also be broken down farther and labeled as Shield, Composite, Cinder, and Lava Dome Volcanoes.

● Vibrations that come from sudden movement of a tectonic plate cause earthquakes.

○ Typically, this happens at a transform boundary.

● The Focus is the location, in the Earth, where the Earthquake starts.

● The initial surface location of the Earthquake is the epicenter.

● A Seismograph determines the size or magnitude of every Earthquake.

● The Richter scale measures the amplitude of the highest S-Wave, a wave that shakes the ground perpendicular to the direction that the ground is moving.

○ The scale is from zero to 9.5.

● Tsunamis are ginormous waves caused by Earthquakes or Volcano eruptions.

The Rock Cycle

There are three kinds of rock:

● Igneous Rock: Comes from rock melted by heat and pressure below the crust and then cooled. Cooled lava creates these rocks

● Sedimentary: Rocks created from compressed rocks and animal and plant remains.

● Metaphoric: Rocks created by intense heat and pressure that cause a chemical or physical change to already existing rock.

The Atmosphere

Atmosphere: 6 layers of gasses that surround the Earth, which is held together by gravity.

● Troposphere: The layer closest to Earth. It extends from about 0-20 km or 0-12.5 miles from Earth’s surface. It contains about 75-80% of the atmosphere’s mass. The troposphere also contains the air we breathe, meaning it is made of 78% nitrogen and 21% oxygen, the final 1% is greenhouse gasses. 

○ The greenhouses gasses with the most effect to Earth’s conditions are Water Vapor (H2O), Carbon Dioxide (CO2), and Methane (CH4).

○ At the top of the troposphere is the tropopause, a buffer layer where jet streams and air currents take place.

● Stratosphere: The layer above the tropopause sits about 20-50 km or 7.5-31 miles above Earth’s surface. Gasses do not mix well here.

○ The temperature here also increases the greater the distance is from Earth. This is because the Ozone layer is found in the lower half of the stratosphere. The Ozone layer traps high-energy radiation from the sun and protects the troposphere.

● Mesosphere: The third atmosphere layer that extends about 80 km or 50 miles above Earth’s surface. Meteors usually burn up in this layer. Temperatures decrease here, making the coldest point in the atmosphere at -90° C or -130° F, found in the top half of the stratosphere.

● Thermosphere: This layer is about 80 km to 500 km or 50-435 miles above the Earth. Gasses are thin and rarely found here. However, the Auroras, also known as the northern and southern lights, appear here.

● Exosphere: The final layer extends over 10,000 km or 6,200 miles above Earth. The amount of gasses is thinnest here. This is also where stabilities orbit.

Climate

Atmospheric patterns that last over 30 years are considered climate. The two most important factors in describing climate are average temperature and average participation.

Quick Facts:

● More of the Sun’s rays strike the equator than either of the poles.

● The tilt of Earth’s axis causes the seasons.

● Earth’s surface at the equator moves faster than at the poles.

Wind Patterns in the Atmosphere:

● Coriolis Effect: A deflection pattern where winds in the northern hemisphere will deflect westward towards the right and southern hemisphere winds will be deflected to the left.

● Prevailing Winds: Belts of air that blow heat and moisture across the globe unevenly.

● Convection Currents: Warm, moist air masses that rise. This allows cool masses to flow along the Earth’s surface. This process is called horizontal flow.

● Dew Point: Temperature where water vapor condenses into liquid water, creating clouds.

○ When the water droplets get too heavy, they fall to earth as precipitation.

● The cold, dry air mass caused by precipitation then sinks the Earth’s surface. It is then warmed and gains moisture and once again rises. This cycle is called the Convection Cell Rotation.

● Hardly Cells happen on a global level. The process begins over the equator, where the warm and moist air evaporates and rises. The precipitation in that area is abundant; this is where tropical rainforests reside. The cool, dry air descends at about 30 degrees north and south of the equator which leads to chains of deserts.

The Coriolis Effect

Earth’s Revolution Around the Sun

Types of Winds

● Trade Winds, named after their ability to propel trade ships across the ocean, blow between 30 degrees latitude and the equator. The winds are steady and strong and travel at a speed of 11 to 13 mph. Trade winds are created due to the surface currents of Hadley

Cells along with Earth’s rotation.

o Northeast Trade Winds blow only in the Northern Hemisphere.

o The Southern Hemisphere trade winds are called Southeast Trade Winds.

● Westerlies are an air mass that travels from north to east in the northern hemisphere and south to east in the southern hemisphere.

Weather Events

● Monsoons are seasonal winds that are followed by heavy rainfall. This happens when the land heats up and cools down quicker than water. The hot air rises and the cool air sinks creating steady seasonal rainfall.

● When air masses move in from over oceans, they carry lots of water vapor. When the air mass encounters an obstacle such as a mountain, the air is forced to rise. When the mass rises it is forced to precipitate over the ocean. When the mass reaches the other side of the mountain it is little to no moisture left. This is called the Rain Shadow Effect.

● To be classified as a Hurricane, a storm must have winds of at least 120 km/hr and take place in the Atlantic Ocean. Hurricane winds rotate and remove water vapor from the ocean’s surface.

○ This same type of storm is called a typhoon or cyclone in the Pacific Ocean.

● El Niń󠅀o is a climate variation that happens every three to seven years in the tropical Pacific. It lasts for about a year. La Niń󠅀a is the reverse of El Nińo.

Rain Shadow Effect

The Hydrosphere

Water covers about 75% of the Earth; the majority of this is saltwater. The other type of water on Earth is freshwater which contains very little amounts of salts.

● Freshwater: comes from precipitation. Bodies of freshwater include lakes, rivers, ponds, and streams, among other things. As Freshwater travels, it carries sediments that are deposited once the water meets the ocean. In these places, deltas are formed.

○ Deltas are areas where fresh and saltwater meet, causing sediment to build up

○ Estuaries are areas where the arms of the sea extends inland to meet rivers.

■ Estuaries are very rich in diversity. Ex.: saltwater marshes, mangroves, etc

○ Wetlands are areas along the shore of fresh water bodies.

■ These include swamps, bogs, and prairie potholes.

○ The layers of Freshwater:

■ Littoral zone is the very shallow zone that receives the most sunlight. Rooted plants grow here.

■ Limnetic zone is the surface of open water where the depth of sunlight is reached. Most organisms that live here are short livid and rely on photosynthesis.

■ Profundal zone is too deep for sunlight to penetrate. Photosynthesizing plants and organisms do not live here.

■ Benthic zone is the deepest layer with low temperatures and little oxygen.

● Saltwater

○ Barrier Islands: Landforms that lie on the edge of coastal shores that are made from sediment buildup.

■ Coral reef: A type of Barrier Island created from living organisms instead of sediment. Due to ocean acidification rising, many coral reefs are in danger of dying or drying out.

○ Zones of Saltwater:

■ Coastal Zone: Ocean water closest to land, typically called the shore.

■ Euphotic Zone: Upper layers of the water. This is the warmest region of the ocean and holds the highest level of dissolved oxygen.

■ Bathyal zone: Middle region; little light is received in this area which makes photosynthesizing organisms small in amount.

■ Abyssal zone: Deepest region in the ocean; it is extremely cold and receives no light. The levels of oxygen are low but nutrient levels are high.

● Both fresh and saltwater experience seasonal movements of water from the bottom full of nutrients; this is called upwelling.

Ocean Currents

Ocean currents heavily affect the temperatures and precipitation all over Earth.

● Gulf Streams, a type of current, carry sun-warmed water northward along the east coast of the United States and as far as the UK.

● Another important current is the Ocean Conveyor Belt, which sends cold water into the depths of the Pacific, and makes upwellings in the other part of the Pacific.

Water Use

Water is used for many different things in a daily routine. Agriculture is one of the biggest water use industries in the world. Nearly 75% of the global demand for water is used for crop irrigation. The exponential population growth around the world has made water scarce for some communities. As a way to deal with this, solutions attempted every day.

● A popular solution currently is the Interbasin transfer, where water is transferred from a far away source through pipelines and aqueducts.

● Another solution is Groundwater, water that comes from underground that resides in places called aquifers. Aquifers are confined, where the water is harder to transport, or unconfined, where the water flows horizontally.

Countries are labeled as water-stressed or water-scarce.

Water-stressed

● Renewable annual water supply of about 1000-2000 m3 per person

Water-scarce

● Less than 1000 m3 per person and lack sufficient freshwater resources.

● About 4 billion people in the world experience water scarcity for at least a month every year. 500-700 million people, in 43 countries, experience water scarcity year round.

● In the U.S, specific regions are considered water-stressed. However, the United States uses water faster than it can be replenished. Solutions are being thought of but for now, there are the Riparian Rights and the Prior Appropriation Rights. The first means the people who own that land have a say on how the water in that area is used and the second says that if you have historically used a water source, rights are given to you as well.

The Pedosphere

Soil is a critical link between abiotic, the nonliving, and biotic, the living aspects of Earth. Soil is composed of about 45% broken down minerals, 25% air, 25% water and 5% organic matter. Its physical and chemical features such as color and texture categorize soil. 

● The U.S. Department of Agriculture divides soil into 3 size classes: clay, slit, and sand.

Clay

● Size: 0.002 mm

Silt

● Size: 0.05-0.002 mm

Sand

● Size: 2.0-0.05 mm

● Loam is a soil’s texture if it has the optimal amount of each particle size for plant growth. To reach loam, the soil should be 7-27% clay, 28-50% slit, and less than 52% sand.

● Soil Acidity and Soil Alkalinity: Soil’s PH level is typically in the range of 4-8, this means soils are anywhere from neutral to slightly acidic. However, the more acidic soil is, the more it can dissolve heavier metals like mercury or aluminum, which is harmful.

● Soil comes from weathering, the breaking down of rocks and organic matter.

○ Physical Weathering or Mechanical Weathering: Rock is broken down into smaller pieces without changing the chemical makeup. Done by wind and water.

○ Chemical Weathering: This is when rocks have chemical reactions to water, air, or dissolved minerals. This process typically takes place in warm and moist habitats; an example of chemical weathering would be rust.

○ Biological Weathering: Weathering done by living organisms. This can be done physically or chemically. Think plant roots or lichens.

● Soil has layers, called horizons, and each one has special properties that make it unique.

○ Eluviation: Movement of water borne minerals, humus and other materials from high soil levels to lower soil levels. This is due to water being pulled down by gravity. E horizon lacks minerals and materials due to this.

○ Illuviation: This is when the materials from eluviation deposit in a lower level. This is prominent in B horizon.

○ Leeching: This process specifically applies to dissolved organic and chemical compounds that are lost from the soil profile by draining into groundwater. This happens in A horizon.

● Arable soil: Soil suitable for plant growth. It has good levels of nutrients such as nitrogen, potassium, and phosphorus. Loamy soil is considered the best. It can take up to 3,000 years for arable soil to be created making it a non-renewable resource.

● Soil Structure: Soil’s ability to stay together or aggregate.

○ These clumps of soil are held together by clay and organic matter

● Plow pan/Hard pan: Unfertile soil due to the repeated plowing and digging to raise crops.

● Monoculture: Widespread practice of planting one type of crop over a large area. This leads to lack of biodiversity.

● Crop rotation: Different crops are planted in one area each growing season.

● Polyculture: Planting several crops in one area during each growing season.

● Green Revolution: A boom in agricultural productivity due to the industrialization of agricultural techniques. This has left many negative impacts on the environment.

● Saltization: Soil is water-logged; when it dries out, all the leftover salt resides in a layer at the top.

● Drip irrigation: Only allows an area as much water as necessary and delivers it straight to the roots.

● Soil and Conservation Act of 1977: Soil and water conservation programs were established to help landowners and users. It also set up conditions to continue analyzing soil and water.

● Food Security Act of 1985: Discouraged the conversion of wetlands to non-wetlands and denied federal farm supplements to wetlands converted to agricultural lands and rewarded the revival of wetlands.