AP Environmental Science Unit 4 Earth Systems and Resources

Unit 4: Earth Systems and Resources ● The Lithosphere ○ Tectonic Plates - parts of the lithosphere that float on the asthenosphere ● Earth’s Tectonic Plates ■ Plate Boundaries - the edges of tectonic plates ● Types of Plate Boundaries ○ Convergent Boundary - two plates are pushed toward and into each other ○ Divergent Boundary - two plates move away from each other ○ Transform Fault Boundary - two plates slide against each other in opposite directions ■ Subduction - an older and denser plate sinks beneath the younger and lighter plate ■ Ocean-continent convergence - the oceanic plate is subducted beneath the less dense continental plate, forming a deep ocean trench ○ Eg: Cascade Range is an example of ocean-continent convergence ○ Earthquakes - geological events resulting from vibrations deep in the Earth that release energy ■ Epicenter - Initial surface location of the earthquake ■ Seismograph - an instrument that measures size or magnitude ■ Richter Scale - measures amplitude of the highest S-wave ○ Volcanoes - geological events resulting from plate movement ■ Volcano Classification ● Active - Erupted within the last 10,000 years ● Dormant - Has not erupted within the last 10,000 years but is expected to erupt again ● Extinct - Is not expected to erupt again ○ Recharging - build up of pressure between eruptions ■ Volcano Creation ● Subduction Zone - Occurs at convergent boundaries between oceanic and continental plates ○ Eg: Ring of Fire ● Rift Valley - Occurs at divergent boundaries usually between oceanic plates. New ocean floor is formed as magma fills in the gap between separating plates. ○ Eg: East African Rift ● Hotspots - Found in the middle of tectonic plates. Columns of unusually hot magma rise from deep in the mantle, partially melting and weakening the mantle in the lower lithosphere. ○ Eg: Hawaiian Islands ■ Types of Volcanoes ● Shield Volcanoes - Tall, Broad base, Gentle slope ○ Eg: Kohala ● Composite Volcanoes - Tall, Broad base, Steep slope ○ Eg: Mount Fuji ● Cinder Cones - Small, Short, Steep slope, Symmetrical cone, Bowl-like crater, ○ Eg: Sunset Crater ● Lava Domes - Small, Short, Steep slope, Dome ○ Eg: Mount St. Helens ● The Atmosphere ○ Layer of the Atmosphere ■ Exosphere ● Gases are thinnest ■ Thermosphere ● Gases are very thin ● Auroras occur ■ Ionosphere ● Absorbs X-rays and ultraviolet radiation from Sun ■ Mesosphere ● Air pressure extremely low ● Temperature decreases with altitude ● Where meteors usually burn up before striking Earth ■ Stratosphere ● Includes the ozone layer ● Gases are not well mixed ● Gradually warmer with altitude ■ Tropopause ● Between the troposphere and the stratosphere ■ Troposphere ● Where weather takes place ● Usually well-mixed ● Gradually colder with altitude ● Contains 99% of water vapor and clouds ○ Greenhouse Gases ■ Types of Greenhouse Gases ● Water Vapor - H₂O - 0-4% of troposphere ● Carbon Dioxide - CO₂ - 0.033% of the troposphere ● Methane - CH₄ - 0.0002% of the troposphere ○ Weather & Climate ■ Weather ● Day-to-Day properties ● Wind Speed + Directions ● Temperature ● Amount of Sunlight ● Pressure ● Humidity ■ Climate ● Patterns that are constant over many years ● Average Temperature ● Average Precipitation Amounts ○ Seasons - the motion of the Earth around the Sun that results in a variation in insolation, the amount of solar radiation that reaches a given area ■ Northern Hemisphere Tilted Towards the Sun ● North = Summer ● South = Winter ■ Southern Hemisphere Tilted Towards the Sun ● North = Winter ● South = Summer ● The Hydrosphere ○ Includes Earth’s oceans and freshwater bodies ○ Covers about 75% of planet Earth ○ Freshwater ■ Contains minimal quantities of dissolved salts ■ Usually comes from precipitation from atmospheric water vapor ■ Watershed - an area of land that collects rainwater and drains it into a particular stream or river ■ Freshwater Biomes ● Deltas ○ Landforms that forms at the juncture of a river and ocean ○ Made of deposited sediment ● Estuaries ○ Sites where the “arm” of the sea extends inland to meet the mouth of a river ○ Often rich with many different types of plant and animal species ○ Water usually has a high concentration of nutrients and sediments ● Wetlands ○ Ecologically diverse ecosystems ○ Found along the shores of fresh bodies of water ■ Eg: Marshes, swamps, bogs, prairie potholes, and floodplains ○ Saltwater ■ Saltwater Biomes (Examples) ● Barrier Islands ○ Landforms that lie off coastal shores ○ Spits of land ○ Created by buildup of deposited sediments ○ Boundaries constantly shifting as water moves around them ○ Function to buffer the shoreline behind them ● Coral Reef ○ A type of barrier island ○ Formed by a community of living things ○ Home to a large diversity of species ○ Extremely delicate ○ Vulnerable to physical stresses, changes in light intensity, changes in water temperature, and ocean depth and pH ○ Water Problem & Issues ■ Water Risk ● The possibility of an area experiencing a water-related challenge such as water scarcity, water stress, flooding or drought ■ Water Stress ● Occurs when demand for water exceeds the available amount during a certain period, or when poor quality restricts water use. Water-stressed countries have a renewable annual water supply of about 1,000-2,000 m³ per person. ■ Water Scarcity ● A lack of sufficient available water resources to meet demand for water in a region. It affects every continent and around 2.8 billion people around the world at least one month out of every year. Water-scarce countries have a renewable annual water supply of less than 1,000 m³ per person ○ Water Conservation ● Includes Policies, strategies, and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand for water. ● Soil & Soil Dynamics ○ The Pedosphere ■ What is Soil? ● A complex, ancient material teeming with living organisms ● Consists of ○ Finely broken-down or weathered rock (45%) ○ Living and dead organic matter (~5%) ○ Air (~25%) ○ Water (~25%) ■ The Chemistry of Soil: pH ● pH substances ranges from 0-14 ● pH is the measure of the concentration of hydrogen ions ● Most soils have a pH between 4 to 8 ● Soil can be acidic (<7) or alkaline/basic (>7) ■ The Importance of Soil ● Links the abiotic and biotic components of the world ● Plays an active role in nutrient cycling ● Supports plant life by supplying a physical foundation for growth, water, and nutrients ● Nonrenewable resource ● Rocks ○ Rock Cycle ■ ○ Types of Rocks ■ Igneous ● Rock is melted by heat and pressure below the crust ○ Eg: Basalt, Granite ■ Sedimentary ● Forms as a sediment; builds up and is compressed ○ Eg: Limestone, shale, coal, chert ■ Metamorphic ● Formed by transforming an existing rock via a large amount of pressure and heat ○ Eg: Slate, marble ○ Rock Weathering ■ Types of Weathering ● Physical ○ Rock is weakened and worn down by physical forces, usually wind or water ○ No change in the chemistry of the rock ○ Dominates in cold or dry environments ● Chemical ○ Rock is subjected to chemical alteration through reactions with water, oxygen, or dissolved minerals ○ Breakdown and reorganization of rock minerals ○ Dominates in warm or moist environments ● Biological ○ Weathering that takes place as the result of the activities of living organisms ○ Organisms can weather rock by physical or chemical means ○ Types of Soil ■ Sand ● Large particles ● Don’t easily adhere together ● Large pores ● More space for water but it drains away quickly ■ Clay ● Small particles ● Easily adhere to each other ● Small pores ● Less space for water but is held in soil and doesn’t drain ○ Soil Problems ■ Enough arable soil is needed to meet our agricultural needs ■ Soil fertility is a must ○ Erosion ● The removal of soil, rock, or dissolved material from one location on the Earth’s crust and transportation to another location ● Problems w. Modern Agriculture ○ Monoculture vs. Polyculture ■ Monoculture ● Planting just one type of crop in a large area ● Common in modern agriculture ● Leeches soil of specific nutrients ● Decreases crop genetic diversity, making crops more susceptible to pests and diseases ■ Polyculture ● Planting many types of crops in a large area ● Increases sustainability ● Limits nutrient depletion in soil ● Increases genetic diversity ● Crop rotation another good solution ○ Other Problems ● Damaged soil due to large machinery ● Repeated plowing breaks down soil aggregates; this leaves plow pan, or hard pan, which is hard, infertile soil ● Large energy consumption, including burning fossil fuels ● Pollution in the form of pesticides and fertilizers ○ Green Revolution ■ What is it? ● A huge increase in worldwide agricultural productivity over the past 50 years ● Due to mechanization of farming that resulted from the Industrial Revolution ■ Cons ● Many detrimental effects on the environment ● Use of chemical pesticides lead to new pesticide-resistance insects ● Over-irrigation has caused salinization of soil and land degradation ■ Solutions ● Genetically modified plants decrease the need for pesticide use ● Drip irrigation adds only the water required and delivers water directly to plants’ roots ○ Soil Conservation ■ Practices to Conserve Soil Properties ● Using manure, compost, and the residue of plants to increase the amount of organic matter in the soil ● Organic agriculture, a method of farming that uses compost, manure, crop rotation, and non-chemical methods to manage soil fertility and pest control ● Changing tillage practices to reduce soil breakup and erosion, including contour plowing and strip planting ● Using trees and other winds barriers to reduce wind force