earth science

• the 4 spheres

  1. biosphere
  2. geosphere
  3. hydrosphere
  4. atmosphere
• hydrosphere

  • encompasses all forms of water in environment
  • includes oceans, lakes, rivers, snow, glaciers, water under earth's surface, water vapour in atmosphere
  • water continuously cycles through 3 ecosystem processes
  • evaporation, condensation, precipitation
• geosphere

  • aka lithosphere
  • contains
  • all solid, rocky land on earth's surface (crust)
  • semi-solid land under crust (mantle)
  • liquid land near centre of planet (core)
• geosphere constantly shaped by external forces

  • sun, wind, ice, water + chemical changes
• atmosphere

  • gaseous part of earth
  • upper portion of atmosphere protects organisms of biosphere from sun's UV radiation
  • absorbs + emits heat
• solar energy

  • when reaching earth, it is absorbed + reflected by earth's atmosphere + surface
  • heats earth's surface unevenly + global winds help redistribute thermal energy around earth
  • ocean currents also redistribute thermal energy around earth
  • enters biosphere through photosynthesis + cellular respiration
• amount of solar energy reaching different regions of earth varies

  • earth = spherical
  • strikes earth at different angles
  • receives more direct solar energy at lower latitudes
  • lower latitudes become warmer
• earth's major wind systems result from

  • convection currents
  • warm air near surface rises + cools
  • cool air is denser + sinks, creating wind that moves warm + cool air around earth
  • coriolis effect - change in direction of moving air, water, or other objects due to earth's rotation
• when air temperature changes, weather occurs
• ocean currents

  • move thermal energy around earth
  • surface currents created by wind
  • 5 major sets of surface currents - 1 in each main ocean basin
  • warm currents - move heat toward poles (warm water from equator to higher, colder latitudes)
  • cold currents - move cold water from colder, higher latitudes to tropical regions
• biotic elements

  • living parts of environment
  • include all microorganisms, plants + animals on/above/under earth
• biodiversity - large variety of organisms; indicator of healthy ecosystem
• biosphere

  • cannot survive w/out elements from all other spheres
  • plants + animals need water from hydrosphere, minerals from geosphere, gases from atmosphere
  • air, water, and land all provide homes
  • all living things dependent on non-living things for energy, water, space - living things use nutrients + decomposers recycle nutrients into inorganic material that can form part of the soil
• abiotic elements - non-living parts of an environment
• abiotic + biotic interactions

  • oxygen for cellular respiration
  • water for survival
  • nutrients = chemicals required for plant + animal growth
  • light required for photosynthesis
  • soil anchors plants, absorbs/holds water, provides nutrients for plants + supports many species of small organisms
• food chain - a model that describes how food energy is passed from one living thing to another
• each step in a food chain is called a trophic level
• energy flows from producers (plants) to primary consumers (herbivores) to secondary + tertiary consumers (carnivores)
• producers

  • living things that make their own food to get energy they need to live; then becomes an energy source
  • usually through photosynthesis by plants/single-celled organisms
• decomposition

  • breaking down of dead organic material
  • decomposers - bacteria + fungi - living things that break down dead material to get energy they need
• limits to length of food chain

  • most transferred energy between organisms is lost to environment as unusable heat
  • some energy already used to support life functions (growth, cellular respiration)
  • some energy stored in excreted wastes
  • less energy available to each organism in food chain
• consumers

  • living things that eat producers/other consumers to get energy
  • herbivores - primary consumers that eat plants
  • carnivores - secondary consumers that eat primary consumers
  • omnivores - eat plants + animals - interconnected food chains form food webs
  • detrivores - eat bodies of small dead organisms/plant matter + animal wastes
• photosynthesis - cellular respiration

  • store energy - release energy
  • use carbon dioxide + water - use glucose + oxygen
  • produce glucose + oxygen - produce carbon dioxide + water
• photosynthesis - series of chemical changes in which green plants capture sun's light energy + transform it into chemical energy stored in energy-rich food compounds such as sugar
• cellular respiration - series of chemical changes that let living things release energy stored in energy-rich food compounds such as sugars to fuel all life functions
• water cycle

  • evaporation - heat from sun causes water at earth's surface to evaporate
  • condensation - as warm air rises, it cools + condenses, forming clouds
  • precipitation - water falls back to earth's surface when it rains/snows
  • water moves over earth's surface + moves downhill back into the ocean water due to gravity
• transpiration - process by which water is absorbed by roots of plants, carried through plants, and lost as water vapour through small pores in leaves; how water moves through biosphere
• great ocean conveyer belt

  • massive system of deep-water currents that move deep water, thermal energy, and nutrients around earth
  • movements based on temperature + salt content of water
  • cold water is denser + sinks/displaces warm water
  • saltier water is more dense + sinks/displaces less salty water
• great ocean conveyer belt - movement of nutrients

  • moves nutrients (nitrogen, phosphorus) around ocean
  • surface water that sinks doesn't have many nutrients
  • after water sinks, bacteria in deep water break down organic material + return nutrients to water
  • when deep water returns to surface, it has higher concentration of nutrients
• water pollution

  • any physical, biological, or chemical change in water quality that has an adverse effect on organisms or makes water unsuitable for desired uses
  • synthetic chemicals/pollutants enter environment in air, water, + soil
  • decomposers cannot break them down through biodegradation process so they stay in environment for long time
• source of pollution

  1. point sources
  2. non-point sources
• point sources

  • eg. factories, power plants, sewage treatment plants, oil wells
  • easy to monitor + regulate
• non-point sources

  • eg. run-off farms, lawns, construction sites, logging areas, roads, parking lots
  • difficult to monitor, regulate, + treat since pollution = periodic
• bioaccumulation

  • gradual build-up of chemicals/pollutants in cells + tissues of organisms
  • accumulation - chemical taken up + stored faster than it is broken down/excreted
  • via food intake, skin contact, respiration
  • form birth defects + affect body systems
  • eg. red tide - algae toxins taken in by clams, human shellfish, PCBS + orcas, raptors
• biomagnification - increase in concentration of pollutants in tissues of organisms that are successively higher levels in food chain/web
• bioremediation

  • method using living organisms to help clean up chemical pollution naturally
  • eg. some microorganisms naturally feed on chemicals + reduce them to non-toxic compounds
  • eg. plants act as stabilizers, reduce wind, water erosion that spreads contaminants
• DDT + raptors

  • DDT pesticide used to control disease-carrying mosquitoes
  • now banned
  • birds lay infertile, thin-shelled eggs + broken before hatched
• PCBS + orcas

  • synthetic chemicals in plastic used in industrial products
  • now banned
  • stays in organisms (orca's blubber) for long time
  • interfere w immune system
  • more susceptible to disease
• nutrient cycles

  • nutrients - chemicals required for growth/life processes
  • carbon, oxygen hydrogen, nitrogen, phosphorus
  • there are sources, stores, + sinks for each nutrient
  • nutrients flow in + out of stores
  • w/out interference, amount of nutrients flowing into a store equals the amount flowing out
• carbon stores

  • carbon atoms - fundamental unit in cells of all living things
  • short term storage - aquatic + terrestrial organisms, CO2 in atmosphere, top layers of ocean
  • long term storage - middle + lower ocean layers, coal/oil/gas deposits in land + ocean sediments
  • carbon stored in decomposing remains of organisms buried deep in ground transform into carbon-rich fossil fuels