Earth’s Lithosphere “In the developed world. . We no longer honor our relationship to the soil. . . Soil has simply become one more resource - a substance necessary for crop production and for holding up buildings. . . “ (Elena Wilken. . . World Watch article, 1995)
Let’s start with the Lithosphere 3 major zones of Earth: Core - very hot, solid & liquid Mantle - solid zone, largest (68% of its mass, rich in iron, silicon, oxygen & Magnesium Crust - outermost & thinnest portion, consists of continental crust (29%) & oceanic crust (covers 71% of Earth’s surface)
Plate Tectonics and Macroevolution • The continents are not locked in place. • They drift about Earth’s surface on plates of crust floating on a flexible layer called the mantle. • California’s infamous San Andreas fault • Is at a border where two plates slide past each other.
KQED Quest: Hayward Fault • http://www.kqed.org/quest/television/the-hayward-fault-predictable-peril
About 250 million years ago • Plate movements formed the supercontinent Pangaea. • Many extinctions occurred, allowing survivors to diversify.
About 180 million years ago • Pangaea began to break up, causing geographic isolation & new species
Tectonic Movement is A Natural Part of Planet, but Can we predict earthquakes? • http://www.kqed.org/quest/television/earthquakes-breaking-new-ground
Earth’s Lithosphere Crust contains 8 elements make up 98.5% of weight of Earth’s crust (O, Si, Al, Fe, Ca, Na, K, Mg) Minerals (any naturally occurring inorganic substance found in Earth’s crust as a crystalline solid) Nonrenewable fossil fuels Potentially renewable soil nutrients (eroded rock, mineral nutrients, decaying organic matter, water, air & living organisms)
Earth’s “continental crust” Earth’s land surface: Only 11% arable (useable for agriculture) Rest too nutrient poor, cold, wet, dry, etc. Possible to add 24% more to arable land category if we irrigate & use fertilizers Total to possibly 35% of land surface potentially arable
Element = Carbon • Carbon is essential to life as we know it • Carbon is the basic building block for all organic compounds necessary for life (carbohydrates, proteins, fats, DNA) • To study life is to study Carbon Chemistry!
Organic Compounds • Compounds which contain : • C (Carbon) combined with : • H (Hydrogen • O (Oxygen) • N (Nitrogen) • S (Sulfur) • P (Phosphorus) • Cl (Chlorine) • F (Fluorine) • All other compounds are called inorganic compounds
Carbon Cycle • It involves natural processes • A global gaseous cycle (atmospheric cycle in which a large portion of a given element (C) exists in gaseous form (C02) in atmosphere • Nutrients (like Carbon) are recycled in various chemical forms (cyclic movement of carbon in different chemical forms) • C cycles from the abiotic environment to the living organisms and back to the abiotic environment
CARBON DIOXIDE • C02 Cycles fairly rapidly from the atmosphere, through soil and organisms, and back to atmosphere • Key component of nature’s thermostat • If too much C02 removed from atmosphere, the atmosphere will cool • If cycle generates too much C02, the atmosphere will get warmer • So C02 does affect the BIOSPHERE ( and can determine temperature & possibly change climate)
Some CO2 is utilized to produce biomass in trees and plants Which can form fossil fuels after millions of years of decomposition and compaction (as buried organic material) When fossil fuels (coal, oil,gas) go through combustion(burning process), CO2 is released back into the atmosphere
Terrestrial producers (green plants and trees) remove CO2 from the air PHOTOSYNTHESIS takes place 6CO2 + 6H2O + solar energy is converted into C6H12O6 (glucose)+ 6O2 (oxygen) Consumers and decomposers breakdown glucose (consumption) and utilize oxygen for respiration The Hydrocarbons get converted back to CO2 in the atmosphere
Humans and causes of increases in CO2 (all unsustainable practices): • Cut down trees (producers of oxygen and users of CO2) • Industries • Transportation (i.e.,cars) • Buildings
Increased amounts of carbon: • Global warming (rising sea/water level) • May lead to extinction of certain plants, insect and animals, which could cause an imbalance in the food chain. • Acidification on oceans
carbon dioxide dissolved carbonate and bicarbonate carbon containing minerals in rocks There are three types of C Cycles • Atmospheric cycle • Hydrological cycle • Sedimentary cycle
Discuss as a team: • Should we, as individuals & as a country, go on a carbon diet? What does this mean? • A huge amount of carbon is sequestered in tropical forests. What does this mean and why should we care about this information? • Should we pay a carbon tax to save tropical forests? Why or why not? Write responses in Your journals!
Science News Reading Activity • Read the article “Soils Hidden Secrets” (Charles Pet tit) • We will have a QUIZ on Wednesday • You may use HANDWRITTEN notes, but you may not use the printed article or typed notes.