Science Behind Environmental Science Chapter 2 Science Behind Environmental Science

Conservation of Matter Matter can be changed from one form to another Cannot be created or destroyed by ordinary physical or chemical processes

Conservation of Matter In nature Organisms use food supply Little waste generated Natural processes can recycle this waste

Conservation of Matter Human population generates waste that is not easily disposed of may persist in nature indefinitely may be harmful or toxic

Ecosystems Organisms and surrounding environment Abiotic Biotic all the biotic and abiotic components Abiotic nonliving components of ecosystem Biotic living components of ecosystem

Biotic versus Abiotic Biotic Abiotic trees decaying logs deer wolves squirrels worms in soil bacteria in soil Abiotic water oxygen gas atmosphere amount of sunlight acidity of water type of soil acidity of soil

Energy Laws First Law of Energy Energy cannot be created or destroyed Can be converted radiant to chemical energy chemical energy to heat or kinetic energy chemical energy to thermal energy thermal energy to electrical energy

Energy Laws Second Law of Energy Every time energy is converted . . . some energy is lost as heat

Flow of Energy An ecosystem is an energy system All processes depend on energy Nothing happens without flow of energy Energy = ability to do work moves from concentrated areas to become dispersed and unorganized

Flow of Energy Energy source in most ecosystems = sun

Energy Flow Complete ecosystem has three types of organisms Producers Transformers Decomposers

Energy Flow Producers Transformers Decomposers produce new food from photosynthesis usually green plants Transformers change food into more complex organic molecules Decomposers break down organic materials for reuse

Energy Flow Four fundamental biotic processes synthesis photosynthesis respiration decomposition

Synthesis Change in composition, size, shape, structure Organisms use nutrients, minerals, water to produce growth and reproduction Synthesis means “to make or form”

Photosynthesis Converts water and carbon dioxide into sugar requires a catalyst chlorophyll green pigment requires energy from sun

Photosynthesis Photosynthesis original source of most food also produces oxygen

Respiration Breaks down food to release energy converts sugar into water, carbon dioxide, and energy Both plants and animals undergo respiration

Decomposition A special type of cellular respiration Organic matter broken down to smaller organic compounds Recycles chemicals in bodies of organisms Follow-up Questions: Oxygen is converted to what molecule during cellular respiration? Glucose is converted to what molecule during cellular respiration? What waste product is given off during decomposition?

Ultimate Concept John Muir Everything on Earth part of an ecosystem “When we try to pick out anything by itself, we find it hitched to everything else in the universe.” Everything on Earth part of an ecosystem Everything is connected Doing something to one part affects some or all parts of system

Natural Cycles Living organisms mostly composed of carbon, hydrogen, nitrogen, and oxygen

Natural Cycles These elements used over and over again Carbon atom found in sugar molecule of plant Sugar consumed by an animal Atom becomes part of animal muscle When animal dies, it enters decomposers Eventually, atom taken up by a plant again

Elemental Cycle The circular flow of elements from living organisms to nonliving matter All elements making up living tissue all have elemental cycles Two important elemental cycles carbon nitrogen

Carbon Cycle Carbons atoms cycle between living organisms most abundant element in living organisms the atmosphere the oceans the soil

Carbon Cycle Carbon enters living organisms through photosynthesis takes carbon dioxide (CO2) from atmosphere using light, turns CO2 into sugars sugars used to form plant tissue roots, stems, leaves

Carbon Cycle Carbon in plant material can enter animals Animals consume plants Respiration by plants and animals returns CO2 to atmosphere Plants and animals die decay and release CO2 as gas may form fossil fuels

Carbon Cycle Carbon dioxide returns to atmosphere through respiration through decay of plants and animals by burning fossil fuels Living organisms die and are converted to fossil fuels

Carbon Cycle Oceans absorb and release CO2 high atmospheric carbon content: Oceans absorb CO2 low atmospheric carbon content: Oceans release CO2 to atmosphere Oceans have maintained carbon content Carbon in atmosphere remains fairly constant

Carbon Cycle and Global Warming Carbon content of atmosphere has been rising Burning of fossil fuels has increased Carbon content of atmosphere has increased Studies indicate that increasing carbon content is associated with increasing global temperatures

Cure for Global Warming? Oceanic algae addition of iron to seawater stimulates algae growth growth takes carbon dioxide from atmosphere Scientists debate where CO2 goes next bottom of the ocean or back to atmosphere?

Nitrogen Cycle Nitrogen cycles from nitrogen gas in atmosphere to nitrates in soil back to atmosphere as nitrogen gas

Nitrogen Cycle Nitrogen makes up 80 percent of air most abundant element in atmosphere must be combined with oxygen before it can be used by organisms

Nitrogen Cycle Nitrogen fixation Nitrogen gas converted to nitrates Nitrogen fixation can occur several ways bacteria industrial processes lightning and decay

Nitrogen Cycle Nitrogen fixation bacteria capable of converting nitrogen to nitrates

Nitrogen Cycle Nitrogen-fixing bacteria found in soil roots of some plants capable of making own nitrogen fertilizer

Nitrogen Cycle Nitrogen fixation industrial processes converts nitrogen gas to nitrates nitrogen first converted to ammonia ammonia then converted to nitrates nitrates used to make fertilizers

Nitrogen Cycle Nitrogen fixation lightning decay electrical current passes through nitrogen converts nitrogen gas to useable compounds decay nitrates released by decaying wastes also released from decaying organisms

Nitrogen Cycle Denitrification Accomplished by nitrates are broken down returns nitrogen gas to atmosphere Accomplished by some bacteria Nitrates in runoff enter surface water

Water One of most important resources environmental effects and benefits maintains more even temperature in environment erosion dilutes and flushes away contaminants

Water Biological effects and benefits required nutrient controls temperature of organisms solvent for nutrients cools surface of skin and leaves provides protection for some species

Water Cycle Water moves from What drives the water cycle? ocean to atmosphere to land in form of rain and snow to rivers and stream back to ocean What drives the water cycle? solar energy and gravity

Water Cycle Water enters atmosphere evaporation from oceans transpiration controlled evaporation from pores in plant leaves sweating breathing Moisture from these sources forms clouds

Water Cycle Moisture collects in atmosphere to form clouds Clouds release stored water rain and snow Gravity draws water to Earth’s surface Gravity draws water back to ocean

Energy Flow Ecologists represent energy flow with food chain Sequence of organisms that eat and are eaten Starts with producers

Energy Flow Producers eaten by herbivores also called primary consumers

Energy Flow Ecologists represent energy flow with food chain Herbivores eaten by carnivores meat-eating organisms also called secondary consumers

Energy Flow Decomposers final stop in the food chain break down tissues of other organisms

sun A typical food chain Tertiary consumer top carnivore Secondary consumer carnivore Primary consumer heterotrophs herbivore Producer autotrophs Decomposers Fungi Bacteria

Energy Flow Food chain in ecosystems more complex Forms food webs Usually many food chains are interwoven Forms food webs Many food chains linked together Also forms a food pyramid arranges organisms in a ranking order rank related to dominance in food web

Ecosystem Change Human intervention may change food chains Human activity may displace some organisms Many times, top predators are removed

Ecosystem Change Some organisms cannot adapt to human presence decline in number replaced by organisms that tolerate humans

Biological Succession Always occurring Environments are rarely stable always changing Two types primary secondary

Biological Succession Primary succession occurs where no organisms existed before cooled lava is an example Over time, lichen and fungi appear Pioneer species: first organisms growing in new environment Soil begins to develop and plants appear

Biological Succession Climax community plants that occupy environment when succession complete

Biological Succession Secondary succession occurs when ecosystem is damaged forest fire is an example ecosystem changed by fire supports organisms from earlier stage in succession

Biological Succession Change that occurs in an environment One kind of organism replaces another Also called ecological succession two forms primary secondary

Disturbances Disturbances are often necessary for community development & survival

Ecological cycle fire as part of a natural community cycle

Ecological succession The sequence of community changes after a disturbance transition in species composition over ecological time years or decades Mt. St. Helens

{ Succession From bare soil, then… bacteria lichens & mosses grasses Change in species mix over time From bare soil, then… bacteria lichens & mosses grasses shrubs trees { make soil

Succession from mosses & lichens = pioneer species to shrubs & trees

Climax forest The species mix of climax forest is dependent on the abiotic factors of the region solar energy levels temperature rainfall fertility & depth of soil birch, beech, maple, hemlock