1.1.4 and 2.5.4 Thermodynamics nutrient cycles

Two basic processes must occur in an ecosystem: A cycling of chemical elements. Flow of energy. Energy flows through systems while materials circulate around systems.

Cycling of Chemical Elements TRANSFERS: normally flow through a system and involve a change in location. TRANSFORMATIONS: lead to an interaction within a system in the formation of a new end product, or involve a change of state.

Groundwater movement (slow) Surface runoff (rapid) Water “hydrologic” Cycle Precipitation to ocean Evaporation From ocean Surface runoff (rapid) Ocean storage Condensation Transpiration Rain clouds Infiltration and percolation from plants Groundwater movement (slow) Runoff Surface runoff (rapid)

combustion of wood (for clearing land; or for fuel Terrestrial carbon Cycle photosynthesis aerobic respiration Terrestrial rocks Soil water (dissolved carbon) Land food webs producers, consumers, decomposers, detritivores Atmosphere (mainly carbon dioxide) Peat, fossil fuels combustion of wood (for clearing land; or for fuel sedimentation volcanic action death, burial, compaction over geologic time leaching runoff weathering

nitrogen Cycle Gaseous Nitrogen (N2) In Atmosphere Nitrogen Fixation NO3 – in soil Nitrogen Fixation by industry for agriculture Fertilizers Food Webs On Land NH3, NH4+ 1. Nitrification bacteria convert NH4+ to nitrate (NO2–) loss by leaching uptake by autotrophs excretion, death, decomposition bacteria convert to ammonia (NH3+) ; this dissolves to form ammonium (NH4+) Ammonification bacteria, fungi convert the residues to NH3 , this dissolves to form NH4+ 2. Nitrification bacteria convert NO2- to nitrate (NO3-) Denitrification by bacteria Nitrogenous Wastes, Remains In Soil Gaseous Nitrogen (N2) In Atmosphere NO2 – © 2004 Brooks/Cole – Thomson Learning

Phosphorous Cycle GUANO FERTILIZER ROCKS LAND FOOD WEBS DISSOLVED IN OCEAN WATER MARINE FOOD WEBS MARINE SEDIMENTS weathering agriculture uptake by autotrophs death, decomposition sedimentation settling out DISSOLVED IN SOIL WATER, LAKES, RIVERS uplifting over geolgic time mining excretion

sulfur Cycle Hydrogen sulfide (H2S) + Water (H2O) Sulfur dioxide (SO2) and Sulfur trioxide (SO3) Dimethyl (DMS) Industries Sulfuric acid (H2SO4) Oceans Ammonia (NH2) Oxygen (O2) Ammonium sulfate [(NH4)2SO4] Animals Plants Sulfate salts (SO42-) Decaying organisms Sulfur (S) Fog and precipitation (rain, snow) Aerobic conditions in soil and water Anaerobic conditions in soil and water Volcanoes hot springs Atmosphere sulfur Cycle

Flow of Energy Thermodynamics is the study of the energy transformations that occur in a system. It is the study of the flow of energy through nature. Within a system energy cannot be re-used.

1st Law of Thermodynamics States that energy can be transferred and transformed, but it CANNOT be created nor destroyed. Law of Conservation of Energy. Energy of the universe is constant.

Thermal equilibrium = inputs equal outputs over a long period of time.

2nd Law of Thermodynamics States that every transformation results in a reduction of the FREE ENERGY (useable energy). Energy transfers and transformations increase ENTROPY (disorder, randomness or chaos). Law of Entropy. Energy always tends to go from a more usable (higher quality) form to a less usable (lower quality) form. You can’t get something for nothing No such thing as a free lunch

Second Law of Thermodynamics

Any conversion is less than 100% efficient and therefore some energy is lost or wasted. Usually this energy is lost in the form of HEAT (= random energy of molecular movement). We usually summarize it as respiration. Solar energy Waste heat Chemical (photosynthesis) (food) Mechanical (moving, thinking, living)

Only 25% of chemical “E” stored in gasoline is transformed in to motion of the car and 75% is lost as heat!!

Without adding energy to a system, the system will break down .

Heat 10 100 1,000 10,000 Usable energy available at each tropic level (in kilocalories) Producers (phytoplankton) Primary consumers (zooplankton) Secondary (perch) Tertiary (human) Decomposers