Matter cycles • Organisms are reservoirs of these atoms, in various forms • Organisms are part of the cycling of these atoms, via various metabolic processes

water cycle Reservoir: most locked in oceans; limited fresh water for life

water cycle Abiotic: evaporation, condensation, precipitation cycle • transpiration – water moves through plants from roots to leaves, then to atmosphere; keeps plants upright • moved into organic molecules via photosynthesis • produced in respiration as sugars -> ATP

carbon cycle Reservoir: • CO2 in the atmosphere (0.03% of atmospheric gases) • A greenhouse gas, blocking the escape of long wavelength terrestrial radiation • Increased CO2 is correlated with increased global temperatures

carbon Biotic: • C brought into ecosystem producers, as CO2, via photosynthesis • Transferred between organisms in feeding relationships and returned to abiotic reservoirs via respiration • Incomplete decomposition created organic C deposits - the non-renewable, CO2 releasing fuels of today Abiotic: • CO2 in atmosphere • oceans are CO2 sinks, but how much? H20 + CO2 -> carbonic acid

phosphorous Reservoir: locked in rocks & sediment

phosphorous Biotic: • Stored in organisms in cell membranes, ATP, nucleic acids • Low availability limits plant growth Abiotic: • continental rocks & sea floor sediments • slow release means limited availability in in soil

nitrogen Reservoir: N2 in atmosphere

nitrogen Biotic: • Used by organisms to construct proteins, nucleic acids Abiotic: • atmospheric form (N2) inaccessible to most organisms • little available in soil

nitrogen • or NH4+ ->N2 released to the atmosphere Denitrification • Bacteria in legume roots turn N2 -> NH3 creating soil source of N for plants nitrogen-fixation 4 1 2 3 • In decomposition organically-bound N -> NH4+ ions ammonification • NH4+ -> nitrates/ nitrates in soil to be used by more plants nitrification

eutrophication • P, N are limiting factors for plant growth, therefore add to fertilizers • runoff introduces P, N to waterways, causing excessive plant growth, aka eutrophication • subsequent decomposition of plant mass robs water of oxygen, affecting fish and aquatic invertebrate populations

eutrophication