Biogeochemical Cycles

Cycles rapid cycling: substances cycle between nutrient rersevoirs (holding areas) quickly slow cycling: substances accumulate and are unavailable to organisms

The Water Cycle

Evaporation from the land (water to the atmosphere) As it cools, water vapor condenses and eventually falls as precipitation

Ground water transports the water in the soil Plants pull water from the ground and lose it to the air through transpiration

Carbon and Oxygen Cycles

Photosynthesis and Cellular Respiration C6H12O6 + 6O2 Energy released 6CO2 + 6H2O Energy from sun Although the processes are very different, the overall equations are very complimentary to one another. Both contribute to the RAPID cycling of carbon and oxygen

Slow cycle Living organisms play an important role in the slow cycling of carbon Trees act as carbon reservoirs (carbon sinks) until they die Deforestation accounts for the return of 2 gigatonnes of carbon into the atmosphere per year

in the ocean, phytoplankton and algae reproduce creating biomass a small % drifts to the ocean floor and is converted to fossil fuel deposits (over millions of years)

Boreal forest is recognized as a significant carbon sink due to the accumulation of peat (muskeg)

Human Impact on Carbon Burning fossil fuels release stored carbon into the atmosphere (as carbon oxides) Wildfires also return carbon from trees into the atmosphere (as carbon oxides)

Nitrogen Cycle

Nitrogen makes up 78.1% of the Earth’s atmosphere N2 is nitrogen gas

Nitrogen Fixation Some bacteria convert atmospheric nitrogen into ammonium these bacteria live in the lumpy roots of legumes and share their ammonium with the plants Plants share their glucose with the bacteria…

Ammonium also produced when decomposers break down organic matter (called ammonification) NH4  NO2-  NO3- Ammonium to nitrite to nitrate to be used by plants

Denitrification denitrifying bacteria convert nitrite or nitrate back to nitrogen gas occurs in environment with very little oxygen

Human Impact on Nitrogen Fertilizers contain nitrogen that may run off into water and create harmful algal blooms Burning fossil fuels contain nitrogen that leads to photochemical smog and acid rain

Wildfires convert N2 into usable nitrates, ammonia and ammonium. Wildfires also warm the soil making it less acidic allowing for greater growth of plants

Phosphorous Cycle

Phosphorous essential nutrient available in limited quantities concentrated in living organisms part of DNA and ATP

phosphorus does not cycle through the atmosphere found in soil and water and gradually released out of rocks

animals eat milk, grain, meat to get phosphorus plants can only use phosphorus if it’s a phosphate (PO4 3-) which dissolves in water

phosphorus keeps the growth of producers in balance, but it also limits the growth of crops how might the increased availability of phosphorus affect the aquatic ecosystem?

Algal Bloom overgrowth of algae caused by excess phosphorus as decomposers break down the organic matter, they use up the oxygen resulting in the death of fish