Ecological Cycles Nitrogen, Carbon-Oxygen, Phosphorus, Sulfur.
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Transcript of Ecological Cycles Nitrogen, Carbon-Oxygen, Phosphorus, Sulfur.
Ecological Cycles
Nitrogen, Carbon-Oxygen, Phosphorus, Sulfur
The Nitrogen cycle
The Nitrogen Cycle
Nitrogen is used by living organisms to produce a number of complex organic molecules like amino acids, proteins, and nucleic acids.
78% of the world’s atmosphere is nitrogen Despite its abundance in the atmosphere,
nitrogen is often the most limiting nutrient for plant growth. This problem occurs because most plants can only take up nitrogen in two solid forms: ammonium ion (NH4+ ) and the ion nitrate (NO3- ) and CONNOT use raw atmospheric nitrogen
Four processes participate in the cycling of nitrogen through the biosphere:
nitrogen fixation atmospheric fixation by lightning biological fixation by certain microbes industrial fixation – making ammonia
decay (ammonification) – bacteria convert dead matter and wastes into ammonia
nitrification – bacteria convert ammonia into nitrates and nitrites
denitrification – bacteria return nitrogen to the atmosphere
Human Influence on Nitrogen Cycle
artificial nitrogen fertilization planting of nitrogen fixing crops N2O has risen in the atmosphere as a
result of agricultural fertilization, biomass burning, cattle and feedlots, and other industrial sources (N2O also destroys ozone)
eutrophication
Water Cycle
Water Cycle – Man’s Influence
Tropical Rain Forest – deforestationLess trees = less tramsiration = less water
in atmosphere = less rainOlalla Reservoir
Huge groundwater store in central U.S.Being depleted faster than replenished
Carbon Cycle
Carbon Cycle
O.03 carbon dioxide in atmospherePlants take in CO2 and release O2 in
PHOTOSYNTHEISAnimals take in O2 and release CO2 in
CELLULAR RESPIRATIONDecay also release CO2 into the
atmosphere
Man’s Influence on Carbon Cycle
Burning fossil fuels releases CO2 into atmosphere
Cellulose in dead plant material is hard to breakdown (too big)
Accumulates undecomposed over time forming peat
Peat over time and under pressure forms fossil fuels
When fossil fuels are burned – releases carbon
Sulfur Cycle
SulfurComponent of proteinsComponent of vitamins
Most sulfur is in rock and mineral slatsReleased naturally into atmosphere from
volcanoes and decomposition in wetlands
In atmosphere, SO2 reacts with water to produce sulfuric acid
Man’s Influence
We release excess SO2 into the atmosphere by:
Burning fossil fuelsRefining petroleum productsMining processes
Chemosynthesis
Ocean vents in trenchesBacteria use hydrogen sulfide H2S as
energy source
Phosphorus Cycle
Phosphorus important inDNA moleculesATPCell membranesBonesTeethshells
Slow cycleNot much in atmosphere – but in soil,
rock, and waterBig water component
Phosphorus Cycle