Transcript Nitrogen cycle - Katy Independent School District

CHOPKIN’S CaFe
 The primary source of the energy that
drives the cycles is the sun
 The water, nitrogen, phosphorus and
carbon cycles are closed systems.
Everything is kept within the system,
nothing leaves nor enters it
 So nutrients a not endless but are
recycled but in limited amounts
 Carbon, nitrogen and phosphorus have to be
recycled and reused and for this, they are called
biogeochemical cycles
 Nutrients such as nitrogen and phosphorus may be
carried away deep ocean and lost from the cycles.
Water Cycle
Water Cycle
Water Cycle
Water Cycle
Water Cycle
Water Cycle
Water cycle
 Earth has a stable water supply with 98% is in abiotic
features like oceans and lakes
 2% is in ice, water vapor and in living organisms
 The cycle is driven by the sun
 Solar heat causes evaporation from bodies of water
 Solar heat also causes transpiration from trees
 Evapotranspiration is evaporation from soil and plants
 Water is drawn into the atmosphere by evaporation
and falls back to earth by precipitation.
 Rain, sleet, hail and snow are four different means
of precipitation
 There is a constant movement of water through the
biotic and abiotic reservoirs
 Runoff may take a long time to reenter the water
cycle if it seeps down into the soil and into an
underground aquifer,(underground reservoir)
Nitrogen cycle
 NH3 ammonia = NH4 ammonium = NO2 nitrite = NO3
nitrate = N2
 Nitrogen is one of the most essential elements on
earth. All living things have N in their amino acids.
 78% of it is in the atmosphere and is unusable
 Instead is used in forms of ammonia and nitrates
 Used in fertilizers that help plants to grow
 In aquatics, N as a major nutrient for aquatic
lifeforms is our concern
 Can be toxic in high concentrations (ammonia)
 The cycle begins with nitrogen fixation
 Nitrogen is fixed chemically by being converted to
ammonium NH4
 Specialized bacteria only can accomplish this but is a very
slow process. Requires an entire season
 It can be artificially done with CH4, methane
 Ammonification, nitrification and assimilation
 Ammonification – caused by water or soil
saphrophytes or decomposers
 Decompose organic compounds and release
ammonium to be used by plants and
phytoplankton
 Nitrification – occurs when other nitrogen-fixing
bacteria oxidize ammonia or ammonium to
produce energy used to make nitrite NO2.
 This is toxic to fish and plants. Another type of
bacteria convert it to nitrate NO3
 Assimilation – when organisms utilize ammonium or
nitrate within their cells to build protein.
 Protists and animals die, urinate of defecate, they
release their nitrogen compounds back to the earth
where saprobes decompose the material to simpler
forms
Nitrogen cycle
Nitrogen cycle
Nitrogen cycle
Nitrogen cycle
Nitrogen cycle – Important
steps
 Stage1 – Entry and Accumulation
Ammonia is introduced into the water via tropical fish waste, uneaten
food, and decomposition. These will break down into ammonia (NH3).
Ammonia is harmful to tropical fish.
 Stage2 – Nitrification Part 1
Soon, bacteria called nitrosomonas will develop and they will oxidize the
ammonia essentially eliminating it. The byproduct of ammonia oxidation
is Nitrites. So we no longer have ammonia, but we now have another
toxin to deal with - Nitrites. Nitrites are just as toxic to tropical fish as
ammonia.
 Stage 3 – Nitrification Part 2
Bacteria called nitrobacter will develop and they will convert the nitrites
into nitrates. Nitrates are not as harmful to tropical fish as ammonia or
nitrites, but nitrate is still harmful in large amounts.
 Stage 4 - Denitrification
Denitrifying bacteria can breakdown nitrates into harmless nitrogen gas
that escapes through the surface of the water.
Nitrogen cycle – Impact on
oceans
 Human activities have a significant
effect on nitrogen cycling. Production
and use of nitrogen fertilizer, combustion
of fossil fuels, and planting crops that fix
nitrogen have unbalanced the
previously stable relationship between
fixation and denitrification. Gaseous
industrial pollutants foul the air in many
cities and wash out in sufficient amounts
to constitute “acid rain” in some parts of
the industrialized world.
Nitrogen – Regulating in an
aquarium
 For a short period of time, a new aquarium is a toxic
cesspool. The water may look clear, but don't be fooled. It's
loaded with toxins. Fortunately ,bacteria that are capable of
converting wastes to safer by-products begin growing in the
tank as soon as fish are added. Unfortunately there aren't
enough bacteria to eliminate all the toxins immediately, so
for a period of several weeks to a month or more, your fish
are at risk.
 Ways to cycle your tank:
1. Use fish food
2. Use substrate or filter media from an established tank
3. Use a liquid bacteria culture, such as Stress Zyme
Carbon Cycle
Carbon Cycle
Carbon Cycle
Carbon Cycle
Carbon Cycle
Carbon Cycle
 Found in aquatic environments as carbonate.
 Causes hard water by combining with calcium
 Will form as a precipitate in warm shallow seas, making
limestone
 Large amounts of carbon are tied up in rocks formed
by decomposition of plants and animals
 Biotic lifeforms use carbon as an essential element.
 Plants use CO2 to create glucose, starches & fats
 Deposits of buried organic compounds
 Sediments containing trees, skeletons, cell walls of
plankton end up at the bottom of lakes, oceans
 Eventually create coal, natural gas and petroleum
deposits
 Cellular respiration and decomposition of plant
tissue release Carbon into the atmosphere and are
short cycle processes
 Volcanic eruptions and human activities such as
burning fossil fuels quickly release C back into the
atmosphere
Carbon – Important steps
Stage 1 – Entry and accumulation
Carbon dioxide enters the waters of the ocean by simple
diffusion.
Stage 2 – Uptake
- Certain forms of sea life biologically fix bicarbonate with
calcium (Ca+2) to produce calcium carbonate (CaCO3). This
substance is used to produce shells and other body parts by
organisms such as coral, clams, oysters.
- Marine plants in the sunlit surface layer of the ocean grab
carbon dioxide from the air to use in photosynthesis
- When the plants die, they sink as so-called “marine snow”
to the deep ocean where the carbon is stored and
prevented from re-entering the atmosphere.
Stage 3
- At the surface of the oceans where the water becomes
warmer, dissolved carbon dioxide is released back into the
atmosphere.
Carbon – Impact on oceans
 In the aquatic ecosystem carbon dioxide can be
stored in rocks and sediments. It will take a long time
before this carbon dioxide will be released, through
weathering of rocks or geologic processes that bring
sediment to the surface of water.

Carbon dioxide that is stored in water will be present
as either carbonate or bicarbonate ions. These ions
are an important part of natural buffers that prevent
the water from becoming too acidic or too basic.
When the sun warms up the water carbonate and
bicarbonate ions will be returned to the atmosphere
as carbon dioxide.
Phosphorus Cycle
 Our atmosphere contains no phosphorus
 Mainly found as phosphates in the earth’s crust then
released into the soil after it rains.
 Similar to hydrolysis but is really carbonation
 Plants use phosphates in the soil and animals eat plants
recycling the phosphorus
 Phosphorus is present in fertilizers and can over-enrich
aquatic environments and cause algae blooms
 Bacteria respond and grow consuming oxygen and
causing fish kills and eutrophication
 Phosphorus remains a phosphate mineral deposit in
the oceans until any geological uplift exposes it at
the surface, (plate tectonics)
 Eutrophication is an increase in the concentration
of phosphorus, nitrogen and other plant nutrients in
lakes or oceans
Phosphorus Cycle
Phosphorus Cycle
Phosphorus Cycle
Phosphorus Cycle
Phosphorus – Impact on oceans
 Phosphorus is usually present in natural water
as phosphates.
 Phosphorus is a plant nutrient needed for
growth and a fundamental element in the
metabolic reactions of plants and animals
(hence its use in fertilizers).
 Sources of phosphorus include human and
animal wastes (i.e., sewage), industrial wastes,
soil erosion, and fertilizers.
 Excess phosphorus causes extensive algal
growth called "blooms," which are a classic
symptom of cultural eutrophication and lead
to decreased oxygen levels in various bodies
of water.
Phosphorus – Important Steps
 Stage 1 – Entry and accumulation
 Phosphorus is not highly soluble, binding tightly to molecules in
soil, therefore it mostly reaches waters by traveling with runoff
soil particles
 Weathering is the breaking down of rocks, soils and minerals
through direct contact with the water
 Leaching is the loss of mineral and organic solutes due to
percolation from soil
Stage 2 – Uptake
 Plants dissolve ionized forms of phosphate. Herbivores obtain
phosphorus by eating plants, and carnivores by eating
herbivores. Herbivores and carnivores excrete phosphorus as a
waste product in urine and feces.
Stage 3 – Decomposition, Sedimentation, and Uplift
 Phosphorus is released back to the soil when plants or animal
matter decomposes
 The final resting place for Phosphorus is in the ocean
sedimentary beds, where it will eventually return to use via
uplifting of sedimentary rock.
Phosphorus – Regulating in
an aquarium
 Fortunately phosphates do not directly harm your fish, even
at high levels. However, the algae blooms that result from
elevated phosphates can ultimately cause problems for
the aquarium inhabitants. For instance, green water can
deplete the oxygen, which in turn can harm the fish.
 Techniques to regulating phosphorus levels:
1. Water Change – Large water changes will help bring
phosphates
down quickly, but if the underlying sources
are still there, it will only
be temporary
2. Tank Cleaning – Scrape the inside of the glass, remove
the rocks and other decorations and scrub them well
3. Phosphate Absorber – Phosphate absorbing media is
very
effective. It can be added to virtually any filter.
NOTE: Generally using chemicals should be your last resort.
Water – Important steps
 The major physical components of the global
water cycle include the evaporation from the
ocean and land surfaces, the transport of
water vapor by the atmosphere, precipitation
onto the ocean and land surfaces, the net
atmospheric transport of water from land areas
to ocean, and the return flow of fresh water
from the land back into the ocean. The
additional components of oceanic water
transport are few, including the mixing of fresh
water through the oceanic boundary layer,
transport by ocean currents, and sea ice
processes
 Evaporation – Precipitation + Runoff = surface
salinity of the ocean
Water – Impact on oceans
 The ocean holds 97% of the total water on the
planet. Besides affecting the amount of
atmospheric water vapor and hence rainfall,
evaporation from the sea surface is important
in the movement of heat in the climate
system.
 The ocean is one of Earth's most valuable
natural resources. It provides food in the form
of fish and shellfish—about 200 billion pounds
are caught each year. It's used for
transportation—both travel and shipping. It
provides a treasured source of recreation for
humans. It is mined for minerals and drilled for
crude oil.
Oxygen Cycle
Figure 1. Oxygen dynamics in coastal waters. Processes that increase dissolved oxygen concentrations are shown with
green boxes. Processes that decrease dissolved oxygen concentrations are shown with orange boxes.
Oxygen – Important steps
Stage 1 – Entry
-diffusion; oxygen is constantly entering the water from
the air, aeration; oxygen is circulated through and
dissolved in water, and photosynthesis by plants and
algae
Stage 2 – Uptake
Respiration by animals and degassing – breaking
down CO2 and other compounds
Stage 3 – Removal
oxygen leaves the ocean surface and enters the
atmosphere by diffusion
Oxygen – Impact on oceans
 Oxygen in water is known as dissolved oxygen or DO.
 Adequate dissolved oxygen is necessary for good water
quality. Oxygen is a necessary element to all forms of life.
Many natural processes require adequate oxygen levels
in order to provide for aerobic life forms.
 Fish and aquatic animals cannot split oxygen from water
(H2O) or other oxygen-containing compounds. Only
green plants and some bacteria can do that through
photosynthesis and similar processes. Virtually all the
oxygen we breath is manufactured by green plants. A
total of three-fourths of the earth’s oxygen supply is
produced by phytoplankton in the oceans.