Nitrogen cycle - PowerPoint Presentation

Slide1

Nitrogen cycleSlide2

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.

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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. Slide4

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

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Phosphorus CycleSlide6

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 – UptakePlants 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.Slide7

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.Slide8

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. Slide9

Carbon CycleSlide10

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

(CaCO

3

). 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.Slide11

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.Slide12

Carbon – Regulating in an aquarium

Carbon is considered chemical filtration. The effectiveness of activated carbon is based on a three-step process.

The first is

adsorption

. Static forces will attract particles and bacteria adsorbing them onto the surface of the carbon. Bacteria that settle on the carbon surface will further consume the waste.

Another process is the diffusion of gases. Absorbed into the carbon, the gases are detoxified. The third process is called

chemisorption

, where particles are irreversibly bound to the carbon and are used to attract other toxins.Slide13

Water CycleSlide14

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 oceanSlide15

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.Slide16

Water – Regulating in an aquarium

When cleaning your aquarium, you should just remove part (10-15%) of the water and replace it with fresh,

dechlorinated

tap water. While you are doing this, you should use your

siphon

to suck up some of the gunk that collects in the gravel and decorations.Slide17

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.Slide18

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 algaeStage 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 diffusionSlide19

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.Slide20

Oxygen – Regulating in an aquarium

The exchange of oxygen is facilitated by water movement. In the aquarium, this movement is created by the flow of water exiting from the filter or by the bubbles that arise from air circulated by a motorized pump through porous aerating devices known as “air stones.” The oxygen that is contained in the bubbles created by air stones or other forms of mechanical filtration is lost to the air and does not add to the dissolved oxygen content of the water. By disturbing the water surface, these bubbles and other forms of water movement create turbulence, which allows atmospheric oxygen to dissolve into the water.