Chemicals are recycled between organic matter and abiotic reservoirs

– Nutrients recycle between• Organisms and abiotic reservoirs• 4 basic steps in cycling

Consumers

Producers

Nutrientsavailable

to producers

Abioticreservoir

Detritivores

3

2

1

4

Figure 37.15

Biochemical Cycles• Involve both abiotic and biotic components• Can be local or global cycles

• Soil is main reservoir in local cycles (Phosphorus)• Air or Gases are reservoirs in global cycles (Carbon,

Nitrogen & Water)

Water moves through the biosphere in a global cycle– Solar heat

• Drives the global water cycle of precipitation, evaporation, and transpiration

Transportover land

Solar energy

Net movement ofwater vapor by wind

Runoff andgroundwater

Percolationthroughsoil

Precipitationover land

Evaporation andtranspiration fromland

Precipitationover ocean

Figure 37.16

Evaporationfrom ocean

What does the level of the chemicals we’re testing tell us about the Chaska

Creek?• We will test:

– Ammonia– Dissolved Oxygen– Carbon Dioxide– pH– Nitrates– Phosphates– Total Hardness

CO2 in atmosphere

Photosynthesis

Cellularrespiration

Burning offossil fuelsand wood

Carbon compoundsin water

Detritus

Primaryconsumers

Higher-levelconsumers

Decomposition

The carbon cycle depends on photosynthesis and respiration– Carbon is taken from the atmosphere (CO2)by photosynthesis

• Used to make organic molecules, and returned to the atmosphere by cellular respiration

» Carbon compounds in animal waste, plant litter & dead organism is consumed by detritivores and they return the carbon via cellular respiration.

Figure 37.17

Why measure Dissolved Oxygen?• O2 is essential to life• Sources are photosynthesis and air (surface

current)– The higher the stream flow the more dissolved oxygen

• Depleted by – Decomposition of dead organisms and waste– Respiration of plants and animals

• Lower the temperature the more O2 water can hold.

• Warm water fish need 02 levels of 4 ppm (parts per million)

• Cold water fish (trout, walleye) need 02 levels of 5 ppm

Why measure Carbon Dioxide (CO2)?

• CO2 is needed for photosynthesis

• Co2 is harmful in high concentrations.– Fish must get ride of CO2 and take in O2

– Very hard to do is CO2 is in high concentrations

• CO2 is 200 times more soluble in water as O2

• Normally less than 10 ppm in streams

Why measure pH?

• pH is a measure of acidity (7 is neutral, 1 is the most acidic and 14 is the least acidic “basic”)

• Problems occur if more acidic than 5 and more “basic” than 8.5)

• CO2 from cellular respiration and decomposition lowers pH, so polluted water is typically more acidic (because of higher rate of decomposition)

• You may need to use it determining ammonia levels. (we’ll talk about this later)

Nitrogen in atmosphere (N2)

Nitrogenfixation

Nitrogen-fixingbacteria in rootnodules of legumes

Detritivores

Decomposition

Ammonium (NH4+)

Nitrates(NO3

–)

Assimilationby plants

Denitrifyingbacteria

Nitrogen-fixingsoil bacteria

Nitrifyingbacteria

The nitrogen cycle relies heavily on bacteria– Various bacteria in soil

• Convert gaseous N2 to compounds that plants use: ammonium (NH4

+) and nitrate (NO3–)

– Detritivores• Decompose organic matter and recycle nitrogen to plants

An ingredient of proteins & nucleic acids = important to organisms

Atmosphere is 80% Nitrogen, making it a large reservoir

Figure 37.18

Why measure Nitrates?• Nitrates are essential for plant growth• High levels are signs of pollution from fertilizer or

sewage• Too much nitrate = algal blooms = decrease in

oxygen levels– Nitrate is a limiting factor on plant growth– Decreases oxygen because oxygen is used up in the

process of decaying all the algal growth and cellular respiration of animals

• Good levels would be under 1 mg/L• High levels can cause “Blue Babies” – umbilical

cord around neck

Why measure Ammonia?• Ammonia is a major metabolic waste produce from

fish• Important to test because even small amount can

cause stress to fish and damage their gills• Two types in water:

– Total Ammonia (NH4+) – Ionized Ammonia– Unionized Ammonia (NH3) – this is toxic to fish

• Temperature and pH effect how much of this is present

• Sources of ammonia in waters include:– runoff of animal wastes – fertilizers from farm land– the discharge of sewage effluents– dairy shed effluents– food-processing wastes such as those from freezing works.

Ammonia Continued…

• Test kit will measure Total Ammonia (Ionized Ammonia)

• Ammonia levels should be at ZERO• If not at zero we have to use temperature and

pH to calculate the Unionized Ammonia levels using this chart…

Total Ammonia (level from kit) x multiplication factor (from table) = Unionized Ammonia Level

Levels higher than .05 mg/l = fish being damaged

Levels 2.0 mg/l or higher = fish will die

How to manage an Ammonia Problem

• Add phosphorus to the water– Will increase plant growth– Plants will recycle the ammonia in the water– This should only be done in small amount,

because of the risk of creating an algae bloom

Weatheringof rocks

Geologicupliftof rocks Runoff

Sedimentation

Leaching

Soil

Plant uptakeof PO4

3–

Consumption

Decomposition

Rain

Plants

The phosphorus cycle depends on the weathering of rock (rock & soil is the reservoir)

– Phosphorus and other soil minerals• Are recycled locally• In soil they are inorganic• Plant convert them into organic compounds for

consumers to eat

Phosphorus is an ingredient of nucleic acids, phospholipids, and ATP.

It is a mineral component of teeth & bone.

Figure 37.19

Why measure Phosphates?

• Enters waterways from – waste – Detergents – Poorly treated sewage– Disturbed soil (construction sites)

• Usually less than .1 ppm (part per million)• Algae and plants take in phosphates easily so

its hard to detect the source• Can cause algal blooms and eutrophication

(Death of a Lake)

Why measure Total Hardness?

• It’s a measure of calcium and magnesium• Source is rock and soil

– 0-50ppm = soft water– 50 – 100 ppm = moderately hard– 200 + = very hard water

• Algae prefer hard water• Fish are stimulated to spawn when water

softens after a heavy rain or melting snow!