Matter Cycles Through The Biosphere

Mr. Alvarez

September 29, 2014

Biosphere

Biosphere- the region of our planet where life resides

Biogeochemical Cycles- the movements of matter within and between ecosystems involve biological, geological, and chemical processes.

The Hydrologic Cycle

Hydrologic Cycle- The movement of water through the biosphere

Transpiration- The release of water from leaves

during photosynthesis

Evapotranspiration- the combined amount of evaporation and transpiration

Runoff- Water moving across the land surface and into streams and rivers, eventually reaching the ocean

Carbon Cycle

• There are 4 main types of processes that move carbon through its cycle

1. Biological processes, such as photosynthesis, respiration and decomposition, that take up and release Carbon and Oxygen

Carbon Cycle cont.

2. Geochemical processes, such as erosion and volcanic activity, release CO2 to the atmosphere and oceans

3. Mixed processes, such as the burial and decomposition of dead organisms and their conversions under pressure into coal and petroleum (fossil fuels), store carbon underground

Carbon Cycle cont.

4. Human activities such as mining, cutting and burning forests, and burning fossil fuels, release carbon dioxide into the atmosphere

Top Carbon Storage Reservoirs:

1. Marine sediments & rocks (& shells)

2. Oceans (dissolved)

3. Fossil Fuels

4. Soil organic matter

5. Forests

Macronutrients

Macronutrients- Six key elements that organisms need in relatively large amounts

Nitrogen

Phosphorus

Potassium

Calcium

Magnesium

Sulfur

Nitrogen

Limiting Nutrient- a nutrient required for growth of an organism but available in a lower quantity than other nutrients

Nitrogen is used to form amino acids, building blocks of proteins and nucleic acids (DNA and RNA)

Make up 3 percent of total body weight

Nitrogen Fixation

• Earth’s atmosphere is 78 percent Nitrogen by volume – Most of this is in gaseous form, N2, which is

unusable

Nitrogen Fixation- converting N2 gas directly into ammonia (NH3) First step in the nitrogen cycle

Occurs in organisms such as cyanobacteria and certain bacteria that live within the roots of legumes (peas, beans, some trees)

Nitrogen Fixing Organisms

• Nitrogen-fixing organisms use the fixed nitrogen to synthesize their own tissues, then excrete excess – Cyanobacteria = water – Bacteria living within plant roots = soil

• Plant provides glucose to bacteria

• Organisms that fix nitrogen can break N2 bond using enzymes – Also adds hydrogen to make NH3

– NH3 is converted into its ionic form, ammonium (NH4+) in the soil

Two Abiotic Ways of Nitrogen Fixation

1. Lightning or combustion reactions convert N2 into Nitrate (NO3

-), which is usable by plants

– Nitrate is carried to earth’s surface during precipitation

2. Humans synthesizing Nitrogen Fertilizers

– Humans now fix more nitrogen than is fixed in nature

Nitrogen Cycle continued

• After producers obtain fixed nitrogen, the assimilate it into their tissues (step 2)

• Consumers obtain nitrogen by eating producers

• Then, producers and consumers die and decompose (step 3)

– Ammonification- fungal and bacterial decomposers use nitrogen-containing wastes and dead bodies as a food source and excrete ammonium

Nitrogen Cycle cont.

Nitrification- nitrifying bacteria converts ammonium into nitrite (NO2

-) and then into nitrate (NO3

-) (step 4) Leaching- the transportation of dissolved

molecules through the soil via groundwater Nitrate ions are repelled by negatively charged soil

particles

Denitrification- bacteria convert nitrate in a series of steps into gases nitrous oxide (N2O) and eventually N2. This is emitted into the atmosphere

Human Impacts on N cycle:

1.Commercial fertilizer overuse

(fixed-N) = mobility

– Eutrophication & fish kills

– Groundwater contamination

Human Impacts on N cycle 2.Combustion of Fossil Fuels

NOx emissions from autos

Global warming & Ozone depletion

Photochemical smog

Acid rain

Phosphorus

• Phosphorus is a major component of DNA and RNA as well as ATP

• Limiting Nutrient second only to Nitrogen

• Also added to soil in the form of fertilizer

• Weathering of rocks is a natural source of phosphorus

The Phosphorus Cycle

Excess Phosphorus

Algal Bloom- rapid growth of algae – Can result from adding even small amounts of

Phosphorus to aquatic ecosystems

• Algal Blooms quickly increase the amount of biomass in the ecosystem

• Algae eventually dies, initiating a massive amount of decomposition, which consumes a large amount of oxygen which leads to Hypoxic Conditions – Hypoxic Conditions- areas of low oxygen

Disturbance

• Disturbance- an event caused by physical, chemical, or biological agents that results in changes in population size or community composition

Types of Disturbances

Natural

• Hurricanes

• Ice storms

• Tsunamis

• Volcanic Eruptions

• Forest Fires

Anthropogenic Disturbances

• Human Settlements

• Agriculture

• Air pollution

• Clear-cutting of Forests

• Removal of entire Mountaintops for Coal Mining

Watershed Studies

• Watershed- all of the land in a given landscape that drains into a particular stream, river, lake or wetland

Resistance versus Resilience

• Resistance- the measure of how much a disturbance can affect the flows of energy and matter – When a disturbance influences populations and

communities, but has no effect on the overall flows of energy and matter = high resistance

• Resilience- the rate at which an ecosystem returns to its original state after a disturbance – A highly resilient ecosystem returns to its original state

rapidly

• Restoration Ecology- A new scientific discipline that is interested in restoring damaged ecosystems

Intermediate Disturbance Hypothesis

• Intermediate Disturbance Hypothesis- ecosystems experiencing intermediate levels of disturbance are more diverse than those with high or low disturbance levels

Ecosystem Services

• Instrumental Value- something that has worth as an instrument or a tool that can be used to accomplish a goal – The value of items such as lumber or

pharmaceutical drugs

• Intrinsic Value- something that has worth independent of any benefit it may provide humans – Moral value of an animal’s life

Provisions

Provisions- goods that humans can use directly

Lumber

Food crops

Medicinal plants

Natural rubber

Furs

Regulating Services

Regulating Services- The service provided by natural systems that helps regulate environmental conditions.

Support Systems

Support Systems- The support services that natural ecosystems provide such as pollination, natural filters and pest control.

Resilience

Resilience- Resilience of an ecosystem ensures that it will continue to provide benefits to humans. This greatly depends on species diversity.

Cultural Services

Cultural services- Ecosystems provide cultural or aesthetic benefits to many people