Test 1- Biogeochemical Cycling (Lecture 4) (CH #)

Biogeochemical Cycle

The ways in which nutrients flow from the nonliving to the living and back to the nonliving components of the ecosystem.

Nutrient Cycling

-Cycling of material elements vital to biological functions. -There are currently 40 nutrients known.

Key processes driving the water cycle? (5)

-Evaporation of liquid water by solar energy. (sun) -Condensation of water vapor into clouds. -Precipitation. -Transpiration by terrestrial plants moves significant amounts of water into the atm. -Groundwater flow returns water to the oceans.

Key processes of the Sulfur Cycle?

-Largest input of sulfur in the atmosphere is due to human activity. (Burning of fossil fuels, industrial). -Once in atmosphere, sulfur dioxide combines with water to give sulfuric acid, which is deposited back in the form of acid rain. (Causes environmental harm) -Sedimentary phase of the sulfur cycle is slow (human mining and extraction).

Key Processes of Nitrogen Cycle?

-Nitrogen enters ecosystems primarily through bacterial nitrogen fixation. -Some nitrogen is fixed by lightning and industrial fertilizer production. -Ammonification by bacteria decomposes organic nitrogen. -In nitrification, bacteria convert NH3 to NO3. -In denitrification, bacteria use NO3 for metabolism instead of O2, releasing N2.

The Nitrogen Cycle

-Nitrogen in the atmosphere is not useful for organisms due to the triple bond that most organisms can't break.

Biological Importance of Nitrogen Cycle?

-Nitrogen is a component of amino acids, proteins, and nucleic acids. -It may be a limiting plant nutrient.

Key processes of the Oxygen Cycle?

-Oxygen is a waste product of photosynthesis and that's how it gets into the atmosphere. -Humans and other organisms take in this O2 and release it as CO2 through respiration. -Oxygen is also indirectly transferred through an ecosystem by the cycling of other nutrients.

Human intervention into Oxygen Cycle?

-Ozone destruction in upper atmosphere. The ozone screens out 99% of harmful UV radiation so it's useful for us. There are chemicals that destroy the ozone. -Smog formation. Formed in the lower ozone atmosphere. Interaction with other pollutants forms smog which if the ozone was too low, when breathed in, is very harmful. -O2 use in aquatic systems due to eutrophication.

Biological importance of Phosphorus Cycle?

-Phosphorus is a component of nucleic acids, phospholipids, and ATP and other energy-storing molecules. -It is a mineral constituent of bones and teeth.

Key Processes of Carbon Cycle?

-Photosynthesis by plants fixes atmospheric CO2. -CO2 is added to the atmosphere by cellular respiration of organisms. -Volcanoes and the burning of fossil fuels add CO2 to the atmosphere.

Biologically available forms of Nitrogen Cycle?

-Plants and algae can use ammonium (NH4+) or nitrate (NO3). -Various bacteria can use NH4+, NO3, or NO2. -Animals can use only organic forms of nitrogen. *Diagram on page 2*

Major Reservoirs of the Phosphorus Cycle?

-Sedimentary rocks. -Phosphate deposits.

Major Reservoirs of Sulfur Cycle?

-Soil, sediments, rocks, and fossil fuels. (Sedimentary) -Small amount in atmosphere. (Gaseous)

Major Reservoirs of Carbon Cycle?

-Soils, oceans, organisms, and the atmosphere (CO2). -Gaseous and Sedimentary phases. *Subcycles of Carbon on Diagram.*

Oxygen in aquatic environments? (pg 59)

-The concentration of oxygen in aquatic environments limits respiration due to gases like O2 not diffusing as fast as they would in air. -In water, the amount of oxygen is greatest near the surface, where an interchange between water and atmosphere takes place. -The quantity of oxygen decreases with depth, as photosynthesis can no longer occur deep down without sunlight. -Gases are not soluble in water.

Human intervention into Nitrogen Cycle

-Use of soil nitrogen: due to fertilizers. -Eutrophication: Addition of excess nutrients to the water. -Carcinogenic Wastes: Cause cancer. -Ozone depletion -Air pollution: Acid rain, smog.

Key processes of the Phosphorus Cycle?

-Weathering of rocks gradually adds phosphate to soil. -Some phosphate drains into groundwater and surface water and moves to the ocean. -Phosphate taken up by plants from soil. -It is returned to soil through decomposers. *Phosphorus Cycle on Diagram*

Methods of Nitrogen Fixation?

1) Atmospheric Fixation 2) Biological Fixation 3) Industrial Fixation

Human Intervention into Phosphorus Cycle?

1) Eutrophication-addition of nutrients to the water system. 2) Use of available phosphorus for crops, detergent, etc. If we could recycle phosphorus, we could reduce eutrophication.

Basic types of Biogeochemical cycles

1) Gaseous cycles- The main pools of nutrients are the atmosphere and the oceans. Global. N, O, CO2. 2) Sedimentary cycles- The main pool is the soil, rocks, and minerals. Regional. P, Ca, S, K.

What are the different storage compartments for nutrient cycling?

1) Inactive, primarily abiotic reservoir such as atmosphere, ocean, and rocks. 2) Active, biotic exchange pool such as plants, animals, soil, and lakes.

Energy Flow

A unidirectional, open (new energy) system. All calories obtained by plants is new energy. Energy typically enters the Earth in the form of sunlight and exits in the form of heat.

Biogeochemical Cycle Example Discussed in Class?

Adding radioactive isotopes to certain elements help us trace them. Spraying Radioactivity P32 on ground showed how P32 was transferred from one trophic level to the next. First herbivores showed up, then decomposers, and then carnivores.

Macronutrients

Needed in large quantities. C, H, O, P, K, N, S, Ca, Fe, Mg. "C Hopkns cafe, mighty good"

Biologically available forms of Carbon Cycle?

Autotrophs convert carbon dioxide(CO2) to organic molecules that are used by heterotrophs and passed through food chains and webs.

Micronutrients

Needed in small quantities. Mo, B, Cu, Mn, Zn, Cl (Morning Bro, Comeon Man Join Class)

Human intervention into Carbon Cycle

Burning of fossil fuels and Deforestation lead to increase amounts of CO2 in the atmosphere. This could lead to a problem because when CO2 is in the air, it traps heat and keeps it from radiating into space. Without changes, Earth's temperature is projected to increase dramatically (GLOBAL WARMING).

Chemical Cycles

Circular, closed system (because the nutrients are being recycled and not lost). Most of the material in the system is reused.

Common Oxygen compounds?

H2O, CO, CO2, SO2, NO2, NO3, PO4, Rocks, Minerals *Oxygen cycle diagram*

Biological Importance of the Sulfur Cycle?

Important for the functioning of proteins and enzymes in plants.

Rhizobium Bacteria

Nitrogen fixing bacteria. Best nitrogen fixers. Live symbiotically. These bacteria infect the roots of leguminous plants, leading to the formation of nodules which is where N2 is fixed.

Reservoirs of the Hydrological Cycle? (4)

Oceans- 97% of earth's water Glacial ice- 2% Freshwater- 1% (groundwater, lakes, rivers, streams, biota, and atmosphere) Atmosphere-negligible amount

Biological Importance of Carbon Cycle?

Organic molecules have a carbon framework.

Is Nitrogen or Phosphorus more of a limiting factor?

Phosphorus because it takes a long physical process to release phosphorus from its storage compartment. Nitrogen has an atmospheric pathway, where as phosphorus doesn't exist in the atmosphere.

Major Reservoirs of Oxygen Cycle?

The atmosphere, so it's gaseous.

Major Reservoirs of the Nitrogen Cycle?

The atmosphere, therefore the cycle is gaseous.

Biologically available forms of Phosphorus?

The only biologically important inorganic form of phosphorus is phosphate (PO43-), which plants absorb and use to synthesize organic compounds.

Biological Importance of Water Cycle?

Water is essential to all organisms and its availability influences rates of ecosystem processes.

How are the gaseous and sedimentary cycles tied to the water cycle?

Water is the medium that moves elements and other minerals through the ecosystem. Without the cycling of water, other cycles would cease.