Nutrient Cycles II: Sulfur and Phosphorus Flashcards
Importance of studying nutrient cycles?
All living organisms are made up of chemical elements
What is the importance of studying nutrient cycles ?
- We can describe ecosystem functioning or community organization by looking at chemical/nutrient flow through the system
- Chemical Nutrients (C,P,S,Fe,etc.) influence primary & secondary productivity of species, communities
- Humans are altering nutrient pools and nutrient cycles, so it is important to measure and understand this
What is Biogeochemical (nutrient) Cycle?
-Movement of chemical elements around an ecosystem via physical and biological processes
What is the purpose of these biogeochemical (nutrient) cycles?
- Nutrients cycle and recycle throughout the ecosystem, and get used over and over again
- For a sustainable ecosystem, nutrient input should equal output but humans are altering balance, either by removal or addition of nutrients
Local Nutrient Cycle Characteristics
- small scale (population or community)
- Phosphorus
- Do not include gaseous phase
Global Nutrient Cycle Characteristics
- Large scale (ecosystem, biosphere)
- O, N, C
- Include gaseous (volatile) phase
- Summation of local cycles
What is Pool?
Mass of element or molecule in a given location or chemical state (units of mass)
-I.e. amount of S in the atmosphere or amount of iron sulfide (FeS2) in the ocean sediment
What is Flux?
Rate of movement into or out of pool (units of mass/ time)
What is Mean Residence Time (MRT)?
Pool divided by flux, average amount of time spent by a single molecule in the pool (units of time)
What is Turnover Rate?
Inverse of MRT, cycles through pool per unit time (units of time -1)
How do Nutrients Enter an Ecosystem?
Physical Processes and Biological Processes
What are the two Physical Processes?
Meteorological and Geological
How do nutrients enter through meteorological?
- Dissolved matter in rain, snow
- Atmospheric gases
- Dust blown by the wind
How do nutrients enter through geological?
- Weathering of rocks, soil
- Elements in water drainage
How do nutrients enter through Biological processes?
movement of animals between ecosystems
Important Facts of Nutrients Entering an Ecosystem
- All nutrients sourced from either minerals in rocks or gases from the atmosphere
- Nutrients taken up by organisms, changed into different forms
- Nutrients repeatedly cycle through an ecosystem
What is the Sulfur Cycle?
Processes by which sulfur moves to and from the environment (minerals, atmosphere) and living organisms
How is Sulfur an essential element?
- Key component in proteins
- Hydrogen sulfide (H2S) for anoxygenic photosynthesis
What are the 6 forms of Sulfur?
- Organic sulfur (contain C backbone with H)
- S^2- (sulfide)
- SO4^2- (sulfate)
- H2S (hydrogen sulfide)
- SO2 (sulfur dioxide)
- (CH3)2S (dimethyl sulfide,DMS)
Dimethyl Sulfide (DMS): Lovelock 1987
- Sourced from blooms of phytoplankton on ocean surface
- Distinct smell to gas- “smell of the shore” or “smell of the sea”
- Seabirds have olfactory cue to find blooms by scent of gas
- Large source of sulfur that goes into atmosphere as gas
- DMS helps drive cloud formation, which may help cool the planet by blocking solar radiation
- DMS production may increase under climate change
What are Some Human Alterations to the Sulfur Cycle?
- Acid Rain
- Burning of fossil fuels has impacted S cycle more than any other nutrient cycle
- Human produce 160% of natural S emissions to atmosphere
What is the Phosphorus (P) Cycle?
Processes by which phosphorus moves to and from the environment and living organisms
-P compounds are usually solids, so atmosphere is not a significant pool or step of P cycle
How is Phosphorus an Essential Element?
- ATP & DNA backbone
- P is limiting for primary producer and microbial growth
What are the Biological Inputs of P Cycle?
From organisms (short, local)
