Nutrient Cycles and Carbon Cycle

Study Notes

Nutrient cycles have three stages: input, throughput, and output
Input: nutrients enter an organism through various means, such as breathing or eating
Throughput: nutrients are used by the organism for growth and function
Output: waste matter is eliminated and unneeded nutrients are returned to the environment

The carbon cycle involves the movement of carbon between the atmosphere, plants, animals, and the ground
Carbon flows from the atmosphere to plants and oceans, then to animals, and finally to the ground and fossil fuels
Carbon sequestration is the process by which carbon sinks remove CO2 from the atmosphere

The nitrogen cycle involves the movement of nitrogen between the atmosphere, soil, water, plants, and animals
Nitrogen flows from the atmosphere to soil and water, then to plants and animals, and finally back to soil and water

Short-term carbon stores include living things, rotting tissues, the atmosphere, and plants
Long-term carbon stores include underground oil, natural gas, coal, sedimentary rock limestone, and the ocean floor

Human activities, such as burning fossil fuels and deforestation, affect the carbon cycle
Burning fossil fuels releases CO2 into the atmosphere, increasing the concentration of CO2 by 30% in the past 160 years
Deforestation releases CO2 into the atmosphere, as trees absorb CO2 during their growth

Human activities, such as industrial fertilizers and automobile emissions, disrupt the nitrogen cycle balance
Industrial fertilizers harm soil and trees, while nitrogen gases from industries and automobiles cause acid precipitation
Excess nitrogen ends up in ecosystem water

The water cycle involves the movement of water between the atmosphere, land, and oceans
The process includes evaporation, condensation, precipitation, and infiltration
Only 3% of the Earth's water is freshwater, and most of it is found in glaciers and ice caps

Human activities affect the water cycle, reducing the availability of freshwater

Phosphorus helps form important molecules like DNA and RNA
Phosphorus exists in the form of inorganic phosphate, which is released into the soil and water as sedimentary rock is eroded
Human activities, such as mining phosphate rock for fertilizers and detergents, impact the phosphorus cycle
Phosphorus is not found as a gas and takes millions of years to replenish
Cultural eutrophication, caused by livestock waste and municipal sewage, leads to eutrophication

The greenhouse effect involves the trapping of heat by greenhouse gases, such as CO2 and methane
The increased concentration of greenhouse gases due to human activities, such as burning fossil fuels, accelerates climate change

Eutrophication: excess nutrients in a lake, leading to increased plant growth and decomposition
Nitrogen runoffs in lakes and ponds increase plant growth, hindering deeper photosynthesis, leading to decomposers feeding on decaying matter, causing further oxygen decline and animal death

A simple food web consists of four stages: producers, primary consumers, secondary consumers, and tertiary consumers
Producers: plants and algae that convert sunlight into energy
Primary consumers: herbivores that feed on producers
Secondary consumers: carnivores that feed on primary consumers
Tertiary consumers: apex predators that feed on secondary consumers