Unit 1: The Living World (Ecosystems) 1.5-1.6

biogeochemical cycles

-Matter moves within and between ecosystems through cycles of biological, geological, and chemical processes

Reservoirs vs Sinks

-Storage big vs storage small

Steady State

a state in which inputs equal outputs, so that the system is not changing over time

Carbon Cycle: Steps

-Moves carbon primarily through the atmosphere and biosphere (though all four spheres are involved)

-Photosynthesis

-Respiration (aerobic)

-Exchange

-Sedimentation

-Burial

-Extraction

-Combustion

Photosynthesis

-Plants using solar energy to convert carbon dioxide and water into glucose and oxygen

Respiration (aerobic)

-Cells convert glucose and oxygen into energy, carbon dioxide, and water

Exchange

-Carbon flowing between atmosphere and ocean

-The amount of carbon released from the ocean into the atmosphere roughly equals the amount of atmospheric CO2 that diffuses into ocean water

Sedimentation

-Formation of limestone and dolomite rock from CaCO3

-Shells, coral

-Can lead to ocean acidification

Burial

-Dead biomass incorporated into ocean sediments before decomposing

Extraction

-Taking out of fossil fuels

Combustion

-Release of carbon into atmosphere or environment

-Humans and volcanoes

-Greenhouse effect --> atmosphere keeps heat in (good)

-Global warming --> heat 2 much (bad)

Nitrogen Cycle: Steps

-Allows for the movement of nitrogen around mainly the biosphere via reservoirs and sinks (though all four spheres are involved)

-The atmosphere is 78% nitrogen

-Nitrogen fixation

-Nitrification

-Assimilation

-Mineralization/Ammonification

-Denitrification

Nitrogen fixation

-Atmospheric nitrogen N2 into forms of nitrogen that plants and algae can use

-Abiotic: Lightning or combustion converts N2→ NO3-

-Biotic: Bacteria (cyanobacteria, bacteria in roots of legumes) convert N2→ NH3 → NH4+

Nitrification

-Conversion of ammonium NH4+ into nitrite (NO2−) into nitrate (NO3−) by nitrifying bacteria

Assimilation

-Plants and algae incorporate nitrogen into their tissues.

Mineralization/Ammonification

-Fungal and bacterial decomposers break organic matter in dead bodies and waste products back into inorganic compounds such as ammonium NH4+

Denitrification

-Nitrate (NO3−) into nitrous oxide (N2O) and eventually, nitrogen gas (N2) --> emitted back into the atmosphere

-Done by anaerobic bacteria

Nitrogen Cycle - Human Impacts

-Nitrogen = limiting factor

-Fertilizers --> Eutrophication

-Leaching - dissolved molecules transported to groundwater through the soil.

-Mining removes nitrogen from the crust/soil

-Municipal sewage may add excess nitrogen to aquatic ecosystems

Phosphorus Cycle: Steps

- Major component of DNA, RNA, and ATP--> limiting reactant

-Does not have an atmospheric component --> travels/cycles relatively slowly

-Assimilation

-Mineralization

-Sedimentation

-Geologic uplift

-Weathering

Assimilation

-Plants and animals on land and in the water take up inorganic phosphate and assimilate the phosphorus into their tissues as organic phosphorus

Mineralization

-Breakdown of organic phosphorus back to inorganic phosphorus

Sedimentation

-Insoluble phosphate precipitates out of the solution in the form of phosphate-laden sediments in the ocean

Geologic uplift

-Rocks push up against each other exposing phosphorus from below.

Weathering

-Rainfall, precipitation, etc breaking down phosphorus

Phosphorus Cycle - Human Impacts

-Fertilizers --> eutrophication/algal blooms (we want low nutrient inputs and high cycling)

-Detergents

Dead Zones

-Areas where the deep water is so low in dissolved oxygen that sea creatures cannot survive (except for some specialized bacteria)—have grown in the past half-century

Hydrologic (Water) Cycle: Steps

-Transpiration

-Evaporation

-Evapotranspiration

-Runoff

-Infiltration

-Condensation

-Precipitation

Transpiration

-The release of water from leaves into the atmosphere during photosynthesis.

Evaporation

-Liquid water turns to water vapor

Evapotranspiration

-The combined amount of evaporation and transpiration.

Runoff

-Water that moves across the land surface and into streams and rivers.

Infiltration

-Water is absorbed by the soil and percolates down into the groundwater

Condensation

-Water vapor turns to liquid water

Precipitation

-Water falls to the ground

Hydrologic Cycle - Human Impacts

-Removal of trees can reduce rates of

evapotranspiration

-Creation of impermeable surfaces - such as with concrete roads and parking lots - so water can't get into the ground --> flooding or high forms of erosion.