The Phosphorus (P) Cycledsapresents.org/staff/john-jackson/files/2019/10/CH4-10.7.19.pdf · by runoff of surface water, or more slowly by the processes of infiltration and ... Pumping,

© 2015 John Wiley & Sons, Inc. All rights reserved.

The Phosphorus (P) Cycle ¨  This cycle has no biologically important gaseous

compounds, so it is essentially NOT found in the atmosphere (other than when dust storms blow various P forms into air temporarily)

Phosphorous Cycle Phosphorus cycles from land to sediments in the

ocean and back to land Ø  Phosphorus erodes from rock as inorganic

phosphates and plants absorb it from the soil/water Ø  Animals obtain phosphorus from their diets Ø  Decomposers release inorganic phosphate into the

environment Ø  Once in cells, phosphates are incorporated into

biological molecules such as nucleic acids and ATP (adenosine triphosphate)

© 2015 John Wiley & Sons, Inc. All rights reserved.

Human Affect on P Cycle

¨  P fertilizers ¤ One of primary limiting nutrients for plant growth

¨  Waste water treatment plants (WWTP) do not remove

¨  2014 – Commercial WWTP began recycling P and other nutrients from treated sewage

© 2015 John Wiley & Sons, Inc. All rights reserved.

The Sulfur (S) Cycle

NOTE: The largest reservoir of sulfur is sedimentary rocks, which hold 7440 x 1018 g of sulfur. Second is the ocean, which contains 1280 x 1018 g of sulfur. All other figures in the diagram are expressed as 1012 g of sulfur per year.

© 2015 John Wiley & Sons, Inc. All rights reserved.

The Sulfur (S) Cycle

¨  Still not fully understood ¨  Sulfur is found primarily in sedimentary rock &

minerals, which can weather & erode & dissolve into the oceans

¨  Main biotic cyclers are bacteria in the ocean or salt marsh ecosystems

¨  These bacteria can produce dimethyl sulfide (CH3SCH3) out of compound released by marine algae ¤ Ocean, Salt marsh - rotten egg smell indicates

dimethyl sulfide production

Sulfur Cycle Sulfur gases enter the atmosphere from natural sources in the ocean and on land

Ø  Sea spray, forest fires and dust storms deliver sulfates (SO4

2-) into the air Ø  Volcanoes release both hydrogen sulfide (H2S) and

sulfur oxides (SOx), as do hydrothermal vents on the sea floor.

Sulfur Cycle Sulfur gases have a short residence time in the atmosphere, because they are very reactive with other compounds Ø  hydrogen sulfide (H2S) reacts with oxygen to

form sulfur oxides (SOx) Ø  Sulfur oxides react with water to produce

sulfuric acid (H2SO4), which is the primary cause of acid rain

Sulfur Cycle A tiny fraction of global sulfur is present in living organisms

Ø  Sulfur is an essential component of proteins Ø  Plant roots absorb SO4

2- and assimilate it by incorporating the sulfur into plant proteins

Ø  Animals assimilate sulfur when they consume plant proteins and covert them to animal proteins

Ø  Bacteria drive the sulfur cycle

© 2015 John Wiley & Sons, Inc. All rights reserved.

The Water (Hydrologic) Cycle

¨  Cycles among organisms, atmosphere, land, and ocean ¤ All organisms use water

¨  Transpiration ¤ Loss of water vapor

from land plants ¤ ~97% of plant water

can be lost this way

Hydrologic Cycle It provides a renewable supply of purified water for terrestrial organisms Ø the hydrologic cycle results in a balance between water in the ocean, on the land, and in the atmosphere Ø Water moves from the atmosphere to the land and ocean in the form of precipitation Ø Water enters the atmosphere by evaporation and transpiration

Hydrologic Cycle… Ø  Water is returned to

the oceans quickly by runoff of surface water, or more slowly by the processes of infiltration and groundwater flow.

Hydrologic Cycle… Ø  Once water

evaporates to become water vapor, it condenses into a liquid or solid in the atmosphere simply by rising, expanding and cooling.

Aerosols Impact the Water Cycle Ø Air pollution may decrease precipitation due

to aerosols Ø Aerosols are tiny particles of air pollution

consisting mostly of sulfates, nitrates, carbon, mineral dusts, and smokestack ash.

Ø Aerosols scatter and absorb sunlight and can cause clouds to form.

© 2015 John Wiley & Sons, Inc. All rights reserved.

Human Affect on Water Cycle

¨  Air pollution may decrease precipitation ¨  Pumping, diverting surface and groundwater

for irrigation ¨  Climate change – warming temperatures are

melting polar ice caps ¤ Sea level rise ¤ Greater frequency of storms predicted