1. Mechanical energy (moving, thinking, living)
Chemical
energy
(photosynthesis)
Chemical
energy
(food)
Solar
energy
Waste
Heat
Waste
Heat
Waste
Heat
Waste
Heat
Figure 2.14
The second law of thermodynamics in action in living systems. Each time energy changes from one form to another, some of the initial input of high-quality energy is degraded, usually to low-quality heat that is dispersed into the environment.
Fig. 2-14, p. 45

2. SUSTAINABILITY AND MATTER AND ENERGY LAWS
Unsustainable High-Throughput Economies: Working in Straight Lines
Converts resources to goods in a manner that promotes waste and pollution.
Figure 2-15

3. Sustainable Low-Throughput Economies: Learning from Nature
Matter-Recycling-and-Reuse Economies: Working in Circles
Mimics nature by recycling and reusing, thus reducing pollutants and waste.
It is not sustainable for growing populations.

4. Sustainable low-waste economy Matter Feedback Energy Feedback Inputs
(from environment)
System
Throughputs
Outputs
(into environment)
Energy
conservation
Low-quality
Energy
(heat)
Energy
Sustainable
low-waste
economy
Waste
and
pollution
Waste
and
pollution
Pollution
control
Matter
Recycle
and
reuse
Figure 2.16
Solutions: lessons from nature. A low-throughput economy, based on energy flow and matter recycling, works with nature to reduce the throughput of matter and energy resources (items shown in green). This is done by (1) reusing and recycling most nonrenewable matter resources, (2) using renewable resources no faster than they are replenished, (3) using matter and energy resources efficiently, (4) reducing unnecessary consumption, (5) emphasizing pollution prevention and waste reduction, and (6) controlling population growth.
Matter
Feedback
Energy Feedback
Fig. 2-16, p. 47

5. Biogeochemical Cycling
The cycling of nutrients through ecosystems via food chains and food webs, including the exchange of nutrients between the biosphere and the hydrosphere, atmosphere and geosphere (e.g., soils and sediments)
This is what we are going to explore more closely in this lecture

6. MATTER CYCLING IN ECOSYSTEMS
Nutrient Cycles: Global Recycling
Global Cycles recycle nutrients through the earth’s air, land, water, and living organisms.
Nutrients are the elements and compounds that organisms need to live, grow, and reproduce.
Biogeochemical cycles move these substances through air, water, soil, rock and living organisms.

7. Transfer v Transformation
Transfers flow through a system and involve a change in location
Transformations lead to interaction within a system in the formation of a new end product or involving a change of state.
As we discuss various cycles, underline transfers, and circle transformations.

8. Flows v Storage
Sometimes matter flows through a cycle and sometimes it is stored.
When a material is flowing through a cycle (conversion), color it green.
When it is being stored (sink), color it red.

9. Nutrient cycles and energy flow

10. The Water Cycle
Figure 3-26

11. Water’s Unique Properties
There are strong forces of attraction between molecules of water.
Water exists as a liquid over a wide temperature range.
Liquid water changes temperature slowly.
It takes a large amount of energy for water to evaporate.
Liquid water can dissolve a variety of compounds.
Water expands when it freezes.

12. Effects of Human Activities on Water Cycle
We alter the water cycle by:
Withdrawing large amounts of freshwater.
Clearing vegetation and eroding soils.
Polluting surface and underground water.
Contributing to climate change.

13. The global carbon cycle

14. The Carbon Cycle: Part of Nature’s Thermostat
Figure 3-27

15. Carbon:
Photosynthesis and Respiration provide a link between the atmosphere and terrestrial
environments.
Decomposition recycles carbon to the soil and back to atmosphere
Fires oxidize organic material to CO2 (burning)
Organic detritus, under intense pressure, changes into coal and petroleum in rock.
Limestone keeps carbon out of circulation
Weathering of exposed limestone releases carbon
A carbon atom cycles about every six years
The basic constituent of all organic compounds

16. Human impacts on the carbon cycle
Human intrusion into the cycle is significant
We are diverting or removing 40% of the photosynthetic effect of land plants
Burning fossil fuels has increased atmospheric CO2 by 35%
Deforestation and soil degradation release significant amounts of CO2 to the atmosphere
Recent reforestation and changed agricultural practices have improved this somewhat

17. The Nitrogen Cycle: Bacteria in Action
Figure 3-29

18. The global nitrogen cycle

19. Major Components of Nitrogen Cycle
Nitrogen cycle is unique in that nitrogen is removed from the atmosphere by microbes, and then taken up by plants in solution when released by the microbes

21. The nitrogen cycle Is a unique cycle
Bacteria in soils, water, and sediments perform many steps of the cycle
Nitrogen is in high demand by aquatic and terrestrial plants
Air is the main reservoir of nitrogen (N)
Nonreactive nitrogen: most organisms can not use it
Reactive nitrogen (Nr): other forms of nitrogen that can be used by organisms

22. Plants take up nitrogen
Plants in terrestrial ecosystems (“non-N-fixing producers”)
Take up Nr as ammonium (NO4) and incorporate it into proteins and nucleic acid compounds
The nitrogen moves through the food chain to decomposers, releasing nitrogen wastes
Soil bacteria (nitrifying bacteria) convert ammonium to nitrate to obtain energy
Nitrate is available for plant uptake
Nitrogen fixation: bacteria and cyanobacteria can use nonreactive N and convert it to a usable form

23. The Nitrogen Cycle Nitrogen Fixation:
Bacteria convert gaseous nitrogen to ammonia:
(N2) (NH3)
Some ammonia enters the ground normally through waste and decay as well (pee, poop and dead things).
Different bacteria convert ammonia to nitrite:
(NH3) (NO2-)
Bacteria use nitrite as an energy source,
and give off nitrate (NO3-) as waste:
Nitrate is then taken up by plants or
released into the atmosphere, where it
becomes gaseous N2 again.
(NO3-)
(N2)

24. Nitrogen fixation

25. Effects of Human Activities on the Nitrogen Cycle
We alter the nitrogen cycle by:
Adding gases that contribute to acid rain.
Adding nitrous oxide to the atmosphere through farming practices which can warm the atmosphere and deplete ozone.
Contaminating ground water
from nitrate ions in inorganic
fertilizers.
Releasing nitrogen into the
troposphere through
deforestation.

27. The global phosphorus cycle

28. The Phosphorous Cycle
Figure 3-31

29. The phosphorus cycle
Mineral elements originate in rock and soil minerals
A shortage of phosphorus is a limiting factor
Excessive phosphorus can stimulate algal growth
As rock breaks down, phosphate is released
Replenishes phosphate lost through leaching or runoff
Organic phosphate: incorporated into organic compounds by plants from soil or water

30. Human impacts on the phosphorus cycle
The most serious intrusion comes from fertilizers
Phosphorus is mined and made into fertilizers, animal feeds, detergents, etc.
When added to soil, it can stimulate production
Human applications have tripled the amount reaching the oceans, accelerating the cycle
It can’t be returned to the soil
Excess phosphorus in water leads to severe pollution
Can cause too many bacteria and fish kills

31. The Sulfur Cycle
Figure 3-32

32. Why sulfur?
-In nature, it can be found as the pure element and as sulfide and sulfate minerals. -It is an essential element for life and is found in two amino acids: cysteine and methionine. -Its commercial uses are primarily in fertilizers, but it is also widely used in black gunpowder, matches, insecticides and fungicides.

33. Effects of Human Activities on the Sulfur Cycle
We add sulfur dioxide to the atmosphere by:
Burning coal and oil
Refining sulfur containing petroleum.
Convert sulfur-containing metallic ores into free metals such as copper, lead, and zinc releasing sulfur dioxide into the environment.

34. Serious consequences of fertilization
Nitric acid has destroyed lakes, ponds, and forests
Atmospheric nitrogen oxides adds to ozone pollution, climate change, and stratospheric ozone depletion
Abundant nitrates are not incorporated into organisms
They are released into the soil, where they leach calcium and magnesium
Eutrophication of waterways
Nitrogen cascade: complex of ecological effects as Nr moves through the environment

35. Comparing the cycles Carbon is mainly found in the atmosphere
Directly taken in by plants
Nitrogen and phosphorus are limiting factors
All three cycles have been sped up by human actions
Acid rain, greenhouse gases, eutrophication
Other cycles exist for other elements (e.g., water)
All go on simultaneously
All come together in tissues of living things