This document discusses biogeochemical cycles and how they relate to the conservation of matter. It explains that biogeochemical cycles track the movement of elements and matter through living and nonliving parts of the Earth system. It notes that human activities can impact biogeochemical cycles by altering natural systems and removing resources from storage. Properly functioning cycles are essential to providing nutrients to support all life on Earth.

1. Biogeochemical Cycles
An Application of Conservation of
Matter

2. Conservation of Matter
• Matter cannot be created or destroyed it can
only change form
– The amount of matter in the universe is finite
(unchanging)
– Atoms (of certain elements) are recycled over and
over again.
– 92 naturally occurring elements make up nearly all matter.
– Go through innumerable chemical reactions to both form and
breakdown compounds.
– For example some of the atoms that now make up your body
may have once been part of a dinosaur, a rock, a tree, and a
panda bear at one point in their existence.

3. Cycles
• Cycles: Track the
movement of matter and
energy through a system.
Recurring series of
events.
• System: A group of
independent but
interrelated parts
forming a unified whole.
– The planet earth can be
viewed as one large
system.

4. Biogeochemical Cycle
• Bio = Biosphere (Living
Things)
• Geo = Geosphere
(Rocks / Earth)
• Chem = Chemical Factors
• Biogeochemical Cycles:
Track the repeating
movement of atoms and
energy through both the
living and nonliving parts
of the earth system.

5. Long Term Storage
• In most cycles only a fraction of the systems total
material is in active circulation.
• Reservoirs: Places where elements are stored or
held for a long period of time. Effectively takes
them out of circulation.
• Residence Time: An estimate of how long matter
is typically stored in a particular reservoir.

6. Human Impact
• Human activities can have a
large impact on biogeochemical
cycles.
– Alter the natural functioning of
systems.
– Can have unforeseen negative
consequences.
• The biggest anthropogenic
(caused by humans) impact is
mining or removing resources
from storage in reservoirs and
putting them back into
circulation.

7. Biogeochemical Cycles and Life
• Properly functioning
cycles are essential to all
life on earth.
• Living things depend on
cycles to provide the
nutrients they need.
• Living things, like all
matter (and elephants)
are made of elements.
Cycles provide those
elemental building blocks.

8. The Human Element?
• Almost 99% of the mass of the
human body (and most other life
forms) is made up of 6 elements:
– Oxygen
– Carbon
– Hydrogen
– Nitrogen
– Calcium
– Phosphorus.
• Only about 0.85% is composed of
another five elements:
– Potassium
– Sulfur
– Sodium
– Chlorine
– Magnesium
• All are necessary to life.
• Around 70% of the human body is
made up of a single compound:
Water.

9. Water
• Is a compound of hydrogen and oxygen.
– H20
• The intermolecular forces (bonds) holding the
atoms of a water molecule together are
extremely strong.
– Makes water a very stable molecule.
• Low Reactivity.
• Not easy to break H2O down to elements or to form new
chemicals.
• Essential to life.
– You could only survive about a week without water.

11. The Processes of the Water Cycle
Evaporation Condensation
Transpiration Precipitation

12. Evaporation
Process in which liquid
changes to gas (vapor)

13. Transpiration
A continuous process
caused by the evaporation
of water from leaves of
plants and its
corresponding uptake
from roots in the soil.

14. Condensation
Condensation is the
process by which matter
changes from a gas (or
vapor) phase into a liquid
phase.
 Ex. Dew on the grass in the
morning, cold glass of liquid, fog
on the inside of a car window

15. Precipitation
• When cloud (water
molecules) particles become
too heavy to remain
suspended in the air, they
fall to the earth as
precipitation.

16. Surface Run-off
 Water, from rain, snowmelt,
or other sources, that flows
over the land surface, and is a
major component of the water
cycle.
 When the ground is saturated,
the water flows into lakes,
streams, rivers, and eventually
ends up in oceans.

17. Groundwater
• The water that is
filtered through the soil
and remains under the
ground.
• Is a major source of
drinking water as well
as agricultural
irrigation.

18. Aquifer

20. “Water, water everywhere... but not a drop to
drink.”
• The overall water cycle "contains" between 1.386 and 1.46 Billion km3 of
water in various states (liquid, solid, or gaseous).
• The vast majority of it, between 96.5 and 97.25%, is in the Oceans.
• Only about 3% of Earth's water is fresh water.
– 2/3rds of that is frozen in the ice sheets near the poles and in glaciers.
– Most of the rest of the fresh water is underground.
– Less than 1% of fresh water is on the surface in lakes, wetlands, and
rivers.
• Only a very small fraction (~.77%) of Earth’s water is suitable for
human consumption.

21. Residence Time in Water Cycle

22. Storage Reservoirs Within the Water
Cycle
• The oceans, glaciers
and ice caps, lakes,
underground aquifers
and the atmosphere
are some examples of
reservoirs.
• Most of earth’s water
is in “long term
storage”.
– Not actively circulating.

23. Human Impact

24. Death of the Aral Sea
• Located in present-day
Kazakhstan and
Uzbekistan.
• 1930’s it was decided
that the area surrounding
the sea could be used to
grow cotton.
• By 1960, millions of acres
of land were irrigated
using water from the two
large rivers that fed the
Aral Sea.
• The sea began to shrink

25. 1967 2007

26. Aral Sea Impacts
• Salinity increased as water
was not replenished
– Hurt the 60,000 employee
fishery industry.
– 3x saltier than the ocean.
• Lost 90% of it’s original
volume.
• Many health impacts for the
people as the dried
salt/pesticide/fertilizer/herb
icide laden dust is carried by
winds
– Increased cancer, higher
infant mortality
• Local climate changed,
growing season shortened,
switch from cotton to rice.

27. Tragedy of the Commons...

28. Tragedy of the Commons
• First proposed by Garrett
Hardin in 1968.
• When individuals, acting
independently and
rationally, will use and
deplete a shared resource.
• Doing so is often not in the
individual or larger societies
best long-term interests.
• Dilemma: If you don’t use it
someone else will.
• Short term personal gain is
at odds with long term
communal well being.

30. Water: The Ultimate Commons
• In most countries water is
viewed as a common
resource.
• If you own land, you own
the rights to use the
water on it and under it.
• The problem: All bodies
of water are
interconnected.
• Can use that water
however you see fit.
• Leads to overuse, and
destruction of watershed.

31. Carrying Capacity
• Since resources are finite Earth, and other
systems, have a maximum carrying capacity.
• Carrying Capacity: The number of individuals a
system (such as earth) can sustainably support at
a given standard of living.
• Sustainable: Can be maintained over
generations.
• Fresh water, and many other resources, are being
used at a rate that is unsustainable. We call this
overconsumption.
• We’re using fresh water at a rate that is faster
than the water cycle can replenish it.

32. Determining Carrying Capacity
• The carrying capacity of a system is
governed by two main factors:
– Population:
• The total number of individuals.
• Each individual has certain basic needs
that have to be met by the system in
order to survive.
– Standard of Living:
• The degree of wealth and material
comfort available to a person or
community.
• How many resources a person is using.
• Since the total amount of resources is
constant, as you approach a system’s
carrying capacity, an increase in
population has to be accompanied by
a decrease in standard of living.

33. Human Population
• There are over
7 Billion people living
on earth today.
• Population is growing
exponentially.
• More people are
being born than are
dyeing.

34. Population History

35. • The human population is
now growing at a rate of
about 3 people/second or
• 260 thousand/day or
• 1.8 million per week or
• 93 million/year

36. • Each dot represents
1 million people

37. Human Population and Resource Use
• Conservation of matter. The total amount of
water and other resources is constant.
• More people means more demand for resources.
• The total amount of water on earth remains the
same. Even as population increases.
• Growing population puts huge stress on system.
– More people competing for the same amount of
water.

38. Unequal Usage
• 25% of the world’s do not have adequate
access to a safe and adequate water
supply.
• Worldwide 1 Billion people make a daily
trip of over 3 hours just to collect water.
• 14,000 people die every day from water
related illness.
• All inclusive estimates (including water
used to produce food) from the United
Nations state that only about 13 gallons of
water per day is the minimum required
amount to sustain a human life.
• With access to just 1.3 gallons of domestic
water each day, more than a billion people
in water poor regions around the globe
survive on the same amount used to flush
a toilet.
• In Honduras people spend 25% of their
annual income on water.

39. USA Water Usage
• The average American uses 80-100
gallons of water a day for domestic use.
• All things considered this number sky
rockets to around 2000 gallons of water
per day.
– Over 1000 times the minimum required
to sustain life.
– Nearly 95 percent of your water footprint
is hidden in the food you eat, energy you
use, products you buy, and services you
rely on.
– Highest per capita water use in developed
world.
• Water Footprint Calculator
• Americans only spend .05% of their
annual income on water.

41. Effects of Excessive Consumption
• Key Problem: Fresh water is being
consumed at a faster rate than it is
being replenished.
– If trend continues we will eventually run
out of water.
– What about Iowa?
• We are doing relatively well. The Jordan
and Dakota Aquifers are being slightly
overused but not at the high rate seen
in other parts of the Midwest.
– In other parts of the Midwest the water
in the Ogallala Aquifer is being removed
8 times faster than it is replenished.
• Only a fraction of consumption goes
towards day-to-day domestic uses.
– 70% Agriculture
– 20% Manufacturing
– 10% Domestic Use

42. Ogallala Aquifer: A Cautionary Tale

43. ANF: America Needs Farmers
• As population increases, so
does demands for foods.
• The food that feeds the
majority of Americans, and
people around the world,
comes from the Midwest.
• How do you balance demand
for food with issues related
to water consumption?
– The key is responsible
management.

44. Irrigation
• With increased demand for
food, people have begun to
farm in less than ideal climate
zones.
– Lack an adequate supply of
natural water.
• Irrigation enables crops to
grow in areas where they
could not survive naturally.
• Problems: Uses lots of water
and is inefficient.
– Efficiency ranges from 50-75%
• Can lead to an increase in soil
salinity that eventually
renders the land totally
unusable.

45. Crop Selection
• Different food crops require different
amounts of water to grow.
• By selecting crops appropriate to your region
the need for irrigation can be vastly reduced.
• For example:
– Growing corn makes sense in South East Iowa
where water is relatively abundant.
– It doesn’t make sense in the Dakota’s where
water is scarce.

47. Water Consumption Per Pound
• Lettuce = 15 Gallons
• Tomatoes = 22 Gallons
• Potatoes = 30 Gallons
• Oranges = 55 Gallons
• Apples = 83 Gallons
• Corn = 107 Gallons
• Tree Nuts = 368 Gallons
• Rice = 403 Gallons
• Eggs = 573 Gallons
• Chicken = 815 Gallons
• Pork = 1630 Gallons
• Beef = 5000 Gallons

48. Managing Runoff and Erosion
• Natural vegetation slows down
the flow of rainwater. More
water is absorbed by the
ground, and eventually
percolates down into aquifers.
• Clearing land for farming leads
to an increase in the rate and
total amount of runoff.
– More fresh water flows into
rivers and is ultimately lost in the
ocean.
– Increased erosion and loss of
nutrient rich topsoil.
• Faster flow rates can lead to
intense Flash Floods.

49. Preventing Erosion
• Plant Buffer Strips: Plant native grasses
or trees along the edges of the field or
on steep slopes.
– CRP Program: Provides compensation for
land that is reverted back to native
species. Intended to encourage
construction of buffer strips and protect
highly erodible land and increase
groundwater recharge.
• Mulching or Cover Crops: Leave waste
material on field after harvest or plant
cover crop.
• Contour Cultivation: Plow in such away
that furrows align to natural contour of
the land and act as miniature dams.

50. Deforestation and Urbanization
• Deforestation: The removal of trees and other natural
vegetation from an area.
– Can be for agriculture, industrial, or civil reasons.
• Urbanization: Rapid growth and physical expansion of
cities.
– The cement jungle.
• Both Deforestation and Urbanization alter the water
cycle in the local area.

51. The Cement Jungle
• Urban Sprawl: The uncontrolled geographic expansion of
development and urbanization out from the city center.
• Impervious Surface: A surface covering that water cannot
pass through.
– All of the precipitation that falls on an impervious surface will
runoff.
– Common examples include cement, asphalt, and rooftops.
– Around 43,000 square miles of the USA is covered with
impervious surface.

54. Effects of Pavement
• When precipitation falls on impervious surfaces it runs off immediately.
• Intensifies and speeds up the water cycle.
– More runoff.
– Flash flooding.
• Flooding occurs more quickly and with greater intensity.
– More erosion.
– Less ground water recharge.
• Rather than being held in the local watershed for later use, this urban runoff is
diverted into sewer systems and routed directly into rivers and ultimately the
ocean.
– Quite literally (fresh) water down the drain.

57. Solutions
• Floodwalls and Levees
– Build a large wall to hold back
floodwaters.
– Problem: Just sends that water
downstream… someone else's
problem.
• Reduce Impervious Surface
– Design cities with parks in key areas.
– Narrow streets.
– New types of permeable pavement.
• Rain Water Capture Systems
– Cisterns
– Trap and hold rainfall for later use.

58. Dams
• Dam: A structure that impounds
(blocks) the flow of water in a stream
or river.
• Used to store large quantities of
water for later use.
– Attempt to rectify problems associated
with urbanization and acceleration of
runoff.
– Reservoir fills with water during wet
season and can be drawn from during
dry season or droughts.
• Allow for controlled release of
water.
– Protect downstream areas from
flooding.
– Outlet flow can be used to generate
electricity
• Hydroelectric power

59. Dam Construction Worldwide
• 845,000 Number of dams in the world.
– Rapid Growth
• 80,000 Number of dams in USA.
• 65 Percentage of the worlds river water that’s
flow is impeded by dams.
• 292 Number of major river systems worldwide
adversely affected by dam construction (over
half).
• 50 Average number of years that a hydroelectric
dam remains useable.
• 85 Percent of the world’s dams that will be
obsolete by 2020.

60. Problems Associated With Dams

61. High Rate of Evaporation
• The water in a reservoir is
largely stagnant (not
flowing).
• Reservoirs, especially in
warm dry areas, are
prone to solar warming
and high evaporation
rates.
• Can also lead to the
creation of a thermocline
and hypoxic (oxygen
deprived) zones.

63. Accumulation of Sediment &
Toxins
• All rivers contain sediments (from
erosion).
• When a river is stilled behind a dam,
the sediments it contains sink to the
bottom of the reservoir.
• Effectively fills in the reservoir,
eventually rendering the dam useless.
– The reservoir behind China’s Three
Gorges Dam is loosing capacity at a
rate of 2.3 percent per year.
• This sediment is no longer deposited
on floodplains.
– Process is crucial to the creation of
fertile farmland.
• Dams also trap many of the toxins and
pollutants carried in river water. These
accumulate in the reservoir over time.

64. Migratory Disruption
• Many fish species,
including salmon and
steelhead trout,
seasonally migrate along
river systems to
spawning grounds.
• Dams block these fishes
ability to travel
upstream.
• Dams represent a major
threat to 91 percent of
endangered fish species.

65. Geographic Footprint of Reservoir
• The construction of a dam and in turn the creation of a reservoir
floods a large area of land behind the dam.
• This destroys the natural ecosystem of the region.
• Displaces people living in the area.
– Three Gorges Dam has displaced at least 1.3 million people.
• Thirteen cities, 140 towns, and 1,350 villages have been intentionally flooded.
• Destroys historic and cultural sites.
– With 635 large dams within its borders, Turkey is one of the world’s
most active dam building countries.
• The proposed Ilisu Dam on the Tigris River would drown the 10,000 year-old
city of Hasankeyf.

67. Catastrophic Failure
• 49: Number of dam failures in the
United States between 2000 and
2007.
• Dam failure can lead to dangerous
flooding downstream.
• The largest catastrophic failure of a
dam was the 1975 Banqiao Dam
failure.
– Killed 26,000 people immediately.
– 145,000 dying of disease later
– Displacing 11,000,000 residents.
• Teton Dam Collapse
• In order to prevent failure in high
water seasons large releases often
have to be made.
– Not as effective of a flood
prevention technique as often
believed.

68. Dam Removal
• There is a large push
to remove the
thousands of obsolete
dams in the USA.
• Restores river system.
• Dam Removal

69. PSA Examples
• We All Live Downstream
• Funny PSA’s
• Save Water
• No Water No Joke