Phys 102: Natural Systems

1
Phys 102 Natural Systems
Vincent Conrad
2
Biogeochemical Cycling
Lecture 10
Phys 102 Natural Systems
Biogeochemical Cycling

• The patterns of cycling nutrients in the
  biosphere involves metabolism by living
  organisms, as well as a series of strictly
  abiotic chemical reactions.
• Understanding the cycle of a single element
  requires the knowledge of an intricate process
• the biology of all organisms that utilize the
  element
• Its geological availability
• Its organic and inorganic chemistry
• Understanding the cycling of biologically
  important elements is truly interdisciplinary in
  nature.
• We generally call this process biogeochemical
  cycling.
• Living organisms are tied to the nonliving
  environment through the Biogeochemical Cycles.
• Living organisms require the availability of
  about 20 to 30 chemical elements for the various
  metabolic processes that take place in their
  bodies.

Vincent Conrad
3
Biogeochemical Cycling
Lecture 10
Phys 102 Natural Systems
Biogeochemical Cycling

• Some products that are metabolized by organisms
  require relatively few nutrients for their
  production (carbohydrates are photosynthesized
  from just water and carbon dioxide).
• Some organic substances, like amino acids and
  proteins, are more complex in their chemical make
  up and therefore require a number of different
  nutrients.
• The types of nutrient needed by life is often
  categorized into two groups
• Macronutrients and Micronutrients.
• Macronutrients are required in relatively large
  amounts. Examples are carbon, oxygen, hydrogen,
  nitrogen and phosphorus which each constitute
  more than 1 of dry weight of an organism.
  Sulfur, chlorine, potassium, sodium, calcium,
  magnesium, iron, and copper are macronutrients
  that constitute 0.2 to 1 of dry organic weight.
• Micronutrients are elements that often constitute
  less than 0.2 of dry organic matter. They
  include aluminum, boron, bromine, chromium,
  cobalt, fluorine, gallium, iodine, manganese,
  molybdenum, selenium, silicon, strontium, tin,
  titanium, vanadium, and zinc.

Vincent Conrad
4
Biogeochemical Cycling
Lecture 10
Phys 102 Natural Systems
Biogeochemical Cycling

• We will look at some of the macronutrient cycles.
  These are driven either directly or indirectly by
  the sun and gravity. The cycles we will examine
  are
• Carbon (C) Cycle
• Nitrogen (N) Cycle
• Oxygen (O) Cycle
• Phosphorus (P) Cycle
• Sulfur (S) Cycle

Vincent Conrad
5
General Cycle
Lecture 10
Phys 102 Natural Systems
General Cycle
Vincent Conrad
6
Carbon Cycle
Lecture 10
Phys 102 Natural Systems
Carbon Cycle

• All life (on Earth) is based on the element
  carbon.
• Carbon is the major chemical constituent of most
  organic matter, from fossil fuels to the complex
  molecules (fats proteins, DNA and RNA) that
  control genetic reproduction in organisms.
• By weight, carbon is not one of the most abundant
  elements within the Earth's crust. The
  lithosphere is only 0.032 carbon by weight while
  oxygen and silicon make up 45.2 and 29.4 of the
  Earth's surface rocks.
• Ecosystems gain most of their carbon dioxide from
  the atmosphere.
• (Remember that carbon dioxide is 0.03 of the atm
  by volume and is also dissolved in water)

Vincent Conrad
7
Carbon Cycle
Lecture 10
Phys 102 Natural Systems
Carbon Cycle

• Autotrophic organisms absorb carbon dioxide to
  produce carbohydrates via photosynthesis.
  Organic matter produced in plants is passed down
  to heterotrophic animals through consumption.
• Carbon is released from ecosystems as carbon
  dioxide gas by the process of respiration.
• Respiration involves the breakdown of
  carbon-based organic molecules into carbon
  dioxide gas and other compounds as by products.
• The detritus food chain contains a number of
  organisms whose primary ecological role is the
  decomposition of organic matter into its abiotic
  components.

Vincent Conrad
8
Carbon Cycle
Lecture 10
Phys 102 Natural Systems
Carbon Cycle
Vincent Conrad

\beginmyslide1Carbon
Cylcle \begincenter
\includegraphicswidth0.8
\columnwidth,height!carboncycle.eps
\endcenter \endmyslide
\be
ginmyslide1Carbon Cylcle
\beginitemize \item Carbon dioxide is
\colordgreenabsorbed by the waters of the
ocean by simple diffusion. \item In seawater,
the \cdiox can remain as is, or can be converted
into carbonate (CO_3-2) or bicarbonate
(HCO_3-). \item Ocean organisms
biologically fix bicarbonate with calcium
(Ca2) to produce calcium carbonate
(CaCO_3). \item This is used to produce
shells, skeletons, coral, etc... \item The
organisms die, shells and body parts sink to the
ocean floor where they accumulate as
carbonate-rich deposits. \item After long
periods of time, these deposits are physically
and chemically altered into sedimentary
rocks. \item Limestone (CaCO_3) found in
sedimentary rock is the largest reservoir for
carbon. \item Oceans are the 2nd largest
reservoir. \enditemize \endmyslide

\beginmyslide1Carbon Cylcle
\begincenter \includegraphicswid
th0.9 \columnwidth,height!carboncycle2.
eps \endcenter \endmyslide

\beginmyslide1Carbon Cycle and Global
Temperature \beginitemize \item The
quantity of \cdiox found in the atmosphere has
been steadily decreasing over the last
several billion years. \item Researchers
theorized that this change is in response to an
increase in the sun's output over the same time
period. \item Higher levels of \cdiox meant the
Earth's temperature was slightly higher than
today. \item This allowed for the flourishing
of plant life despite the lower output of
solar radiation due to the green house effect.
\item As the sun grew more intense, several
biological mechanisms gradually locked some
of the atmospheric carbon dioxide into fossil
fuels and sedimentary rock. \item Thus the
Earth's global average temperature essentially
constant over time. \item This regulating
process has kept the Earth's global average
temperature essentially constant over time. (more
evidence for Gaia hypothesis??)
\enditemize \endmyslide

\beginmyslide1Human
Impact on the Carbon Cycle \beginitemize
\item Since the 1950s humans have greatly
increased the quantity of carbon dioxide found
in the Earth's atmosphere and oceans. \item In
the early 1700s \cdiox was 275 parts per million
(ppm) to just over 365 PPM today. (see graph
lectures 3 \ 4) \item Scientists estimate that
future atmospheric levels of carbon dioxide
could reach an amount between 450 to 600 PPM by
2100. \item Sources are fossil fuel combustion
(65 \ of \cdiox) and the modification of
natural plant cover found in grassland,
woodland, and forested ecosystems (35
\). \item Researchers have shown that natural
ecosystems can store between 20 to 100 times
more carbon dioxide than agricultural land-use
types. \enditemize \endmyslide

\beginmyslide1Nitrogen Cycle
\beginitemize \item Nitrogen is used by
living organisms to produce a number of
complex organic molecules like amino acids,
proteins, and nucleic acids. \item The
complete nitrogen cycle is very complex!! \item
The largest store of nitrogen is found in the
atmosphere (78 \ of atm is N_2 gas) but
this cannot be absorbed by organisms
directly. \item This is because most plants
can only take up nitrogen in two solid forms
ammonium ion (NH_4) and the ion nitrate
(NO_3-). \item Most plants obtain the
nitrogen they need as inorganic nitrate from
the soil. Ammonium is used less by plants for
uptake because in large concentrations it is
extremely toxic. \item The conversion of
atmospheric N_2 into NH_4 and NO_3-
is carried out by certain kinds of bacteria and
is called \colordgreen nitrogen
fixation. \enditemize \endmyslide

\beginmyslide1Nitrogen
Cycle \beginitemize \item Nitrogen
fixation is carried out by \beginitemize
\item Cyanobacteria which live in soil
\item The bacteria rhizobium which lives in the
nodules (small swellings of the roots of
legumes (such as peas beans alfalfa etc)
\enditemize \item Nitrate is very
soluble, easily lost from soil by leaching.
Can be returned to oceans where it can be
returned to the atmosphere by
denitrification. \item Animals receive the
required nitrogen they need for metabolism,
growth, and reproduction by the consumption of
living or dead organic matter containing
molecules composed partially of nitrogen.
\enditemize \begincenter
\includegraphicswidth0.22 \columnwidth,height!,
angle90alder8s.eps \includegraphicswid
th0.37\columnwidth,height!nodules.eps \\
examples of nodules \endcenter \endmysli
de
\beginmyslide1Nitro
gen Cycle \beginitemize \item
\colordgreenAmmonification N is also added
to the soil from animal biomass and manures.
This detritus materials containing N is
broken down by specialised decomposer bacteria.
It enters the soils as ammonia ammonium ions
(NH_4) or atmosphere as gas (NH_4).
This recycles large amounts of nitrogen to
the soil. \item Lightning also plays a
role in N fixation. It causes chemical
reactions that result in solid nitrate compounds
entering the soil through precipitation.
\item \colordgreen Denitrification is
carried out by bacteria that get the oxygen
they need for metabolism from nitrates (rather
than O_2) under anaerobic (O_2 free)
conditions. They convert NO_3- into N_2
or nitrous oxide (N_2O) gas. Both of these
gases then diffuse into the atmosphere.
\enditemize \endmyslide

\beginmyslide1Nitrogen Cycle
\vspace-5mm \begincenter
\includegraphicswidth0.8 \columnwidth,height!
nitrogen.eps \endcenter \endmyslide

\beginmyslide1Nitrogen
Cycle The activities of humans have severely
altered the nitrogen cycle. Some of the major
processes involved in this alteration
include \beginitemize \item Application of
nitrogen fertilizers to crops has caused
increased rates of denitrification and leaching
of nitrate into groundwater. This also comes
from discharge of treated and untreated sewage
and livestock waste. When this excess supply of
nutrients reaches rivers/lakes it can stimulate
rapid growth of algae and other aquatic
plants. \item Large quantities of nitric oxide
(NO) are released into the atm when wood or any
fuel is burned. (NO forms when O and N are
combined at high temps.) NO O_2 \to
NO_2 H_2O \to HNO_3 (nitric acid).
This is one components of acid rain, kills trees
and fish. \item Burning grasslands and clearing
forests removes nitrogen from the soil as well
as producing nitrogen oxides into the
atmosphere. \enditemize \endmyslide

\beginmyslide1Oxygen Cycle
\begincenter \includegraphicswidth0.
7 \columnwidth,height!oxy-cycle.eps
\endcenter \endmyslide
\
beginmyslide1Phosphorus Cycle
\beginitemize \item Phosphorus is essential
for the body's energy transport molecules and
for holding DNA and RNA molecules together.
\item It is used in living organisms as phosphate
ions (PO_43- and HPO_42-) \item The
phosphorous cycle is an example a cycle that does
not have a gas as part of its cycle. Bacteria
are also far less important than in the N
cycle. \item Phosphate are only slightly
soluble in water. Thus often only small
amounts in the soil \to can be a limiting
factor in plant growth. \item Phosphorus
released from breakdown/weathering of phosphate
rock deposits. Carried by water through soil and
is taken up by plants. phosphate particles can
also be carried by wind. \item Animals get
phosphorus from eating producers or primary
consumers. \item By decomposing animal
waste/biomass, producers return P to the
soil. \item Finally through leaching P can end up
in oceans and via sedimentation forms new
phosphate rock deposits. \enditemize \endmys
lide
\beginmyslide1Phos
phorus Cycle \vspace-5mm
\begincenter \includegraphicswidth0.65
\columnwidth,height!phosphoruscycle.eps
\endcenter \endmyslide

\beginmyslide1Phosphorus Cycle There are
two main ways we intervene in the phosphorus
cycle \beginitemize \item Mining large
quantities of phosphate rocks. This is to
produce commercial fertilizers and
detergents. \item Heavy uses of
fertilizers in crop farming can cause large
amounts of phosphates in the runoff water. This
can also come from animal wastes. \item
Since phosphorus is a limiting growth factor, as
with nitrates and ammonium ions, excesses
supply may cause explosive growth of algae
and other kinds of plants that live in water.
\enditemize \endmyslide
\
beginmyslide1Sulphur Cycle
\beginitemize \item The S cycle involves many
physical, chemical and biological agents.
\item S is essential in proteins and vitamins in
organisms. \item Most of the Earth's sulphur
exists in underground rocks. \item It enters
the atm from three main sources
\beginitemize \item Hydrogen sulfide
(H_2S). A poisonous gas with a rotten egg
smell. Comes from active volcanoes and the decay
of organic matter in swamps tidal flats by
anaerobic decomposers. \item Sulphur dioxide
(SO_2) a colourless suffocating gas from
active volcanoes. \item Particles of sulfate
(SO_42-) salts such as ammonium
sulphate, from sea spray. \enditemize
\enditemize \endmyslide

\beginmyslide1Sulphur Cycle
\beginitemize \item Circulates from rocks
deep under the ocean sediment. \item
Sedimentation of organic matter forms fossil fuel
deposits containing S. \item This also
produces sulphates in the soil which are taken up
by plants. \item The action of microorganisms
releases the sulphates in the soil via reduced
sulphur (H_2S). \item In the atm SO_42-
O_2 \to SO_3 (sulphur trioxide) H_2O
\to H_2SO_4 (sulphuric acid) \item
Sulphuric acid is a component of acid rain,
killing trees and fish. \item We intervene in
a major way! About 1/3 of all sulphur compounds
reaching the atm come from human activities.
(99\ SO_2 entering atm from human
activities!) \enditemize \endmyslide

\beginmyslide1Sulphur Cycle
\begincenter \includegraphicswi
dth0.8 \columnwidth,height!ESwe34.eps
\endcenter \endmyslide
\be
ginmyslide1Temperature Regulation
\sidebyside0.40.45 \beginflushleft
\includegraphicswidth1 \columnwidth,height!
we35.eps \endflushleft
\beginitemize \item Dimethyl sulfide (DMS)
produced by oceanic phytoplankton \item It may
provide feedback to regulate global climate
\item It helps form more clouds. \item
Climate warmer \to more DMS \to more clouds
blocking sunlight \to lowering surface
temperatures. \item Was one of initial
precesses that inspired Lovelock's Gaia
Theory of the self regulating earth.
\enditemize \endmyslide

\beginmyslide1Next week
\beginitemize \item Will put the reading for
next week on the web site. So check that
towards the end of the week. \item May be from
the reader, of maybe readings from web sites.
\enditemize \endmyslide

http//www.agen.ufl.edu/chyn/age2062/lect/le
ct.htm
\beginmyslide1
\sidebyside0.40.45
\beginflushleft \includegraphicswidth
1.2 \columnwidth,height!
\endflushleft \beginitemize
\item \enditemize \endmyslide

\beginmyslide1
\beginitemize \item \enditemize
\begincenter \includegraphicswidth
0.7 \columnwidth,height!
\endcenter \endmyslide

\enddocument Local Variables mode
latex TeX-master t End
9
Carbon Cycle
Lecture 10
Phys 102 Natural Systems
Carbon Cycle

• Carbon dioxide is absorbed by the waters of the
  ocean by simple diffusion.
• In seawater, the CO2 can remain as is, or can be
  converted into carbonate carbon dioxide (CO32-)
  or bicarbonate. (HCO3-).
• Ocean organisms biologically fix bicarbonate with
  calcium (Ca2) to produce calcium carbonate
  (CaCO3).
• This is used to produce shells, skeletons, coral,
  etc...
• The organisms die, shells and body parts sink to
  the ocean floor where they accumulate as
  carbonate-rich deposits.
• After long periods of time, these deposits are
  physically and chemically altered into
  sedimentary rocks.
• Limestone (CaCO3) found in sedimentary rock is
  the largest reservoir for carbon.
• Oceans are the 2nd largest reservoir.

Vincent Conrad
10
Carbon Cycle and Temperature
Lecture 10
Phys 102 Natural Systems
Carbon Cycle

• The quantity of carbon dioxide found in the
  atmosphere has been steadily decreasing over the
  last several billion years.
• Researchers theorized that this change is in
  response to an increase in the sun's output over
  the same time period.
• Higher levels of carbon dioxide meant the Earth's
  temperature was slightly higher than today.
• This allowed for the flourishing of plant life
  despite the lower output of solar radiation due
  to the green house effect.
• As the sun grew more intense, several biological
  mechanisms gradually locked some of the
  atmospheric carbon dioxide into fossil fuels and
  sedimentary rock.
• Thus the Earth's global average temperature
  essentially constant over time.
• This regulating process has kept the Earth's
  global average temperature essentially constant
  over time. (More evidence for Gaia hypothesis??)

Vincent Conrad
11
Human Impact on Carbon Cycle
Lecture 10
Phys 102 Natural Systems
Human Impact on the Carbon Cycle

• Since the 1950s humans have greatly increased the
  quantity of carbon dioxide found in the Earth's
  atmosphere and oceans.
• In the early 1700s carbon dioxide was 275 parts
  per million (ppm) to just over 365 ppm today.
• Scientists estimate that future atmospheric
  levels of carbon dioxide could reach an amount
  between 450 to 600 ppm by 2100.
• Sources are fossil fuel combustion (65 of carbon
  dioxide) and the modification of natural plant
  cover found in grassland, woodland, and forested
  ecosystems (35).
• Researchers have shown that natural ecosystems
  can store between 20 to 100 times more carbon
  dioxide than agricultural land-use types.

Vincent Conrad
12
Nitrogen Cycle
Lecture 10
Phys 102 Natural Systems
Nitrogen Cycle

• Nitrogen is used by living organisms to produce a
  number of complex organic molecules like amino
  acids, proteins, and nucleic acids.
• The complete nitrogen cycle is very complex!!
• The largest store of nitrogen is found in the
  atmosphere (78 of atm is N2 gas) but this cannot
  be absorbed by organisms directly.
• This is because most plants can only take up
  nitrogen in two solid forms ammonium ion (NH4)
  and the ion nitrate (NO3-).
• Most plants obtain the nitrogen they need as
  inorganic nitrate from the soil. Ammonium is used
  less by plants for uptake because in large
  concentrations it is extremely toxic.
• The conversion of atmospheric N2 into NH4 and
  NO3- is carried out by certain kinds of bacteria
  and is called nitrogen fixation.

Vincent Conrad
13
Nitrogen Fixation
Lecture 10
Phys 102 Natural Systems
Nitrogen Fixation

• Nitrogen fixation is carried out by
• Cyanobacteria which live in soil
• The bacteria rhizobium which lives in the nodules
  (small swellings of the roots of legumes).
• Nitrate is very soluble, easily lost from soil by
  leaching.
• Can be returned to oceans where it can be
  returned to the atmosphere by denitrification.
• Animals receive the required nitrogen they need
  for metabolism, growth, and reproduction by the
  consumption of living or dead organic matter
  containing molecules composed partially of
  nitrogen.

Vincent Conrad
14
Nitrogen Cycle
Lecture 10
Phys 102 Natural Systems
Nitrogen Cycle

• Ammonification N is also added to the soil from
  animal biomass and manures.
• This detritus material containing N is broken
  down by specialised decomposer bacteria.
• It enters the soils as ammonia ammonium ions
  (NH4) or atmosphere as gas (NH4). This recycles
  large amounts of nitrogen to the soil.
• Lightning also plays a role in N fixation. It
  causes chemical reactions that result in solid
  nitrate compounds entering the soil through
  precipitation.
• Denitrification is carried out by bacteria that
  get the oxygen they need for metabolism from
  nitrates (rather than O2) under anaerobic (O2
  free) conditions. They convert NO3- into N2 or
  nitrous oxide (N2O) gas. Both of these gases then
  diffuse into the atmosphere.

Vincent Conrad
15
Nitrogen Cycle
Lecture 10
Phys 102 Natural Systems
Nitrogen Cycle
Vincent Conrad
16
Nitrogen Cycle
Lecture 10
Phys 102 Natural Systems
Nitrogen Cycle

• The activities of humans have severely altered
  the nitrogen cycle. Some of the major processes
  involved in this alteration include
• Application of nitrogen fertilizers to crops has
  caused increased rates of denitrification and
  leaching of nitrate into groundwater.
• This also comes from discharge of treated and
  untreated sewage and livestock waste.
• When this excess supply of nutrients reaches
  rivers/lakes it can stimulate rapid growth of
  algae and other aquatic plants.
• Large quantities of nitric oxide (NO) are
  released into the atm when wood or any fuel is
  burned. (NO forms when O and N are combined at
  high temps.)
• NO O2 --gt NO2 H2O --gt HNO3 (nitric acid).
• This is one of the components of acid rain, kills
  trees and fish.
• Burning grasslands and clearing forests removes
  nitrogen from the soil as well as producing
  nitrogen oxides into the atmosphere.

Vincent Conrad
17
Phosphorus Cycle
Lecture 10
Phys 102 Natural Systems
Phosphorus Cycle

• Phosphorus is essential for the body's energy
  transport molecules and for holding DNA and RNA
  molecules together.
• It is used in living organisms as phosphate ions
  (PO43- and HPO42-)
• The phosphorous cycle is an example a cycle that
  does not have a gas as part of its cycle.
  Bacteria are also far less important than in the
  N cycle.
• Phosphate are only slightly soluble in water.
  Thus often only small amounts in the soil --gt can
  be a limiting factor in plant growth.
• Phosphorus released from breakdown/weathering of
  phosphate rock deposits. Carried by water through
  soil and is taken up by plants.
• Phosphate particles can also be carried by wind.
• Animals get phosphorus from eating producers or
  primary consumers.
• By decomposing animal waste/biomass, producers
  return P to the soil.
• Finally through leaching P can end up in oceans
  and via sedimentation forms new phosphate rock
  deposits.

Vincent Conrad
18
Phosphorus Cycle
Lecture 10
Phys 102 Natural Systems
Phosphorus Cycle
Vincent Conrad
19
Phosphorus Cycle
Lecture 10
Phys 102 Natural Systems
Phosphorus Cycle

• There are two main ways we intervene in the
  phosphorus cycle
• Mining large quantities of phosphate rocks. This
  is to produce commercial fertilizers and
  detergents.
• Heavy uses of fertilizers in crop farming can
  cause large amounts of phosphates in the runoff
  water. This can also come from animal wastes.
• Since phosphorus is a limiting growth factor, as
  with nitrates and ammonium ions, excesses supply
  may cause explosive growth of algae and other
  kinds of plants that live in water.

Vincent Conrad
20
Sulphur Cycle
Lecture 10
Phys 102 Natural Systems
Sulphur Cycle

• The S cycle involves many physical, chemical and
  biological agents.
• S is essential in proteins and vitamins in
  organisms.
• Most of the Earth's sulphur exists in underground
  rocks.
• It enters the atm from three main sources
• Hydrogen sulfide (H2S). A poisonous gas with a
  rotten egg smell. Comes from active volcanoes and
  the decay of organic matter in swamps tidal flats
  by anaerobic decomposers.
• Sulphur dioxide (SO2) a colourless suffocating
  gas from active volcanoes.
• Particles of sulfate (SO42-) salts such as
  ammonium sulphate, from sea spray.

Vincent Conrad
21
Sluphur Cycle
Lecture 10
Phys 102 Natural Systems
Sulphur Cycle

• Circulates from rocks deep under the ocean
  sediment.
• Sedimentation of organic matter forms fossil fuel
  deposits containing S.
• This also produces sulphates in the soil which
  are taken up by plants.
• The action of microorganisms releases the
  sulphates in the soil via reduced sulphur (H2S).
• In the atm SO42- O2 --gtSO3 (sulphur trioxide)
  H2O --gt H2SO4 (sulphuric acid).Sulphuric acid
  is a component of acid rain, killing trees and
  fish.
• We intervene in a major way! About 1/3 of all
  sulphur compounds reaching the atm come from
  human activities. (99 SO2 entering atm from
  human activities!)

Vincent Conrad
22
Sulphur Cycle
Lecture 10
Phys 102 Natural Systems
Sulphur Cycle
Vincent Conrad
23
Temperature Regulation
Lecture 10
Phys 102 Natural Systems
Sulphur Cycle

• Dimethyl sulfide (DMS) produced by oceanic
  phytoplankton
• It may provide feedback to regulate global
  climate
• It helps form more clouds.
• Climate warmer --gt more DMS --gt more clouds
  blocking sunlight --gt lowering surface
  temperatures.
• Was one of initial processes that inspired
  Lovelock's Gaia Theory of the self regulating
  earth.

Vincent Conrad
24
Oxygen Cycle
Lecture 10
Phys 102 Natural Systems
Oxygen Cycle
Vincent Conrad
25
Phys 102 Natural Systems
Vincent Conrad