BIOL 4120: Principles of Ecology Lecture 2: Adaptation to Physical Environment: Water and Nutrients

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BIOL 4120 Principles of Ecology Lecture 2
Adaptation to Physical Environment Water and
Nutrients

• Dafeng Hui
• Office Harned Hall 320
• Phone [phone]
• Email dhui_at_tnstate.edu

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• Topics (Chapter 2)
• 2.1 Global water cycling
• 2.2 Water has many properties favorable to life
• 2.3 Many inorganic nutrients are dissolved in
  water
• 2.4 Plants obtain water and nutrients from soil
• 2.5 Maintain salt and water balance by plants and
  animals

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2.1 Global Hydrologic (water) cycle between Earth
and atmosphere

• Water is essential for life (75-95 weight of
  living cell)
• Over 75 of the Earths surface is covered by
  water
• Oceans contain 97.
• Polar ice caps and glaciers contain 2.
• Freshwater in lakes, streams, and ground water
  make up less than 1.
• (Saltwater and fresh water)

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Water Cycles between Earth and the Atmosphere

• The water (or hydrologic) cycle is the process by
  which water travels in a sequence from the air to
  Earth and returns to the atmosphere
• Solar radiation is the driving force behind the
  water cycle because it provides energy for the
  evaporation of water

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The Hydrologic Cycle

• Precipitation (PPT)
• Interception
• Infiltration
• Groundwater recharge
• Runoff
• Evaporation (E)
• Transpiration (T)

Distribution of water is not static (processes)
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Global water budget
Land Pools (103 km3) Glaciers
29,000 Groundwater4,000 Lake 229 Soil
67 Fluxes (km3/yr) PPT 111,000 ET
71,000 River flow40,000 Ocean Pools (103
km3) Ocean1.37106 Fluxes (km3/yr) PPT385,000
ET 425,000
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2.2 Properties of water that favorable to life
Basic Structure 1. Covalent bonding of 2H O
atoms 2. Polar-covalent bond 3.
Inter-molecule attraction 4. H-bonds among
water moleculars
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Physical and chemical properties

• Thermal properties of water High specific heat
  capacity
• 1.Specific Heat 1.0 (also called Heat Capacity)
• calories required to raise 1 g H2O 1oC high
• (e.g. from 10 to 11oC) (Stable T in lakes and
  organisms)
• 2. Latent heat energy released or absorbed in
  the transformation of water from one state to
  another.
• 1 calorie to raise 1oC 536 calories to
  change 100oC water to vapor 86 calories ice to
  1oC water
• 3. Peculiar density-temperature relationship
• Density increases as T decreases (when Tgt
  4oC), then decrease to 0oC, freezing (ice), float.

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• Cohesion
• Due to the hydrogen bonding, water molecules tend
  to stick firmly to each other, resisting external
  forces that would break the bonds (drop of
  water, transpiration).

• Surface tension
• Strong attraction within the water body and
  weaker attraction in the surface caused that
  molecules at the surface are drawn downward.

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• High viscosity
• Viscosity measures the force necessary to
  separate the molecules and allow passage of an
  object through liquid.
• Frictional resistance is 100 times greater than
  air.
• Water is 860 times denser than air.
• Organisms in water have similar density to water,
  the neutral buoyancy helps against the force of
  gravity, thus require less investment in
  structure material such as skeletons
• Organisms in deep water need to adapt to the high
  pressure (20 to 1000 atm).

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2.3 Many inorganic nutrients are dissolved in
water
Solution a homogeneous liquid with 2 or more
substances mixed. Solvent dissolving
agent Solute substance that is dissolved Aqueous
solution water as solvent Ions Compounds of
electrically charged atoms Cations
positive Anions negative Practical salinity
units (PSU, o/oo) grams of salt per kilogram of
water. Ocean 35 unit, Fresh water 0.065-0.30
unit)
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Hydrogen ions in ecological systems
Hydrogen ions are very active 1) affect enzyme
activities, and thus influence life processes 2)
dissolve minerals from rocks and soils.
Acidity the abundance of hydrogen ions (H) in
solution. Alkalinity abundance of hydroxyl ions
(OH-) in solution Acidity in water is related to
carbon dioxide (CO2).
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Forms of carbon in water

• Carbon-bicarbonate equilibrium
• Carbon dioxide CO2
• Carbonic acid H2CO3
• Bicarbonate HCO3-
• Carbonate CO32-

CO2 H2O? H2CO3 ?HCO3- H ?CO32- 2H
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• Measurement pH -log(H)
• (value between 1-14)
• Pure water 7 Acidic lt7 Alkaline gt7
• Ocean water tends to be slightly alkaline
  with a pH range of 7.5-8.4

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2.4 Plants obtain water and nutrients from soil

• Plants and animals need water and nutrients to
  growth and reproduce.

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Plants acquire the inorganic nutrients as ions
dissolved in water

• N ammonium (NH4), nitrate (NO3-)
• P phosphate ions (PO43-)
• K K
• Na Na
• Ca Ca2
• The availability in soil is determined by their
  chemical forms in soil, temperature, acidity, and
  presence of other ions.

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2.4.1 Ion exchange capacity is important to soil
fertility

• Soil soluble nutrients are charged particles,
  ions.
• Cations positively charged (Ca2, Mg2, NH4)
• Anions negatively charged (NO3, PO34)
• Ions are attached to soil particles, so they do
  not leach out of the soil.
• Ion exchange capacity total number of charged
  sites on soil particles in a standard volume of
  soil.

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Soils have an excess of negative charged sites

• Cationic exchange dominant (colloids)
• Cation exchange capacity (CEC) total of
  negatively charged sites, located on the leading
  edges of clay particles and Soil Organic Matter.
• Concentration and affinity

Al3 gt H gt Ca2 gt Mg2 gt K NH4 gt Na
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Process of cation exchange in soils
In soils with high Mg or Ca, K is lacking,
why?
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2.4.2 Soil properties and water-holding capacity

• Texture
• Variation in size and shape of soil particles
• Gravel (NOT)
• gt2mm
• Sand
• 0.05mm to 2mm
• Silt
• 0.002mm to 0.05mm
• Clay
• lt0.002mm

Soil texture is percentage of sand, silt and
clay. (Texture chart)
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Sand 58 Clay 14 Silt 28
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Water holding capacity is an essential feature of
soils

• Soil can become saturated if all pores filled
• All water is hold by soil particulars, at field
  capacity (FC)
• Capillary water is usually present
• Extractable by plants
• Wilting point (WP)
• Plant no long extract water
• Available water capacity (AWC)
• All affected by soil texture
• Sand
• Lower capacity
• Clays
• Higher capacity

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Water content at different soils
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2.4.3 Water moves from soil to plant to atmosphere
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Water potential

• Water moving between soil and plants flows down a
  water potential gradient.
• Water potential ( ) is the capacity of water to
  do work, potential energy of water relative to
  pure water.
• Pure Water 0.
• in nature generally negative.
• solute measures the reduction in due to
  dissolved substances.

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Water potential of compartment of
soil-plant-atmosphere

• w p o m
• Hydrostatic pressure or physical pressure (cell
  wall).
• Osmotic potential tendency to attract water
  molecule from areas of low concentrations to
  high. This is the major component of total leaf
  and root water potentials.
• Matric potential tendency to adhere to surfaces,
  such as container walls. Clay soils have high
  matric potentials.

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Water moves from soil to plant to atmosphere
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The cohesion-tension theory explains the movement
of water from the roots to a leaf of a
plant. 1. Through Xylem 2. No metabolic energy
required 3. Depends on physical-chemical
properties of water, driven by water
potential. Stick to each other and adhere to
cell wall.
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BIOL 4120 Principles of Ecology Lecture 2
Adaptation to Physical Environment Water and
Nutrients

• Dafeng Hui
• Office Harned Hall 320
• Phone [phone]
• Email dhui_at_tnstate.edu

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• Recap
• Water properties
• Many inorganic nutrients are dissolved in water
• Nutrients, pH
• Plants obtain water and nutrients from soil
• Soil and nutrient (CEC)
• Soil properties and water (water holding
  capacity)
• Water movement from roots to plants to air

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2.5 Maintenance of salt and water balance

• To maintain proper amount of water and dissolved
  substances in their bodies, organisms must
  balance losses with intake.
• When organisms take in water with solute
  concentration differs from that of their bodies,
  they must either acquire more solutes to make up
  the deficit or get rid of excess solutes
• Uptake of water with solutes
• Evaporation from surface of terrestrial organisms
  into atmosphere
• Solutes left behind, high salt concentration
• Solutes determine osmotic potential of body
  fluids, the mechanisms that organisms use to
  maintain a proper salt balance are referred to as
  osmoregulation.

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2.5.1 Management of salt balance by plants
Transpiration water uptake dissolved salts
along water will get into roots When salts
concentrations in soil water are high, plants
pump excess salts back into soil by active
transport across their root surface, function as
plants kidneys.
One example Mangroves on coastal mudflats Salt
glands on the leaf surface
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2.5.2 Water and salt balance in terrestrial
animals

• Terrestrial
• Input
• Drinking
• Eating
• Produced by metabolism (respiration)
• Output Need to control in extreme environments
• Urine
• Concentrated to avoid water loss (Kidneys).
  Human 4 times high than in blood Kangaroo rat
  14 times
• Feces
• Evaporation
• No sweat glands in some mammals
• salt glands in birds and reptiles
• Breathing

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What happens to ungulates in a hot dry climate
like Africa?
No pants, no sweating to save water, store heat
in body (T up to 46oC at daytime, release heat at
night 36oC) Countcurrent heat exchange to lower
head T Eat at nighttime, more water in
plants Respiration to produce water
Oryx
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2.5.3 Water and salt balance in aquatic animals

• Freshwater (hyper-osmotic, high salt in body)
• Prevent excess uptake of water
• Remove excess water
• Large amounts of very dilute urine
• Retain salt in special cells (gills, kidneys)
• Saltwater (hypo-osmotic, low salt in body)
• If salt concentration is higher than in body,
  dehydrate
• Drinking a lot to gain water
• Some sharks retain urea in the bloodstream
  (balance body surface water loss)
• Ion pumps, gill (fish)
• Kidneys (eliminate salts, marine mammals)
• Salt secreting glands in birds

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The End
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Proportions of the formsof CO2 in Relation to pH
Free
Bicarbonate
Carbonate
pH CO2 HCO3 CO3 4 0.996 0.004 1.26 x
10-9 5 0.962 0.038 1.20 x 10-7
6 0.725 0.275 0.91 x 10-5 7 0.208 0.792 2.60
x 10-4 8 0.025 0.972 3.20 x 10-3
9 0.003 0.966 0.031 10 0.000 0.757 0.243
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• Recap
• Water properties
• Many inorganic nutrients are dissolved in water
• Nutrients, pH
• Plants obtain water and nutrients from soil
• Soil and nutrient (CEC)
• Soil properties and water (water holding
  capacity)
• Water movement from roots to plants to air

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• Recap
• Physical environment water and nutrient
• Water properties
• Inorganic nutrients need to be dissolved in
  water, Nutrients uptake from soil
• Ion exchange capacity is a measure of soil
  fertility
• Soil texture and water holding capacity
• Water movement from soil to plant to
  atmosphere