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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: 963-5777 Email: dhui@tnstate.edu. Topics (Chapter 2): 2.1 Global water cycling 2.2 Water has many properties favorable to life

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biol 4120 principles of ecology lecture 2 adaptation to physical environment water and nutrients

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

Dafeng Hui

Office: Harned Hall 320

Phone: 963-5777

Email: dhui@tnstate.edu

slide2
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

2 1 global hydrologic water cycle between earth and atmosphere
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 Earth’s 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)

water cycles between earth and the atmosphere
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
the hydrologic cycle
The Hydrologic Cycle
  • Precipitation (PPT)
  • Interception
  • Infiltration
  • Groundwater recharge
  • Runoff
  • Evaporation (E)
  • Transpiration (T)

Distribution of water is not static (processes)

global water budget
Global water budget

Land

Pools (10^3 km3):

Glaciers: 29,000

Groundwater:4,000

Lake: 229

Soil: 67

Fluxes (km3/yr):

PPT: 111,000

ET: 71,000

River flow:40,000

Ocean

Pools: (10^3 km3)

Ocean:1.37*10^6

Fluxes: (km3/yr)

PPT:385,000

ET: 425,000

2 2 properties of water that favorable to life
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

physical and chemical properties
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 T> 4oC), then decrease to 0oC, freezing (ice), float.

slide9
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.
slide10
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).
2 3 many inorganic nutrients are dissolved in water
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)

hydrogen ions in ecological systems
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).

forms of carbon in water
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+

slide14
Measurement: pH =-log([H+])

(value between 1-14)

  • Pure water: 7 Acidic: <7 Alkaline: >7
  • Ocean water tends to be slightly alkaline with a pH range of 7.5-8.4
2 4 plants obtain water and nutrients from soil
2.4 Plants obtain water and nutrients from soil
  • Plants and animals need water and nutrients to growth and reproduce.
plants acquire the inorganic nutrients as ions dissolved in water
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.

2 4 1 ion exchange capacity is important to soil fertility
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.

soils have an excess of negative charged sites
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+ > H+ > Ca2+ > Mg2+ > K+ = NH4+ > Na+
process of cation exchange in soils
Process of cation exchange in soils

In soils with high Mg++ or Ca++, K+ is lacking, why?

2 4 2 soil properties and water holding capacity
2.4.2 Soil properties and water-holding capacity
  • Texture
    • Variation in size and shape of soil particles
      • Gravel (NOT)
        • >2mm
      • Sand
        • 0.05mm to 2mm
      • Silt
        • 0.002mm to 0.05mm
      • Clay
        • <0.002mm

Soil texture is percentage of sand, silt and clay. (Texture chart)

slide23

Sand: 58%

Clay: 14%

Silt: 28%

water holding capacity is an essential feature of soils
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
water potential
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.
water potential of compartment of soil plant atmosphere
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.
slide32

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.

biol 4120 principles of ecology lecture 2 adaptation to physical environment water and nutrients1

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

Dafeng Hui

Office: Harned Hall 320

Phone: 963-5777

Email: dhui@tnstate.edu

slide34
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

2 5 maintenance of salt and water balance
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.
2 5 1 management of salt balance by plants
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 plant’s “kidneys”.

One example: Mangroves on coastal mudflats

Salt glands on the leaf surface

2 5 2 water and salt balance in terrestrial animals
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
what happens to ungulates in a hot dry climate like africa
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

2 5 3 water and salt balance in aquatic animals
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
proportions of the forms of co 2 in relation to ph
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

slide43
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

slide44
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