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Lecture 4 (Ch. 5 of text) Properties of Seawater (Part I) Biology is wet Lecture 4 (Ch. 5 of text) Properties of Seawater (Part I) Biology is wet and dynamic - Random walks in biology 1983, by H. C. Berg The most common molecule on the Earth - water Soup as salty as the seawater

Learning Objectives 1. Understand the nature of the water molecule and its unique properties Learning Objectives 1. Understand the nature of the water molecule and its unique properties and how these are altered by the presence of salt in solution. Review of following terminologies: Atoms Temperature Heat Specific Heat Thermodynamics Internal Energy and Entropy 2. Know the types of materials that are dissolved in sea water, their importance and how they vary with time. 3. Explain variations in salinity, temperature, and pressure within the sea and how they alter the chemical and physical properties of the ocean.

Atomic Structure (Ch. 5. 1) • The smallest unit of a substance that retains Atomic Structure (Ch. 5. 1) • The smallest unit of a substance that retains all of its chemical properties • Subatomic particles include protons, neutrons, and electrons • A stable atom of an element is electrically neutral • An ion is an atom with either positive- (excess protons) or negative- (excess electrons) charged • Atoms that chemically bonded to another (either same type or different one) comprise a molecule • An element has isotopes due to its varied no. of neutrons in nucleus

Periodic Table 稀土元素 錒系元素 More likely to loose electrons and be positively charged More Periodic Table 稀土元素 錒系元素 More likely to loose electrons and be positively charged More likely to gain electrons and be negatively charged The charge of an ion is the single most important reason for its ability to bond with other elements

Basic physical notions (Ch. 5. 2) H 2 O: the only substance that can Basic physical notions (Ch. 5. 2) H 2 O: the only substance that can co-exist naturally as a gas, liquid, and solid states on the Earth’s surface 聚合體 States of Matter (e. g. water) Thermodynamics: the kinetic theory of heat

Phase diagram for water Phase diagram for water

a mercury thermometer Precisely, what does the temperature reading mean? Why does the hot-air a mercury thermometer Precisely, what does the temperature reading mean? Why does the hot-air balloon move upward?

State variables What is temperature? it is a measure of the average translational kinetic State variables What is temperature? it is a measure of the average translational kinetic energy associated with the disordered microscopic motion of atoms and molecules. It is measured in (Celsius, Kelvin, and Fahrenheit). using Kinetic temperature definition

Concept of Entropy (熵 ) Thermal Equilibrium = Maximum Entropy d. S = d. Concept of Entropy (熵 ) Thermal Equilibrium = Maximum Entropy d. S = d. Qrev = 0; d. Qrev : heat being reversibly qqqqqadded or removed T

However, the concept of temperature is complicated by internal degrees of freedom Box is However, the concept of temperature is complicated by internal degrees of freedom Box is solid (Constant volume) Heat: 1) Represents the transfer of energy from high to low temperature. Therefore, heat has units of Energy Q 2) An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy. Heat may be defined as energy in transit from a high temperature object to a lower temperature object.

State variables What is Internal Energy? Internal energy = Measure of the Kinetic energy State variables What is Internal Energy? Internal energy = Measure of the Kinetic energy and potential energy on atomic and molecular scales.

There is a difference between Temperature and Internal Energy k = 1. 38 x There is a difference between Temperature and Internal Energy k = 1. 38 x 10 -23 J/◦K

Change of Internal Energy Change of Internal Energy

First Law of Thermodynamics Temperature Pressure First Law of Thermodynamics Temperature Pressure

Specific Heat Capacity? Amount of energy needed to raise temperature of unit volume of Specific Heat Capacity? Amount of energy needed to raise temperature of unit volume of water by one degree C. Units: energy/(mass * degree)

Flow chart of thermodynamics http: //hyperphysics. phy-astr. gsu. edu/hbase/heacon. html#heacon Flow chart of thermodynamics http: //hyperphysics. phy-astr. gsu. edu/hbase/heacon. html#heacon

Flow chart of thermodynamics http: //hyperphysics. phy-astr. gsu. edu/hbase/heacon. html#heacon Flow chart of thermodynamics http: //hyperphysics. phy-astr. gsu. edu/hbase/heacon. html#heacon

Facts: – Water has one of highest heat capacities ccknown, makes water excellent heat Facts: – Water has one of highest heat capacities ccknown, makes water excellent heat cctransfer material – Allows ocean currents to modulate global ccclimate

The amazing water molecule (Ch. 5. 3) Liquid/gas state only Plus high heat capacity The amazing water molecule (Ch. 5. 3) Liquid/gas state only Plus high heat capacity (thermal inertial) and solvent power (Covalent bond) 共價鍵結 (in electricity) (hydrogen bonding)

Water is a powerful solvent – for example Sodium Chloride Rock SALT Ionic bond Water is a powerful solvent – for example Sodium Chloride Rock SALT Ionic bond Cation 陽離 子 Anion 陰離子 Cation: in greek, downward, descend; anode 陽極 Anion: in greek, go up, ascend; cathode 陰極

外層覆蓋物 Hydration: Water (as solvent) dissolves salts (as solute) by surrounding the atoms in 外層覆蓋物 Hydration: Water (as solvent) dissolves salts (as solute) by surrounding the atoms in the salt molecule and neutralizing the ionic bond holding the molecule together.

All solid-state substances sink in their own liquids, except the water ! Mickey’s ears All solid-state substances sink in their own liquids, except the water ! Mickey’s ears loosen when entering the ice house (109. 50 )

Properties of Seawater • • Salinity Temperature Density Pressure Properties of Seawater • • Salinity Temperature Density Pressure

Salinity: the total weight in grams of dissolved salt in 1 KG of seawater Salinity: the total weight in grams of dissolved salt in 1 KG of seawater expressed as ‰ (part per thousand PPT)

Another factor contributing to the dissolution of salts is acidity Another factor contributing to the dissolution of salts is acidity

Sources for acidity in the ocean Carbonic Acid Bicarbonate Ion (重碳酸鹽離子 ) Sources for acidity in the ocean Carbonic Acid Bicarbonate Ion (重碳酸鹽離子 )

Example: Orthoclase (正長石 ) Kaolinite Dissolved Silica Example: Orthoclase (正長石 ) Kaolinite Dissolved Silica

Major constituent (conservative ions) of Seawater (c. f. Table 5. 1) Seawater Rivers (鉀 Major constituent (conservative ions) of Seawater (c. f. Table 5. 1) Seawater Rivers (鉀 ) 35 PPT 0. 088 PPT

Sources of Salt in Seawater Weathering and erosion of rocks on land 陽離子交換 落塵 Sources of Salt in Seawater Weathering and erosion of rocks on land 陽離子交換 落塵 Rate of supply of salts from rivers: 1015 grams/year !

Surprisingly, The Ocean DOES NOT get saltier at least during the past 1. 5 Surprisingly, The Ocean DOES NOT get saltier at least during the past 1. 5 billion years The "steady state" results from the removal rate of salts from the ocean being equal to the input rate. This balance holds because the removal rate of salts is related to their concentration, and increases when their concentration increases

Sinks of Salt in Seawater Removal of salt from seawater occurs by (1) inorganic Sinks of Salt in Seawater Removal of salt from seawater occurs by (1) inorganic process, such as a. evaporation-precipitation loop through the formation of supersaturated solution, b. wind, c. adsorption, and (2) organic process such as diatoms having silica shells and forams with carbonate shells that are precipitated from the uptake of Si 4+ and Ca 2+ from seawater (Ch. 4) 石膏

The equilibrium state of salinity of seawater gives a hint toward the grand sedimentary The equilibrium state of salinity of seawater gives a hint toward the grand sedimentary cycle in geologic time frame

If rivers are the primary supply of salts. Why is CALCIUM and BICARBONATE so If rivers are the primary supply of salts. Why is CALCIUM and BICARBONATE so little in seawater? Seawater Rivers 35 PPT 0. 088 PPT

… different processes removing different elements HCO 3 and Ca are used biologically very … different processes removing different elements HCO 3 and Ca are used biologically very rapidly (non-conservative) Na and Cl are removed very slowly, by absorption on clay particles (conservative) Elements have different residence times, decided by reactive speed and demanding by ocean biota (see Table 5. 8)

Residence time the average time a component spends in a system (such as monthly Residence time the average time a component spends in a system (such as monthly stipend in your account). C = total amount r = the removal rate (units of [C]/time)

slow absorption removal Rapid biological removal slow absorption removal Rapid biological removal

The ocean gets thoroughly stirred, by currents, every ~1, 600 years, . This is The ocean gets thoroughly stirred, by currents, every ~1, 600 years, . This is called the mixing time of the ocean: the time it takes the ocean to mix thoroughly Salts stay in seawater much longer than 1, 600 years Salt well mixed Constant proportion of relative constituents salts of seawater

The Hydrological Cycle The Hydrological Cycle

Surface Salinity (which season? ) Subsidence regions Evaporation − Precipitation (c. f. Fig. 5 Surface Salinity (which season? ) Subsidence regions Evaporation − Precipitation (c. f. Fig. 5 -12 of text)

Spread out of Mediterranean seawater Spread out of Mediterranean seawater

Effects of salinity on the properties of water Effects of salinity on the properties of water

Chemical/physical structure of the oceans (Ch. 5. 5) Chemical/physical structure of the oceans (Ch. 5. 5)

January Winter July Summer July-January Summer-Winter January Winter July Summer July-January Summer-Winter

Why is the deep ocean cold? Why is the deep ocean cold?

Transfer of Heat to the Ocean (heat flux) Absorption of solar radiation decreases rapidly Transfer of Heat to the Ocean (heat flux) Absorption of solar radiation decreases rapidly with depth

Vertical Structure of Temperature Thermocline Vertical Structure of Temperature Thermocline

Vertical Structure of Temperature Outstanding question: what sets the depth of thermocline? Vertical Structure of Temperature Outstanding question: what sets the depth of thermocline?

Salinity How do the water masses move? c. f. Fig. 5. 13 b Temperature Salinity How do the water masses move? c. f. Fig. 5. 13 b Temperature

Vertical profiles DENSITY: controls the movement and stability of the ocean water masses Vertical profiles DENSITY: controls the movement and stability of the ocean water masses

Next time we will talk more about DENSITY and PRESSURE in the OCEAN Next time we will talk more about DENSITY and PRESSURE in the OCEAN