Marine Sediment and Water

I. Marine Sediment A. Sediments are dissolved particles of dirt, dust and debris that have settled in the ocean.

B. They tell us about past climates, movements of ocean floor, circulation patterns and nutrient supplies. C. Core samples allow oceanographers to study sediment through time. * What happens in the abyss stays in the abyss.

D. Often become sedimentary rock E. Particles from eroded rock and living organisms.

1. particles from eroded rock called Lithogenous (most is quartz) a. includes illite clays b. beach sands c. glacial deposits d. volcanogenic particles

2. particles produced by plants and animals in the sea are called Biogenous sediments.

F. The smaller the particle the further it is carried from shore. 1. Example, coarse sand is found near Atlantic coastal margin while Maganese nodules (crystallization of sea water metals)and clay are found in the abyssal plain.

2. Neretic deposits – found near shore (coarse and heavy) 3. Pelagic deposits – found in the deep sea (fine and light)

G. Origin 1. Rivers carry sediment eroded from precipitation a. Asia is responsible for most river origin sediment delivered to ocean basins.

2. Glaciers – grind sediment from land as they move toward the sea. 3. Wind – wind is the major force bringing continental sediments to the open ocean.

H. Random bit of information – Calcium carbonate (limestone)dissolves best in cold water with lots of carbon dioxide.

II. Properties of water.water

A.Water is one of the most amazing and important substances on earth. 1. It controls our weather 2. It dissolves almost anything 3. It stores massive quantities of heat 4. It makes life possible 5. Carries sediment to the oceans. 6. Destroys mountains 7. Etc.

B. Phases of water. 1. Like most substances, water has 3 phases: solid, liquid and vapor. 2. Phases of water are determined primarily by temperature and pressure.

3. The amount of energy that must be added to one gram of liquid water to raise it’s temp by one degree is called a calorie (4.184 joules)

4.It takes more energy to change water from liquid to vapor than to change it from solid to liquid.

5. Evaporation- water changing phase from liquid to vapor only at the surface (unlike boiling) a. When water evaporates from the ocean, the ocean temp. drops *This is why we sweat.

C. Bonding- Covalent and Hydrogen bonding give water many of it’s properties. 1. Water molecules (H 2 O) are polar (like a magnet) with a + and – side.

a. This polarity causes hydrogen bonds between neighboring H 2 O molecules. b. Polarity gives water many of its UNUSUAL characteristics.

2. The bonds between the Hydrogen (H) atoms and Oxygen (O) atom in a water molecule are Covalent. a. Covalent bonds are very strong and share electrons between participating atoms.

D. Viscosity – how easily a liquid flows – lower viscosity = easier flow 1. Water viscosity decreases with increase in temp. 2. Water viscosity increases as it becomes more salty.

E. Surface tension – force allowing liquid to resists outside forces.Surface tension 1. Surface tension is high in water 2. caused by hydrogen bonding of water.

3. allows some insects to glide across surface of water.somewater

4. Allows water to “pile up above the rim of a glass” when over-filled. 5. Water with Memory?????Memory?????

III. Chemistry of Seawater A. Seawater contains many dissolved substances, mostly salt. 1. There is enough salt in the oceans to cover the earth in a 500ft deep layer.

B. Salinity= amount of solid material dissolved in water. 1. Seawater has a salinity of about 3.5% a. I.E. 35 parts per thousand. 2. By weight, the most abundant dissolved ions in seawater are sodium and chloride..

3. The rule of constancy of composition refers to the fact that major ions in seawater are in constant proportions. a. that means changes in salinity are due to loss or gain of water molecules rather than addition of more solute (like salt).

4. However, it is not always even in salinity. a. a region of rapid salinity change with depth is most properly called a halocline

5. Gas dissolved in water also plays a role in salinity. a. as pressure increases the amount of gas that dissolves in water increases.

b. as temperature increases the amount of gas dissolved in water decreases.

c. A product of photosynthesis is Oxygen. d. Respiration produces Carbon Dioxide.

6. Salinity changes freezing a. Surface ocean water does not usually freeze because its salinity decreases the freezing point below 0 degrees celcius.

C. Density. 1. The most significant factor influencing ocean water density is temperature. a. At high latitudes the density of seawater is strongly controlled by pressure with depth.

2. As water becomes colder the density increases. a. In the fall lakes “turn over” because water reaches its maximum density before it reaches its freezing temperature.