20 1 Properties of Ocean Water (1) for walkabout notes.notebook. April 24, 2018

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1 Although pure water is tasteless, odorless and colorless, ocean water is not pure. Ocean water is a complex mixture of: dissolved solids and gasses, small particles of matter, tiny organisms, chemicals that sustains a variety of plant and animal life. Apr 17 3:34 PM 1

2 Dissolved Gasses: The two primary gasses in the atmosphere are: Nitrogen, N 2, and Oxygen, O 2. This is true also for the ocean water. CO 2 is also present in larger quantities in ocean water, as well as other atmospheric gasses. How gasses enter the ocean? 1. Water from streams and rivers 2. Volcanic eruptions from beneath the oceans 3. Released directly into the ocean by the marine organisms that live in the ocean a. Photosynthesis 4. Most enters the ocean directly from the atmosphere Apr 17 3:38 PM 2

3 Temperature and Dissolved Gasses Gasses dissolve more readily in cold water than in warm water. Therefore water at the surface of an ocean in a cold region dissolves gasses more readily, than oceans located near the equator. The Oceans as a Carbon Sink The oceans contain 60 times as much carbon as the atmosphere does, because dissolved CO 2 may have been trapped in the oceans for hundreds to thousands of years. (Why the oceans are called a carbon sink.) This dissolved CO 2 in the oceans is important in the regulation of Earth s climate. Apr 18 1:40 PM 3

4 Dissolved Solids 97% of all water on Earth is salt water. Ocean water is 96.5% pure water and 3.5% is dissolved sea salts. o These salts are composed of about 75 chemical elements: (6 most abundant) Chlorine Sodium Magnesium Sulfur calcium potassium Apr 16 3:12 PM 4

5 o Halite (made up of sodium and chloride ions) makes up more than 85% of the ocean s dissolved solids. o Trace elements also exist in very small amounts: i.e. gold, zinc or phosphorous. Sources of Dissolved Solids Come from three main sources: 1. Volcanic eruptions 2. Chemical weathering of rock on land o Each year 400 billion kilograms of dissolved solids enter the oceans from rivers. 3. Chemical reactions between sea water and newly formed sea floor rocks. Apr 16 3:13 PM 5

6 Salinity of ocean water Salinity is the measure of the amount of dissolved salts and other solids in a given liquid. Salinity is measured by the number of grams of dissolved solids per 1,000 g of ocean water. Ex: 1000 g of ocean water contained 35g of solids, the salinity would be 35 parts salt per 1,000 parts of ocean water : or 35% 0. (35 parts per thousand = salinity. 3.5% salty) Freshwater is less than 0.1% salt or has a salinity of 1% 0. Apr 18 1:49 PM 6

7 Factors that change salinity Precipitation (rain / snow) Evaporation (leaves remaining salts behind) If the rate if evaporation is greater than the rate of precipitation; salinity of the surface water increases. Equatorial regions (more rainfall b/c highest precipitation) salinity levels are lower. Apr 18 1:57 PM 7

8 Temperature of Ocean Water Varies depending on depth and location on the surface of the oceans. Affected by the amount of solar energy and the movement of the water in the ocean. o Tropics surface temp s can reach 30 C o Polar surface temp s drop to 1.9 C Also surface temperature decreases as latitude increases. Apr 18 2:00 PM 8

9 Thermocline The sun cannot warm water below the surface layer (approx feet) the temperature of the water decreases sharply as depth increases. This layer is the thermocline. Warm water is less dense than cold water and the thermocline marks the area between the warm surface water and the cold deep water. Apr 16 3:40 PM 9

10 Deep water In the deep zones, the temperature is usually about 2 C. The colder the water is the denser it is. This cold deep water controls the slow movement of deep ocean currents. The cold deep water holds more dissolved gases than the warm, shallow ocean water does. Apr 18 2:16 PM 10

11 Density of Ocean Water The mass of a substance per unit of volume is that substance s DENSITY. Pure water is 1g/cm 3 Salt water is denser than pure water. (between 1.026g/cm 3 and 1.028g/cm 3 ) Two factors affect the density of ocean water. Salinity dissolved solids add mass Temperature ocean water become denser as it gets colder. (Temperature has a greater impact on density) Apr 18 2:18 PM 11

12 Color of Ocean Water The color of ocean water is determined by the way it absorbs or reflects sunlight. Water absorbs most of the wavelengths of white light (all the colors of ROY G BIV). Only the blue wavelength tends to be reflected. Why is ocean water color important? Organisms, like phytoplankton, can affect the color of ocean water. Phytoplankton absorb red and blue light but reflect green. Therefore, the presence or amount of phytoplankton can affect the shade of blue of the ocean s water. Apr 18 2:21 PM 12

13 Presence or absence of phytoplankton can determine the health of the ocean. A lack of phytoplankton may be because of pollution. Sep 2 7:40 PM 13

14 Attachments Oceans.asf Salt_Water.asf