LESSON 3: MORE ABOUT WATER

THINKING – 97% OF EARTH’S WATER IS SALTY……… Where does the salt in the ocean come from?

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Does the ocean have the same “saltiness” everywhere? Why or why not? Do you have any evidence to support your answer? (i.e. – visits, readings)

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How might salt affect marine organisms?

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THINKING – 97% OF EARTH’S WATER IS SALTY……… Where does the salt in the ocean come from?

Minerals, rivers, sediments

Does the ocean have the same “saltiness” everywhere? Why or why not? Do you have any evidence to support your answer? (i.e. – visits, readings)

Yes, depends on the volume of the body of water as well as temperature which leads to evaporation. How might salt affect marine organisms?

They have to adapt to ranging saltiness, most organism prefer 0.9% saltiness for homeostasis.

WATER: THE UNIVERSAL SOLVENT

Water’s unequal distribution of electrons gives it extreme solubilityThis is called polarity

Many salts in the ocean easily dissolve in waterSalts typically contain a metal and nonmetalCreates an ionic bond which is a transfer of electrons

Let’s draw an ionic compound: Na – atomic number? Cl – atomic number?

11

17

When water interacts with salt, the NaCl ionizes meaning it splits into individual ions

This is what happens when a substance dissolves.

Na+ is attracted to the negative side of water

Cl- is attracted to the positive side of water

PROPERTIES OF COMPOUNDS AND MOLECULES

Conductivity – ability of a substance to carry an electric charge

Created by dissolved salts

Pure or distilled water has no ions therefore does not conduct electricity

PROPERTIES OF COMPOUNDS AND MOLECULES

Salinity – measure of dissolved salts in water

Seawater contains sulfate, magnesium, calcium, potassium, and bicarbonate in addition to sodium chloride

Average salinity = 35 ppt (3.5%)

PROPERTIES OF COMPOUNDS AND MOLECULES

Distilled water has no salinity

Fresh and tap water have very low salinityWater is considered fresh if < 1 ppt salt

Expressed in practical salinity units or PSU.1 PSU = 1 ppt

GLOBAL MAP OF SEA SURFACE SALINITY

ORGANIZE YOUR DATA

Type of Water Average Salinity (PSU

Distilled

Tap

Fresh

Salt

ORGANIZE YOUR DATA

Type of Water Average Salinity (PSU)

Distilled 0

Tap 0.5

Fresh 1

Salt 35

WHY IS THE SEA SALTY?

Water’s excellent ability to act as a solvent carries materials all over Earth. Similarly, the water in your blood helps carry oxygen, vitamins, minerals, and nutrients to your body’s cells.

WHERE DOES IT COME FROM?

From Land: 4 billion tons of salt are carried by rivers into oceans each year

HYDROTHERMAL VENT AT SEAFLOOR

From inside the Earth:Volcanoes, hydrothermal vents, and other processes at seafloor spew minerals from Earth’s crust into ocean

PARTICLES DEPOSITED BY WIND

From the Atmosphere:

Particles carried by wind are deposited into ocean

Both natural and human-made

SALINITY AND MARINE ORGANISMS

Brackish – water that is somewhere between salty and fresh

Estuaries – where rivers meet the sea Mangrove forests and salt marshes

“Nurseries of the sea” Young organisms develop

here Prevent erosion

NOAA ESTUARY VIDEOS

Based on the videos:

Describe 3 important roles of estuaries.

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Based on what you know about density from the last Lesson, describe how the fresh water and salt water in an estuary would form layers.

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North Carolina Estuaries

Southwest Florida Estuary

NOAA ESTUARY VIDEOS

Describe 3 important roles of estuaries. Provide a habitat for commercial and recreational fish

Protect coastlinesFilter pollutants from the waterServe as a resting place for migratory birdsProvide a habitat for juvenile fish, seabirds, and shellfish

NOAA VIDEOS

Based on what you know about density from the last Lesson, describe how the fresh water and salt water in an estuary would form layers. Fresh water from the river will lay atop the salt water because fresh water is less dense.

OSMOREGULATION: A BALANCE ACT

Why do you are fingers looks wrinkled after swimming or being in the bath too long?

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Actually they are swelling!! Liquid in your cells has a higher salinity than the fresh water surrounded them.

Osmosis occurs – do you recall? Movement of water from high to low concentration Challenge: Is this hypotonic or hypertonic?

Hypotonic!!!

BECAUSE OF THE PROCESS OF OSMOSIS, MANY BONY FISH IN THE OCEAN LOSE WATER TO THEIR HIGHLY SALINE ENVIRONMENT. IN ORDER TO STAY HYDRATED, THEY DRINK A LOT OF SEAWATER AND SECRETE THE SALTS THROUGH SPECIALIZED CELLS AND EXCRETE CONCENTRATED URINE.

FRESHWATER FISH EXPERIENCE THE OPPOSITE PROBLEM. IF IT WAS NOT FOR OSMOREGULATION, THEIR CELLS WOULD BE CONSTANTLY TAKING ON WATER, LIKE YOUR SKIN CELLS IN THE BATH. INSTEAD, FRESHWATER FISH PRODUCE A LOT OF DILUTE URINE, WHICH GETS RID OF EXCESS WATER IN THEIR SYSTEMS.

LAB 2: INVESTIGATING SURFACE TENSION

COHESION

Recall from Bio I: Water is “stickiness” due to hydrogen bonding.

Leads to surface tension.

COHESION

SURFACE TENSION

ASTRONAUT LEROY CHIAO WATCHES A WATER BUBBLE FLOAT BETWEEN HIM AND THE CAMERA ON THE INTERNATIONAL SPACE STATION. MATERIALS ONBOARD ARE EXPOSED TO MICROGRAVITY, ALLOWING THE PROPERTIES OF WATER TO BE UNDERSTOOD MORE CLEARLY.

Water droplet on a leaf onboard the International Space Station. The spherical nature of water is shown in an environment with virtually no gravity.

Mangrove trees in the U.S. Virgin Islands showing off their roots. Water's property of cohesion allows materials to be distributed through the bodies of living things like plants and animals.

SPONGES, SUCH AS THIS LARGE ONE WITH A ROCK HIND HIDING INSIDE, ARE FILTER FEEDERS. THEY PUMP WATER IN THROUGH THEIR PORES AND REMOVE FOOD PARTICLES.

EVALUATE

List the following types of water in order of increasing salinity:Brackish waterDistilled waterSalt WaterFresh Water

Distilled water

Fresh water

Brackish water

Salt water

EXPLAIN HOW THE CHEMICAL STRUCTURE IS RELATED TO:

A. Cohesion

B. Salinity

Give 2 examples of how marine organisms are affected by the properties of water such as density, ability to exist in all 3 states of matter, ability to dissolve materials, high heat capacity, and cohesion.

THE HUDSON RIVER BORDERS NEW YORK AND NEW JERSEY AND IS AN INTERESTING STUDY IN SALINITY. THE RIVER BEGINS HIGH IN THE MOUNTAINS OF NEW YORK STATE AND RUNS FRESH FOR HUNDREDS OF MILES, EVEN AS FAR SOUTH AS MANHATTAN DURING SPRING RAINSTORMS AND SNOWMELT. SALTY WATER FROM THE ATLANTIC OCEAN PUSHES UPRIVER DUE TO THE TIDES. DURING DROUGHT CONDITIONS WHEN FRESH WATER IS SCARCE, SALT WATER EXTENDS AS FAR NORTH AS POUGHKEEPSIE.