Lesson 3: More about water

Thinking – 97% of earth’s water is salty……… Where does the salt in the ocean come from? __________________________________________________ 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) ________________________________________________________________ ________________________________________________________________ How might salt affect marine organisms? ______________________________________________________________

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 solubility This is called polarity Many salts in the ocean easily dissolve in water Salts typically contain a metal and nonmetal Creates 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 salinity Water 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 Tap 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 Hydrothermal vent at seafloor

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: North Carolina Estuaries Southwest Florida Estuary Based on the videos: Describe 3 important roles of estuaries. ____________________________________________________________________ ____________________________________________________________________ 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. ____________________________________________________________________ ____________________________________________________________________

NOAA estuary Videos Describe 3 important roles of estuaries. Provide a habitat for commercial and recreational fish Protect coastlines Filter pollutants from the water Serve as a resting place for migratory birds Provide 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? _______________________________________________________________ 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 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 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 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 water Distilled water Salt Water Fresh 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.