Unit 4 Lesson 3 Water on Earth S8.D.1.3.1-4

Water Cycle When water evaporates from a plant Why clouds float?

The Sun powers the Water cycle Water cycle for kids

Watershed An area of land that drains rain or snow into a particular body of water An area of land that water flows over to reach a river is the river’s watershed

Chesapeake Bay Watershed We live in both the Susquehanna River and Chesapeake Bay watersheds About 150 different rivers and streams flow into Chesapeake Bay In the bay, fresh water from rivers mixes with saltwater from oceans

Pollution in Watersheds Pollution anywhere in a watershed can lead to pollution in a body of water Runoff can wash soil, fertilizers, litter, toxic chemicals, and other pollutants into creeks rivers  bay ocean Farmers often add nutrients to soil to help crops grow Nutrients can make their way to a body of water and cause an overgrowth of algae (Algal Bloom) Algae depletes the water of oxygen that other organisms need to live

Freshwater Bodies Lentic Systems Lotic Systems Water is still or almost still Lake, wetlands Lotic Systems Creeks, streams, and rivers Water is moving from high elevation to lower elevation Flow rate or current rate at which water flows Organisms have adaptations to prevent them from being swept downstream

Changes to Lentic Systems Changes in flow rate, temperature ,and water quality can affect a river’s/stream’s Biodiversity (variety of organisms that can live there) Heavy rainfall can increase flow rate Power plants use river water for cooling Litter and pollutants can move into a stream from the watershed Bill Nye- Rivers and Streams

Wetlands Marshes, swamps, bogs Link Marshes, swamps, bogs An area of land that is underwater for all or part of the year Form when water washes over land from rivers, creeks, streams, and lakes How they Help? Filter pollutants, excess nutrients, and sediments out of the water that moves through them Improve quality of water that flows to other bodies of water downstream

Saltwater Bodies Oceans cover 70% of Earth Estuary- the wide part of a river where it nears the sea; fresh and salt water mix Bay- body of water that connects to an ocean

Saltwater vs Freshwater Why are oceans salty? Salinity Is the dissolved salt content (NaCl) in water Measured in ppm (parts per million) Oceans have a salinity of 35,000 ppm (35 ppt) Freshwater has a salinity of about 500 ppm Why are some lakes salty? Wiki seawater

Saltwater vs Freshwater Density Saltwater is denser than freshwater density of saltwater is 1.025g/ml Conductivity Pure water will not conduct electricity Freshwater is a poor conductor of electricity (has few dissolved ions) Saltwater is a good conductor of electricity When salt dissolves in water Na(+) ions and Cl(-) ions form Saltwater

Saltwater vs Freshwater Freezing and Boiling point Salt lowers the freezing point and higher the boiling point For every 29.2g of salt per liter of water (kg), the freezing point lowers by 3.3 F Freshwater freezes at 32 F……..Seawater freezes at ~28 F For every 29.2g of salt per liter of water (kg), the boiling point raises 0.9 F Freshwater boils at 212 F……..Seawater boils at ~213F The above numbers assume seawater’s salinity is 35 ppt. The salinity of seawater is not constant everywhere