Activity 3

Salt Water and Fresh Water

LEARNING OBJECTIVES

LO1.2

Use scientific reasoning to ask questions, make observations, and investigate ideas to acquire knowledge and solve problems.

LO2.1

Analyze interactions between two Earth systems at a time.

LO2.2

Understand how the water cycle connects the hydrosphere to the other spheres.

LO4

Understand that science ideas can be used to protect humans, Earth’s resources, and its environment.

Introduction

Water is one of the most abundant resources on Earth, making up over 70 percent of Earth’s surface. Although it is plentiful, it is not always accessible or useful to humans. Much of Earth’s water is salt water found in the oceans. Salt water cannot be used for drinking or cooking without undergoing a process called desalination, the removal of salt.

Fresh water is water that does not contain salt. The most abundant source of fresh water is glacial ice, but this source is inaccessible. Accessible fresh water actually makes up a very small percentage of water on Earth. Instead, we get usable fresh water from rivers, lakes, streams, and groundwater. Groundwater is water that seeps underground after precipitation occurs. It travels through porous space and collects in the water table, a layer of Earth that is permanently saturated with water.