Ocean Water

Introduction

If you were to view the planet Earth from space, you would see that most of its surface is covered by water. Most of this is ocean water that cannot be consumed. Why can’t ocean water be consumed? The reason is that ocean water contains large amounts of salt, which make it undrinkable.

Salinity is a measurement of the saltiness or concentration of salt in water. Ocean water contains many different salts, but the most abundant is sodium chloride, also known as table salt. Sodium chloride makes up 86% of all the ions present in ocean water. Other salts that can be found in ocean water at significant levels are calcium chloride and magnesium chloride.

In this experiment, you will use a Conductivity Probe to measure the conductivity of salt water. You will learn to convert conductivity values in millisiemens per centimeter (mS/cm) to salinity values in parts per thousand (ppt). In Part I, you will model the change in ocean conductivity due to evaporation during sunlight. In Part II, you will model the change in conductivity near the mouth of a freshwater river as it flows into an ocean.

Objectives

In this experiment, you will

• Measure the conductivity of a water sample using a Conductivity Probe.
• Determine the effect of evaporation on the conductivity of ocean water.
• Model the conductivity change when a freshwater river flows into an ocean.
• Calculate salinity changes.