Ocean Chemistry Goal: Describe salinity and factors that are affected by changes in salinity levels. Agenda: 1. Wrap up ‘Ocean Profile’ lab 2. Warm-up for Chemistry 3. Salinity Reading 4. Demo./Notes

Warm-up How is salt added to the ocean?

The Water Cycle Life could not exist without the water cycle The water cycle continuously moves water between the atmosphere, the land, and the oceans.

The Water Cycle Water vapor condenses and falls to the Earth’s surface as precipitation Some of this water percolates into the soil to become ground water Some runs across the surface into lakes, rivers, and the ocean The water is heated by the sun and reenters the atmosphere by evaporation

Precipitation Evaporation Condensation Evaporation Percolation

Characteristics of Ocean Water Ocean water is salty! The salt is called Sodium chloride Why???

Salinity The amount of dissolved solids in a given amount of liquid is called salinity Measured in ppt (parts per thousand) For example: 1000 grams of ocean water can be evaporated and leave 35 grams of solids behind

How did the oceans get salty? Water flows from land into the oceans and brings minerals as it flows over rocks and slowly wears them down At the same time, water is evaporating and leaving the minerals behind

Stop and Think Describe three factors that influence salinity and their relationships.

Factors Affecting Salinity: Climate Coastal waters in places with hotter, drier climates typically have higher salinity. Why? Higher rate of EVAPORATION Removes water but leaves salt behind Coastal waters in cooler, more humid places typically have a lower salinity Lower rate of evaporation Evaporation = Salinity

Factors Affecting Salinity: River runoff Coastal waters near an emptying river tend to have lower salinity Why? The freshwater dilutes the saltwater Coastal waters not near an emptying river tend to have higher salinity Fresh water = Salinity

Factors Affecting Salinity: Movement Some parts of the ocean move less than other parts Bays, gulfs, seas, open ocean where there’s no current Slower moving areas of water develop higher salinity Less circulation (no currents running through them) so salt settles here Faster moving areas of water develop lower salinity Movement = Salinity

Warm-up Exchange paragraphs with a partner and discuss the answers.

Temperature Zones The temperature of ocean water decreases as depth increases This change is NOT gradual Water in the ocean can be divided into three layers by temperature Water at the surface is much warmer than the average water temperature

Ocean Temperature Zones Surface Zone Thermocline Deep Zone Warm, mixed by waves— aka “mixed zone” Sunlight, plant growth Temp depends on latitude Temperature drops rapidly with depth Uniformly cold 1-3 degrees C Polar creep—ocean current

Warm-up How do thermocline graphs differ depending on latitude and seasons? Describe different latitudes and seasons.