Why Is Ocean Water Salty? | Earth's Ocean | Dr Binocs Show | Peekaboo Kidz

Summary

In this episode, Dr. Binox explains why ocean water is salty, focusing on two main sources: runoff from the land and hydrothermal fluids from the seafloor. Rainwater, slightly acidic, erodes rocks and carries dissolved minerals into the ocean, where salt remains while other minerals are filtered out by organisms. Additionally, underwater volcanic activity releases heated water carrying metals like iron and copper, further increasing salinity. Unlike lakes and rivers, which lack the same salt accumulation, the ocean's salt plays a crucial role in sustaining marine life, highlighting the importance of preserving ocean ecosystems.

Takeaways

• 😀 Oceans cover 70% of Earth's surface and account for 97% of all water on Earth.
• 😀 Around 3.5% of ocean water is salt, which equals 220 million tons of salt per cubic mile of sea water.
• 😀 Ocean water salt comes from two main sources: runoff from land and openings in the seafloor.
• 😀 Rainwater collects carbon dioxide, becomes slightly acidic, and picks up minerals like salt from rocks on the land.
• 😀 Freshwater becomes salty when it flows into the ocean and some minerals are removed by organisms, but salt stays.
• 😀 Hydrothermal fluids from the seafloor contribute to ocean salinity by releasing metals like iron, zinc, and copper into the water.
• 😀 When ocean water seeps into cracks in the seafloor and is heated by magma, it undergoes chemical reactions, increasing its salt content.
• 😀 Lakes and rivers don't get salty like oceans because their water is continually flowing, preventing salt accumulation.
• 😀 Aquatic life depends on salty ocean water, making it essential for Earth's ecosystems.
• 😀 The two most common minerals in seawater are chloride and sodium, which together make up 85% of all dissolved minerals in the ocean.
• 😀 We must keep our oceans clean and free from pollution to ensure the health of marine life and the Earth’s ecosystem.

Q & A

Why is ocean water salty?

Ocean water is salty due to two main factors: runoff from the land and hydrothermal fluids from the sea floor. Runoff carries dissolved minerals like salt into the ocean, while hydrothermal fluids release additional salts from the sea floor.

How much of the Earth's surface is covered by oceans?

Oceans cover approximately 70% of Earth's surface.

What percentage of Earth's water is contained in oceans?

About 97% of all Earth's water is contained in the oceans.

What is the salt concentration in ocean water?

Ocean water contains about 3.5% salt, which may seem low but equates to around 220 million tons of salt per cubic mile of seawater.

Where does the salt in the ocean primarily come from?

Salt in the ocean comes mainly from two sources: runoff from the land, which picks up minerals and salt from eroded rocks, and hydrothermal fluids from the sea floor, where heated water releases minerals like salt.

Why is rainwater slightly acidic before it reaches the surface?

Rainwater collects carbon dioxide from the atmosphere as it falls, which causes it to become slightly acidic before it hits the Earth's surface.

How do organisms in the ocean affect salt levels in seawater?

When rainwater flows into the ocean, organisms extract minerals like calcium from it. Salt, however, tends to remain in the water, contributing to its salinity.

Why aren’t lakes and rivers salty like the oceans?

Lakes and rivers have some salt, but because they are constantly flowing, the salt doesn't accumulate as it does in the ocean. The salt is carried away and eventually reaches the ocean.

What role do hydrothermal fluids play in ocean salinity?

Hydrothermal fluids from vents in the sea floor are heated by magma from Earth's core. This heat causes chemical reactions that increase the salt and mineral content in the water, making the ocean saltier.

What are the two most common minerals in seawater?

The two most common minerals in seawater are chloride and sodium, which together make up around 85% of all dissolved minerals in the ocean.