Why is the Ocean Water Salty?

Overview

• Oceans cover 70% of Earth's surface and account for 97% of all water.
• Ocean water is approximately 3.5% salt, equating to 220 million tons per cubic mile.

Sources of Ocean Salt

1. Runoff from Land

   • Rainwater absorbs carbon dioxide from the atmosphere, becoming slightly acidic.
   • This acidic rainwater erodes rocks, picking up salts and minerals.
   • As water flows to the ocean, organisms extract some minerals, but salt remains, making the ocean salty.

2. Openings in the Sea Floor

   • Saltwater seeps through cracks in the sea floor.
   • Heated by magma, causing chemical reactions that:
     • Remove oxygen, magnesium, and sulfates.
     • Add metals like iron, zinc, and copper.
   • Heated water exits with additional metals, contributing to ocean's salinity.

Why Aren’t Lakes and Rivers Salty?

• Lakes and rivers have some salt but are continuously flowing.
• Flow prevents salt accumulation, carrying salts to the ocean.

Importance of Ocean Salinity

• Salty water supports marine life and plays a crucial role in Earth's ecosystem.
• Need to protect oceans from pollution to preserve aquatic life.

Interesting Facts

• Two most common minerals in seawater: Chloride and Sodium.
• Together, they make up 85% of all dissolved minerals in the ocean.

Conclusion

• Understanding ocean salinity helps in appreciating the balance of marine ecosystems and the importance of environmental conservation.