A new study by Japanese scientists suggests that during the Archean eon, Earth’s oceans may have appeared green, not blue.
Key Findings of Study:
- Reasons for greening of ocean in earlier times
- During the Archaean eon (4.0 billion to 2.5 billion years ago), there was no oxygen in atmosphere or oceans.
- Iron from rocks and underwater volcanoes dissolved into oceans.
- The first life forms, anaerobic bacteria, began performing photosynthesis, which produced oxygen as a byproduct.
- This oxygen reacted with the iron in the seawater, forming oxidised iron (Fe(III)), which caused the oceans to appear green
- During the Archaean eon (4.0 billion to 2.5 billion years ago), there was no oxygen in atmosphere or oceans.
- Evolution of Cyanobacteria:
- These were photosynthetic bacteria (not true algae) that evolved in iron-rich, green oceans.
- They used two pigments: chlorophyll (for normal sunlight) and phycoerythrobilin (PEB) (better for green light).
- This helped them survive in varying light and ocean conditions.
- These bacterias flooded Earth’s atmosphere with oxygen and also paved the way for complex life.
Other Possible Colors of the ocean
- Purple Oceans: High sulfur content from intense volcanic activity and low oxygen levels could lead to the rise of purple sulfur bacteria, turning oceans a deep violet.
- Red Oceans: Intense weathering of rocks in tropical climates or blooms of red algae (associated with "red tides") could stain oceans red.
- Today, such algae blooms are linked to nutrient runoff near coasts.
Why does the ocean appear Deep blue?
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