What color are icebergs (冰山)? White or blue? Surprisingly, there are green icebergs in Antarctica (南极). Their unusual color has confused scientists for years. But scientists have finally solved the mystery of the green icebergs.
Icebergs are large pieces of ice in the sea. Icebergs form after breaking away from glaciers (冰川).
Most icebergs are white. There are also many icebergs in Antarctica that are blue. Glacial ice has a lot of small air bubbles (气泡). The icebergs appear to be blue because the air bubbles reflect blue light.
However, there are no air bubbles in green icebergs, which means these icebergs are made out of sea ice rather than glacial ice.
But why does sea ice look green? Scientists at the University of Washington, US, recently found the reason— iron oxide (氧化铁). It comes from rock dust found on the Antarctic mainland. After studying the green icebergs, scientists found that they have 500 times more iron than glacial ice. The iron comes from bedrock in the ocean. When glaciers grind (碾磨) against bedrock, a powder (粉末) that is rich in iron is created. The powder later mixes with ocean water, which then freezes as green sea ice, Stephen Warren from the university suggested.
This is an important finding because these green icebergs can deliver iron to far parts of the ocean. There, tiny sea plants use the iron as a nutrient (营养物). We thought green icebergs were interesting. But now they may actually be important.
