Why do leaves change colour in the fall?
October 7th, 2009
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Golden path.
Ever wander what makes the trees change colour? As if they were magically transformed by Bob Ross?
Leaves process water and carbon dioxide with the help of phontosynthesis. These nutrients are processed into glucose (building block for growth and energy in plants) with the help of chlorophyll. Chlorophyll is what gives leaves their green colour.
As seasons change, the days get shorter and sunlight more rare. Because there are not enough nutrients for the trees in the form of water or sunlight during the colder seasons, they start “shutting down” for the winter by slowing down production of chlorophyll. As chlorophyll fades away, yellow and orange colors (xanthophyl, carotene) start showing.
In trees like maple, glucose is trapped after photosynthesis stops. Glucose in the leaves turns red with colder autumn nights and sunlight. And brown leaves are stained with trapped waste.
Pretty cool.
Photo by Ian Muttoo
Sinking deltas threaten millions of lives
September 21st, 2009
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deltas are sinking, increasing the flood risk faced by hundreds of millions of people, scientists report.
Damming and diverting rivers means that much less sediment now reaches many delta areas, while extraction of gas and groundwater also lowers the land.
Rivers affected include the Colorado, Nile, Pearl, Rhone and Yangtze.
About half a billion people live in these regions, the researchers note in the journal Nature Geoscience.
They calculate that 85% of major deltas have seen severe flooding in recent years, and that the area of land vulnerable to flooding will increase by about 50% in the next 40 years as land sinks and climate change causes sea levels to rise.
Lena river delta (NASA)
Most of the world’s major river deltas are sinking, increasing the flood risk faced by hundreds of millions of people, scientists report.
Damming and diverting rivers means that much less sediment now reaches many delta areas, while extraction of gas and groundwater also lowers the land.
Rivers affected include the Colorado, Nile, Pearl, Rhone and Yangtze.
About half a billion people live in these regions, the researchers note in the journal Nature Geoscience.
They calculate that 85% of major deltas have seen severe flooding in recent years, and that the area of land vulnerable to flooding will increase by about 50% in the next 40 years as land sinks and climate change causes sea levels to rise.
Image of a single molecule captured for the first time
August 28th, 2009
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Image of a single molecule
The detailed chemical structure of a single molecule has been imaged for the first time, say researchers.
The physical shape of single carbon nanotubes has been outlined before, using similar techniques – but the new method even shows up chemical bonds.
