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Chemical secrets of feathers

By Pat, 15 March 2013 News

X-ray fluorescent images of feathers.

Feathers showing the distributions of bromine and zinc.
Image: ANSTO

Birds are an important part of many ecosystems. New Australian research shows that bird feathers could be used to measure just how healthy some ecosystems are.

Bird feathers constantly grow, fall out and are replaced. Birds absorb chemicals, including pollutants, from their environment through the food they eat. Some of these chemicals find their way into the feathers.

It was already possible to measure a number of chemicals present in feathers, however this involved crushing the feather and turning it into ash. This destructive process meant the total amount of a chemical in a feather could be measured, but not where it was located. A chemical might be evenly distributed throughout a feather, or concentrated in a smaller area.

In a recent study, synchrotron X-rays were focused in a narrow beam onto a tiny spot of the feather. In this technique, some of X-rays are absorbed, and X-rays of different energies are emitted. Different chemical elements emit X-rays of different energies. The more atoms of an element there are, the more X-rays of that energy will be emitted. This makes it possible to both detect and measure which elements are present on a particular spot of a feather. By doing this for every spot on the feather, it is possible to map the distribution of elements in a feather.

The researchers found that the element zinc was concentrated in bands in the feather, like tree rings. These bands are thought to develop as a bird grows, showing chemicals circulating in the bird’s body at the time of feather growth. The researchers concluded that this method could be used to monitor bird health by measuring the distribution of harmful chemicals in feathers.

As birds play such a significant role in their environment, the X-ray mapping of feathers could also be used to monitor the health of the birds’ environments.

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