Seeing the light: DIY spectrometry for safe water in disaster zones

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spectrometryFinding safe drinking water is often one of the biggest concerns in the immediate aftermath of a disaster. Pipelines might have broken, rivers are disrupted and vital infrastructure is destroyed. Sewerage may leak into the water supply, spreading diseases. Usually clean water sources can become polluted by chemicals, including fuel, pesticides and other highly toxic substances.

It is not always immediately obvious if water is contaminated. Trace amounts of chemicals may be invisible to the naked eye, but still be more than enough to make a person sick.

The Public Laboratory for Open Technology and Science (PLOTS) is a US non-profit organisation focused on ‘civic science’, including training local people in how to use scientific methods to improve their communities. Since the DeepWater Horizon spill of 2010, PLOTS has been working on developing do-it-yourself spectrometry kits to help people test whether water or other substances (such as sand) are contaminated.

Even light that appears white is composed of a spectrum of colours. Not all of these colours are visible to the human eye, for example infrared and ultraviolet. When hit with ultraviolet light, different kinds of oils and chemical compositions fluoresce, giving off different colour signatures that can then be analysed. In the context of a natural or man-made disaster, knowing which chemicals are present in what quantities in a water source could save lives.

 

Accessible and Affordable

 

spectrometry2The Public Laboratory set out to create a range of inexpensive, easy to use spectrometers for use by communities. A spectrometer is a device which breaks down and analyses the strength of the different colours in light. Commercial spectrometers can cost tens of thousands of dollars. PLOTS’s most simple spectrometer is essentially constructed from a cardboard tube and a DVD, and you can buy it for $10 or make one yourself from the instructions on their website.

Everyone who has seen a DVD has probably observed the way white light turns into colours on the reflective side. When light is channelled in the right way through the cardboard tube, the grooves of the DVD act as a ‘diffraction grating’, breaking down light into its component colours. The home-made spectrometer can be placed over the camera on a smartphone or laptop, and the results can be analysed online with the Spectral Workbench platform.

There are some limitations to the current Public Lab DIY spectrometer kit in disaster settings. An obvious one is that it needs access to the internet, to a smartphone or laptop and therefore also to a power source for charging, none of which are necessarily guaranteed in a disaster zone. It can also be a bit fiddly to use correctly, for example through using too much light which leads to overexposure, just like with a traditional camera. Instead of just resulting in a bad photo, however, overexposure or incorrect use will lead to distorted results which could have significant consequences if the sample being analysed is drinking water.

Even whilst acknowledging the limitations, however, the ongoing development of the DIY spectrometry kit by the PLOTS community represents an exciting step forward towards protecting the health and well-being of communities in disaster zones. For more information, check out their page here or watch the video below.

 

 

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Elise Thomas

Elise Thomas

Elise Thomas is a Masters candidate in International Affairs at the Graduate Institute of International and Development Studies.

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