Tales of the riverbank

Naomi Hudson, 30, is doing a PhD in hydrology at Birmingham University

As a scientist I had always been interested in pollution, but I had not seen it as a career. Originally I wanted to work in the oil industry because I thought there was a lot of money in it, but I've gone from being a geologist to a hydrologist and my focus is now on analysing water for pollution.

After doing a BSc in geology, I worked for 18 months on North Sea exploration rigs. But because the oil industry is quite volatile and the amount of work varies considerably, I changed career and joined the graduate training scheme at Severn Trent Water, where I ended up looking at how sewage is treated and the subsequent impact on rivers. I also attended meetings with the Environment Agency and became interested in their point of view. When I saw the PhD advertised, it was a question of right place, right subject, right time.

My PhD is about finding out what sort of organic matter is present in water, for example rivers, and how much of it there is. My research involves using a spectrophotometer, a machine which measures light. River waters contain different organic compounds which can come from natural sources (like plants and aquatic life), and human influenced sources (like discharges from sewage treatment works).

I use the spectrophotometer to shine light through water samples, taken from rivers around Birmingham and Derby, and then look at the different wavelengths of light emitted. The test only takes a minute and requires just four millilitres of water. The machine gives a readout, something like a 3D map, with peaks that relate to specific organic compounds. Rivers tend to have a typical "map" shape, while sewage discharges have a different typical "map". I can then see if there are any peaks associated with discharges from sewage treatment plants, agricultural waste or other pollutants.

The spectrophotometer has been used to look at sea water for the past 20 years, but only more recently to test for pollution in rivers. The technique is important because it's quick and can be used in the field, which means it could replace the standard five-day lab test used by the water industry. It could also be used for rapid response to pollution events, and to test for clean drinking water in a disaster management situation.

Essentially I'm working for myself and managing myself which is lovely compared to working in industry. Nowadays I'm becoming a bit of a water bore. There is a little river which passes through the village where I live and I can't pass it without wondering if I should take a sample.