Oceans and streams contribute to global warming

Chalk streams may impact on global warming

10 December 2007

Dr Mark Trimmer, from Queen Mary’s School of Biological and Chemical Sciences discussed how English chalk streams and ocean microbes could be contributing to global warming, at a Science Media Centre press briefing this week.

Greenhouse gas from English streams

Dr Trimmer looked at a plant that covers up to three quarters of the surface of some chalk streams and found that it helps methane generated in the sediment beneath the plants to escape into the atmosphere. “We found similar emissions to some UK peat bogs” said Dr Trimmer. “This changes our perception of the health of the ecosystem and it indicates another disadvantage of agriculture.”

Over 90 per cent of the methane emissions from the river Frome in Dorset that reach the atmosphere do so via the stems of water crowfoot. The plant also causes a build-up of sediment from neighbouring farmland, which aids the production of methane by bacteria in the stream.

“Chalk streams are a British specialty habitat and a priority under the UK’s Biodiversity Action Plan. They have a high status but there is growing concern about their ecological decline.”

Dr Trimmer estimates that the total area of chalk streams in the UK is around 20 km2. The situation he observed in Dorset is likely to be widespread. More research is needed to understand methane emissions from chalk streams fully. “There is obvious climatic concern for any unquantified potential source of methane.”

Nitrous oxide from ocean microbes

Dr Trimmer also found that a large amount of the greenhouse gas nitrous oxide is produced by bacteria in the oxygen poor parts of the ocean using nitrites.

Dr Trimmer looked at nitrous oxide production in the Arabian Sea, which accounts for up to 18 per cent of global ocean emissions. He found that the gas is primarily produced by bacteria trying to make nitrogen gas.

“A third of the ‘denitrification’ that happens in the world’s oceans occurs in the Arabian Sea (an area equivalent to France and Germany combined)” said Dr Trimmer. “Oxygen levels decrease as you go deeper into the sea. At around 130 metres there is what we call an oxygen minimum zone where oxygen is low or non-existent. Bacteria that produce nitrous oxide do well at this depth.”

Gas produced at this depth could escape to the atmosphere. Nitrous oxide is a powerful greenhouse gas some 300 times more so than carbon dioxide, it also attacks the ozone layer and causes acid rain.

“Recent reports suggest increased export of organic material from the surface layers of the ocean under increased atmospheric carbon dioxide levels. This could cause an expansion of the oxygen minimum zones of the world triggering ever greater emissions of nitrous oxide.”

Ends

Dr Trimmer spoke at a press briefing held at the Science Media Centre, London on Monday 10 December 2007 at 10.30am. For press enquiries please contact Lucy Goodchild at SGM on +44 (0) 118 988 1843 or mobile telephone +44 (0) 7824 88 30 10

For further information contact Dr Mark Trimmer, Queen Mary, University of London, tel: +44 (0) 20 7882 3007, email: m.trimmer@qmul.ac.uk

For further information, please contact:

Siân Halkyard
Acting Head of Communications
Queen Mary, University of London
Tel: +44 (0) 20 7882 7454
email: s.halkyard@qmul.ac.uk

Notes to Editors:

The Society for General Microbiology
The Society for General Microbiology is the largest microbiology society in Europe, and has over 5,500 members worldwide. The Society provides a common meeting ground for scientists working in research and in fields with applications in microbiology including medicine, veterinary medicine, pharmaceuticals, industry, agriculture, food, the environment and education.

The SGM represents the science and profession of microbiology to government, the media and the general public; supporting microbiology education at all levels; and encouraging careers in microbiology.

Queen Mary, University of London

Queen Mary, University of London is one of the UK's leading research-focused higher education institutions with some 15,000 undergraduate and postgraduate students.

Amongst the largest of the colleges of the University of London, Queen Mary’s 3,000 staff deliver world class degree programmes and research across 21 academic departments and institutes, within three sectors: Science and Engineering; Humanities, Social Sciences and Laws; and the School of Medicine and Dentistry.

Queen Mary is ranked 11th in the UK according to the Guardian analysis of the 2008 Research Assessment Exercise, and has been described as ‘the biggest star among the research-intensive institutions’ by the Times Higher Education.

The College has a strong international reputation, with around 20 per cent of students coming from over 100 countries.

Queen Mary has an annual turnover of £220 million, research income worth £61 million, and generates employment and output worth £600 million to the UK economy each year.

Queen Mary, as a member of the 1994 Group of research-focused universities, has made a strategic commitment to the highest quality of research, but also to the best possible educational, cultural and social experience for its students. The College is unique amongst London's universities in being able to offer a completely integrated residential campus, with a 2,000-bed award-winning Student Village on its Mile End campus.

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