Biosciences Seminar Speaker - 30 January 2014

Biosciences Seminar Series - Lent 2014
30 January 2014 - 1pm - Zoology Museum (Wallace 129)

Myth and Mystery of Mid-water Methane

Prof. Kam Tang

(Swansea University, UK)

Source: http://news.bbc.co.uk/1/hi/8437703.stm

Given the current concerns about Global Warming, you might well have heard about greenhouse gases and the greenhouse effect. Basically, there are certain gases in the atmosphere, such as CO2 or water vapour, which absorb and emit radiation in the thermal infrared range, thereby causing the retention of a large amount of solar radiation, which otherwise would be reflected back into the space. This is called the greenhouse effect and a large part of Earth would be frozen without this process.

Source: www.columbia.edu

Since the Industrial Revolution, however, the atmospheric concentration of the greenhouse gases has risen drammatically, with obvious consequences for the current Global Warming. For example, one of the most potent greenhouse gases is methane (CH4) and the current concentration in the atmosphere is 2.5 times higher than in pre-industrial times: 

Source: www.eea.europa.eu     

There are various sources that contribute to the produciton and release of methane into the atmosphere, including methane gas released by dairy cows (e.g. see here) Crucially, we lack a good understanding of the global methane cycle, especially in the aquatic environment.

Our seminar speaker of this week, Prof. Kam Tang, dedicates his research to fill this gap. He is interested in understanding the mechanisms of microbial and planktonic processes, which form the basis of acquatic ecosystems, and their consequences for geochemical processes. Kam previously was based in the US and very recently joined us at the Department of Biosciences at Swansea University. Hence we are delighted to open our Lent seminar series with the first talk by Kam! And to give you more detail, here is the abstract of his talk:

Abstract

Methane is a potent greenhouse gas that is naturally produced by microorganisms. The prevalent view is that microbial methane production can happen only under anoxic condition. Paradoxically, methane oversaturation has been observed in well-oxygenated lake and ocean water columns around the world. 

In this seminar I will present some of the work we did in German lakes that addresses this ‘Methane Paradox’. Using a combination of field sampling, incubation experiments, and modeling, we show that the recurring mid-water methane peak in Lake Stechlin, northeast Germany, was not dependent on methane input from the littoral zone or bottom sediment or on the presence of known micro-anoxic zones. 

Source: http://s3.sci.hr/2013/BioMAR/biomar.html

The methane peak repeatedly overlapped with oxygen oversaturation in the seasonal thermocline. Incubation experiments and isotope analysis indicated active methane production, which was likely linked to photosynthesis and/or nitrogen fixation, whereas photoinhibition of methane oxidation allowed accumulation of methane in the oxygen-rich upper layer. 

Mid-water methane oversaturation was also observed in nine other lakes that collectively showed a strongly negative gradient of methane concentration within 0–20% dissolved oxygen (DO) in the bottom water, and a positive gradient within ≥ 20% DO in the upper water column. Further investigation into the responsible organisms and biochemical pathways will help improve our understanding of the global methane cycle. 

Looking forward to welcome you to our new Lent term seminar series - everyone is welcome!