Welcome to the Rhubarb talks website

The 'Rhubarb Talks' are a series of seminars by PhD students for PhD students at NOCS.

Upcoming seminars are posted below and cover a whole range of scientific exploits. Talks are held every other Monday afternoon at 4.30pm in the postgrad lounge (node 086) and are accompanied by nibbles and refreshments.

For more info or to volunteer for a talk, please contact The Rhubarb Team: Liz (E.Sargent@noc.soton.ac.uk),
Rosanna (R.Greenop@noc.soton.ac.uk), Maike (mjsp106@soton.ac.uk) or Sara (Sara.Cregeen@noc.soton.ac.uk)

Thursday, March 29, 2012

Tuesday 3rd of April Liz Sargent will present: Assessing the direct contribution of TRICHODESMIUM TO export

 Trichodesmium, a colonial marine cyanobacterium, is integrally involved in ocean biogeochemical cycling as it is a significant supplier of fixed nitrogen to the warm surface ocean.  Recent reports have suggested that Trichodesmium is also important in the subsurface layer, and actively fixes nitrogen in the deep chlorophyll maximum (DCM); however, the role Trichodesmium plays in the biogeochemistry of deeper waters has yet to be described.  This study focuses on Trichodesmium’s involvement in the direct export process.  Contrary to previous expectations, results suggest that despite its buoyancy this organism is a constituent of sinking material. Sampling on research cruises in the eastern subtropical and tropical Atlantic, and in the Gulf of Mexico showed Trichodesmium was commonly present below 100 m in three forms: tufted colonies, free filaments, and free filaments included in aggregations with other organisms/faecal matter.  The Marine Snow Catcher (MSC), a 100 L messenger-operated PVC closing water bottle, and in situ Stand Alone Pumping Systems (SAPS) were used to collect sinking particles, which were imaged and preserved for post-cruise assessment.  All sub-DCM MSC collections between 80-250 m in areas where Trichodesmium was a significant counterpart of the surface population included negatively buoyant colonies sinking at 12 - 120 m d-1, as well as free filaments; SAPS collections also revealed the presence of free filaments in low concentrations as deep as 500 m. Further microscopic analysis of these colonies will allow for the elucidation of the mechanism of sinking in Trichodesmium, such as gas vacuole collapse, as well as aiding in describing its involvement in the export flux of POC and PON. 

Monday, March 12, 2012

March 12th 2012 Cathy Cole and Carolyn Graves

Methane Hydrates: A greehouse gas time bomb?

It¹s getting harder and harder to disagree that climate change is really happening. Since the Industrial Revolution, atmospheric concentrations of carbon dioxide have soared as a result of human activities, and current levels are the highest in 650,000 years (IPCC, 2007). But what about other gases in our atmosphere? Methane, for example, is over 60 times more powerful than carbon dioxide as a greenhouse gas. There is far less of it in our atmosphere, just 0.5% compared with CO2, but that has not always been the case. Methane hydrates are a type of mineral made up of methane gas locked into a crystal lattice of frozen water, a bit like ice. Deep sea sediments hold an estimated 3000 Giga tons of carbon in the form of methane hydrates, and these rocks are extremely sensitive to small changes in temperature and pressure. On dissociation, the release of methane can lead to a runaway global warming effect.

March 5th 2012

Climate change science: how does the science work, what are its strengths and limitations?

Michael Henehen


Unfortunately, even as a scientist, it is often difficult to differentiate the chaff from the wheat with regards climate change science. Too often, climate change is viewed from within a political, or religious frame: a dogma that one may choose to identify oneself with, rather than an empirical fact. Even among those who are comfortable that man-made climate change is a reality, there is a worrying lack of understanding about the fundamentals of climate change: how it happens, how we know it is happening, etc. Here I'll be presenting a talk that I gave at the Art House earlier this month that attempts to cut through a lot of this and get down to the basics- how does climate change happen, has it happened before, and what has happened since we've started burning fossil fuels.
I'll then go through and discuss some of the most common arguments thrown out by contrarians.