Monday, 9 July 2012

Day 3 - Coring at Goban Spur

I'm studying possible effects of oil pollution in the deep-sea on ecosystem function. I will do this using sediment cores collected from the 1000 metre deep seafloor on the coastal shelf at Goban Spur.  I will add hydrocarbons from a mixture of crude oil and seawater, and measure respiration rate of the living organisms in the mud. I'm running this experiment for my PhD.

We will be arriving at Goban Spur Saturday morning and the first task will be to deploy a CTD to collect water samples. CTD's measure Conductivity (salinity), Temperature, and Depth.

CTD footage taken on an earlier expedition
I will be taking these samples from as near to the sediment-water interface as possible. This is so that I can make up a water accommodated fraction of crude oil and bottom seawater – by mixing the two together slowly for about 24 hours. I will add this in serial dilutions to replicate cores and also run a set of control cores to which I will only add clean bottom seawater.

Charlie checks the megacorer

I will then seal the core tubes to make them into experimental microcosms, keeping them at ambient bottom water temperature in an incubation chamber. I will measure the declining oxygen concentration in the microcosms over about 48 hours and at the end of this slice and preserve mud from the top 10cm for later analyses of the bacteria and fauna present.

I will also collect a set of ‘background’ cores at Goban Spur. These cores will not be used in the experiment but will instead be sliced and preserved immediately. Later I will compare bacteria and fauna present in these cores with the experiment cores.

Today’s blog is brought to you by Charlie Main, a PhD student at NOC.