64PE376 - Diary 2

Late submission for September 4 blog post

That my blog entry for yesterday is being posted today is telling of the activity aboard the R/V Pelagia. Much has happened in the past 48 hours since our arrival at our study site, a methane seep site in the North Sea near the gas production platform B13.

The scientific party on this expedition is an enthused group of biologists, chemists, geologists, physicists with lines of expertise crossing in complex and wondrous ways. To this point, we have characterized the location of the methane seepage at the seafloor, measured the distribution of methane and bubbles within the water column, captured evidence of methane release to the atmosphere, and we are beginning to appreciate how the physical environment is altered by and alters the expulsion of fluids and gases. We are also collecting samples to investigate how the ecology of the sediments and water column are influenced by the constant infusion of methane, a source of carbon and energy for the biota. It has been a thrilling and inviting experience; an opportunity for which I am profoundly grateful. Despite the insight we have gained, I already sense a tinge of remorse that the time left to explore and study this remarkable natural laboratory is dwindling.

My role in this program is to provide real-time and continuous measurements of methane and carbon dioxide concentrations in surface water and atmosphere. We use a laser based commercially-available technology known as cavity ring-down spectrometry (CRDS) integrated with peripheral devices developed by scientists at the US Geological Survey, University of Rochester and Texas A&M University. That I am here with such a powerful and robust tool is testament to relentless support provided by countless individuals at these institutions and others.

The image above is a photograph of the component of the analytical system that monitors surface water methane and carbon dioxide. This device in union with a system for monitoring air intakes from four elevations about the vessel allow us to calculate greenhouse gas fluxes in ways unimaginable prior to the implementation of this technology.
The photograph on the left is an example of where air and meteorological data are collected on the bow mast. The air and data are transmitted through a series of cables and tubing strangling the Pelagia and her inhabitants. Despite my greatest efforts to maintain a low-profile and a small footprint (no small task for a bloody American!), my concoction of data transmitting devices, tubes, pumps, hoses and cables are seemingly everywhere. We have literally used thousands of cable ties to hold it all in place. Our fearless (and patient) Chief Scientist Corina Brussaard is hardly able to keep an eye on her team, including Jens Greinert, for whom Janine Nauw patiently waits to have her go at the Niskin bottle (below). 

Already with our system, we have been able to detect persistently elevated concentrations of methane in the surface water and atmosphere in the vicinity of the seep with concentrations dropping sharply just a short distance from the site. In one case, we observed a pulse of surface water methane greater than 1000 nanomolar (nM)! To put that in context, it is the highest surface water concentration from the ocean that I know of and it is about 500 times greater than a typical ocean setting. But in general, we are seeing concentrations within the surface plume in the 100 nM range, which is low and disappointing to many of my colleagues now spoiled by our early observation of 1000 nM, but comparable to settings where methane fluxes to the atmosphere may be globally relevant. In short, we are working at a site, where we able to test hypotheses germane marine systems imminently susceptible to climate change triggered positive feedbacks; especially those at high latitude where access is complicated by logistical and geopolitical factors.

I end this blog with an anecdote that summarizes my perspective and appreciation of working with this fine team of technicians, scientists and crew. (It also provides an excuse for my delayed blog post.) Last night the centrifuge being used by acting pore water chemists Petra Bombach and Daniene Kool failed. Rather than throwing in the towel and missing the opportunity to describe the pore fluid response to methane seepage, they consulted with Jens to contrive a pore fluid vacuum extraction system composed of a spare pump for the CRDS, syringe needles used by gas chromatograph analyst Piet van Gaever, serum bottles used for storing microbiological samples and various fitting provided by me. This modest, but effective and elegant assembly allowed them to rescue the pore water program. Nice work guys!

Well, time is waning and there is much to do…gotta run!