Tuesday, March 15, 2016

A day in the life of a CTD watch - part 3/3

We are almost back to shore!

In about 12 hours, we will return to Fremantle for the final stop of the I08S cruise.

It’s hard to believe that the cruise is almost over. Just 10 days ago, in the midst of our caffeine fueled, non-stop sampling expedition, my time on this ship felt like it would never come to an end. But looking back, two days removed from our last station, those 25 days of sampling are already starting to feel like a distant memory. It’s funny how the mind works.

This cruise has been an overwhelmingly positive experience for me. Never have I learned and accomplished so much in such a short period of time. In hindsight, I am amazed at how quickly we, the CTD watch, went from being complete neophytes at sea to being reasonably competent sea-going oceanographers. Now we can sling together bowline knots and tag-line several tons of oceanographic equipment like it’s nobody’s business. 

OK, that's enough nostalgia for now. The purpose of this blog post is to finish my description of what we do as CTD watch standers. I’ve already talked about how prep, deploy and recover the rosette. Here, I will show you how collect water samples.

Water floweth from the rosette.
When I said our lives revolve around the rosette, I meant that literally. Our rosette has 36 Niskin bottles, numbered 1-36, arranged in a circle. The bottles are sampled sequentially. For a particular station, we may collect as many as 12 different samples on every Niskin bottle. On a full station, we collect samples for CFCs, oxygen, dissolved inorganic carbon (DIC), pH, alkalinity, oxygen and nitrogen isotopes, dissolved organic carbon (DOC), radio-carbons, nutrients, chlorophyll and salinity (check out this cruise blog post for more info about why collect these samples). Since some analyses are sensitive to atmospheric exposure, samples have to collected in a specific order. CFCs and oxygen always go first.  They are followed by DIC, pH, alkalinity and the list goes on. 

Whatcha looking at? Andrew Barna collecting samples to measure oxygen concentration.
At first, the whole process might seem chaotic. There is a lot of shouting, bumping and swaying as people try to fill their sample bottles while the ship is moving at full speed. On the busiest days, the atmosphere inside the sampling room has the same buzz as a Farmer’s market on a Saturday morning.   

Alison being sample cop. Be careful or she might write you a ticket.
However, there is order to this apparent pandemonium. Everyone knows what to do and is aware of the order in which things must happen. As a fail-safe, there is always a “sample-cop” who keeps track of what everyone samples and issues permission to sample a specific bottle. On our shift, Alison usually plays the role of sample cop, but occasionally (usually when relatively few samples are being collected) she would delegate this responsibility to one of the students on the CTD watch.

Natalie filling in as sample cop. When it's not too crazy, Alison lets one of us be sample cop.
Sampling the rosette can take anywhere from 45 minutes to two and half hours, depending on how many people show up and the number of samples they collect. This also depends on how close we are to meal time.

Maverick, Dave and David huddling around the rosette to collect their samples.

John Ballard collecting samples for nutrient analysis. Nutrients people like to work alone.

Joseph Gum treating his samples for oxygen analysis.
By my description, you might think this is mind-numbingly repetitive work. It is, BUT there is rarely a dull moment in the sampling room. The rosette is somewhat of a social hub. Besides, the mess hall, this is the one place on the ship where all the science party congregate regularly. While stand around the rosette, we share stories and tell jokes to let time slip by faster. In our boredom, we even created names and elaborate backstories for some of the Niskin bottles. It’s all in good in fun and it makes what could easily be a miserable chore something that we actually look forward to doing.

Drip, drip, little April shower! Natalie and Sarah having good time while filtering their radiocarbon samples . 

Andrew and David sharing a laugh.

Dave "poisoning" his alkalinity sample.

Charlene, the CFCs queen, doing her last lap around the rosette on this cruise

Me (yellow bib) about to collect my last nitrate sample.
Once all the samples are collected, we dump the excess water and start prepping for the next station, which at that point is often less than an hour away.

Dave emptying the Niskins at the end of sampling session as Natalie starts prepping the rosette for the upcoming launch.
I hope this series of posts gave you a feel for the work we do on a research vessel. After conversing with some of the more senior scientists, I have to appreciate how hectic and taxing this cruise has been. Since our stations are relatively shallow and closely spaced together, the sampling never really stops. As soon as we are done with one station, we are pulling up to the next. I am reassured by my colleagues that not all cruises are like this. Even still, this cruise has whet my appetite for more time at sea.

That's all for now. As this cruise comes to an end, I will also try to wrap up this blog. It has been a great pleasure sharing my experience with all of you.

Till next time,

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