Sunday, September 25, 2011

Moments of Fun

We’re working hard on the Melville, but we still need to let off steam every once in a while. We don’t get too much time off, so we put what we’ve got to good use.

Tonight we had spa night out on deck. We had back rubs, temporary tattoos and toenail painting. The main event, however, were the mud masks. We used sediment from the multi-corer and made exfoliating masks. Almost the entire science team and some of the crew joined in on the festivities. Even the captain was styling in his mask and sunglasses!

Earlier in the cruise we had water fight. We were off the coast of French Guiana to change some of the science crew. We welcomed the new scientists with buckets, squirt bottles, and sample jars – anything that could hold water (and didn’t have anything toxic in it) became weapons. Some labs were more prepared than others and brought water guns and balloons from home. After about 2 hours the free for all wound down, and everyone returned to prep for the second half of the cruise.

Among the other time off activities are card games – cribbage is very popular, as there’s a tournament currently going on. We’re almost to the final game, which will be Dave the bosun versus Debbie or Brandon, both from the zooplankton team (yours truly was knocked out in the first round).

The other thing we do to waste time is watch the water. If I walk out to the fantail or bow during the sunset (and to a lesser extent sunrises) there’s bound to be people sitting out; watching, taking pictures, chatting, and just relaxing after a long shift.

Monday, September 12, 2011

Instruments 1 or: Everything you Never Wanted to Know About CTDs

We’ve spent about a week onboard, and as I’m settling into shipboard life, I’ll try to post more often.

The most used sampling instruments are the CTD (conductivity, temperature, depth) rosettes. These have two functions – collecting water samples and measuring some basic parameters within the water column. As the instrument is lowered, it constantly records salinity, temperature and depth information, along with data on light and chlorophyll levels, which we use to decide where sample. Usually, we sample at the surface, the deepest point in the cast (anywhere from 200 to 2,500 meters), the chlorophyll max, and some predetermined light levels.

The samples are collected with Niskin bottles. The tops and bottoms remain open through the downcast, where we use the data to decide on the best depth sample. The bottles are individually closed when electronic actuators are tripped, which releases the end caps, sealing the bottle tight. On deck we sample through a spigot into our various sampling bottles. We have two CTDs - one with 24 ten liter bottles, and one with 12 thirty liter bottles.

When we’re sampling we need to follow a specific order. First the researchers studying dissolved gasses get to sample, because as the bottle empties, there’s more air to contaminate the samples. Other chemistry, such as dissolved organic matter comes next, since it’s easy to contaminate the spigots. Then we collect samples that need to be processed quickly, such as chlorophyll a, and organisms that need to stay alive for experiments. Finally, samples that need as much water as possible, aren’t time dependant, or aren’t easily contaminated get whatever remains.

Most scientists onboard use water from the CTDs, and that can lead to some drama when too many people want water from a limited number of CTD casts. Tish Yager, the head scientist, has done a wonderful job making sure everyone who needs water gets it, sometimes adding other CTD casts to keep everything running smoothly. For example, earlier this week, a CTD cast ran out of water before we could sample for biogenic silica or TEP (transparent exopolymer particles), two parameters that the carpenter lab uses. Now we have our own CTD cast every station, which other groups have begun to take advantage of and to get some of the water that remains. As people get into a more consistent work schedule, these problems will be less common.

Sunday, September 4, 2011

Anchors Aweigh!

We’ve made it to the tropics, landing in Barbados A little nuclear waste, and we'll have dozens of pizza devouring superheroesThursday afternoon. After stepping out into the sweltering heat, we took a terrifying cab ride to our hotel. We spent the rest of the afternoon relaxing by the beach, and sleeping off our jet lag. That evening, some of the hotel employees came found us on the beach, and brought us to some newly hatched turtles. The turtles, confused by the hotel lights, were crawling away from the ocean. We helped the employees collect the turtles, to be brought to a more remote beach, and released.

The next two days went by as a blur, unpacking all of our gear, and setting up our lab space (often followed by rearranging many times). Finally, at 16:00 Saturday, we sailed out. After relaxing on the bow, many of us went right back to the labs to finish moving our gear.

After the long days prepping the boat, we’ve finally begun the real work. We came on station about 200 miles south of Barbados at about noon Sunday. The CTD rosette was deployed to 1000 meters (as a test, usually we’ll only sample to 200 m). Our lab took samples for dissolved organic matter, essential for phytoplankton growth; and biogenic silica, which diatoms need for growth. Both samples were brought into the lab to filter, for the BSi we collect the matter that remains on the filter, and for DOM we keep the filtered water. We’ll collect the rest of our samples tomorrow morning, when we send out another CTD cast.