WE have passed 60 degrees latitude South and have taken more than half of our 20 Drake Survey samples.

The sample stations are selected by Chief Scientist, Colm Sweeney. They are near to the locations he tested in his 2006 Drake Survey.

At each station, the Captain stops the ship so that the Electronic Technician (ET) can lower the Conductivity Temperature Depth (CTD) profiler to do a hydro-cast.

The ET lowers the CTD approximately 4,000 meters at 50 meters per minute. Sensors on the CTD provide a profile of various ocean parameters and a computer onboard the ship generates a graph showing the seawater temperature, salinity and oxygen level.

Using this data, Sweeney selects the sample depths. As the ET brings the CTD back up to the surface, he fires Niskin bottles at the selected depths. Each fired bottle collects 10 liters of seawater. A single cast takes about four hours.

Once the CTD is back onboard ship, there is lots of action. As a Lab Technician, my primary role is to take seawater samples from the Niskin bottles. It's cold and wet work. Over my thermal layers, I put on Wellington boots, fisherman's overalls and gloves.

Depending how many samples have been taken, what time of day it is and how many people are sampling, it can take up to two hours. I work the night shift, 12 am to 12 pm. The ET's usually bring the CTD in around midnight, 6 am and noon. This coincides with meal times - we eat fast.

A "bottle cop" keeps track of all the samples, bottles and scientists to make sure everything is labelled correctly. He assigns me a set of bottles. The size and shape of the bottle differs depending on what will be analyzed from the sample: Carbon Dioxide, Oxygen, salinity or nutrients.

If I am assigned a bottle which will be tested for CO2, I open the Niskin bottle and attach a tube to feed seawater into my glass bottle. This helps to prevent air bubbles. I rinse three times, then fill the bottle with seawater, letting it overflow for one final rinse. I was shocked to discover how much precious seawater drawn from the depths of the ocean gets thrown right back in!

I then fill the bottle with seawater and add a drop of Mercuric Chloride Solution (poison). We call this "pickle juice." It kills all living matter, so no gaseous exchange can occur once we have taken the samples.

After a flurry of activity, sampling is finished. We deliver some specimens to the wet lab to be analyzed onboard the ship and others to a freezer to be analyzed later in the United States.

At full speed, crossing the Drake Passage takes three or four days. Stopping 20 times as we sail South, we hope to make the crossing in less than ten days.