26 March 2004
Friday, 26 March 2004
Getting into the swing of things
Close to midnight last night the injection of iron and tracer gases was completed. Overnight mapping confirmed the creation of a patch. Measured iron concentrations in the patch were, as expected, up to 3 nM. This morning brought the beginning of our routine sampling schedule with two CTDs. The gas cast, which is always a circus, led the two casts this morning. On each of these CTD casts, we collect water for our respective experiments. Some of the gas people are looking at tracer gases injected into the patch, while others are looking at naturally occurring gases, such as nitrous oxide, carbon monoxide (CO) or dissolved oxygen.
Today in the relatively calm conditions, the RHIB (rigid hull inflatable boat) was deployed for the first time. Craig Stevens and Brian Ward had an opportunity to test the various near surface profilers i.e. SkinDeEP, SCAMP, and TRAMP.
During this experiment, with the assistance of Cliff Law (from NIWA), I will be examining the production of one of the dissolved gases, carbon monoxide, as it is produced by the action of sunlight. CDOM or Coloured Dissolved Organic Matter, is naturally occurring carbon dissolved in the water. When it absorbs sunlight in the water column it breaks down and one of its products is carbon monoxide. Carbon monoxide produced in the water column eventually leaks out into the atmosphere where it is plays an important role in atmospheric chemistry.
My goal on this voyage to measure the efficiency of the carbon monoxide production, otherwise known as the Apparent Quantum Yield (AQY) for CO. This measurement has been made in a few other locations in the world’s oceans and today it is unclear if this value changes from location to location. I would like to get a better estimate of CO AQY in this region of the world’s oceans.
Lori Ziolkowski (Dalhousie University)