The CTD Up Close

As a follow up to Katie’s fantastic post about the process of water sampling using a CTD, we wanted to share a video of what deploying and retrieving the CTD actually looks like.

And to bring you up close and personal, the photos below show the type of bottle that each seawater sample is collected in. Oxygen is the first to be sampled, because it is a dissolved gas and is sensitive to air entering the Niskin bottles as seawater is taken out of the bottom by each sampler. The person sampling oxygen therefore sets the pace for the rest of the scientists sampling water around the rosette. Each sample is shown below in the order we sample in:

Taking a water sample from the CTD to measure oxygen concentration. Photo credit: Emma Hodgson

2) pH and carbonate ion concentration

3) DIC concentration

4) Total alkalinity

5) Nutrient concentrations

6) Last comes the salinity water sample, because salinity is very stable.

7) Chlorophyll concentration (only comes from the Niskin that sampled the surface)

8) Domoic acid concentration (a toxin from harmful algal blooms)

Letting the water out after all samples are taken

 

The video was created by: Melissa Ward, and the bottle photos were taken by: Emma Hodgson. Both contributed to creating the post.