Southwestern Atlantic Research Cruise


  The southwestern Atlantic Ocean is recognized as one of the primary CO2 sinks of the world ocean and one of the most biologically productive areas. However, little information is available about the water-column distributions of 231Pa and 230Th in this region. Therefore, under the framework of GEOTRACES program, we participated in cruise JC057 to collect seawater sample for 231Pa and 230Th measurement. The cruise set sail from Punta Arenas, Chile to Las Palmas, Spain during March, 2011 (Principal Investigator Micha J.A. Rijkenberg ). The investigated area ranges from 0.2oS to 49.5oS and 28oW to 52.7oW along the Atlantic GEOTRACES GA02 section. This section is ideally suited for 231Pa and 230Th study in that:

1)      the section captures all the major water masses ( North Atlantic Deep Water, Antarctica Intermediate Water, Antarctica Bottom Water) along the meridional water path, which gives us a chance to study how the distributions of 231Pa and 230Th are affected by deep ocean circulation;

2)      the section covers areas with a productivity gradient, which makes it possible for us to look at the distribution pattern of 231Pa and 230Th under the influence of particle flux and composition;

3)      the section features high dust input from Africa and river input from South America, which provides us more information on processes that might also affect 231Pa and 230Th in the ocean.


Fig. 1.  Transect of JC057 cruise along Atlantic GEOTRACES GA02 section. Red dots indicate stations where full water-column samples were collected. Blue dots indicate stations where surface samples were collected.

  During the cruise, seawater samples were collected from Stainless Steel CTD rosette under strict sampling protocols to avoid any potential contamination. We managed to collect 130 full water-column seawater samples and 6 surface seawater samples from 18 stations sampled. Once collected, seawater samples were acidified with HCl on board. And they were then sealed with a screw top and Parafilm, packed in two zip-lock bags and stored in the container at room temperature until arrival at home laboratory for further analysis.


Fig. 2. Seawater sample collection on board during JC057 cruise





People involved

Feifei Deng

Royal Netherlands Institute for Sea Research (NIOZ)





GEOTRACES International Data Assembly Center