Cruise report from R/V Argos week 11, 1997

Type: Report
Author: Lars Andersson, Bengt Yhlen


Skagerrak: The surface temperatures varied between 3.3 and 4.8 oC and surface salinites from 24 psu in the Baltic water to 33.5 in the remaining area. The spring bloom was almost over, except along the Jutland coast where nitrogen rich water from the North Sea was found. Kattegat and the Sound: The pycnocline was located at between 6 and 15 metres depth. The extremely early springbloom was over and the nutrients concentrations had returned to normal values. The Baltic Proper: The surface temperature was about 3 oC in the south and decreased to 1.5 oC in the north. In the southern part the pycnocline was located at a depth of 25 metres in the Arkona- and 45 metres in the Bornholm Basin, and in the central and northern parts between 60 to 90 metres. All nutrients, except phosphate, showed normal winter concentrations. Phosphate, on the other hand, showed very low concentrations, especially in the Arkona Basin where the spring bloom had started. Oxygen conditions in the bottom water are displayed in a figure. At Christiansö, where 6.85 ml/l oxygen was found in the bottom water at the end of February, the concentration had now decreased to 6.10 ml/l. This is still extremely high. Hydrogen sulphide was only found in the Gotland Deep below 175 meters depth.