Cruise Report, RV ATAIR, Cruise 0671013-1, Bremerhaven —- Skagen - Aberdeen, 19 Jul — 11 Aug 2022 | 23 
Artificial radionuclides can be detected in the North Sea and the Baltic Sea from the following 
sources: 
global fallout from atmospheric nuclear weapons tests in the 1950s and 1960s 
discharges from the reprocessing plants in Sellafield and La Hague 
Fallout from the Chernobyl nuclear reactor accident in 1986 
discharges from nuclear facilities such as nuclear power plants and research reactors 
The task of the /ntegrated Monitoring and Information System for Monitoring Radioactivity in 
the Environment (IMIS) is to continuously monitor the environment in order to be able to quickly 
and reliably detect even minor changes in radioactivity in the environment and to record long- 
term trends. In a radiological emergency, the IMIS is used as a tool to fulfil the tasks of the 
German Federal Radiological Situation Centre (RLZ). 
To fulfil these tasks, sampling during cruise 067/013-1 was carried out at selected stations 
distributed across the entire North Sea and adjacent regions (Figure 5.7). One station (GN808, 
Skagerrak) was used to collect data from four distinct depth levels of the water column using 
large-volume samplers (LVS), which had a capacity of either 270 or 333 litres. The 333-litre 
LVS was tested for the first time during the cruise. Station GN808 was visited twice, with the 
LVS being used on both occasions to obtain the required amount of water, as closing the LVS 
oroperly at the first station visit was only partially successful. All other samples were taken from 
the sea surface and prepared on board for storage. Subsequent analysis was conducted at 
the BSH’s “M32 — Marine Radioactivity” section. 
Samples for determining the activity contration of the following radionuclides were taken during 
the cruise: cesium-137 (*”Cs), strontium-90 (®Sr) and tritium (°H). 
On-board sampling to determine the activity concentration of '°7Cs followed the 
Procedures’ Manual as outlined by Hintze et al. (2022). Seawater was collected and 
passed through an ion exchanger. The ion exchanger was then transferred into a 
sontainer. This container also served as a measurement source. Once on land, any 
remaining water was pipetted off so that the measurement source could be placed on 
a suitable detector. 
On-board sampling to determine the activity concentration of *Sr was carried out 
according to the Procedures’ Manual as outlined by Hintze et al. (2023). The 
seawater was acidified and filled into 35-litre barreis. Further processing on board 
Nas not possible. 
On-board sampling to determine the activity concentration of °H was conducted 
according to the Procedures’ Manual as outlined by Becker et al. (2023). The 
seawater was filled into one-litre glass bottles. Initial processing on board was not 
oossible due to limited laboratory capacity. 
The underlying Procedures’ Manuals should be understood in the same way as DIN standards: 
they are reviewed by a panel of experts and checked editorially and scientifically. They are re- 
axamined every five years. even If no changes have been made to the procedure. to allow for