HELCOM common monitoring relevant to radioactivity in the marine environment is documented on a general level in the HELCOM Monitoring Manual under the sub-programme: Contaminants in biota and sub-programme: Contaminants in water.
Monitoring methodology including methods, frequency and stations is described in detail in MORS Guidelines (HELCOM Recommendation 26/3).
Over ten laboratories from the nine countries bordering Baltic Sea have contributed to the monitoring programmes of the Baltic Sea by analyzing radionuclides in marine samples. The various analytical methods used in the different laboratories are summarized in the HELCOM thematic assessment: Radioactivity in the Baltic Sea, 1999–2006 (HELCOM 2009).
The monitoring activities relevant to the indicator that are currently carried out by HELCOM Contracting Parties are described in the HELCOM Monitoring Manual in the relevant Monitoring Concept Tables.
Sub-programme: Contaminants in biota
Monitoring Concept Table
Sub-programme: Contaminants in water
Stations are described in detail in the MORS Guidelines (HELCOM Recommendation 26/3) and in the HELCOM MORE map service.
The current annual sampling of biota and seawater is considered to be of adequate frequency for the core indicator. The monitoring of biota in each sub-basin depends on the availability of certain species during the time of monitoring cruises and cannot be secured at all times.
Optimal monitoring figure 1. Monitoring stations for biota (left) and seawater (right) used to assess trends in radioactive Cs-137. Dark blue symbols indicate data series incorporated into the specific assessment period 2011-2016 and pale blue symbols indicate those stations also within the overall assessment period presented. HELCOM scale 2 assessment units are used for this indicator.
Gaps in monitoring in relation to the HELCOM assessment units are defined in HELCOM Monitoring and Assessment Strategy Annex 4: 137Cs in seawater is sampled in all HELCOM sub-basins except for the Quark and the Åland Sea.
Currently, the coverage of 137Cs in herring extends to most of the HELCOM sub-basins. There are, however, no samples from the Northern Baltic Proper, Gulf of Riga, The Sound, or the Great Belt. Also, the northern part of Eastern Gotland Basin is not covered by annual samplings.
137Cs in flatfish is sampled only in the most relevant southern Baltic Sea sub-basins.