The MIO hosted this year the SNO SOMLIT intercomparison week

More than 30 people from 12 marine stations participated in this event organized by members of the SOMLIT station in Marseille (N. Garcia, G. Grégori, M. Lafont, V. Lagadec, S. Nunige, P. Raimbault) from October 18 to 20, 2022 in the OCEANOMED building. The intercomparison consists of a series of exercises carried out annually for all hydrological variables measured by the SNO SOMLIT requiring a sampling step (all parameters of the hydrological and pico-nanoplankton series except temperature and salinity).

The objective of the intercomparisons is multiple:

To measure the repeatability (inter-station) and reproducibility (between stations) of the measurements made
To refine the common protocols on the basis of the results, if necessary
Allow field operators and analysts from different SOMLIT teams to meet in a friendly atmosphere and thus federate the teams
Participate in staff training

The intercomparisons take place as follows: field operators and analysts from SOMLIT teams meet in one of the network's marine stations for three days. The day after the installation of the equipment, large volumes of water are taken and stored in drums (For Marseille in 2022: 1000 liters!). The water is transferred to a 350-liter stainless steel sampling tank equipped with 15 Niskin-type taps.  The water is taken simultaneously by a member of each team directly from the tank using the bottle usually used in each station. The usual protocol is then performed on each sample. Dissolved parameters related to gases (Oxygen, pH) are taken first followed by nutrients. For particulate parameters, the tank is filled again. Homogenization is ensured by two blades located at different levels in the tank. The samples are then taken simultaneously and processed according to the usual protocol, parameter by parameter. Five replicates are performed for each parameter and per team. Sampling and sample processing (addition of reagents, filtration, etc.) for all the parameters of the intercomparison are carried out during the day. The analyses are performed in the following days or weeks, back in the laboratories. The next day is devoted to workshops generally dedicated to a specific work on a particular protocol.

The results are statistically processed in order to identify satisfactory, questionable and doubtful results and the possible causes of non-conformity of the results. At the end of each intercomparison, a summary document is produced which summarizes all the information and results obtained as well as the corrective and/or preventive actions taken if necessary. A synthesis of all the intercomparisons is also made. It shows a continuous improvement of results since the implementation of the SOMLIT network quality process.