Mass spectrometry – based imaging techniques for iodine-127 and iodine-129 detection and localization in the brown alga Laminaria digitata

129 I is one of the main radioisotopes iodine derived from nuclear fuel cycle that can be found sustainably in environment due to its long half-life. In coastal marine environment, brown macroalgae, such laminariales (or kelps), are known naturally feature highest rates accumulation, and an important source biogenic volatile iodinated compounds released atmosphere. These seaweeds therefore likely significantly marked by but also potential vectors radioactive iodine. order better understand chemical isotopic speciation algal tissues, we combined mass spectrometry-based imaging approaches natural samples Laminaria digitata young sporophytes, collected at two different locations along south coast English Channel (Roscoff Goury). Laser desorption ionization (LDI) electrospray-ionization techniques (DESI), coupled with spectrometry, confirmed predominance inorganic ? species on surface fresh algae, a peripheral localization when applied micro-sections. Moreover, isotope was not detected plantlet or stipe sections near Roscoff L. Goury, La Hague, where controlled liquid discharges ORANO Hague reprocessing plant occur. At subcellular scale, cryo-fixed micro-sections blade both sites were further analyzed secondary ion spectrometry (nano-SIMS), leading similar results. Even if signal for much weaker than 127 revealed some differences extracellular distribution between stable isotopes. Altogether LDI nano-SIMS complementary powerful detection isotopes samples, understanding uptake mechanisms environment. • LDI- DESI MS detect surfaces. Radioactive algae Channel. showed tissue digitata. Nano-SIMS suggested distributions seawater crucial transfer seaweeds.