Natural isotopic tracers are powerful tools allowing to constrain deep ocean circulations and marine particle fluxes in the present and past ocean. The use of a model describing both the physical transport and the chemical reactions (in particular with particulate matter). Their study is the main aim of the GEOTRACES international program (www.geotraces.org). The use of a model describing both the physical transport and the chemical reactions (in particular interactions with particles) experience by tracers will allow to optimize the interpretation of the tracer data collected during the GEOTRACES program. The aim of this thesis is to develop a realistic representation of the stock and flux of the small marine particles that transport these tracers within the framework of the of the physical transport-biogeochemistry coupled model NEMO-PISCES. These developments will benefit to the study of isotopic tracers but also to the other applications of the NEMO-PISCES model such as the impact of climate change on the ocean.