Obiettivo In this project, we will focus on factors controlling the sinking marine particles and biogeochemical processes between particle/solution interface in an open continental shelf region (Baltic Sea). The Thorium isotopes are used as particles tracers in the water column in order to parameterize the marine processes and the vertical fluxes of sinking material. However, the quantity and the quality of the matter flux estimated from shallow sediment traps have been questioned based on some artifacts (hydrodynamicbiases, preservation of matter, presence of swimmers). In this project, we will focus on the using of 234Th to calibrate sediment traps and factors controlling the POC/234Th ratio which is used to obtain a vertical Particulate Organic Carbon (POC) export . ThePOC/234Th ratio evolution depends on the nature and the size of marine particles. To improve the understanding of this process, we need to study the complex Th interactions with marine organic matter and then the plankton communities. In this project, we will examine a new technique used to obtain the truly settling particles( SPLITT) in order to develop a scavenging Th model which include colloidal matter. Therefore, incubations experiment containing plankton species and Th isotopes will allow to improve the current234Th-based POC sinking estimates. The training content is based on experimental data, which depend on the future cruises in 2003 in the Baltic Sea. After the collection of samples, we need to extract and purify Th isotopes which will be analyzed with a mass spectrometer (TIMS ) and a multicollector-ICP. These methods are routinely used in the host institution. In parallel, we will use the new SPLITT technique to measure Th isotopes on colloidal matter and the new method to measure 234Thactivities on small samples with beta counter and developed in the host institution. One of the final objectives of this project is to obtain a model describing mechanisms of POC/234Th variations in order to apply the234Th method (to estimate a POC export) in shelf regions. Then, an improvement on the Th scavenging model with a large spectrum of marine particles (included colloids and gravitoids) will allow to have a good comprehension of marine processes ('vertical fluxes of sinking material). Campo scientifico natural sciencesphysical sciencescondensed matter physicssoft matter physics Programma(i) FP5-EESD - Programme for research, technological development and demonstration on "Energy, environment and sustainable development, 1998-2002" Argomento(i) 1.1.4.-3. - Key action Sustainable Marine Ecosystems Invito a presentare proposte Data not available Meccanismo di finanziamento RGI - Research grants (individual fellowships) Coordinatore SWEDISH MUSEUM OF NATURAL HISTORY Contributo UE Nessun dato Indirizzo Frescativaegen 40 104 05 STOCKHOLM Svezia Mostra sulla mappa Costo totale Nessun dato
