Pedro André de Jesus Mendes

• In this work the dynamics of organo-mineral aggregates in submarine canyons were investigated, as were their role in the transport of organic matter and pollutants from the productive continental shelf to the deep sea floor, and the effect of this transport on the biological degradation of organic matter. Also addressed were the methodological problems present in the investigation of particle dynamics in the benthic boundary layer. The work focuses on two large canyons of the Iberian Margin, with very distinct morphologies and hydrodynamic regimes. Although several studies have focused on the geology, hydrodynamics and sediment dynamics in submarine canyons, this work is one of the first to address the role of the two-layer nature of the sediment surface in the transport and fate of particulates in submarine canyons. This study brings forth new information on the role of organo-mineral aggregates as important components of the transport and preservation of organic matter in submarine canyons. It also identifies organo-mineral aggregates as preferential vector for transport of persistent organic pollutants. Additionally, this work shows the significant effect of physical variables on the resuspension of organo-mineral aggregates, and the bias that they bring to the current methodologies for its estimation.