Temporal and spatial microplastic distribution in the deep North Atlantic Ocean (2000 m) in relation to environmental factors and concentrations of persistent organic pollutants (POPs)

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In the proposed project, we have formulated three hypotheses: H1) Regional differences are caused by differences in dominating transport pathways and polymer compositions within the microplastic fluxes. H2) A gradient of microplastic flux rates exist from south to the north with increasing microplastic fluxes in more northern locations because of higher biological production rates and H3) The similar transport mechanisms for POPs and plastics from the atmosphere to the deep ocean are evidenced by a positive correlation of POPs and microplastic abundances in sediment trap samples. We are aiming at evaluating microplastic abundances and its polymer composition in sediment trap samples in terms of seasonal, annual, and regional patterns (H1) using sediment trap samples from different sampling sites L1 (Kiel276), L2, L3, BATS, and NB. This will reveal seasonal and annual patterns as well as in addition to the temporal resolution, provide spatial microplastic distributions within the 2000 m depth of North Atlantic Ocean. Using temporally resolved microplastic abundances combined with available data on currents and particle, lithogenic, and biogenic fluxes, transport pathways and potential sources of microplastics will be assessed. Additionally the comparison of microplastic abundances in sediment trap samples in relation to environmental parameters and natural particle flux and its components (H2) will be carried out. As microplastic is strongly suspected of acting as a vector for toxic substances, transporting high concentrations of POPs across the oceans, the evaluation of microplastic and POP fluxes in the deep Atlantic Ocean offers a valuable opportunity to elucidate this property for the deep sea (H3). Due to the high number of potential POP substances potentially detectable in sinking material were chosen, still present in environmental samples, such as polycyclic aromatic hydrocarbons (PAHs), chlorinated diphenyl’s (PCBs), and Dichlorodiphenyltrichloroethane (DDT).