Horizontal and vertical oceanic distribution, transport, and impact of microplastics
Less than approximately 10% of the plastic entering the ocean can currently be accounted for, likely due to fragmentation into small microplastics (MP) unquantifiedby modern techniques or export from the surface ocean. It is not known how much plastic debris actually floats at the ocean surface, what mechanisms control plastic transport and fate from land to the deep sea, and what ecological impact this may have. The HOTMIC project seeks to address these knowledge gaps by focusing on a model land-ocean linkage between western Europe and the North Atlantic ocean gyre. The objective of HOTMIC is to map the distribution of MP, including particles < 10μm and microfibers,in water, sediment, and biota from coastal ocean to open ocean gyre to deep sea. This project will quantify processes controlling lateral and vertical transport of MP, including biofouling, (bio)aggregation, and deposition, for incorporation into global ocean models. To understand MP fate in the ocean, HOTMIC will examine microplastic weathering signatures during ocean transport, and evaluate the predominant mechanisms that create the weathering signature, including biological effects of bioshredding and ingestion. These objectives will besupported by a diverse suite of analytical techniques. In order to achieve comprehensive detection of MP particles < 10 μm and microfibers, HOTMIC will develop and optimize novel analytical methods based on a combination of non-destructive (Raman & FT-IR spectrometry, microscopy), and destructive techniques (hydrolytic depolymerization, HPLC, Py-GC/MS, EGA/MS). In addition, HOTMIC will develop Raman spectroscopy techniques for automated detection of MP incl. particles < 10μm and microfibers to greatly increase sample throughput, and 2D and 3D imaging of MP in biota. HOTMIC will use field and experimental measurements to
understandtransport and fate of small MP and microfibers, and to evaluate the risks of these contaminants for marine environments and organisms