RamaCam - In situ holographic imaging and chemical spectroscopy for long term scalable analysis of marine particles in deep-sea environments

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While modern day ocean sensors are capable of measuring the concentration of chemicals dissolved in seawater to such high sensitivities that we rarely need to sample them, many chemicals form tiny particles in seawater, often with diameters smaller than the width of a human hair, and these act as a blind spot for most of today's sensors. The only way to study these particles in detail, is to recover samples and analyse them in a laboratory. Marine particles include plankton, dead skin shed from whales and fish, faecal pellets as well as micro-plastics and other types of human litter. If you took a bottle of seawater from the surface of the ocean and compared it to seawater from the deep-sea, the number of large particles would be much higher in the surface water, because light from the sun provides energy that can be used by plankton, which form a large proportion of the particles where sunlight can reach within 200 m of the ocean surface. At the same time, we also know that most particles sink, and so it is important for us to understand why there are so few particles in the deep-sea, how much material is sinking to the seafloor, what it is made out of, how fast it sinks, and what proportion of it makes it back up to the sea surface or gets washed on-shore. The reason this is important, is that particles that sink to the seafloor are thought to play an important role in removing carbon from our atmosphere. At the same time, scientists are worried that litter and plastics may accumulate on the seafloor and damage the fragile seafloor ecosystems that exist at an average depth of more than 3800 m below the ocean's surface. The aim of this project, is to demonstrate new ways in which we can improve our ability to study the distribution of different types of particles in the deep-sea. The sensor that will be developed will analyse large volumes of seawater, almost 2/3 of a drinks can a second, in order to gather data in the deep-sea where the relative number of particles is small. The sensor will count the number of particles that pass through it, study their appearance and also perform laser based chemical analysis to identify what these particles are made out of. An important aspect of this work is to achieve this in a compact, low power way. The last point is important to allow large numbers of this new type of sensor to be used to study vast regions of the ocean for several years at a time. This innovative work will be carried out by researchers based in the UK and in Japan, both island nations with a long history of marine research, who will combine their expertise to overcome the difficult challenges that are involved in achieving our goal. By helping researchers in the future achieve a better understanding how particles in the ocean behave, and this can in turn help our governments decide what kinds of policies need to be put in place to preserve our ocean and our atmosphere.