MantaRay: A novel autonomous sampling instrument for in situ measurements of environmental microplastic particle concentrations

Presented here is the initial hardware and software design of a prototype autonomous microplastic sampling instrument. Microplastics are defined as particles of plastic <; 5 mm greatest dimension. They are becoming pervasive in the world ocean due to anthropogenic pollution. The ocean has spatially variable concentrations of surface microplastics, so attempting to identify trends in global dispersal patterns is difficult and expensive using current research techniques. Understanding the global dispersion patterns and degradation rates of microplastics will help to uncover the associated human and ecosystem impacts. A novel low-cost oceanographic sensor has been developed that can determine the concentration of marine microplastics over large spatial areas. This sensor can remove plastic particulates from seawater and archive them for later analysis, determine microplastic concentrations for 28 discrete samples recording GPS position, and simultaneously measure salinity and water temperature. This sensor has been designed around the open-source Arduino platform, allowing for maximum implementation of additional sensors and systems in future prototypes. The MantaRay sensor can be implemented on a drifter, mooring, or Autonomous Underwater Vehicle to gather diverse data on the dispersion of microplastics. This sensor could drastically cut research costs associated with studying deep-sea microplastic concentrations and increase our understanding of plastic dispersion and degradation rates in marine ecosystems.