MantaRay: the first in-situ sampler to quantify and identify microplastics
WHAT WILL THE SENSOR DO?
The MantaRay Microplastic Sampler seeks to automate the manual process of dragging a neuston net behind a boat, sieving through the sample, separating microplastic particles, taking size measurements of each particle, determining the chemical composition of each particle, and back-calculating the concentration of microplastics in a given area. The sampler will automate this entire process and deliver information back to the user in real time via a coastal cell phone communication link. This way, the sampler can be deployed for a month out at sea, collecting data every day and reporting it back without the need to send people into the field.
HOW DOES IT WORK?
The MantaRay uses a pump to circulate water through the instrument. As water enters the sampler, an optical sensor analyzes the water for different particles. Based on the optical fingerprint of each particle (e.g. plankton, suspended sediment, organic debris, polyethylene, polypropylene, polystyrene, etc.), MantaRay will make an informed decision about whether to filter out the particle or let it pass through the instrument and back out into the water column. If a plastic particle is detected by the optical sensor, a laser based sizing module takes a rough measurement on the particle size, and a series of valves divert the particle onto a 70μm filter where it can be saved for later analysis. MantaRay will save the particle type, particle size, and particle concentration (calculated from total water pumped through the sampler by the number of particles detected) in a log file that will be offloaded to an onshore server at the end of each day. MantaRay holds 30 discrete 70μm filters that are changed for each sample, so time series data at a single location or spatial data over large areas can be calculated using the sampler.
HOW WILL THE DATA BE USED?
The data gathered from MantaRay will give us a better idea of the concentration of microplastic particles in different areas of the ocean. Cities can use this data to determine how rainfall and urban runoff contribute to plastic pollution in rivers and harbors. States can monitor specific points along a watershed to try to determine the point source of plastic pollution before it reaches the ocean. Scientists can use MantaRay to survey the water column to determine how the density of different plastics change over time, and how much plastic is raining down into the deep ocean. Data gathered over large spatial scales can help us build "heat maps" (see right) of surface plastic pollution and infer point sources. Additional data gathered within the top several meters of the ocean can help us to understand the role that wind plays in mixing plastics in the surface layer. This data can be used to decrease the error rate in computer models that simulate plastic transport over large areas. Plastic pieces that are recovered by the sensor can be analyzed for persistent organic pollutants (POPs) or to study the bacterial life thriving on the surface of the pieces. The concentration of microplastics in a given area can be correlated to things like overall ecosystem health to show how marine plastics are affecting the environment. All of this data can provide the evidence necessary to create change at the regulatory level and help make the case for a reduction in our plastic use going forward.