Overview
The scientific study of plastic pollution is still relatively novel. It encompasses multiple disciplines depending on the type of information sought and there is disagreement among researchers about, for example, methods for quantifying plastic in the environment. There are questions about movement through the environment, toxicology (to humans and organisms throughout the food chain), facilitation of pathogen spread, degradation mechanisms, outcomes and timelines of breakdown, or affects on nutrient cycling, to name a few.
Goals
The baseline goal of monitoring and quantifying plastic pollution is still far from consensus, though there is fairly strong agreement on the type of steps performed. For example, samples can be collected from the water column, sediment, or different types of organisms (such as deep sea limpets). There are different types of instruments that can be used to this end, from a simple bucket scoop to a plankton net. Once the sample is collected, it undergoes processing in the lab.
Laboratory
The steps generally include a density separation, organic material digestion, staining with a fluorescent dye, and finally quantification of (micro)plastic. The purpose of the density separation is to divide the plastic from the rest of the sample—usually, a dense solution (for example, highly concentrated salt) is mixed with the sample so that the less dense plastic floats to the top layer, which is subsequently removed. Another step is the organic matter digestion, which removes material that could be potentially mistaken for plastic in the quantification step after the sample has been dyed. The final step is to mix the sample with a dye that fluoresces under blue light, which enables quantification of microplastic particles.
Future
This is one example of a workflow from sample collection to microplastic quantification. It is one of many possible solutions that have been proposed, and each step is performed slightly differently depending on the type of researcher, materials used, and the goal of the research.