A study by Woods Hole scientists has found that microplastics have been accumulating in the sediments of Waquoit Bay salt marshes at increasing rates since as far back as 1950, when plastics came into widespread use. Javier Lloret, a researcher at the Marine Biological Laboratory and the lead author of the study, described salt marshes as âdepositional environmentsâ that âgrow verticallyâ as cordgrasses and other plant life die off, forming layers of peat sediment. âIf you go deeper into those sediments, you are going back in time; you need to imagine this like the rings in a tree trunk,â Dr. Lloret said. âIn the last 25 years only, the number of microplastic particles that we find in the sediments has doubled.â