Microplastics in ocean sediments increased exponentially from 1945 to 2009, serving as a geological proxy for the Anthropocene.

Microplastics (< 5 mm) have long been a concern in marine debris research, but quantifying the smallest microplastics (< 333 μm) has been hampered by appropriate collection methods, like net tows. We modified standard epifluorescence microscopy methods to develop a new technique to enumerate < 333 μm microplastics (mini‐microplastics) from filtered surface seawater samples and salp stomach contents. This permitted us to distinguish mini‐microplastics from phytoplankton and suspended particles. We found seawater mini‐microplastic concentrations that were 5–7 orders of magnitude higher than published concentrations of > 333 μm microplastics. Mini‐microplastics were the most abundant in nearshore waters and more evenly distributed from the California Current through the North Pacific Subtropical Gyre. Every salp examined had ingested mini‐microplastics, regardless of species, life history stage, or oceanic region. Salps ingested significantly smaller plastic particles than were available in ambient surface seawater. The blastozooid stage of salps had higher ingestion rates than oozooids.

A novel approach to sampling microplastics: Applied Ocean Sciences is creating a sensor that is faster, more efficient, and less expensive than current sampling methods and will be the first sensor to allow near real-time abundance measurements for microplastics in a water sample. Microplastics are turning up everywhere we look for them. Microplastics (plastic particles < 5mm) have been found in various parts of the environment, including the oceans, the atmosphere, soil, and sea ice. They’re also making their way into our food and water, appearing in seafood, fruits, vegetables, beer, soda, tea, sea salt, honey, and both tap and bottled water. Alarmingly, microplastics are also being found within the human body – detected in our blood, lungs, and stool – and even in the placenta and breastmilk, revealing that exposure begins at the earliest stages of development. While research on the effects of microplastics on human health is still relatively preliminary, the harmful impacts of chemicals associated with plastics are well-documented.