When you think of microplastic pollution, plastic debris less than five millimeters in size, you likely envision the ocean—probably because ocean gyres gained notoriety for being a microplastic soup.But what about our lakes, rivers, forests and fields? They can be just as contaminated with microplastic debris as the oceans.Until recently, these environments were described as conduits—ways for plastics to get to the oceans. But now we're seeing rivers, lakes and soil in a different light, as reservoirs for plastic particles.We now know that agricultural land, surface waters, freshwater lakes and river sediments are also contaminated.In the past five years, researchers have started to study the sources, fates and effects of microplastics in freshwater and terrestrial ecosystems, but only a handful of studies have been done so far.Microplastics in Our Great LakesHere in North America, when we think of freshwater, we often think of the Laurentian Great Lakes. They hold more than one fifth of the world's freshwater, are the basis of billions of dollars in economic activity and are a point of pride for those living on their shorelines.For the Indigenous peoples of Canada, the Great Lakes hold even more importance. There are more than 75 First Nations communities in the Great Lakes watershed, all of whom fish the waters for food or sport.It is no secret, however, that the Great Lakes have had their share of ecological problems. Most have been caused by us, including the ongoing issues of nutrient-loading, invasive species like zebra and quagga mussels, tributary dams and reduced ice cover.Recent research now shows the Great Lakes also contain microplastic pollution, with the highest concentrations in heavily urbanized areas, like Toronto and Detroit.