MICROPLASTICS & FRESHWATER: WHAT YOU NEED TO KNOW (PLUS RESOURCES)

The situation

When we think of plastic pollution, most of us imagine the ocean with images of sun-bleached or barnacle-covered laundry baskets, fishing debris, or other detritus. We may recall that one photo of the albatross that was going around, with its belly full of plastic. Or, we see what looks like a blue soup: clear ocean water with small, floating bits swirling about, the occasional plastic bag wafting into view.

We imagine marine examples because those are what has captured the public eye with myriad documentaries, photos, videos, and research projects taking place at sea or along our coastlines.

Microplastics in the freshwater environment are still considered to be a contaminant of “emerging concern” that is to say, we still don’t know much about them!

Plus, microplastics in freshwater are a lot harder to see with the naked eye…maybe that’s why they’re called microplastics! 😉

Why is it important to understand microplastics in freshwater?

Because we don’t know much about this issue, we also can’t assess the risk they pose to both aquatic life and human health. But risks they do pose! Microplastics – whether they are primary or secondary – are composed of plastic, made from petroleum with a whole slew of additives (phthalates, bisphenol-A, among others). They (and plastic pollution generally) also have the ability to soak up toxins from their surroundings, in addition to being physically damaging (even in organisms as small as phytoplankton). This toxin-soaking can have a “bioaccumulation” effect where toxins are accumulated as they advance up trophic levels (for example zooplankton ingests microplastics, which are then ingested by a small fish, then a larger fish, and then finally a fish we humans might consume).

In order to manage any risk, we have to know something about the issue and that requires two things: data and regular monitoring. As Kennedy Bucci and Chelsea Rochman suggest in their recent paper, ‘Microplastics: a multidimensional contaminant requires a multidimensional framework for assessing risk:

…microplastic pollution exists as a complex and dynamic mixture of particles, that varies over temporal and spatial scales.

Bucci and Rochman, 2022

They advocate for a multi-disciplinary approach to assessing microplastic risks and instead of simplifying the process, to actually incorporate all of what makes microplastics complex – it is in that complexity that connections can be made.

Resources

There is much to learn about microplastics in freshwater and the research just keeps on coming. Besides the two papers we’ve cited above, here are a few more that informed our own understanding, to help get you started learning more.

• Blair, 2017 – “Micro- and Nanoplastic Pollution of Freshwater and Wastewater Treatment Systems”
• Vermaire et al 2017 – ‘Microplastic abundance and distribution in the open water and sediment of the Ottawa River, Canada, and its tributaries’
• Claudia Campanale, et al 2020 – ‘A Practical Overview of Methodologies for Sampling and Analysis of Microplastics in Riverine Environments’
• Cox et al 2021 – ‘Distribution, abundance and spatial variability of microplastic pollution on the surface of Lake Superior’